Main sequence of star forming galaxies beyond the Herschel confusion limit

Abstract

Context. Deep far-infrared (FIR) cosmological surveys are known to be affected by source confusion, causing issues when examining the main sequence (MS) of star forming galaxies. In the past this has typically been partially tackled by the use of stacking. However, stacking only provides the average properties of the objects in the stack. Aims. This work aims to trace the MS over 0.2 ≤ z < 6.0 using the latest de-blended Herschel photometry, which reaches ≈ 10 times deeper than the 5σ confusion limit in SPIRE. This provides more reliable star formation rates (SFRs), especially for the fainter galaxies, and hence a more reliable MS. Methods. We built a pipeline that uses the spectral energy distribution (SED) modelling and fitting tool CIGALE to generate flux density priors in the Herschel SPIRE bands. These priors were then fed into the de-blending tool XID+ to extract flux densities from the SPIRE maps. In the final step, multi-wavelength data were combined with the extracted SPIRE flux densities to constrain SEDs and provide stellar mass (M ) and SFRs. These M and SFRs were then used to populate the SFR-M plane over 0.2 ≤ z < 6.0. Results. No significant evidence of a high-mass turn-over was found; the best fit is thus a simple two-parameter power law of the form log(SFR) = α[log(M ) − 10.5] + β. The normalisation of the power law increases with redshift, rapidly at z 1.8, from 0.58 ± 0.09 at z ≈ 0.37 to 1.31 ± 0.08 at z ≈ 1.8. The slope is also found to increase with redshift, perhaps with an excess around 1.8 ≤ z < 2.9. Conclusions. The increasing slope indicates that galaxies become more self-similar as redshift increases. This implies that the specific SFR of high-mass galaxies increases with redshift, from 0.2 to 6.0, becoming closer to that of low-mass galaxies. The excess in the slope at 1.8 ≤ z < 2.9, if present, coincides with the peak of the cosmic star formation history.

Automated Mining of the ALMA Archive in the COSMOS Field (A3COSMOS). II. Cold Molecular Gas Evolution out to Redshift 6

“…This functional form also uses cosmic age as a free parameter (as in our function). 6 We compared various MS in the literature (e.g., Whitaker et al 2014;Sargent et al 2014;Béthermin et al 2015;Schreiber et al 2015;Lee et al 2015;Tomczak et al 2016;Pearson et al 2018), finding that the Speagle et al (2014) cosmic age MS function provides the most reasonable fitting (see Appx. A.5).…”

A panchromatic spatially resolved analysis of nearby galaxies – I. Sub-kpc-scale main sequence in grand-design spirals

“…This picture finds its confirmation in the existence of a tight relation between the galaxy stellar mass (M ) and its star formation rate (SFR): the Main Sequence (MS) of star-forming galaxies (SFGs), observed up to z∼6 with a fairly constant scatter of ∼0.3 dex (e.g. Noeske et al 2007;Elbaz et al 2007;Daddi et al 2007;Pannella et al 2009;Santini et al 2009;Oliver et al 2010;Rodighiero et al 2014;Sobral et al 2014;Steinhardt et al 2014; Spea-E-mail: andrea.enia@unipd.it gle et al 2014;Whitaker et al 2014;Shivaei et al 2015;Schreiber et al 2015;Renzini & Peng 2015;Santini et al 2017;Pearson et al 2018;Popesso et al 2019a). Galaxies seem to oscillate around the MS relation as a consequence of multiple events of central compaction of gas followed by inside-out gas depletion, thus related with the flows of cold gas in galaxies (Tacchella et al 2015).…”

NuSTAR Discovery of a Compton-thick, Dust-obscured Galaxy: WISE J0825+3002

“…The derived stellar mass and SFR are (5.3 ± 4.4) × 10 10 M and 85 ± 39 M yr −1 , respectively, where SFR was estimated based only on resultant parameters of SFH output by CIGALE (see Boquien et al 2019, for more detail). This means that WISE0825+3002 lies above the main sequence of normal star-forming galaxies at similar redshift on M * -SFR plane (e.g., Elbaz et al 2007;Pearson et al 2018), indicating that WISE0825+3002 has an active star formation. This trend is roughly consistent with that of other IR-bright DOGs (Toba et al 2017b).…”