The VIMOS Ultra Deep Survey: The reversal of the star-formation rate − density relation at 2 < z < 5

Abstract

Utilizing spectroscopic observations taken for the VIMOS Ultra-Deep Survey (VUDS), new observations from Keck/DEIMOS, and publicly available observations of large samples of star-forming galaxies, we report here on the relationship between the star-formation rate (SFR) and the local environment (δgal) of galaxies in the early universe (2 &lt; z &lt; 5). Unlike what is observed at lower redshifts (z ≲ 2), we observe a definite, nearly monotonic increase in the average SFR with increasing galaxy overdensity over more than an order of magnitude in δgal. The robustness of this trend is quantified by accounting for both uncertainties in our measurements and galaxy populations that are either underrepresented or not present in our sample (e.g., extremely dusty star-forming and quiescent galaxies), and we find that the trend remains significant under all circumstances. This trend appears to be primarily driven by the fractional increase of galaxies in high-density environments that are more massive in their stellar content and are forming stars at a higher rate than their less massive counterparts. We find that, even after stellar mass effects are accounted for, there remains a weak but significant SFR–δgal trend in our sample implying that additional environmentally related processes are helping to drive this trend. We also find clear evidence that the average SFR of galaxies in the densest environments increases with increasing redshift. These results lend themselves to a picture in which massive gas-rich galaxies coalesce into proto-cluster environments at z ≳ 3, interact with other galaxies or with a forming large-scale medium, subsequently using or losing most of their gas in the process, and begin to seed the nascent red sequence that is present in clusters at slightly lower redshifts.

Metal content of the circumgalactic medium around star-forming galaxies at z ∼ 2.6 as revealed by the VIMOS Ultra-Deep Survey

“…Standard data processing was performed using the VIPGI environment (Scodeggio et al 2005), followed by redshift measurements using the EZ package (Garilli et al 2010). The final UV rest-frame flux-limited sample is broadly representative of the bulk of the star-forming galaxy population at these redshifts (2 < z < 5) (Lemaux et al 2022). A critical aspect of VUDS is the large comoving volume covered, totalling 1 deg 2 in three fields: COSMOS (Scoville et al 2007), ECDFS (Giacconi et al 2002), and VVDS02h (Le Fèvre et al 2005.…”

“…In this work we seek to characterize the presence of low-(LIS: O i+Si ii, C ii, Si ii, Fe ii), intermediate-(IIS: Al iii), and high-ionization (HIS: Si iv, C iv) state metal absorption (see Table 2) in the CGM of a star-forming galaxy population at ⟨z⟩ ∼ 2.6 using UV spectra obtained from the large VIMOS Ultra Deep Survey (VUDS; Le . We use thousands of galaxies with the most reliable redshift measurements and the highest S/N spectra (with reliability flags 3 and 4; see Le Fèvre et al 2015;Tasca et al 2017), a sample broadly representative of the bulk of the star-forming galaxy population at these redshifts (Lemaux et al 2022). To detect the dim signal coming from low-and high-ionization line absorptions produced in the CGM of these star-forming galaxies, we stack the spectra of close (in projection) background galaxies to establish the metal distribution in the CGM and explore their dependence on the physical and morphological properties of starforming galaxies (e.g.…”

Metal content of the circumgalactic medium around star-forming galaxies at z $\sim$ 2.6 as revealed by the VIMOS Ultra-Deep Survey

“…Standard data processing was performed using the VIPGI environment (Scodeggio et al 2005), followed by redshift measurements using the EZ package (Garilli et al 2010). The final UV rest-frame flux-limited sample is broadly representative of the bulk of the star-forming galaxy population at these redshifts (2 < z < 5) (Lemaux et al 2022). A critical aspect of VUDS is the large comoving volume covered, totalling of 1 deg 2 in three fields: COSMOS (Scoville et al 2007), ECDFS (Giacconi et al 2002), and VVDS02h (Le Fèvre et al 2005.…”

“…In this work, we seek to characterize the presence of low-(LIS: O i+Si ii, C ii, Si ii, Fe ii), intermediate-(IIS: Al iii) and high-ionization (HIS: Si iv, C iv) state metal absorption (see Table 2) in the CGM of a star-forming galaxy population at z ∼ 2.6 using UV spectra obtained from the large VIMOS Ultra Deep Survey (VUDS; Le . We use thousands of galaxies with the most reliable redshift measurements and the highest S/N spectra (with reliability flags 3 and 4; see Le Fèvre et al 2015;Tasca et al 2017), a sample broadly representative of the bulk of the star-forming galaxy population at these redshifts (Lemaux et al 2022). To detect the dim signal coming from low-and high ionization line absorptions produced in the CGM of these star-forming galaxies, we stack the spectra of close (in projection) background galaxies to establish the metal distribution in the CGM and explore their dependence on the physical and morphological properties of starforming galaxies (e.g., impact parameter b, star formation rate, stellar mass, galaxy effective radius and azimuthal angle) at the peak epoch of cosmic star formation activity in the Universe.…”

The ALPINE–ALMA [C ii] Survey: The Infrared–Radio Correlation and Active Galactic Nucleus Fraction of Star-forming Galaxies at z ∼ 4.4–5.9

“…Nine ALPINE galaxies are covered by the NB2071 and NB2083 narrow-band imaging taken with the Multi-Object Infrared Camera and Spectrograph (Ichikawa et al 2006;Suzuki et al 2008) on the Subaru Telescope, as part of the Charting Cluster Construction with the VUDS (Le Fèvre et al 2015) and ORELSE (Lubin et al 2009) surveys (Lemaux et al 2022;Shen et al 2021). These observations are designed to target the [O II] emission in the massive protocluster PCl J1001 +0220 at z ∼ 4.57 and its surroundings in the COSMOS field (Lemaux et al 2018).…”