Rest-frame FUV-to-FIR view of Lyman break galaxies at $z\sim3$: 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 $z\sim3$ 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 ($\beta_{\mathrm{UV}}$), and stellar mass (M$_{*}$), and then, stacked at optical ($BVriz$ bands), near-infrared ($YJHKs$ bands), IRAC (3.6, 4.5, 5.6 and 8.0 $\mu$m), MIPS (24$\mu$m), PACS (100 and 160~$\mu$m), SPIRE (250, 350, and 500~$\mu$m), and AzTEC (1.1mm) observations. We obtain thirty rest-frame FUV-to-FIR spectral energy distribution (SEDs) of LBGs at $z\sim3$, and analyse them with CIGALE SED-fitting analysis code. We are able to derive fully consistent physical parameters (M$_{*}$, $\beta_{\mathrm{UV}}$, $L_{\mathrm{FUV}}$, $L_{\mathrm{IR}}$, 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 $L_{\mathrm{FUV}}$, $\beta_{\mathrm{UV}}$, and M$_{*}$. We used the so-called IR-excess ($IRX \equiv L_{\mathrm{IR}} / L_{\mathrm{FUV}}$) to investigate the dust attenuation as a function of $\beta_{\mathrm{UV}}$ and M$_{*}$. 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$_{*}$. Stepper dust attenuations curves than Calzetti's are favoured in low stellar mass LBGs ($\log(M_{*} [M_{\odot}]) < 10.25$), while grayer ones are favoured in high stellar mass LBGs ($\log(M_{*} [M_{\odot}]) > 10.25$).