target.snia

target.snia#

This module provides the SNeIa class, a pre-defined Transient class.

It means the basic _MODEL functionality has been defined.

See the corresponding documentation page in “List of transient classes” for more detail on this Transient class.

The SNeIa is defined as such:

The SNeIa class.#

class SNeIa( Transient ):
    _KIND = "SNIa"
    _TEMPLATE_SOURCE = "salt2"
    _VOLUME_RATE = 2.35 * 10**4 # Perley 2020
    _MODEL = dict( redshift ={"param":{"zmax":0.2}, "as":"z"},

                    x1={"model":"nicolas2021"},

                    c={"model":"intrinsic_and_dust"},

                    t0={"model":"uniform",
                        "param":{"mjd_range":[59000, 59000+365*4]} },

                    magabs={"model":"tripp1998",
                            "input":["x1","c"]
                           },

                    magobs={"model":"magabs_to_magobs",
                            "input":["z", "magabs"]},

                    x0={"model":"magobs_to_x0",
                        "input":["magobs"]},

                    radec={"model":"random",
                           "param":dict(ra_range=[0, 360],
                           dec_range=[-30, 90]),
                           "as":["ra","dec"]}
                     )

Pre-defined models for the SNeIa parameters (color, stretch, magnitude) are also defined:

class skysurvey.target.snia.SNeIaColor[source]#

Bases: object

A class to model the color of SNe Ia.

static color_rvs(size, a=3.63, loc=-0.416, scale=1.62)[source]#

Draw random variates from an alpha function.

This is used to model the color of SNe Ia.

Parameters:

size (int) – The number of random variates to draw.
a (float, optional) – The alpha parameter of the alpha function. The default is 3.63.
loc (float, optional) – The location parameter of the alpha function. The default is -0.416.
scale (float, optional) – The scale parameter of the alpha function. The default is 1.62.

Returns:

The drawn random variates.

Return type:

ndarray

static asymetric_gaussian(xx='-0.3:1:0.001', cint=-0.05, sigmalow=0.03, sigmahigh=0.1)[source]#

Get an asymetric gaussian distribution.

As in Scolnic and Kessler 2016 (https://arxiv.org/pdf/1603.01559).

Parameters:

xx (str, optional) – The x-axis of the color distribution. It should be a string with the format “min:max:step”. The default is “-0.3:1:0.01”. This is evaluated as np.r_[xx].
cint (float, optional) – The mean of the intrinsic color distribution. The default is -0.05.
sigmalow (float, optional) – The standard deviation for the bluer tails. The default is 0.03.
sigmahigh (float, optional) – The standard deviation for the redder tails. The default is 0.1.

Returns:

A tuple containing the x-axis and the pdf.

Return type:

tuple

static intrinsic_and_dust(xx='-0.3:1:0.001', cint=-0.075, sigmaint=0.05, tau=0.14)[source]#

Get an exponential decay convolved with and intrinsic gaussian color distribution.

As in Ginolin et al. 2024 (https://arxiv.org/pdf/2406.02072).

Parameters:

xx (str, optional) – The x-axis of the color distribution. It should be a string with the format “min:max:step”. The default is “-0.3:1:0.01”. This is evaluated as np.r_[xx].
cint (float, optional) – The mean of the intrinsic color distribution. The default is -0.075.
sigmaint (float, optional) – The standard deviation of the intrinsic color distribution. The default is 0.05.
tau (float, optional) – The decay constant of the dust distribution. The default is 0.14.

Returns:

A tuple containing the x-axis and the pdf.

Return type:

tuple

class skysurvey.target.snia.SNeIaStretch[source]#

Bases: object

A class to model the stretch of SNe Ia.

static nicolas2021(xx='-4:4:0.005', mu1=0.33, sigma1=0.64, mu2=-1.5, sigma2=0.58, a=0.45, fprompt=0.5)[source]#

Get the pdf of the Nicolas (2021) model.

Parameters:

xx (str or array, optional) – Definition range for the parameters. Draws will be done from this array given the pdf that will be estimated for it. If a string is given, it is evaluated as np.r_[xx]. The default is “-4:4:0.005”.
mu1 (float, optional) – The mean of the first gaussian. The default is 0.33.
sigma1 (float, optional) – The standard deviation of the first gaussian. The default is 0.64.
mu2 (float, optional) – The mean of the second gaussian. The default is -1.50.
sigma2 (float, optional) – The standard deviation of the second gaussian. The default is 0.58.
a (float, optional) – The relative influence of both modes (1 or 2) in the delayed environment. a>0.5 means more mode 1. The default is 0.45.
fprompt (float, optional) – The fraction of prompt SNe Ia. This is ignored if redshift is given. The default is 0.5.

Returns:

A tuple containing the x-axis and the pdf.

Return type:

tuple

class skysurvey.target.snia.SNeIaMagnitude[source]#

Bases: object

A class to model the magnitude of SNe Ia.

static tripp1998(x1, c, mabs=-19.3, sigmaint=0.1, alpha=-0.14, beta=3.15, rng=None)[source]#

Get the 2-parameter absolute (natural) SNe Ia magnitude.

Parameters:

x1 (array) – The lightcurve stretch. x1 and c must have the same size.
c (array) – The lightcurve color. x1 and c must have the same size.
mabs (float, optional) – The average absolute magnitude at c=0 and x1=0. The default is -19.3.
sigmaint (float, optional) – The scale of the normal grey scatter (on mabs). The default is 0.10.
alpha (float, optional) – The stretch linear law coefficient. The default is -0.14.
beta (float, optional) – The color linear law coeeficient. The default is 3.15.
rng (None, int, Generator) – Random number generator seed. (docstring extracted from np.random.default_rng(), see this for complete documentation). If None, then fresh, unpredictable entropy will be pulled from the OS. If an int, then the seed will start from this. If passed a Generator, it will be returned unaltered.

Returns:

The absolute magnitude, with the same format as x1 and c.

Return type:

array

classmethod tripp_and_step(x1, c, isup, mabs=-19.3, sigmaint=0.1, alpha=-0.14, beta=3.15, gamma=0.1, rng=None)[source]#

Get the 2-parameter and step absolute (natural) SNe Ia magnitude.

Parameters:

x1 (array) – The lightcurve stretch. x1 and c must have the same size.
c (array) – The lightcurve color. x1 and c must have the same size.
isup (array) – An array of 0 or 1, flagging which target has +gamma/2 (1) or -gamma/2 (0).
mabs (float, optional) – The average absolute magnitude at c=0 and x1=0. The default is -19.3.
sigmaint (float, optional) – The scale of the normal grey scatter (on mabs). The default is 0.10.
alpha (float, optional) – The stretch linear law coefficient. The default is -0.14.
beta (float, optional) – The color linear law coefficient. The default is 3.15.
gamma (float, optional) – The step’s amplitude. The default is 0.1.

Returns:

The absolute magnitude, with the same format as x1, c and isup.

Return type:

array

classmethod tripp_and_massstep(x1, c, hostmass, mabs=-19.3, sigmaint=0.1, alpha=-0.14, beta=3.15, gamma=0.1, split=10, rng=None)[source]#

Get the 2-parameter and mass step absolute (natural) SNe Ia magnitude.

Parameters:

x1 (array) – The lightcurve stretch. x1 and c must have the same size.
c (array) – The lightcurve color. x1 and c must have the same size.
hostmass (array) – The host stellar mass.
mabs (float, optional) – The average absolute magnitude at c=0 and x1=0. The default is -19.3.
sigmaint (float, optional) – The scale of the normal grey scatter (on mabs). The default is 0.10.
alpha (float, optional) – The stretch linear law coefficient. The default is -0.14.
beta (float, optional) – The color linear law coeeficient. The default is 3.15.
gamma (float, optional) – The step’s amplitude. The default is 0.1.
split (float, optional) – The host mass boundary between low-mass and high-mass hosts. The default is 10.

Returns:

The absolute magnitude, with the same format as x1, c and isup.

Return type:

array

class skysurvey.target.snia.SNeIa[source]#

Bases: Transient

A class to model SNe Ia.

Parameters:

_KIND (str, optional) – The kind of transient. The default is “SNIa”.
_TEMPLATE (str, optional) – The template to use. The default is “salt2”.
_RATE (float, optional) – The rate of SNe Ia. The default is 2.35 * 10**4.
_AMPLITUDE_NAME (str, optional) – The name of the amplitude. The default is “x0”
_MODEL (dict, optional) –
The model to use. The default is a dictionary with the following keys:
- redshift: The redshift of the SNe Ia.
- x1: The stretch of the SNe Ia.
- c: The color of the SNe Ia.
- t0: The time of maximum of the SNe Ia.
- magabs: The absolute magnitude of the SNe Ia.
- magobs: The observed magnitude of the SNe Ia.
- x0: The amplitude of the SNe Ia.
- radec: The ra and dec of the SNe Ia.

target.snia

Contents

target.snia#