Rest-frame FUV-to-FIR view of Lyman break galaxies at $z\sim 3$: Templates and dust attenuation

Abstract

This work explores from a statistical point of view the rest-frame Far-ultraviolet (FUV) to Far-infrared (FIR) emission of a population of Lyman break galaxies (LBGs) at $z\sim 3$ that cannot be individually detected from current FIR observations. We perform a stacking analysis over a sample of $\sim$17000 LBGs at redshift $2.5<z<3.5$ in the COSMOS field. The sample is binned as a function of UV luminosity ($L_{\mathrm{FUV}}$), UV continuum slope (${\hat{I}}_{\mathrm{UV}}^2$), and stellar mass (M${}_{\ast }$), and then, stacked at optical ($BVriz$ bands), near-infrared ($YJHKs$ bands), IRAC (3.6, 4.5, 5.6 and 8.0 $\hat{I}¼$m), MIPS (24$\hat{I}¼$m), PACS (100 and 160~$\hat{I}¼$m), SPIRE (250, 350, and 500~$\hat{I}¼$m), and AzTEC (1.1mm) observations. We obtain thirty rest-frame FUV-to-FIR spectral energy distribution (SEDs) of LBGs at $z\sim 3$, and analyse them with CIGALE SED-fitting analysis code. We are able to derive fully consistent physical parameters (M${}_{\ast }$, ${\hat{I}}_{\mathrm{UV}}^2$, $L_{\mathrm{FUV}}$, $L_{\mathrm{IR}}$, A${}_{FUV}$, SFR, and slope of the dust attenuation law), and build a semi-empirical library of thirty rest-frame FUV-to-FIR stacked LBG SEDs as a function of $L_{\mathrm{FUV}}$, ${\hat{I}}_{\mathrm{UV}}^2$, and M${}_{\ast }$. We used the so-called IR-excess ($IRX\equiv L_{\mathrm{IR}}/L_{\mathrm{FUV}}$) to investigate the dust attenuation as a function of ${\hat{I}}_{\mathrm{UV}}^2$ and M${}_{\ast }$. Additionally, the SED-fitting analysis results provide a diversity of dust attenuation curve along the LBG sample, and their slope are well correlated with M${}_{\ast }$. Stepper dust attenuations curves than Calzetti's are favoured in low stellar mass LBGs ($\log (M_{\ast }[M_{\odot }])<10.25$), while grayer ones are favoured in high stellar mass LBGs ($\log (M_{\ast }[M_{\odot }])>10.25$).

20 pages, 12 figures, Accepted for publication in A&A