Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Host Galaxies of z=4 Quasars   We have undertaken a project to investigate the host galaxies and
environments of a sample of quasars at z~4. In this paper, we describe deep
near-infrared imaging of 34 targets using the Magellan I and Gemini North
telescopes. We discuss in detail special challenges of distortion and
nonlinearity that must be addressed when performing PSF subtraction with data
from these telescopes and their IR cameras, especially in very good seeing. We
derive black hole masses from emission-line spectroscopy, and we calculate
accretion rates from our K_s-band photometry, which directly samples the
rest-frame B for these objects. We introduce a new isophotal diameter technique
for estimating host galaxy luminosities. We report the detection of four host
galaxies on our deepest, sharpest images, and present upper limits for the
others. We find that if host galaxies passively evolve such that they brighten
by 2 magnitudes or more in the rest-frame B band between the present and z=4,
then high-z hosts are less massive at a given black hole mass than are their
low-z counterparts. We argue that the most massive hosts plateau at <~10L*. We
estimate the importance of selection effects on this survey and the subsequent
limitations of our conclusions. These results are in broad agreement with
recent semi-analytical models for the formation of luminous quasars and their
host spheroids by mergers of gas-rich galaxies, with significant dissipation,
and self-regulation of black hole growth and star-formation by the burst of
merger-induced quasar activity.

1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph