Mastodawn

Knud Jahnke Sep 18, 2023

15 years ago I had to scrape #HST #NICMOS parallel observations for random coverage of 1<z<2 #quasar #hostgalaxies in the near-infrared, to find 10 that I could analyse in terms of structure and stellar mass.

With #ESAEuclid we will cover 15.000 deg^2 and probably cover 10.000 of such quasars. Or 100.000? At lower angular resolution, but much better defined PSF.

https://ui.adsabs.harvard.edu/abs/2009ApJ...706L.215J/abstract

Massive Galaxies in COSMOS: Evolution of Black Hole Versus Bulge Mass but not Versus Total Stellar Mass Over the Last 9 Gyr?

We constrain the ratio of black hole (BH) mass to total stellar mass of type-1 active galactic nuclei (AGNs) in the COSMOS survey at 1 < z < 2. For 10 AGNs at mean redshift z ~ 1.4 with both Hubble Space Telescope (HST)/ACS and HST/NICMOS imaging data, we are able to compute the total stellar mass M *,total, based on rest-frame UV-to-optical host galaxy colors which constrain mass-to-light ratios. All objects have virial M BH estimates available from the COSMOS Magellan/IMACS and zCOSMOS surveys. We find within errors zero difference between the M BH-M *,total relation at z ~ 1.4 and the M BH-M *,bulge relation in the local universe. Our interpretation is (1) if our objects were purely bulge-dominated, the M BH-M *,bulge relation has not evolved since z ~ 1.4. However, (2) since we have evidence for substantial disk components, the bulges of massive galaxies (M *,total = 11.1 ± 0.3 or log M BH ~ 8.3 ± 0.2) must have grown over the last 9 Gyr predominantly by redistribution of the disk into the bulge mass. Since all necessary stellar mass exists in galaxies at z = 1.4, no star formation or addition of external stellar material is required, but only a redistribution, e.g., induced by minor and major merging or through disk instabilities. Merging, in addition to redistributing mass in the galaxy, will add both BH and stellar/bulge mass, but does not change the overall final M BH/M *,bulge ratio. Since the overall cosmic stellar and BH mass buildup trace each other tightly over time, our scenario of bulge formation in massive galaxies is independent of any strong BH feedback and means that the mechanism coupling BH and bulge mass until the present is very indirect. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, the XMM-Newton telescope, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA, the European Southern Observatory under Large Program 175.A-0839, the Magellan Telescope which is operated by the Carnegie Observatories, and the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

NASA/ADS

Corrado Jun 28, 2023

#Starlight and the #firstblackholes: #Researchers detect the #hostgalaxies of #quasars in the #earlyuniverse

https://phys.org/news/2023-06-starlight-black-holes-host-galaxies.html

Starlight and the first black holes: Researchers detect the host galaxies of quasars in the early universe

New images from the James Webb Space Telescope (JWST) have revealed, for the first time, starlight from two massive galaxies hosting actively growing black holes—quasars—seen less than a billion years after the Big Bang. A new study in Nature finds the black holes have masses close to a billion times that of the sun, and the host galaxy masses are almost one hundred times larger, a ratio similar to what is found in the more recent universe. A powerful combination of the Subaru Telescope and the JWST has paved a new path to study the distant universe.

Phys.org

Knud Jahnke Nov 29, 2022

So, have you taken notice that we have now seen the stellar #hostgalaxies of #quasars at z=6.4? Using #JWST we looked at the first two SHELLQ quasars which are ~x10 fainter than the most luminous quasars at high-z. And their host galaxies can clearly be seen. Off-center and massive (logM*~10^8.5). This was not attainable with HST or from the ground.

http://arxiv.org/abs/2211.14329

Detection of stellar light from quasar host galaxies at redshifts above 6

The detection of starlight from the host galaxies of quasars during the reionization epoch ($z>6$) has been elusive, even with deep HST observations. The current highest redshift quasar host detected, at $z=4.5$, required the magnifying effect of a foreground lensing galaxy. Low-luminosity quasars from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) mitigate the challenge of detecting their underlying, previously-undetected host galaxies. Here we report rest-frame optical images and spectroscopy of two HSC-SSP quasars at $z>6$ with JWST. Using NIRCam imaging at 3.6$μ$m and 1.5$μ$m and subtracting the light from the unresolved quasars, we find that the host galaxies are massive (stellar masses of $13\times$ and $3.4\times$ $10^{10}$ M$_{\odot}$, respectively), compact, and disk-like. NIRSpec medium-resolution spectroscopy shows stellar absorption lines in the more massive quasar, confirming the detection of the host. Velocity-broadened gas in the vicinity of these quasars enables measurements of their black hole masses ($1.4\times 10^9$ and $2.0\times$ $10^{8}$ M$_{\odot}$, respectively). Their location in the black hole mass - stellar mass plane is consistent with the distribution at low redshift, suggesting that the relation between black holes and their host galaxies was already in place less than a billion years after the Big Bang.

arXiv.org