Star formation history of $\rm{0.1\leq\,\textit{z}\,\leq\,1.5}$ mass-selected galaxies in the ELAIS-N1 Field

TL;DR

This study investigates the star formation history of mass-selected galaxies between redshifts 0.1 and 1.5 in the ELAIS-N1 field, revealing how specific star formation rates evolve with mass and redshift using radio stacking techniques.

Contribution

It presents a novel analysis of sSFR evolution in mass-selected galaxies across a wide redshift range using deep radio data and multi-wavelength diagnostics.

Findings

Massive galaxies have the lowest sSFRs, consistent with previous studies.

The sSFR-mass relation steepens with redshift, indicating downsizing.

sSFR evolution follows a power law with redshift, with different slopes for all galaxies and star-forming galaxies.

Abstract

We measure the specific star formation rates of \textit{K}-band selected galaxies from the ELAIS-N1 by stacking GMRT data at 610 MHz. We identify a sample of SFGs, spanning $\rm{0.1\leq\,\textit{z}\,\leq\,1.5}$ and $\rm{10^{8.5}<\,{\textit{M}_{\star}}/{\textit{M}_{\odot}}<10^{12.4}}$, using a combination of multi-wavelength diagnostics obtained from the deep LoTSS multi-wavelength catalogue. We measure the flux densities in the radio map and estimate the radio SFR in order to probe the nature of the galaxies below the noise and confusion limits. The massive galaxies in our sample have the lowest sSFRs which is in agreement with previous studies. For the different populations, we show that the sSFR-mass relation steepens with redshift, with an average slope of $\rm{\langle \beta_{All} \rangle\,=\, -0.49\pm0.01}$ for the whole sample, and $\rm{\langle \beta_{SFG} \rangle\,=\, -0.42\pm0.02}$ for the SFGs. Our results indicate that galaxy populations undergo 'downsizing', whereby most massive galaxies form their stars earlier and more rapidly than low mass galaxies. Both populations show a strong decrease in their sSFR toward the present epoch. The sSFR evolution with redshift is best described by a power law $\rm{(1\,+\,\textit{z})^\textit{n}}$, where $\rm{\langle \textit{n}_{ALL}\rangle\sim4.94\pm0.53}$ for all galaxies, and $\rm{\langle \textit{n}_{SFG}\rangle \sim3.51\pm0.52}$ for SFGs. Comparing our measured sSFRs to results from literature, we find a general agreement in the \textit{sSFR-M$_{\star}$} plane.