def __init__(self, e0, emission_field, sigma=None, prng=None):
self.e0 = parse_value(e0, "keV")
if isinstance(sigma, (float, YTQuantity)) or (isinstance(
sigma, tuple) and isinstance(sigma[0], float)):
# The broadening is constant
try:
self.sigma = parse_value(sigma, "keV")
except YTUnitConversionError:
try:
self.sigma = parse_value(sigma, "km/s")
self.sigma *= self.e0 / clight
self.sigma.convert_to_units("keV")
except YTUnitConversionError:
raise RuntimeError(
"Units for sigma must either be in dimensions of "
"energy or velocity! sigma = %s" % sigma)
else:
# Either no broadening or a field name
self.sigma = sigma
self.emission_field = emission_field
if prng is None:
self.prng = np.random
else:
self.prng = prng
self.spectral_norm = None
self.redshift = None
def make_point_sources(area, exp_time, positions, sky_center,
spectra, prng=None):
r"""
Create a new :class:`~pyxsim.event_list.EventList` which contains
point sources.
Parameters
----------
area : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The collecting area to determine the number of events. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The exposure time to determine the number of events. If units are
not specified, it is assumed to be in seconds.
positions : array of source positions, shape 2xN
The positions of the point sources in RA, Dec, where N is the
number of point sources. Coordinates should be in degrees.
sky_center : array-like
Center RA, Dec of the events in degrees.
spectra : list (size N) of :class:`~soxs.spectra.Spectrum` objects
The spectra for the point sources, where N is the number
of point sources. Assumed to be in the observer frame.
prng : integer or :class:`~numpy.random.RandomState` object
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is to use the :mod:`numpy.random` module.
"""
prng = parse_prng(prng)
spectra = ensure_list(spectra)
positions = ensure_list(positions)
area = parse_value(area, "cm**2")
exp_time = parse_value(exp_time, "s")
t_exp = exp_time.value/comm.size
x = []
y = []
e = []
for pos, spectrum in zip(positions, spectra):
eobs = spectrum.generate_energies(t_exp, area.value, prng=prng)
ne = eobs.size
x.append(YTArray([pos[0]] * ne, "deg"))
y.append(YTArray([pos[1]] * ne, "deg"))
e.append(YTArray.from_astropy(eobs))
parameters = {"sky_center": YTArray(sky_center, "degree"),
"exp_time": exp_time,
"area": area}
events = {}
events["xsky"] = uconcatenate(x)
events["ysky"] = uconcatenate(y)
events["eobs"] = uconcatenate(e)
return EventList(events, parameters)
def make_point_sources(area, exp_time, positions, sky_center,
spectra, prng=None):
r"""
Create a new :class:`~pyxsim.event_list.EventList` which contains
point sources.
Parameters
----------
area : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The collecting area to determine the number of events. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The exposure time to determine the number of events. If units are
not specified, it is assumed to be in seconds.
positions : array of source positions, shape 2xN
The positions of the point sources in RA, Dec, where N is the
number of point sources. Coordinates should be in degrees.
sky_center : array-like
Center RA, Dec of the events in degrees.
spectra : list (size N) of :class:`~soxs.spectra.Spectrum` objects
The spectra for the point sources, where N is the number
of point sources. Assumed to be in the observer frame.
prng : integer or :class:`~numpy.random.RandomState` object
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is to use the :mod:`numpy.random` module.
"""
prng = parse_prng(prng)
spectra = ensure_list(spectra)
positions = ensure_list(positions)
area = parse_value(area, "cm**2")
exp_time = parse_value(exp_time, "s")
t_exp = exp_time.value/comm.size
x = []
y = []
e = []
for pos, spectrum in zip(positions, spectra):
eobs = spectrum.generate_energies(t_exp, area.value, prng=prng)
ne = eobs.size
x.append(YTArray([pos[0]] * ne, "degree"))
y.append(YTArray([pos[1]] * ne, "degree"))
e.append(YTArray.from_astropy(eobs))
parameters = {"sky_center": YTArray(sky_center, "degree"),
"exp_time": exp_time,
"area": area}
events = {}
events["eobs"] = uconcatenate(e)
events["xsky"] = uconcatenate(x)
events["ysky"] = uconcatenate(y)
return EventList(events, parameters)
def __init__(self, e0, emin, emax, emission_field, alpha, prng=None):
self.e0 = parse_value(e0, "keV")
self.emin = parse_value(emin, "keV")
self.emax = parse_value(emax, "keV")
self.emission_field = emission_field
self.alpha = alpha
self.prng = parse_prng(prng)
self.spectral_norm = None
self.redshift = None
def __init__(self, e0, emin, emax, emission_field, alpha, prng=None):
self.e0 = parse_value(e0, "keV")
self.emin = parse_value(emin, "keV")
self.emax = parse_value(emax, "keV")
self.emission_field = emission_field
self.alpha = alpha
self.prng = parse_prng(prng)
self.spectral_norm = None
self.redshift = None
def test_parse_value():
t_yt = parse_value(YTQuantity(300.0, "ks"), "s")
t_astropy = parse_value(Quantity(300.0, "ks"), "s")
t_float = parse_value(300000.0, "s")
t_tuple = parse_value((300.0, "ks"), "s")
assert t_astropy == t_yt
assert t_float == t_yt
assert t_tuple == t_yt
def create_empty_list(cls, exp_time, area, wcs, parameters=None):
events = {"xpix": np.array([]),
"ypix": np.array([]),
"eobs": YTArray([], "keV")}
if parameters is None:
parameters = {}
parameters["ExposureTime"] = parse_value(exp_time, "s")
parameters["Area"] = parse_value(area, "cm**2")
parameters["pix_center"] = wcs.wcs.crpix[:]
parameters["sky_center"] = YTArray(wcs.wcs.crval[:], "deg")
parameters["dtheta"] = YTQuantity(wcs.wcs.cdelt[0], "deg")
return cls(events, parameters)
def __init__(self, e0, emin, emax, emission_field, alpha, prng=None):
self.e0 = parse_value(e0, "keV")
self.emin = parse_value(emin, "keV")
self.emax = parse_value(emax, "keV")
self.emission_field = emission_field
self.alpha = alpha
if prng is None:
self.prng = np.random
else:
self.prng = prng
self.spectral_norm = None
self.redshift = None
def make_background(area, exp_time, fov, sky_center, spectrum, prng=None):
r"""
Create a new :class:`~pyxsim.event_list.EventList` which is filled
uniformly with background events.
Parameters
----------
area : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The collecting area to determine the number of events. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The exposure time to determine the number of events. If units are
not specified, it is assumed to be in seconds.
fov : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The field of view of the event file. If units are not
provided, they are assumed to be in arcminutes.
sky_center : array-like
Center RA, Dec of the events in degrees.
spectrum : :class:`~soxs.spectra.Spectrum`
The spectrum for the background.
prng : integer or :class:`~numpy.random.RandomState` object
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is to use the :mod:`numpy.random` module.
"""
prng = parse_prng(prng)
fov = parse_value(fov, "arcmin")
exp_time = parse_value(exp_time, "s")
area = parse_value(area, "cm**2")
t_exp = exp_time.value / comm.size
e = spectrum.generate_energies(t_exp, area.value, prng=prng)
fov_model = FillFOVModel(sky_center[0], sky_center[1], fov.value)
ra, dec = fov_model.generate_coords(e.size, prng=prng)
parameters = {
"sky_center": YTArray(sky_center, "degree"),
"exp_time": exp_time,
"area": area
}
events = {}
events["xsky"] = YTArray(ra.value, "degree")
events["ysky"] = YTArray(dec.value, "degree")
events["eobs"] = YTArray(e.value, "keV")
return EventList(events, parameters)
def __init__(self, e0, emission_field, sigma=None, prng=None):
self.e0 = parse_value(e0, "keV")
if isinstance(sigma, (float, YTQuantity)) or (isinstance(sigma, tuple) and isinstance(sigma[0], float)):
# The broadening is constant
try:
self.sigma = parse_value(sigma, "keV")
except YTUnitConversionError:
try:
self.sigma = parse_value(sigma, "km/s")
self.sigma *= self.e0/clight
self.sigma.convert_to_units("keV")
except YTUnitConversionError:
raise RuntimeError("Units for sigma must either be in dimensions of "
"energy or velocity! sigma = %s" % sigma)
else:
# Either no broadening or a field name
self.sigma = sigma
self.emission_field = emission_field
self.prng = parse_prng(prng)
self.spectral_norm = None
self.redshift = None
def generate_events(self,
area,
exp_time,
angular_width,
source_model,
sky_center,
parameters=None,
velocity_fields=None,
absorb_model=None,
nH=None,
no_shifting=False,
sigma_pos=None,
prng=None):
"""
Generate projected events from a light cone simulation.
Parameters
----------
area : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`
The collecting area to determine the number of events. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`
The exposure time to determine the number of events. If units are
not specified, it is assumed to be in seconds.
angular_width : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`
The angular width of the light cone simulation. If units are not
specified, it is assumed to be in degrees.
source_model : :class:`~pyxsim.source_models.SourceModel`
A source model used to generate the events.
sky_center : array-like
Center RA, Dec of the events in degrees.
parameters : dict, optional
A dictionary of parameters to be passed for the source model to use,
if necessary.
velocity_fields : list of fields
The yt fields to use for the velocity. If not specified, the following will
be assumed:
['velocity_x', 'velocity_y', 'velocity_z'] for grid datasets
['particle_velocity_x', 'particle_velocity_y', 'particle_velocity_z'] for particle datasets
absorb_model : string or :class:`~pyxsim.spectral_models.AbsorptionModel`
A model for foreground galactic absorption, to simulate the absorption
of events before being detected. This cannot be applied here if you
already did this step previously in the creation of the
:class:`~pyxsim.photon_list.PhotonList` instance. Known options for
strings are "wabs" and "tbabs".
nH : float, optional
The foreground column density in units of 10^22 cm^{-2}. Only used if
absorption is applied.
no_shifting : boolean, optional
If set, the photon energies will not be Doppler shifted.
sigma_pos : float, optional
Apply a gaussian smoothing operation to the sky positions of the
events. This may be useful when the binned events appear blocky due
to their uniform distribution within simulation cells. However, this
will move the events away from their originating position on the
sky, and so may distort surface brightness profiles and/or spectra.
Should probably only be used for visualization purposes. Supply a
float here to smooth with a standard deviation with this fraction
of the cell size. Default: None
prng : integer or :class:`~numpy.random.RandomState` object
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is to use the :mod:`numpy.random` module.
"""
prng = parse_prng(prng)
area = parse_value(area, "cm**2")
exp_time = parse_value(exp_time, "s")
aw = parse_value(angular_width, "deg")
tot_events = defaultdict(list)
for output in self.light_cone_solution:
ds = load(output["filename"])
ax = output["projection_axis"]
c = output[
"projection_center"] * ds.domain_width + ds.domain_left_edge
le = c.copy()
re = c.copy()
width = ds.quan(aw * output["box_width_per_angle"],
"unitary").to("code_length")
depth = ds.domain_width[ax].in_units(
"code_length") * output["box_depth_fraction"]
le[ax] -= 0.5 * depth
re[ax] += 0.5 * depth
for off_ax in axes_lookup[ax]:
le[off_ax] -= 0.5 * width
re[off_ax] += 0.5 * width
reg = ds.box(le, re)
photons = PhotonList.from_data_source(
reg,
output['redshift'],
area,
exp_time,
source_model,
parameters=parameters,
center=c,
velocity_fields=velocity_fields,
cosmology=ds.cosmology)
if sum(photons["num_photons"]) > 0:
events = photons.project_photons("xyz"[ax],
sky_center,
absorb_model=absorb_model,
nH=nH,
no_shifting=no_shifting,
sigma_pos=sigma_pos,
prng=prng)
if events.num_events > 0:
tot_events["xsky"].append(events["xsky"])
tot_events["ysky"].append(events["ysky"])
tot_events["eobs"].append(events["eobs"])
del events
del photons
parameters = {
"exp_time": exp_time,
"area": area,
"sky_center": YTArray(sky_center, "deg")
}
for key in tot_events:
tot_events[key] = uconcatenate(tot_events[key])
return EventList(tot_events, parameters)
def write_fits_file(self, fitsfile, fov, nx, overwrite=False):
"""
Write events to a FITS binary table file. The result is a
standard "event file" which can be processed by standard
X-ray analysis tools.
Parameters
----------
fitsfile : string
The name of the event file to write.
fov : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The field of view of the event file. If units are not
provided, they are assumed to be in arcminutes.
nx : integer
The resolution of the image (number of pixels on a side).
overwrite : boolean, optional
Set to True to overwrite a previous file.
"""
from astropy.time import Time, TimeDelta
events = communicate_events(self.events)
fov = parse_value(fov, "arcmin")
if comm.rank == 0:
exp_time = float(self.parameters["exp_time"])
t_begin = Time.now()
dt = TimeDelta(exp_time, format='sec')
t_end = t_begin + dt
dtheta = fov.to("deg").v / nx
wcs = pywcs.WCS(naxis=2)
wcs.wcs.crpix = [0.5 * (nx + 1)] * 2
wcs.wcs.crval = self.parameters["sky_center"].d
wcs.wcs.cdelt = [-dtheta, dtheta]
wcs.wcs.ctype = ["RA---TAN", "DEC--TAN"]
wcs.wcs.cunit = ["deg"] * 2
xx, yy = wcs.wcs_world2pix(self["xsky"].d, self["ysky"].d, 1)
keepx = np.logical_and(xx >= 0.5, xx <= float(nx) + 0.5)
keepy = np.logical_and(yy >= 0.5, yy <= float(nx) + 0.5)
keep = np.logical_and(keepx, keepy)
n_events = keep.sum()
mylog.info("Threw out %d events because " % (xx.size - n_events) +
"they fell outside the field of view.")
col_e = pyfits.Column(name='ENERGY',
format='E',
unit='eV',
array=events["eobs"].in_units("eV").d[keep])
col_x = pyfits.Column(name='X',
format='D',
unit='pixel',
array=xx[keep])
col_y = pyfits.Column(name='Y',
format='D',
unit='pixel',
array=yy[keep])
cols = [col_e, col_x, col_y]
if "channel_type" in self.parameters:
chantype = self.parameters["channel_type"]
if chantype == "pha":
cunit = "adu"
elif chantype == "pi":
cunit = "Chan"
col_ch = pyfits.Column(name=chantype.upper(),
format='1J',
unit=cunit,
array=events[chantype][keep])
cols.append(col_ch)
time = np.random.uniform(size=n_events,
low=0.0,
high=float(
self.parameters["exp_time"]))
col_t = pyfits.Column(name="TIME",
format='1D',
unit='s',
array=time)
cols.append(col_t)
coldefs = pyfits.ColDefs(cols)
tbhdu = pyfits.BinTableHDU.from_columns(coldefs)
tbhdu.name = "EVENTS"
tbhdu.header["MTYPE1"] = "sky"
tbhdu.header["MFORM1"] = "x,y"
tbhdu.header["MTYPE2"] = "EQPOS"
tbhdu.header["MFORM2"] = "RA,DEC"
tbhdu.header["TCTYP2"] = "RA---TAN"
tbhdu.header["TCTYP3"] = "DEC--TAN"
tbhdu.header["TCRVL2"] = float(self.parameters["sky_center"][0])
tbhdu.header["TCRVL3"] = float(self.parameters["sky_center"][1])
tbhdu.header["TCDLT2"] = -dtheta
tbhdu.header["TCDLT3"] = dtheta
tbhdu.header["TCRPX2"] = 0.5 * (nx + 1)
tbhdu.header["TCRPX3"] = 0.5 * (nx + 1)
tbhdu.header["TLMIN2"] = 0.5
tbhdu.header["TLMIN3"] = 0.5
tbhdu.header["TLMAX2"] = float(nx) + 0.5
tbhdu.header["TLMAX3"] = float(nx) + 0.5
if "channel_type" in self.parameters:
rmf = RedistributionMatrixFile(self.parameters["rmf"])
tbhdu.header["TLMIN4"] = rmf.cmin
tbhdu.header["TLMAX4"] = rmf.cmax
tbhdu.header["RESPFILE"] = os.path.split(
self.parameters["rmf"])[-1]
tbhdu.header["PHA_BINS"] = rmf.n_ch
tbhdu.header["ANCRFILE"] = os.path.split(
self.parameters["arf"])[-1]
tbhdu.header["CHANTYPE"] = self.parameters["channel_type"]
tbhdu.header["MISSION"] = self.parameters["mission"]
tbhdu.header["TELESCOP"] = self.parameters["telescope"]
tbhdu.header["INSTRUME"] = self.parameters["instrument"]
tbhdu.header["EXPOSURE"] = exp_time
tbhdu.header["TSTART"] = 0.0
tbhdu.header["TSTOP"] = exp_time
tbhdu.header["AREA"] = float(self.parameters["area"])
tbhdu.header["HDUVERS"] = "1.1.0"
tbhdu.header["RADECSYS"] = "FK5"
tbhdu.header["EQUINOX"] = 2000.0
tbhdu.header["HDUCLASS"] = "OGIP"
tbhdu.header["HDUCLAS1"] = "EVENTS"
tbhdu.header["HDUCLAS2"] = "ACCEPTED"
tbhdu.header["DATE"] = t_begin.tt.isot
tbhdu.header["DATE-OBS"] = t_begin.tt.isot
tbhdu.header["DATE-END"] = t_end.tt.isot
hdulist = [pyfits.PrimaryHDU(), tbhdu]
if "channel_type" in self.parameters:
start = pyfits.Column(name='START',
format='1D',
unit='s',
array=np.array([0.0]))
stop = pyfits.Column(name='STOP',
format='1D',
unit='s',
array=np.array([exp_time]))
tbhdu_gti = pyfits.BinTableHDU.from_columns([start, stop])
tbhdu_gti.name = "STDGTI"
tbhdu_gti.header["TSTART"] = 0.0
tbhdu_gti.header["TSTOP"] = exp_time
tbhdu_gti.header["HDUCLASS"] = "OGIP"
tbhdu_gti.header["HDUCLAS1"] = "GTI"
tbhdu_gti.header["HDUCLAS2"] = "STANDARD"
tbhdu_gti.header["RADECSYS"] = "FK5"
tbhdu_gti.header["EQUINOX"] = 2000.0
tbhdu_gti.header["DATE"] = t_begin.tt.isot
tbhdu_gti.header["DATE-OBS"] = t_begin.tt.isot
tbhdu_gti.header["DATE-END"] = t_end.tt.isot
hdulist.append(tbhdu_gti)
pyfits.HDUList(hdulist).writeto(fitsfile, overwrite=overwrite)
comm.barrier()
def write_fits_image(self,
imagefile,
fov,
nx,
emin=None,
emax=None,
overwrite=False):
r"""
Generate a image by binning X-ray counts and write it to a FITS file.
Parameters
----------
imagefile : string
The name of the image file to write.
fov : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The field of view of the image. If units are not provided, they
are assumed to be in arcminutes.
nx : integer
The resolution of the image (number of pixels on a side).
emin : float, optional
The minimum energy of the photons to put in the image, in keV.
emax : float, optional
The maximum energy of the photons to put in the image, in keV.
overwrite : boolean, optional
Set to True to overwrite a previous file.
"""
fov = parse_value(fov, "arcmin")
if emin is None:
mask_emin = np.ones(self.num_events, dtype='bool')
else:
mask_emin = self["eobs"].d > emin
if emax is None:
mask_emax = np.ones(self.num_events, dtype='bool')
else:
mask_emax = self["eobs"].d < emax
mask = np.logical_and(mask_emin, mask_emax)
dtheta = fov.to("deg").v / nx
xbins = np.linspace(0.5, float(nx) + 0.5, nx + 1, endpoint=True)
ybins = np.linspace(0.5, float(nx) + 0.5, nx + 1, endpoint=True)
wcs = pywcs.WCS(naxis=2)
wcs.wcs.crpix = [0.5 * (nx + 1)] * 2
wcs.wcs.crval = self.parameters["sky_center"].d
wcs.wcs.cdelt = [-dtheta, dtheta]
wcs.wcs.ctype = ["RA---TAN", "DEC--TAN"]
wcs.wcs.cunit = ["deg"] * 2
xx, yy = wcs.wcs_world2pix(self["xsky"].d, self["ysky"].d, 1)
H, xedges, yedges = np.histogram2d(xx[mask],
yy[mask],
bins=[xbins, ybins])
if parallel_capable:
H = comm.comm.reduce(H, root=0)
if comm.rank == 0:
hdu = pyfits.PrimaryHDU(H.T)
hdu.header["MTYPE1"] = "EQPOS"
hdu.header["MFORM1"] = "RA,DEC"
hdu.header["CTYPE1"] = "RA---TAN"
hdu.header["CTYPE2"] = "DEC--TAN"
hdu.header["CRPIX1"] = 0.5 * (nx + 1)
hdu.header["CRPIX2"] = 0.5 * (nx + 1)
hdu.header["CRVAL1"] = float(self.parameters["sky_center"][0])
hdu.header["CRVAL2"] = float(self.parameters["sky_center"][1])
hdu.header["CUNIT1"] = "deg"
hdu.header["CUNIT2"] = "deg"
hdu.header["CDELT1"] = -dtheta
hdu.header["CDELT2"] = dtheta
hdu.header["EXPOSURE"] = float(self.parameters["exp_time"])
hdu.writeto(imagefile, overwrite=overwrite)
comm.barrier()
def project_photons(self,
normal,
area_new=None,
exp_time_new=None,
redshift_new=None,
dist_new=None,
absorb_model=None,
sky_center=None,
no_shifting=False,
north_vector=None,
prng=None):
r"""
Projects photons onto an image plane given a line of sight.
Returns a new :class:`~pyxsim.event_list.EventList`.
Parameters
----------
normal : character or array-like
Normal vector to the plane of projection. If "x", "y", or "z", will
assume to be along that axis (and will probably be faster). Otherwise,
should be an off-axis normal vector, e.g [1.0, 2.0, -3.0]
area_new : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`, optional
New value for the (constant) collecting area of the detector. If
units are not specified, is assumed to be in cm**2.
exp_time_new : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`, optional
The new value for the exposure time. If units are not specified
it is assumed to be in seconds.
redshift_new : float, optional
The new value for the cosmological redshift.
dist_new : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`, optional
The new value for the angular diameter distance, used for nearby sources.
This may be optionally supplied instead of it being determined from the
cosmology. If units are not specified, it is assumed to be in Mpc. To use this, the
redshift must be zero.
absorb_model : :class:`~pyxsim.spectral_models.AbsorptionModel`
A model for foreground galactic absorption.
sky_center : array-like, optional
Center RA, Dec of the events in degrees.
no_shifting : boolean, optional
If set, the photon energies will not be Doppler shifted.
north_vector : a sequence of floats
A vector defining the "up" direction. This option sets the orientation of
the plane of projection. If not set, an arbitrary grid-aligned north_vector
is chosen. Ignored in the case where a particular axis (e.g., "x", "y", or
"z") is explicitly specified.
prng : :class:`~numpy.random.RandomState` object or :mod:`~numpy.random`, optional
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is the :mod:`numpy.random` module.
Examples
--------
>>> L = np.array([0.1,-0.2,0.3])
>>> events = my_photons.project_photons(L, area_new=10000.,
... redshift_new=0.05)
"""
if prng is None:
prng = np.random
if redshift_new is not None and dist_new is not None:
mylog.error("You may specify a new redshift or distance, " +
"but not both!")
if sky_center is None:
sky_center = YTArray([30., 45.], "degree")
else:
sky_center = YTArray(sky_center, "degree")
dx = self.photons["dx"].d
if isinstance(normal, string_types):
# if on-axis, just use the maximum width of the plane perpendicular
# to that axis
w = self.parameters["Width"].copy()
w["xyz".index(normal)] = 0.0
ax_idx = np.argmax(w)
else:
# if off-axis, just use the largest width to make sure we get everything
ax_idx = np.argmax(self.parameters["Width"])
nx = self.parameters["Dimension"][ax_idx]
dx_min = (self.parameters["Width"] /
self.parameters["Dimension"])[ax_idx]
if not isinstance(normal, string_types):
L = np.array(normal)
orient = Orientation(L, north_vector=north_vector)
x_hat = orient.unit_vectors[0]
y_hat = orient.unit_vectors[1]
z_hat = orient.unit_vectors[2]
n_ph = self.photons["NumberOfPhotons"]
n_ph_tot = n_ph.sum()
parameters = {}
zobs0 = self.parameters["FiducialRedshift"]
D_A0 = self.parameters["FiducialAngularDiameterDistance"]
scale_factor = 1.0
if (exp_time_new is None and area_new is None and redshift_new is None
and dist_new is None):
my_n_obs = n_ph_tot
zobs = zobs0
D_A = D_A0
else:
if exp_time_new is None:
Tratio = 1.
else:
exp_time_new = parse_value(exp_time_new, "s")
Tratio = exp_time_new / self.parameters["FiducialExposureTime"]
if area_new is None:
Aratio = 1.
else:
area_new = parse_value(area_new, "cm**2")
Aratio = area_new / self.parameters["FiducialArea"]
if redshift_new is None and dist_new is None:
Dratio = 1.
zobs = zobs0
D_A = D_A0
else:
if dist_new is not None:
if redshift_new is not None and redshift_new > 0.0:
mylog.warning(
"Redshift must be zero for nearby sources. Resetting redshift to 0.0."
)
zobs = 0.0
D_A = parse_value(dist_new, "Mpc")
else:
zobs = redshift_new
D_A = self.cosmo.angular_diameter_distance(
0.0, zobs).in_units("Mpc")
scale_factor = (1. + zobs0) / (1. + zobs)
Dratio = D_A0*D_A0*(1.+zobs0)**3 / \
(D_A*D_A*(1.+zobs)**3)
fak = Aratio * Tratio * Dratio
if fak > 1:
raise ValueError(
"This combination of requested parameters results in "
"%g%% more photons collected than are " % (100. *
(fak - 1.)) +
"available in the sample. Please reduce the collecting "
"area, exposure time, or increase the distance/redshift "
"of the object. Alternatively, generate a larger sample "
"of photons.")
my_n_obs = np.int64(n_ph_tot * fak)
Nn = 4294967294
if my_n_obs == n_ph_tot:
if my_n_obs <= Nn:
idxs = np.arange(my_n_obs, dtype='uint32')
else:
idxs = np.arange(my_n_obs, dtype='uint64')
else:
if n_ph_tot <= Nn:
idxs = np.arange(n_ph_tot, dtype='uint32')
prng.shuffle(idxs)
idxs = idxs[:my_n_obs]
else:
Nc = np.int32(n_ph_tot / Nn)
idxs = np.zeros(my_n_obs, dtype=np.uint64)
Nup = np.uint32(my_n_obs / Nc)
for i in range(Nc + 1):
if (i + 1) * Nc < n_ph_tot:
idtm = np.arange(i * Nc, (i + 1) * Nc, dtype='uint64')
Nupt = Nup
else:
idtm = np.arange(i * Nc, n_ph_tot, dtype='uint64')
Nupt = my_n_obs - i * Nup
prng.shuffle(idtm)
idxs[i * Nup, i * Nup + Nupt] = idtm[:Nupt]
del (idtm)
# idxs = prng.permutation(n_ph_tot)[:my_n_obs].astype("int64")
obs_cells = np.searchsorted(self.p_bins, idxs, side='right') - 1
delta = dx[obs_cells]
if isinstance(normal, string_types):
if self.parameters["DataType"] == "cells":
xsky = prng.uniform(low=-0.5, high=0.5, size=my_n_obs)
ysky = prng.uniform(low=-0.5, high=0.5, size=my_n_obs)
elif self.parameters["DataType"] == "particles":
xsky = prng.normal(loc=0.0, scale=1.0, size=my_n_obs)
ysky = prng.normal(loc=0.0, scale=1.0, size=my_n_obs)
xsky *= delta
ysky *= delta
xsky += self.photons[axes_lookup[normal][0]].d[obs_cells]
ysky += self.photons[axes_lookup[normal][1]].d[obs_cells]
if not no_shifting:
vz = self.photons["v%s" % normal]
else:
if self.parameters["DataType"] == "cells":
x = prng.uniform(low=-0.5, high=0.5, size=my_n_obs)
y = prng.uniform(low=-0.5, high=0.5, size=my_n_obs)
z = prng.uniform(low=-0.5, high=0.5, size=my_n_obs)
elif self.parameters["DataType"] == "particles":
x = prng.normal(loc=0.0, scale=1.0, size=my_n_obs)
y = prng.normal(loc=0.0, scale=1.0, size=my_n_obs)
z = prng.normal(loc=0.0, scale=1.0, size=my_n_obs)
if not no_shifting:
vz = self.photons["vx"]*z_hat[0] + \
self.photons["vy"]*z_hat[1] + \
self.photons["vz"]*z_hat[2]
x *= delta
y *= delta
z *= delta
x += self.photons["x"].d[obs_cells]
y += self.photons["y"].d[obs_cells]
z += self.photons["z"].d[obs_cells]
xsky = x * x_hat[0] + y * x_hat[1] + z * x_hat[2]
ysky = x * y_hat[0] + y * y_hat[1] + z * y_hat[2]
del (delta)
if no_shifting:
eobs = self.photons["Energy"][idxs]
else:
# shift = -vz.in_cgs()/clight
# shift = np.sqrt((1.-shift)/(1.+shift))
# eobs = self.photons["Energy"][idxs]*shift[obs_cells]
shift = -vz[obs_cells].in_cgs() / clight
shift = np.sqrt((1. - shift) / (1. + shift))
eobs = self.photons["Energy"][idxs]
eobs *= shift
del (shift)
eobs *= scale_factor
if absorb_model is None:
detected = np.ones(eobs.shape, dtype='bool')
else:
detected = absorb_model.absorb_photons(eobs, prng=prng)
events = {}
dtheta = YTQuantity(np.rad2deg(dx_min / D_A), "degree")
events["xpix"] = xsky[detected] / dx_min.v + 0.5 * (nx + 1)
events["ypix"] = ysky[detected] / dx_min.v + 0.5 * (nx + 1)
events["eobs"] = eobs[detected]
events = comm.par_combine_object(events, datatype="dict", op="cat")
num_events = len(events["xpix"])
if comm.rank == 0:
mylog.info("Total number of observed photons: %d" % num_events)
if exp_time_new is None:
parameters["ExposureTime"] = self.parameters[
"FiducialExposureTime"]
else:
parameters["ExposureTime"] = exp_time_new
if area_new is None:
parameters["Area"] = self.parameters["FiducialArea"]
else:
parameters["Area"] = area_new
parameters["Redshift"] = zobs
parameters["AngularDiameterDistance"] = D_A.in_units("Mpc")
parameters["sky_center"] = sky_center
parameters["pix_center"] = np.array([0.5 * (nx + 1)] * 2)
parameters["dtheta"] = dtheta
return EventList(events, parameters)
def from_data_source(cls,
data_source,
redshift,
area,
exp_time,
source_model,
parameters=None,
center=None,
dist=None,
cosmology=None,
velocity_fields=None):
r"""
Initialize a :class:`~pyxsim.photon_list.PhotonList` from a yt data source.
The redshift, collecting area, exposure time, and cosmology are stored in the
*parameters* dictionary which is passed to the *source_model* function.
Parameters
----------
data_source : :class:`~yt.data_objects.data_containers.YTSelectionContainer`
The data source from which the photons will be generated.
redshift : float
The cosmological redshift for the photons.
area : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`.
The collecting area to determine the number of photons. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`.
The exposure time to determine the number of photons. If units are
not specified, it is assumed to be in seconds.
source_model : :class:`~pyxsim.source_models.SourceModel`
A source model used to generate the photons.
parameters : dict, optional
A dictionary of parameters to be passed for the source model to use, if necessary.
center : string or array_like, optional
The origin of the photon spatial coordinates. Accepts "c", "max", or a coordinate.
If not specified, pyxsim attempts to use the "center" field parameter of the data_source.
dist : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`, optional
The angular diameter distance, used for nearby sources. This may be
optionally supplied instead of it being determined from the *redshift*
and given *cosmology*. If units are not specified, it is assumed to be
in Mpc. To use this, the redshift must be set to zero.
cosmology : :class:`~yt.utilities.cosmology.Cosmology`, optional
Cosmological information. If not supplied, we try to get
the cosmology from the dataset. Otherwise, LCDM with
the default yt parameters is assumed.
velocity_fields : list of fields
The yt fields to use for the velocity. If not specified, the following will
be assumed:
['velocity_x', 'velocity_y', 'velocity_z'] for grid datasets
['particle_velocity_x', 'particle_velocity_y', 'particle_velocity_z'] for particle datasets
Examples
--------
>>> thermal_model = ThermalSourceModel(apec_model, Zmet=0.3)
>>> redshift = 0.05
>>> area = 6000.0 # assumed here in cm**2
>>> time = 2.0e5 # assumed here in seconds
>>> sp = ds.sphere("c", (500., "kpc"))
>>> my_photons = PhotonList.from_data_source(sp, redshift, area,
... time, thermal_model)
"""
ds = data_source.ds
if parameters is None:
parameters = {}
if cosmology is None:
if hasattr(ds, 'cosmology'):
cosmo = ds.cosmology
else:
cosmo = Cosmology()
else:
cosmo = cosmology
mylog.info(
"Cosmology: h = %g, omega_matter = %g, omega_lambda = %g" %
(cosmo.hubble_constant, cosmo.omega_matter, cosmo.omega_lambda))
if dist is None:
if redshift <= 0.0:
msg = "If redshift <= 0.0, you must specify a distance to the source using the 'dist' argument!"
mylog.error(msg)
raise ValueError(msg)
D_A = cosmo.angular_diameter_distance(0.0,
redshift).in_units("Mpc")
else:
D_A = parse_value(dist, "Mpc")
if redshift > 0.0:
mylog.warning(
"Redshift must be zero for nearby sources. Resetting redshift to 0.0."
)
redshift = 0.0
if center == "center" or center == "c":
parameters["center"] = ds.domain_center
elif center == "max" or center == "m":
parameters["center"] = ds.find_max("density")[-1]
elif iterable(center):
if isinstance(center, YTArray):
parameters["center"] = center.in_units("code_length")
elif isinstance(center, tuple):
if center[0] == "min":
parameters["center"] = ds.find_min(center[1])[-1]
elif center[0] == "max":
parameters["center"] = ds.find_max(center[1])[-1]
else:
raise RuntimeError
else:
parameters["center"] = ds.arr(center, "code_length")
elif center is None:
parameters["center"] = data_source.get_field_parameter("center")
parameters["FiducialExposureTime"] = parse_value(exp_time, "s")
parameters["FiducialArea"] = parse_value(area, "cm**2")
parameters["FiducialRedshift"] = redshift
parameters["FiducialAngularDiameterDistance"] = D_A
parameters["HubbleConstant"] = cosmo.hubble_constant
parameters["OmegaMatter"] = cosmo.omega_matter
parameters["OmegaLambda"] = cosmo.omega_lambda
D_A = parameters["FiducialAngularDiameterDistance"].in_cgs()
dist_fac = 1.0 / (4. * np.pi * D_A.value * D_A.value *
(1. + redshift)**2)
spectral_norm = parameters["FiducialArea"].v * parameters[
"FiducialExposureTime"].v * dist_fac
source_model.setup_model(data_source, redshift, spectral_norm)
p_fields, v_fields, w_field = determine_fields(
ds, source_model.source_type)
if velocity_fields is not None:
v_fields = velocity_fields
if p_fields[0] == ("index", "x"):
parameters["DataType"] = "cells"
else:
parameters["DataType"] = "particles"
if hasattr(data_source, "left_edge"):
# Region or grid
le = data_source.left_edge
re = data_source.right_edge
elif hasattr(data_source,
"radius") and not hasattr(data_source, "height"):
# Sphere
le = -data_source.radius + data_source.center
re = data_source.radius + data_source.center
else:
# Compute rough boundaries of the object
# DOES NOT WORK for objects straddling periodic
# boundaries yet
if sum(ds.periodicity) > 0:
mylog.warning("You are using a region that is not currently "
"supported for straddling periodic boundaries. "
"Check to make sure that this is not the case.")
le = ds.arr(np.zeros(3), "code_length")
re = ds.arr(np.zeros(3), "code_length")
for i, ax in enumerate(p_fields):
le[i], re[i] = data_source.quantities.extrema(ax)
dds_min = get_smallest_dds(ds, parameters["DataType"])
le = np.rint((le - ds.domain_left_edge) /
dds_min) * dds_min + ds.domain_left_edge
re = ds.domain_right_edge - np.rint(
(ds.domain_right_edge - re) / dds_min) * dds_min
width = re - le
parameters["Dimension"] = np.rint(width / dds_min).astype("int")
parameters["Width"] = parameters["Dimension"] * dds_min.in_units("kpc")
citer = data_source.chunks([], "io")
photons = defaultdict(list)
for chunk in parallel_objects(citer):
chunk_data = source_model(chunk)
if chunk_data is not None:
number_of_photons, idxs, energies = chunk_data
photons["NumberOfPhotons"].append(number_of_photons)
photons["Energy"].append(ds.arr(energies, "keV"))
photons["x"].append(chunk[p_fields[0]][idxs].in_units("kpc"))
photons["y"].append(chunk[p_fields[1]][idxs].in_units("kpc"))
photons["z"].append(chunk[p_fields[2]][idxs].in_units("kpc"))
photons["vx"].append(chunk[v_fields[0]][idxs].in_units("km/s"))
photons["vy"].append(chunk[v_fields[1]][idxs].in_units("km/s"))
photons["vz"].append(chunk[v_fields[2]][idxs].in_units("km/s"))
if w_field is None:
photons["dx"].append(ds.arr(np.zeros(len(idxs)), "kpc"))
else:
photons["dx"].append(chunk[w_field][idxs].in_units("kpc"))
source_model.cleanup_model()
concatenate_photons(photons)
# Translate photon coordinates to the source center
# Fix photon coordinates for regions crossing a periodic boundary
dw = ds.domain_width.to("kpc")
for i, ax in enumerate("xyz"):
if ds.periodicity[i] and len(photons[ax]) > 0:
tfl = photons[ax] < le[i].to('kpc')
tfr = photons[ax] > re[i].to('kpc')
photons[ax][tfl] += dw[i]
photons[ax][tfr] -= dw[i]
photons[ax] -= parameters["center"][i].in_units("kpc")
mylog.info("Finished generating photons.")
mylog.info("Number of photons generated: %d" %
int(np.sum(photons["NumberOfPhotons"])))
mylog.info("Number of cells with photons: %d" % len(photons["x"]))
return cls(photons, parameters, cosmo)
def from_data_source(cls, data_source, redshift, area,
exp_time, source_model, point_sources=False,
parameters=None, center=None, dist=None,
cosmology=None, velocity_fields=None):
r"""
Initialize a :class:`~pyxsim.photon_list.PhotonList` from a yt data
source. The redshift, collecting area, exposure time, and cosmology
are stored in the *parameters* dictionary which is passed to the
*source_model* function.
Parameters
----------
data_source : :class:`~yt.data_objects.data_containers.YTSelectionContainer`
The data source from which the photons will be generated.
redshift : float
The cosmological redshift for the photons.
area : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The collecting area to determine the number of photons. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The exposure time to determine the number of photons. If units are
not specified, it is assumed to be in seconds.
source_model : :class:`~pyxsim.source_models.SourceModel`
A source model used to generate the photons.
point_sources : boolean, optional
If True, the photons will be assumed to be generated from the exact
positions of the cells or particles and not smeared around within
a volume. Default: False
parameters : dict, optional
A dictionary of parameters to be passed for the source model to use,
if necessary.
center : string or array_like, optional
The origin of the photon spatial coordinates. Accepts "c", "max", or
a coordinate. If not specified, pyxsim attempts to use the "center"
field parameter of the data_source.
dist : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The angular diameter distance, used for nearby sources. This may be
optionally supplied instead of it being determined from the
*redshift* and given *cosmology*. If units are not specified, it is
assumed to be in kpc. To use this, the redshift must be set to zero.
cosmology : :class:`~yt.utilities.cosmology.Cosmology`, optional
Cosmological information. If not supplied, we try to get the
cosmology from the dataset. Otherwise, LCDM with the default yt
parameters is assumed.
velocity_fields : list of fields
The yt fields to use for the velocity. If not specified, the
following will be assumed:
['velocity_x', 'velocity_y', 'velocity_z'] for grid datasets
['particle_velocity_x', 'particle_velocity_y', 'particle_velocity_z'] for particle datasets
Examples
--------
>>> thermal_model = ThermalSourceModel(apec_model, Zmet=0.3)
>>> redshift = 0.05
>>> area = 6000.0 # assumed here in cm**2
>>> time = 2.0e5 # assumed here in seconds
>>> sp = ds.sphere("c", (500., "kpc"))
>>> my_photons = PhotonList.from_data_source(sp, redshift, area,
... time, thermal_model)
"""
ds = data_source.ds
if parameters is None:
parameters = {}
if cosmology is None:
if hasattr(ds, 'cosmology'):
cosmo = ds.cosmology
else:
cosmo = Cosmology()
else:
cosmo = cosmology
if dist is None:
if redshift <= 0.0:
msg = "If redshift <= 0.0, you must specify a distance to the " \
"source using the 'dist' argument!"
mylog.error(msg)
raise ValueError(msg)
D_A = cosmo.angular_diameter_distance(0.0, redshift).in_units("Mpc")
else:
D_A = parse_value(dist, "kpc")
if redshift > 0.0:
mylog.warning("Redshift must be zero for nearby sources. "
"Resetting redshift to 0.0.")
redshift = 0.0
if isinstance(center, string_types):
if center == "center" or center == "c":
parameters["center"] = ds.domain_center
elif center == "max" or center == "m":
parameters["center"] = ds.find_max("density")[-1]
elif iterable(center):
if isinstance(center, YTArray):
parameters["center"] = center.in_units("code_length")
elif isinstance(center, tuple):
if center[0] == "min":
parameters["center"] = ds.find_min(center[1])[-1]
elif center[0] == "max":
parameters["center"] = ds.find_max(center[1])[-1]
else:
raise RuntimeError
else:
parameters["center"] = ds.arr(center, "code_length")
elif center is None:
if hasattr(data_source, "left_edge"):
parameters["center"] = 0.5*(data_source.left_edge+data_source.right_edge)
else:
parameters["center"] = data_source.get_field_parameter("center")
parameters["fid_exp_time"] = parse_value(exp_time, "s")
parameters["fid_area"] = parse_value(area, "cm**2")
parameters["fid_redshift"] = redshift
parameters["fid_d_a"] = D_A
parameters["hubble"] = cosmo.hubble_constant
parameters["omega_matter"] = cosmo.omega_matter
parameters["omega_lambda"] = cosmo.omega_lambda
if redshift > 0.0:
mylog.info("Cosmology: h = %g, omega_matter = %g, omega_lambda = %g" %
(cosmo.hubble_constant, cosmo.omega_matter, cosmo.omega_lambda))
else:
mylog.info("Observing local source at distance %s." % D_A)
D_A = parameters["fid_d_a"].in_cgs()
dist_fac = 1.0/(4.*np.pi*D_A.value*D_A.value*(1.+redshift)**2)
spectral_norm = parameters["fid_area"].v*parameters["fid_exp_time"].v*dist_fac
source_model.setup_model(data_source, redshift, spectral_norm)
p_fields, v_fields, w_field = determine_fields(ds,
source_model.source_type,
point_sources)
if velocity_fields is not None:
v_fields = velocity_fields
if p_fields[0] == ("index", "x"):
parameters["data_type"] = "cells"
else:
parameters["data_type"] = "particles"
citer = data_source.chunks([], "io")
photons = defaultdict(list)
for chunk in parallel_objects(citer):
chunk_data = source_model(chunk)
if chunk_data is not None:
ncells, number_of_photons, idxs, energies = chunk_data
photons["num_photons"].append(number_of_photons)
photons["energy"].append(energies)
photons["pos"].append(np.array([chunk[p_fields[0]].d[idxs],
chunk[p_fields[1]].d[idxs],
chunk[p_fields[2]].d[idxs]]))
photons["vel"].append(np.array([chunk[v_fields[0]].d[idxs],
chunk[v_fields[1]].d[idxs],
chunk[v_fields[2]].d[idxs]]))
if w_field is None:
photons["dx"].append(np.zeros(ncells))
else:
photons["dx"].append(chunk[w_field].d[idxs])
source_model.cleanup_model()
photon_units = {"pos": ds.field_info[p_fields[0]].units,
"vel": ds.field_info[v_fields[0]].units,
"energy": "keV"}
if w_field is None:
photon_units["dx"] = "kpc"
else:
photon_units["dx"] = ds.field_info[w_field].units
concatenate_photons(ds, photons, photon_units)
c = parameters["center"].to("kpc")
if sum(ds.periodicity) > 0:
# Fix photon coordinates for regions crossing a periodic boundary
dw = ds.domain_width.to("kpc")
le, re = find_object_bounds(data_source)
for i in range(3):
if ds.periodicity[i] and photons["pos"].shape[0] > 0:
tfl = photons["pos"][:,i] < le[i]
tfr = photons["pos"][:,i] > re[i]
photons["pos"][tfl,i] += dw[i]
photons["pos"][tfr,i] -= dw[i]
# Re-center all coordinates
if photons["pos"].shape[0] > 0:
photons["pos"] -= c
mylog.info("Finished generating photons.")
mylog.info("Number of photons generated: %d" % int(np.sum(photons["num_photons"])))
mylog.info("Number of cells with photons: %d" % photons["dx"].size)
return cls(photons, parameters, cosmo)
def make_xrb_particles(data_source, age_field, scale_length,
sfr_time_range=(1.0, "Gyr"), prng=None):
r"""
This routine generates an in-memory dataset composed of X-ray binary particles
from an input data source containing star particles.
Parameters
----------
data_source : :class:`~yt.data_objects.data_containers.YTSelectionContainer`
The yt data source to obtain the data from, such as a sphere, box, disk,
etc.
age_field : string or (type, name) field tuple
The stellar age field. Must be in some kind of time units.
scale_length : string, (ftype, fname) tuple, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The radial length scale over which to scatter the XRB particles
from their parent star particle. Can be the name of a smoothing
length field for the stars, a (value, unit) tuple, or a YTQuantity.
sfr_time_range : string, (ftype, fname) tuple, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`, optional
The recent time range over which to calculate the star formation rate from
the current time in the dataset. Default: 1.0 Gyr
prng : integer or :class:`~numpy.random.RandomState` object
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is to use the :mod:`numpy.random` module.
"""
prng = parse_prng(prng)
ds = data_source.ds
ptype = data_source._determine_fields(age_field)[0][0]
t = data_source[age_field].to("Gyr")
m = data_source[(ptype, "particle_mass")].to("Msun")
sfr_time_range = parse_value(sfr_time_range, "Gyr")
recent = t < sfr_time_range
n_recent = recent.sum()
if n_recent == 0:
sfr = 0.0
else:
sfr = (m[recent].sum()/sfr_time_range).to("Msun/yr").v
mylog.info("%d star particles were formed in the last " % n_recent +
"%s for a SFR of %4.1f Msun/yr." % (sfr_time_range, sfr))
mtot = m.sum()
npart = m.size
scale_field = None
if isinstance(scale_length, tuple):
if isinstance(scale_length[0], string_types):
scale_field = scale_length
elif isinstance(scale_length, string_types):
scale_field = (ptype, scale_length)
if scale_field is None:
if isinstance(scale_length, tuple):
scale = YTArray([scale_length[0]]*npart, scale_length[1])
elif isinstance(scale_length, YTQuantity):
scale = YTArray([scale_length]*npart)
else:
scale = YTArray([scale_length[0]]*npart, "kpc")
else:
scale = data_source[scale_length]
scale = scale.to('kpc').d
N_l = lmxb_cdf(Lcut)*mtot.v*1.0e-11
N_h = hmxb_cdf(Lcut)*sfr
N_all = N_l+N_h
if N_all == 0.0:
raise RuntimeError("There are no X-ray binaries to generate!")
# Compute conversion factors from luminosity to count rate
lmxb_factor = get_scale_factor(alpha_lmxb, emin_lmxb, emax_lmxb)
hmxb_factor = get_scale_factor(alpha_hmxb, emin_hmxb, emax_hmxb)
xp = []
yp = []
zp = []
vxp = []
vyp = []
vzp = []
lp = []
rp = []
ap = []
if N_l > 0.0:
F_l = np.zeros(nbins+1)
for i in range(1, nbins+1):
F_l[i] = lmxb_cdf(Lbins[i])
F_l /= F_l[-1]
invcdf_l = InterpolatedUnivariateSpline(F_l, logLbins)
n_l = prng.poisson(lam=N_l*m/mtot)
mylog.info("Number of low-mass X-ray binaries: %s" % n_l.sum())
for i, n in enumerate(n_l):
if n > 0:
randvec = prng.uniform(size=n)
l = YTArray(10**invcdf_l(randvec)*1.0e38, "erg/s")
r = YTArray(l.v*lmxb_factor, "photons/s/keV")
# Now convert output luminosities to bolometric
l *= bc_lmxb
x = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
y = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
z = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
x += data_source[ptype, "particle_position_x"][i].to("kpc")
y += data_source[ptype, "particle_position_y"][i].to("kpc")
z += data_source[ptype, "particle_position_z"][i].to("kpc")
vx = YTArray([data_source[ptype, "particle_velocity_x"][i]]*n).to('km/s')
vy = YTArray([data_source[ptype, "particle_velocity_y"][i]]*n).to('km/s')
vz = YTArray([data_source[ptype, "particle_velocity_z"][i]]*n).to('km/s')
xp.append(x)
yp.append(y)
zp.append(z)
vxp.append(vx)
vyp.append(vy)
vzp.append(vz)
lp.append(l)
rp.append(r)
ap.append(np.array([alpha_lmxb]*n))
if N_h > 0.0:
F_h = np.zeros(nbins+1)
for i in range(1, nbins+1):
F_h[i] = hmxb_cdf(Lbins[i])
F_h /= F_h[-1]
invcdf_h = InterpolatedUnivariateSpline(F_h, logLbins)
n_h = prng.poisson(lam=N_h*m/mtot)
mylog.info("Number of high-mass X-ray binaries: %s" % n_h.sum())
for i, n in enumerate(n_h):
if n > 0:
randvec = prng.uniform(size=n)
l = YTArray(10**invcdf_h(randvec)*1.0e38, "erg/s")
r = YTArray(l.v*hmxb_factor, "photons/s/keV")
# Now convert output luminosities to bolometric
l *= bc_hmxb
x = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
y = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
z = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
x += data_source[ptype, "particle_position_x"][i].to("kpc")
y += data_source[ptype, "particle_position_y"][i].to("kpc")
z += data_source[ptype, "particle_position_z"][i].to("kpc")
vx = YTArray([data_source[ptype, "particle_velocity_x"][i]]*n).to('km/s')
vy = YTArray([data_source[ptype, "particle_velocity_y"][i]]*n).to('km/s')
vz = YTArray([data_source[ptype, "particle_velocity_z"][i]]*n).to('km/s')
xp.append(x)
yp.append(y)
zp.append(z)
vxp.append(vx)
vyp.append(vy)
vzp.append(vz)
lp.append(l)
rp.append(r)
ap.append(np.array([alpha_hmxb]*n))
xp = uconcatenate(xp)
yp = uconcatenate(yp)
zp = uconcatenate(zp)
vxp = uconcatenate(vxp)
vyp = uconcatenate(vyp)
vzp = uconcatenate(vzp)
lp = uconcatenate(lp)
rp = uconcatenate(rp)
ap = uconcatenate(ap)
data = {"particle_position_x": (xp.d, str(xp.units)),
"particle_position_y": (yp.d, str(yp.units)),
"particle_position_z": (zp.d, str(zp.units)),
"particle_velocity_x": (vxp.d, str(vxp.units)),
"particle_velocity_y": (vyp.d, str(vyp.units)),
"particle_velocity_z": (vzp.d, str(vzp.units)),
"particle_luminosity": (lp.d, str(lp.units)),
"particle_count_rate": (rp.d, str(rp.units)),
"particle_spectral_index": ap}
dle = ds.domain_left_edge.to("kpc").v
dre = ds.domain_right_edge.to("kpc").v
bbox = np.array([[dle[i], dre[i]] for i in range(3)])
new_ds = load_particles(data, bbox=bbox, length_unit="kpc",
time_unit="Myr", mass_unit="Msun",
velocity_unit="km/s")
return new_ds
def from_data_source(cls,
data_source,
redshift,
area,
exp_time,
source_model,
point_sources=False,
parameters=None,
center=None,
dist=None,
cosmology=None,
velocity_fields=None):
r"""
Initialize a :class:`~pyxsim.photon_list.PhotonList` from a yt data
source. The redshift, collecting area, exposure time, and cosmology
are stored in the *parameters* dictionary which is passed to the
*source_model* function.
Parameters
----------
data_source : :class:`~yt.data_objects.data_containers.YTSelectionContainer`
The data source from which the photons will be generated.
redshift : float
The cosmological redshift for the photons.
area : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The collecting area to determine the number of photons. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The exposure time to determine the number of photons. If units are
not specified, it is assumed to be in seconds.
source_model : :class:`~pyxsim.source_models.SourceModel`
A source model used to generate the photons.
point_sources : boolean, optional
If True, the photons will be assumed to be generated from the exact
positions of the cells or particles and not smeared around within
a volume. Default: False
parameters : dict, optional
A dictionary of parameters to be passed for the source model to use,
if necessary.
center : string or array_like, optional
The origin of the photon spatial coordinates. Accepts "c", "max", or
a coordinate. If not specified, pyxsim attempts to use the "center"
field parameter of the data_source.
dist : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The angular diameter distance, used for nearby sources. This may be
optionally supplied instead of it being determined from the
*redshift* and given *cosmology*. If units are not specified, it is
assumed to be in kpc. To use this, the redshift must be set to zero.
cosmology : :class:`~yt.utilities.cosmology.Cosmology`, optional
Cosmological information. If not supplied, we try to get the
cosmology from the dataset. Otherwise, LCDM with the default yt
parameters is assumed.
velocity_fields : list of fields
The yt fields to use for the velocity. If not specified, the
following will be assumed:
['velocity_x', 'velocity_y', 'velocity_z'] for grid datasets
['particle_velocity_x', 'particle_velocity_y', 'particle_velocity_z'] for particle datasets
Examples
--------
>>> thermal_model = ThermalSourceModel(apec_model, Zmet=0.3)
>>> redshift = 0.05
>>> area = 6000.0 # assumed here in cm**2
>>> time = 2.0e5 # assumed here in seconds
>>> sp = ds.sphere("c", (500., "kpc"))
>>> my_photons = PhotonList.from_data_source(sp, redshift, area,
... time, thermal_model)
"""
ds = data_source.ds
if parameters is None:
parameters = {}
if cosmology is None:
if hasattr(ds, 'cosmology'):
cosmo = ds.cosmology
else:
cosmo = Cosmology()
else:
cosmo = cosmology
if dist is None:
if redshift <= 0.0:
msg = "If redshift <= 0.0, you must specify a distance to the " \
"source using the 'dist' argument!"
mylog.error(msg)
raise ValueError(msg)
D_A = cosmo.angular_diameter_distance(0.0,
redshift).in_units("Mpc")
else:
D_A = parse_value(dist, "kpc")
if redshift > 0.0:
mylog.warning("Redshift must be zero for nearby sources. "
"Resetting redshift to 0.0.")
redshift = 0.0
if isinstance(center, string_types):
if center == "center" or center == "c":
parameters["center"] = ds.domain_center
elif center == "max" or center == "m":
parameters["center"] = ds.find_max("density")[-1]
elif iterable(center):
if isinstance(center, YTArray):
parameters["center"] = center.in_units("code_length")
elif isinstance(center, tuple):
if center[0] == "min":
parameters["center"] = ds.find_min(center[1])[-1]
elif center[0] == "max":
parameters["center"] = ds.find_max(center[1])[-1]
else:
raise RuntimeError
else:
parameters["center"] = ds.arr(center, "code_length")
elif center is None:
if hasattr(data_source, "left_edge"):
parameters["center"] = 0.5 * (data_source.left_edge +
data_source.right_edge)
else:
parameters["center"] = data_source.get_field_parameter(
"center")
parameters["fid_exp_time"] = parse_value(exp_time, "s")
parameters["fid_area"] = parse_value(area, "cm**2")
parameters["fid_redshift"] = redshift
parameters["fid_d_a"] = D_A
parameters["hubble"] = cosmo.hubble_constant
parameters["omega_matter"] = cosmo.omega_matter
parameters["omega_lambda"] = cosmo.omega_lambda
if redshift > 0.0:
mylog.info(
"Cosmology: h = %g, omega_matter = %g, omega_lambda = %g" %
(cosmo.hubble_constant, cosmo.omega_matter,
cosmo.omega_lambda))
else:
mylog.info("Observing local source at distance %s." % D_A)
D_A = parameters["fid_d_a"].in_cgs()
dist_fac = 1.0 / (4. * np.pi * D_A.value * D_A.value *
(1. + redshift)**2)
spectral_norm = parameters["fid_area"].v * parameters[
"fid_exp_time"].v * dist_fac
source_model.setup_model(data_source, redshift, spectral_norm)
p_fields, v_fields, w_field = determine_fields(
ds, source_model.source_type, point_sources)
if velocity_fields is not None:
v_fields = velocity_fields
if p_fields[0] == ("index", "x"):
parameters["data_type"] = "cells"
else:
parameters["data_type"] = "particles"
citer = data_source.chunks([], "io")
photons = defaultdict(list)
for chunk in parallel_objects(citer):
chunk_data = source_model(chunk)
if chunk_data is not None:
ncells, number_of_photons, idxs, energies = chunk_data
photons["num_photons"].append(number_of_photons)
photons["energy"].append(energies)
photons["pos"].append(
np.array([
chunk[p_fields[0]].d[idxs], chunk[p_fields[1]].d[idxs],
chunk[p_fields[2]].d[idxs]
]))
photons["vel"].append(
np.array([
chunk[v_fields[0]].d[idxs], chunk[v_fields[1]].d[idxs],
chunk[v_fields[2]].d[idxs]
]))
if w_field is None:
photons["dx"].append(np.zeros(ncells))
else:
photons["dx"].append(chunk[w_field].d[idxs])
source_model.cleanup_model()
photon_units = {
"pos": ds.field_info[p_fields[0]].units,
"vel": ds.field_info[v_fields[0]].units,
"energy": "keV"
}
if w_field is None:
photon_units["dx"] = "kpc"
else:
photon_units["dx"] = ds.field_info[w_field].units
concatenate_photons(ds, photons, photon_units)
c = parameters["center"].to("kpc")
if sum(ds.periodicity) > 0:
# Fix photon coordinates for regions crossing a periodic boundary
dw = ds.domain_width.to("kpc")
le, re = find_object_bounds(data_source)
for i in range(3):
if ds.periodicity[i] and photons["pos"].shape[0] > 0:
tfl = photons["pos"][:, i] < le[i]
tfr = photons["pos"][:, i] > re[i]
photons["pos"][tfl, i] += dw[i]
photons["pos"][tfr, i] -= dw[i]
# Re-center all coordinates
if photons["pos"].shape[0] > 0:
photons["pos"] -= c
mylog.info("Finished generating photons.")
mylog.info("Number of photons generated: %d" %
int(np.sum(photons["num_photons"])))
mylog.info("Number of cells with photons: %d" % photons["dx"].size)
return cls(photons, parameters, cosmo)
def make_xrb_particles(data_source,
age_field,
scale_length,
sfr_time_range=(1.0, "Gyr"),
prng=None):
r"""
This routine generates an in-memory dataset composed of X-ray binary particles
from an input data source containing star particles.
Parameters
----------
data_source : :class:`~yt.data_objects.data_containers.YTSelectionContainer`
The yt data source to obtain the data from, such as a sphere, box, disk,
etc.
age_field : string or (type, name) field tuple
The stellar age field. Must be in some kind of time units.
scale_length : string, (ftype, fname) tuple, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The radial length scale over which to scatter the XRB particles
from their parent star particle. Can be the name of a smoothing
length field for the stars, a (value, unit) tuple, or a YTQuantity.
sfr_time_range : string, (ftype, fname) tuple, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`, optional
The recent time range over which to calculate the star formation rate from
the current time in the dataset. Default: 1.0 Gyr
prng : integer or :class:`~numpy.random.RandomState` object
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is to use the :mod:`numpy.random` module.
"""
prng = parse_prng(prng)
ds = data_source.ds
ptype = data_source._determine_fields(age_field)[0][0]
t = data_source[age_field].to("Gyr")
m = data_source[(ptype, "particle_mass")].to("Msun")
sfr_time_range = parse_value(sfr_time_range, "Gyr")
recent = t < sfr_time_range
n_recent = recent.sum()
if n_recent == 0:
sfr = 0.0
else:
sfr = (m[recent].sum() / sfr_time_range).to("Msun/yr").v
mylog.info("%d star particles were formed in the last " % n_recent +
"%s for a SFR of %4.1f Msun/yr." % (sfr_time_range, sfr))
mtot = m.sum()
npart = m.size
scale_field = None
if isinstance(scale_length, tuple):
if isinstance(scale_length[0], string_types):
scale_field = scale_length
elif isinstance(scale_length, string_types):
scale_field = (ptype, scale_length)
if scale_field is None:
if isinstance(scale_length, tuple):
scale = YTArray([scale_length[0]] * npart, scale_length[1])
elif isinstance(scale_length, YTQuantity):
scale = YTArray([scale_length] * npart)
else:
scale = YTArray([scale_length[0]] * npart, "kpc")
else:
scale = data_source[scale_length]
scale = scale.to('kpc').d
N_l = lmxb_cdf(Lcut) * mtot.v * 1.0e-11
N_h = hmxb_cdf(Lcut) * sfr
N_all = N_l + N_h
if N_all == 0.0:
raise RuntimeError("There are no X-ray binaries to generate!")
# Compute conversion factors from luminosity to count rate
lmxb_factor = get_scale_factor(alpha_lmxb, emin_lmxb, emax_lmxb)
hmxb_factor = get_scale_factor(alpha_hmxb, emin_hmxb, emax_hmxb)
xp = []
yp = []
zp = []
vxp = []
vyp = []
vzp = []
lp = []
rp = []
ap = []
if N_l > 0.0:
F_l = np.zeros(nbins + 1)
for i in range(1, nbins + 1):
F_l[i] = lmxb_cdf(Lbins[i])
F_l /= F_l[-1]
invcdf_l = InterpolatedUnivariateSpline(F_l, logLbins)
n_l = prng.poisson(lam=N_l * m / mtot)
mylog.info("Number of low-mass X-ray binaries: %s" % n_l.sum())
for i, n in enumerate(n_l):
if n > 0:
randvec = prng.uniform(size=n)
l = YTArray(10**invcdf_l(randvec) * 1.0e38, "erg/s")
r = YTArray(l.v * lmxb_factor, "photons/s/keV")
# Now convert output luminosities to bolometric
l *= bc_lmxb
x = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
y = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
z = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
x += data_source[ptype, "particle_position_x"][i].to("kpc")
y += data_source[ptype, "particle_position_y"][i].to("kpc")
z += data_source[ptype, "particle_position_z"][i].to("kpc")
vx = YTArray([data_source[ptype, "particle_velocity_x"][i]] *
n).to('km/s')
vy = YTArray([data_source[ptype, "particle_velocity_y"][i]] *
n).to('km/s')
vz = YTArray([data_source[ptype, "particle_velocity_z"][i]] *
n).to('km/s')
xp.append(x)
yp.append(y)
zp.append(z)
vxp.append(vx)
vyp.append(vy)
vzp.append(vz)
lp.append(l)
rp.append(r)
ap.append(np.array([alpha_lmxb] * n))
if N_h > 0.0:
F_h = np.zeros(nbins + 1)
for i in range(1, nbins + 1):
F_h[i] = hmxb_cdf(Lbins[i])
F_h /= F_h[-1]
invcdf_h = InterpolatedUnivariateSpline(F_h, logLbins)
n_h = prng.poisson(lam=N_h * m / mtot)
mylog.info("Number of high-mass X-ray binaries: %s" % n_h.sum())
for i, n in enumerate(n_h):
if n > 0:
randvec = prng.uniform(size=n)
l = YTArray(10**invcdf_h(randvec) * 1.0e38, "erg/s")
r = YTArray(l.v * hmxb_factor, "photons/s/keV")
# Now convert output luminosities to bolometric
l *= bc_hmxb
x = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
y = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
z = YTArray(prng.normal(scale=scale[i], size=n), "kpc")
x += data_source[ptype, "particle_position_x"][i].to("kpc")
y += data_source[ptype, "particle_position_y"][i].to("kpc")
z += data_source[ptype, "particle_position_z"][i].to("kpc")
vx = YTArray([data_source[ptype, "particle_velocity_x"][i]] *
n).to('km/s')
vy = YTArray([data_source[ptype, "particle_velocity_y"][i]] *
n).to('km/s')
vz = YTArray([data_source[ptype, "particle_velocity_z"][i]] *
n).to('km/s')
xp.append(x)
yp.append(y)
zp.append(z)
vxp.append(vx)
vyp.append(vy)
vzp.append(vz)
lp.append(l)
rp.append(r)
ap.append(np.array([alpha_hmxb] * n))
xp = uconcatenate(xp)
yp = uconcatenate(yp)
zp = uconcatenate(zp)
vxp = uconcatenate(vxp)
vyp = uconcatenate(vyp)
vzp = uconcatenate(vzp)
lp = uconcatenate(lp)
rp = uconcatenate(rp)
ap = uconcatenate(ap)
data = {
"particle_position_x": (xp.d, str(xp.units)),
"particle_position_y": (yp.d, str(yp.units)),
"particle_position_z": (zp.d, str(zp.units)),
"particle_velocity_x": (vxp.d, str(vxp.units)),
"particle_velocity_y": (vyp.d, str(vyp.units)),
"particle_velocity_z": (vzp.d, str(vzp.units)),
"particle_luminosity": (lp.d, str(lp.units)),
"particle_count_rate": (rp.d, str(rp.units)),
"particle_spectral_index": ap
}
dle = ds.domain_left_edge.to("kpc").v
dre = ds.domain_right_edge.to("kpc").v
bbox = np.array([[dle[i], dre[i]] for i in range(3)])
new_ds = load_particles(data,
bbox=bbox,
length_unit="kpc",
time_unit="Myr",
mass_unit="Msun",
velocity_unit="km/s")
return new_ds
def write_fits_file(self, fitsfile, fov, nx, overwrite=False):
"""
Write events to a FITS binary table file. The result is a
standard "event file" which can be processed by standard
X-ray analysis tools.
Parameters
----------
fitsfile : string
The name of the event file to write.
fov : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The field of view of the event file. If units are not
provided, they are assumed to be in arcminutes.
nx : integer
The resolution of the image (number of pixels on a side).
overwrite : boolean, optional
Set to True to overwrite a previous file.
"""
from astropy.time import Time, TimeDelta
events = communicate_events(self.events)
fov = parse_value(fov, "arcmin")
if comm.rank == 0:
exp_time = float(self.parameters["exp_time"])
t_begin = Time.now()
dt = TimeDelta(exp_time, format='sec')
t_end = t_begin + dt
dtheta = fov.to("deg").v / nx
wcs = pywcs.WCS(naxis=2)
wcs.wcs.crpix = [0.5*(nx+1)]*2
wcs.wcs.crval = self.parameters["sky_center"].d
wcs.wcs.cdelt = [-dtheta, dtheta]
wcs.wcs.ctype = ["RA---TAN", "DEC--TAN"]
wcs.wcs.cunit = ["deg"] * 2
xx, yy = wcs.wcs_world2pix(self["xsky"].d, self["ysky"].d, 1)
keepx = np.logical_and(xx >= 0.5, xx <= float(nx)+0.5)
keepy = np.logical_and(yy >= 0.5, yy <= float(nx)+0.5)
keep = np.logical_and(keepx, keepy)
n_events = keep.sum()
mylog.info("Threw out %d events because " % (xx.size-n_events) +
"they fell outside the field of view.")
col_e = pyfits.Column(name='ENERGY', format='E', unit='eV',
array=events["eobs"].in_units("eV").d[keep])
col_x = pyfits.Column(name='X', format='D', unit='pixel',
array=xx[keep])
col_y = pyfits.Column(name='Y', format='D', unit='pixel',
array=yy[keep])
cols = [col_e, col_x, col_y]
if "channel_type" in self.parameters:
chantype = self.parameters["channel_type"]
if chantype == "pha":
cunit = "adu"
elif chantype == "pi":
cunit = "Chan"
col_ch = pyfits.Column(name=chantype.upper(), format='1J',
unit=cunit, array=events[chantype][keep])
cols.append(col_ch)
time = np.random.uniform(size=n_events, low=0.0,
high=float(self.parameters["exp_time"]))
col_t = pyfits.Column(name="TIME", format='1D', unit='s',
array=time)
cols.append(col_t)
coldefs = pyfits.ColDefs(cols)
tbhdu = pyfits.BinTableHDU.from_columns(coldefs)
tbhdu.name = "EVENTS"
tbhdu.header["MTYPE1"] = "sky"
tbhdu.header["MFORM1"] = "x,y"
tbhdu.header["MTYPE2"] = "EQPOS"
tbhdu.header["MFORM2"] = "RA,DEC"
tbhdu.header["TCTYP2"] = "RA---TAN"
tbhdu.header["TCTYP3"] = "DEC--TAN"
tbhdu.header["TCRVL2"] = float(self.parameters["sky_center"][0])
tbhdu.header["TCRVL3"] = float(self.parameters["sky_center"][1])
tbhdu.header["TCDLT2"] = -dtheta
tbhdu.header["TCDLT3"] = dtheta
tbhdu.header["TCRPX2"] = 0.5*(nx+1)
tbhdu.header["TCRPX3"] = 0.5*(nx+1)
tbhdu.header["TLMIN2"] = 0.5
tbhdu.header["TLMIN3"] = 0.5
tbhdu.header["TLMAX2"] = float(nx)+0.5
tbhdu.header["TLMAX3"] = float(nx)+0.5
if "channel_type" in self.parameters:
rmf = RedistributionMatrixFile(self.parameters["rmf"])
tbhdu.header["TLMIN4"] = rmf.cmin
tbhdu.header["TLMAX4"] = rmf.cmax
tbhdu.header["RESPFILE"] = os.path.split(self.parameters["rmf"])[-1]
tbhdu.header["PHA_BINS"] = rmf.n_ch
tbhdu.header["ANCRFILE"] = os.path.split(self.parameters["arf"])[-1]
tbhdu.header["CHANTYPE"] = self.parameters["channel_type"]
tbhdu.header["MISSION"] = self.parameters["mission"]
tbhdu.header["TELESCOP"] = self.parameters["telescope"]
tbhdu.header["INSTRUME"] = self.parameters["instrument"]
tbhdu.header["EXPOSURE"] = exp_time
tbhdu.header["TSTART"] = 0.0
tbhdu.header["TSTOP"] = exp_time
tbhdu.header["AREA"] = float(self.parameters["area"])
tbhdu.header["HDUVERS"] = "1.1.0"
tbhdu.header["RADECSYS"] = "FK5"
tbhdu.header["EQUINOX"] = 2000.0
tbhdu.header["HDUCLASS"] = "OGIP"
tbhdu.header["HDUCLAS1"] = "EVENTS"
tbhdu.header["HDUCLAS2"] = "ACCEPTED"
tbhdu.header["DATE"] = t_begin.tt.isot
tbhdu.header["DATE-OBS"] = t_begin.tt.isot
tbhdu.header["DATE-END"] = t_end.tt.isot
hdulist = [pyfits.PrimaryHDU(), tbhdu]
if "channel_type" in self.parameters:
start = pyfits.Column(name='START', format='1D', unit='s',
array=np.array([0.0]))
stop = pyfits.Column(name='STOP', format='1D', unit='s',
array=np.array([exp_time]))
tbhdu_gti = pyfits.BinTableHDU.from_columns([start,stop])
tbhdu_gti.name = "STDGTI"
tbhdu_gti.header["TSTART"] = 0.0
tbhdu_gti.header["TSTOP"] = exp_time
tbhdu_gti.header["HDUCLASS"] = "OGIP"
tbhdu_gti.header["HDUCLAS1"] = "GTI"
tbhdu_gti.header["HDUCLAS2"] = "STANDARD"
tbhdu_gti.header["RADECSYS"] = "FK5"
tbhdu_gti.header["EQUINOX"] = 2000.0
tbhdu_gti.header["DATE"] = t_begin.tt.isot
tbhdu_gti.header["DATE-OBS"] = t_begin.tt.isot
tbhdu_gti.header["DATE-END"] = t_end.tt.isot
hdulist.append(tbhdu_gti)
pyfits.HDUList(hdulist).writeto(fitsfile, overwrite=overwrite)
comm.barrier()
def write_fits_image(self, imagefile, fov, nx, emin=None,
emax=None, overwrite=False):
r"""
Generate a image by binning X-ray counts and write it to a FITS file.
Parameters
----------
imagefile : string
The name of the image file to write.
fov : float, (value, unit) tuple, :class:`~yt.units.yt_array.YTQuantity`, or :class:`~astropy.units.Quantity`
The field of view of the image. If units are not provided, they
are assumed to be in arcminutes.
nx : integer
The resolution of the image (number of pixels on a side).
emin : float, optional
The minimum energy of the photons to put in the image, in keV.
emax : float, optional
The maximum energy of the photons to put in the image, in keV.
overwrite : boolean, optional
Set to True to overwrite a previous file.
"""
fov = parse_value(fov, "arcmin")
if emin is None:
mask_emin = np.ones(self.num_events, dtype='bool')
else:
mask_emin = self["eobs"].d > emin
if emax is None:
mask_emax = np.ones(self.num_events, dtype='bool')
else:
mask_emax = self["eobs"].d < emax
mask = np.logical_and(mask_emin, mask_emax)
dtheta = fov.to("deg").v/nx
xbins = np.linspace(0.5, float(nx)+0.5, nx+1, endpoint=True)
ybins = np.linspace(0.5, float(nx)+0.5, nx+1, endpoint=True)
wcs = pywcs.WCS(naxis=2)
wcs.wcs.crpix = [0.5*(nx+1)]*2
wcs.wcs.crval = self.parameters["sky_center"].d
wcs.wcs.cdelt = [-dtheta, dtheta]
wcs.wcs.ctype = ["RA---TAN","DEC--TAN"]
wcs.wcs.cunit = ["deg"]*2
xx, yy = wcs.wcs_world2pix(self["xsky"].d, self["ysky"].d, 1)
H, xedges, yedges = np.histogram2d(xx[mask], yy[mask],
bins=[xbins, ybins])
if parallel_capable:
H = comm.comm.reduce(H, root=0)
if comm.rank == 0:
hdu = pyfits.PrimaryHDU(H.T)
hdu.header["MTYPE1"] = "EQPOS"
hdu.header["MFORM1"] = "RA,DEC"
hdu.header["CTYPE1"] = "RA---TAN"
hdu.header["CTYPE2"] = "DEC--TAN"
hdu.header["CRPIX1"] = 0.5*(nx+1)
hdu.header["CRPIX2"] = 0.5*(nx+1)
hdu.header["CRVAL1"] = float(self.parameters["sky_center"][0])
hdu.header["CRVAL2"] = float(self.parameters["sky_center"][1])
hdu.header["CUNIT1"] = "deg"
hdu.header["CUNIT2"] = "deg"
hdu.header["CDELT1"] = -dtheta
hdu.header["CDELT2"] = dtheta
hdu.header["EXPOSURE"] = float(self.parameters["exp_time"])
hdu.writeto(imagefile, overwrite=overwrite)
comm.barrier()
def generate_events(self, area, exp_time, angular_width,
source_model, sky_center, parameters=None,
velocity_fields=None, absorb_model=None,
nH=None, no_shifting=False, sigma_pos=None,
prng=None):
"""
Generate projected events from a light cone simulation.
Parameters
----------
area : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`
The collecting area to determine the number of events. If units are
not specified, it is assumed to be in cm^2.
exp_time : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`
The exposure time to determine the number of events. If units are
not specified, it is assumed to be in seconds.
angular_width : float, (value, unit) tuple, or :class:`~yt.units.yt_array.YTQuantity`
The angular width of the light cone simulation. If units are not
specified, it is assumed to be in degrees.
source_model : :class:`~pyxsim.source_models.SourceModel`
A source model used to generate the events.
sky_center : array-like
Center RA, Dec of the events in degrees.
parameters : dict, optional
A dictionary of parameters to be passed for the source model to use,
if necessary.
velocity_fields : list of fields
The yt fields to use for the velocity. If not specified, the following will
be assumed:
['velocity_x', 'velocity_y', 'velocity_z'] for grid datasets
['particle_velocity_x', 'particle_velocity_y', 'particle_velocity_z'] for particle datasets
absorb_model : string or :class:`~pyxsim.spectral_models.AbsorptionModel`
A model for foreground galactic absorption, to simulate the absorption
of events before being detected. This cannot be applied here if you
already did this step previously in the creation of the
:class:`~pyxsim.photon_list.PhotonList` instance. Known options for
strings are "wabs" and "tbabs".
nH : float, optional
The foreground column density in units of 10^22 cm^{-2}. Only used if
absorption is applied.
no_shifting : boolean, optional
If set, the photon energies will not be Doppler shifted.
sigma_pos : float, optional
Apply a gaussian smoothing operation to the sky positions of the
events. This may be useful when the binned events appear blocky due
to their uniform distribution within simulation cells. However, this
will move the events away from their originating position on the
sky, and so may distort surface brightness profiles and/or spectra.
Should probably only be used for visualization purposes. Supply a
float here to smooth with a standard deviation with this fraction
of the cell size. Default: None
prng : integer or :class:`~numpy.random.RandomState` object
A pseudo-random number generator. Typically will only be specified
if you have a reason to generate the same set of random numbers, such as for a
test. Default is to use the :mod:`numpy.random` module.
"""
prng = parse_prng(prng)
area = parse_value(area, "cm**2")
exp_time = parse_value(exp_time, "s")
aw = parse_value(angular_width, "deg")
tot_events = defaultdict(list)
for output in self.light_cone_solution:
ds = load(output["filename"])
ax = output["projection_axis"]
c = output["projection_center"]*ds.domain_width + ds.domain_left_edge
le = c.copy()
re = c.copy()
width = ds.quan(aw*output["box_width_per_angle"], "unitary").to("code_length")
depth = ds.domain_width[ax].in_units("code_length")*output["box_depth_fraction"]
le[ax] -= 0.5*depth
re[ax] += 0.5*depth
for off_ax in axes_lookup[ax]:
le[off_ax] -= 0.5*width
re[off_ax] += 0.5*width
reg = ds.box(le, re)
photons = PhotonList.from_data_source(reg, output['redshift'], area,
exp_time, source_model,
parameters=parameters,
center=c,
velocity_fields=velocity_fields,
cosmology=ds.cosmology)
if sum(photons["num_photons"]) > 0:
events = photons.project_photons("xyz"[ax], sky_center,
absorb_model=absorb_model, nH=nH,
no_shifting=no_shifting,
sigma_pos=sigma_pos,
prng=prng)
if events.num_events > 0:
tot_events["xsky"].append(events["xsky"])
tot_events["ysky"].append(events["ysky"])
tot_events["eobs"].append(events["eobs"])
del events
del photons
parameters = {"exp_time": exp_time,
"area": area,
"sky_center": YTArray(sky_center, "deg")}
for key in tot_events:
tot_events[key] = uconcatenate(tot_events[key])
return EventList(tot_events, parameters)