The rocky road to quiescence: compaction and quenching of quasar host galaxies at z ∼ 2

Journal
Date Issued
2021
Author(s)
Stacey, H. R.
•
McKean, J. P.
•
Powell, D. M.
•
Vegetti, S.
•
•
•
Auger, M. W.
•
Ivison, R. J.
•
van der Werf, P. P.
DOI
Abstract
We resolve the host galaxies of seven gravitationally lensed quasars at redshift 1.5-2.8 using observations with the Atacama Large (sub)Millimetre Array. Using a visibility plane lens modelling technique, we create pixellated reconstructions of the dust morphology, and CO line morphology and kinematics. We find that the quasar hosts in our sample can be distinguished into two types: (1) galaxies characterized by clumpy, extended dust distributions (Reff ∼ 2 kpc) and mean star formation rate (SFR) surface densities comparable to sub-mm-selected dusty star-forming galaxies (ΣSFR ∼ 3 M⊙ yr-1 kpc-2 ) and (2) galaxies that have sizes in dust emission similar to coeval passive galaxies and compact starbursts (Reff ∼ 0.5 kpc), with high mean SFR surface densities (ΣSFR = 400-4500 M⊙ yr-1 kpc-2 ) that may be Eddington-limited or super-Eddington. The small sizes of some quasar hosts suggest that we observe them at a stage in their transformation into compact spheroids via dissipative contraction, where a high density of dynamically unstable gas leads to efficient star formation and black hole accretion. For the one system where we probe the bulk of the gas reservoir, we find a gas fraction of just 0.06 ± 0.04 and a depletion time-scale of 50 ± 40 Myr, suggesting it is transitioning into quiescence. In general, we expect that the extreme level of star formation in the compact quasar host galaxies will rapidly exhaust their gas reservoirs and could quench with or without help from active galactic nucleus feedback.
Volume
500
Issue
3
Start page
3667
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2021MNRAS.500.3667S
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

staa3433.pdf

Description
Pdf editoriale
Size

6.03 MB

Format

Adobe PDF

Checksum (MD5)

8851c0b5ed9c36f8837e913d58ad5e49

Loading...
Thumbnail Image
Name

Stacey2021_compressed.pdf

Description
Pdf editoriale
Size

5.07 MB

Format

Adobe PDF

Checksum (MD5)

f08074751c4dfab11e9347c3725a65af