Spatially resolved Kennicutt-Schmidt relation at z ≈ 7 and its connection with the interstellar medium properties
Abstract
We exploit moderately resolved [O $\scriptstyle \rm III$], [C $\scriptstyle \rm II$] and dust continuum ALMA observations to derive the gas density (n), the gas-phase metallicity (Z), and the deviation from the Kennicutt-Schmidt (KS) relation (κs) on $\approx \, \rm sub-kpc$ scales in the interstellar medium (ISM) of five bright Lyman Break Galaxies at the Epoch of Reionization (z ≈ 7). To do so, we use GLAM, a state-of-art, physically motivated Bayesian model that links the [C $\scriptstyle \rm II$]and [O $\scriptstyle \rm III$]surface brightness (Σ[CII], Σ[OIII]) and the SFR surface density (ΣSFR) to n, κs, and Z. All five sources are characterized by a central starbursting region, where the Σgas versus ΣSFR align ≈10 × above the KS relation (κs ≈ 10). This translates into gas depletion times in the range tdep ≈ 80 - 250 Myr. The inner starbursting centres are characterized by higher gas density (log (n/cm-3) ≈ 2.5-3.0) and higher metallicity (log (Z/Z⊙) ≈ -0.5) than the galaxy outskirts. We derive marginally negative radial metallicity gradients (∇log Z ≈ -0.03 ± 0.07 dex/kpc), and a dust temperature (Td ≈ 32 - 38 K) that anticorrelates with the gas depletion time.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2024
- DOI:
- 10.1093/mnras/stad3150
- arXiv:
- arXiv:2309.07957
- Bibcode:
- 2024MNRAS.527...10V
- Keywords:
-
- galaxies: evolution;
- galaxies: high-redshift;
- galaxies: ISM;
- dark ages;
- reionization;
- first stars;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 13 pages, 7 figures. Resubmitted to MNRAS after addressing the referee comments