2SFM: 2 star-forming modes

2SFM: 2 star-forming modes


Material associated to 2SFM family of models of galaxy evolution



-> Béthermin et al. (2012, astro-ph:1208.6512, ApJL 757 23, hereafter B12) counts model:


Abstract: We reproduce the mid-infrared to radio galaxy counts with a new empirical model based on our current understanding of the evolution of main-sequence (MS) and starburst (SB) galaxies. We rely on a simple Spectral Energy Distribution (SED) library based on Herschel observations: a single SED for the MS and another one for SB, getting warmer with redshift. Our model is able to reproduce recent measurements of galaxy counts performed with Herschel, including counts per redshift slice. This agreement demonstrates the power of our 2 Star-Formation Modes (2SFM) decomposition for describing the statistical properties of infrared sources and their evolution with cosmic time. We discuss the relative contribution of MS and SB galaxies to the number counts at various wavelengths and flux densities. We also show that MS galaxies are responsible for a bump in the 1.4 GHz radio counts around 50 uJy. Material of the model (predictions, SED library, mock catalogs...) is available online.



Counts tables: Table containing counts for several popular passbands can be found here.













 Radio_counts.txt (1.4 GHz)


Counts grids: Our model is able to predict number counts at several wavelengths. The following IDL savesets contains grids containing dN/dS/dz (number of sources per flux and redshift interval in Jy^-1/sr) for a large range of flux and redshift.


The variable stored in this files are:

band: name of the passband filter used

lambda:  (in microns)

Snu: vector of flux (in Jy)

z: vector of redshift

dndsnudz: counts of all sources (in gal/Jy/sr, Nflux x Nredshift x Nband array)

dndsnudz_ms: counts of main sequence galaxies

dndsnudz_sb: counts of main sequence galaxies

dndsnudz_lensed: counts of lensed galaxies

dndsnudz_ms_lensed: counts of lensed main sequence galaxies

dndsnudz_sb_lensed: counts of lensed starburst galaxies


Bethermin2012model_grids.save (32 Mo)



SEDs: The SEDs used in the counts model were based on Magdis et al. (2012, hereafter M12) SED library. The main-sequence (MS) SEDs is just an re-interpolation on the 8 templates of M12 on a finer redshift grid following the parametric evolution of U (radiation field intensity in Draine&Li model) provided in B12. The starburst (SB) SEDs are based on the G20 template of M12, but build with other U values following the parametric form used in B12. If you use the grids released on this website, please cite both M12 and B12.


SED for an IR galaxies following exactly the mean U = f(z) relation of B12 (no scatter):


This IDL file contains:

- lambda_grids: vector of wavelengths (in microns).

- z_grids: vector of redshift.

- snu_grids_ms: array of flux as a function of observed wavelength and redshift for MS templates.

- snu_grids_sb: array of flux as a function of observed wavelength and redshift for SB templates.

The SEDs are in Jy and normalized at LIR = 1 Lsun. The redshift effect is thus included in the computation and lambda_grids is thus observer frame.


SED library with scatter in U (0.2 dex):


Same type of grid with an extra dimension for scatter in U (distance to the mean relation given in the sigma vector).


Effective SEDs at a given redshift (from B12 model):


- lambda_grids: vector of wavelengths (in microns).

- z_grids: vector of redshift.

- snumean_ms: array of mean flux as a function of observed wavelength and redshift of MS galaxies.

- snumean_sb: array of mean flux as a function of observed wavelength and redshift of SB galaxies.

- snu_eff: array of flux as a function of observed wavelength and redshift for effective SED (i.e. mean SEDs of all galaxies at a given redshift). These templates are not normalized to LIR = 1 Lsun, but take into account the excess caused by starburst as explained in Béthermin et al. (2013). 
- snu_eff_norm: same library but normalized at LIR = 1 Lsun.


Original SED library at: http://georgiosmagdis.pbworks.com/


Mock catalog: PRELIMINARY mock catalog for a virtual observation of a 1 deg2 field, based on the Béthermin et al. (2012) model (but without AGN activity and lensing).


This IDL save file contains:

- fieldsize: field size in sr.

- zlist: list of redshift

- mstarlist : list of stellar masses in Msun.

- lirlist: list of bolometric IR luminosity in Lsun.

- sfrlist: list of SFR in Msun/yr.

- typelist: list of type (MS or SB)

- Snulist: array of flux densities in Jy.

- band: list of band where flux density is computed.



If you have any problems or special request, please contact matthieu bethermin (at) cea fr.

#537 - Mise à jour : 12/04/2013


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