Quiescent galaxies at z=4: formation and evolution
| Main Author: | Francesco Valentino |
|---|---|
| Format: | info Proceeding |
| Terbitan: |
, 2019
|
| Online Access: |
https://zenodo.org/record/3519283 |
Daftar Isi:
- We present our spectroscopic study of quenching/quiescent galaxies at z~4, resulted in the confirmation of 2 systems and a tentative constraint on a third one with Keck/MOSFIRE and VLT/X-Shooter. The confirmed objects include a compact system at z=4.01 with a measured stellar velocity dispersion of 268+/-59 km/s, fully consistent with z~2 quiescent galaxies. The absence of nebular emission lines and far-infrared detections confirms a suppressed star formation. From the joint modeling of the spectrum and the SED, we derive stellar masses of log(M*/Msun)~11, placing these galaxies >1-2 dex below the main sequence. Such modeling suggests that these sources experienced a strong (SFR~1200-3500 Msun/yr) and short (~50 Myr) burst of star formation in their past, properties reminiscent of the population of sub-mm galaxies (SMGs), generally indicated as candidate progenitors. We thus compare the comoving number densities and the expected properties of the progenitors with observations of z>4 SMGs, finding a fair agreement with the deepest surveys detecting not only the most extreme starbursts, but also more normal galaxies. Exploring the Illustris-TNG simulation, we do retrieve populations of quiescent galaxies at z~3-4 and SMGs at z~4-5, with number densities and properties in rough agreement with the observations at z~3, but in increasing tension at higher redshift. We find that not all the progenitors of z~4 quiescent galaxies shine as bright SMGs in their past and, conversely, not all bright SMGs quench by z~3. This cautions against the blind assumption of a univocal connection between the two populations at high redshift.