101 research outputs found
X-ray - Infrared relation of AGNs and search for highly obscured accretion in the AKARI NEP Field
The infrared Astronomical Satellite AKARI conducted deep ( 0.4 deg)
and wide ( deg) surveys around the North Ecliptic Pole (NEP) with
its InfraRed Camera (IRC) with nine filters continuously covering the 2-25
m range. These photometric bands include three filters that fill the
`Spitzer gap' between the wavelength coverages of IRAC and MIPS. This unique
feature has enabled us to make sensitive mid-infrared detection of AGN
candidates at z 1-2, based on the Spectral Energy Distribution (SED)
fitting including hot dust emission in the AGN torus. This enables us to
compare X-rays and the AGN torus component of the infrared emission to help us
identify highly absorbed AGNs, including Compton-thick ones. We report our
results of the Chandra observation of the AKARI NEP Deep Field and discuss the
prospects for upcoming Spectrum-RG (eROSITA+ART-XC) on the AKARI Wide field.Comment: 4 pages, 2 figures. Submitted for publication in the proceedings of
the IAU Symp. 341 "PanModel2018 : Challenges in Panchromatic Galaxy Modelling
with Next Generation Facilities
Clustering Measurements of broad-line AGNs: Review and Future
Despite substantial effort, the precise physical processes that lead to the
growth of super-massive black holes in the centers of galaxies are still not
well understood. These phases of black hole growth are thought to be of key
importance in understanding galaxy evolution. Forthcoming missions such as
eROSITA, HETDEX, eBOSS, BigBOSS, LSST, and Pan-STARRS will compile by far the
largest ever Active Galactic Nuclei (AGNs) catalogs which will allow us to
measure the spatial distribution of AGNs in the universe with unprecedented
accuracy. For the first time, AGN clustering measurements will reach a level of
precision that will not only allow for an alternative approach to answering
open questions in AGN/galaxy co-evolution but will open a new frontier,
allowing us to precisely determine cosmological parameters. This paper reviews
the large-scale clustering measurements of broad line AGNs. We summarize how
clustering is measured and which constraints can be derived from AGN clustering
measurements, we discuss recent developments, and we briefly describe future
projects that will deliver extremely large AGN samples which will enable AGN
clustering measurements of unprecedented accuracy. In order to maximize the
scientific return on the research fields of AGN/galaxy evolution and cosmology,
we advise that the community develop a full understanding of the systematic
uncertainties which will, in contrast to today's measurement, be the dominant
source of uncertainty.Comment: referred review article, paper is in print in Acta Polytechnica, 7
pages, 3 figure
Chandra Observations of Six QSOs at z 3
We report the results of our Chandra observations of six QSOs at
from the Palomer Transit Grism Survey. Our primary goal is to investigate the
possible systematic change of between and ,
between which a rapid rise of luminous QSO number density with cosmic time is
observed. The summed spectrum showed a power-law spectrum with photon index of
, which is similar to other unabsorbed AGNs. Combining our
QSOs with X-ray observations of QSOs at from literaure/archive,
we find a correlation of with optical luminosity. This is
consistent with the fact that the luminosity function slope of the luminous end
of the X-ray selected QSOs is steeper than that of optically-selected QSOs. We
discuss an upper limit to the redshift dependence of using a
Monte-Carlo simulation. Within the current statistical errors including the
derived limits on the redshift dependence of , we found that
the behaviors of the X-ray and optically-selected QSO number densities are
consistent with each other.Comment: 13 Pages, 3 Figures, Astronomical Journal in press, An entry in Table
2 corrected--Log Lx for PC 1000+4751 from 44.0 (incorrect) to 45.0 (correct).
A few minor errors correcte
Soft X-ray AGN Luminosity Function from ROSAT Surveys II. Table of the binned Soft X-ray Luminosity Function
This is the second paper of our investigation of the 0.5-2 keV soft X-ray
luminosity function (SXLF) of active galactic nuclei (AGN) using results from
ROSAT surveys of various depth. The large dynamic range of the combined sample,
from shallow large-area ROSAT All-Sky Survey (RASS)-based samples to the
satellite's deepest pointed observation on the Lockman Hole, enabled us to
trace the behavior of the SXLF. While the first paper (Miyaji, Hasinger,
Schmidt 2000, hereafter paper I) emphasized the global behavior of the SXLF,
cosmological evolution and contribution to the soft X-ray background, this
paper presents actual numerical values for practical use of our results.
To present the binned SXLF, we have used an improved estimator, which is free
from biases associated with the conventional 1/Va estimator.Comment: 8 pages, 2 figures, 6 ASCII Tables with a ReadMe file. To appear in
A&A. Replaced for an insignificant minor fi
Clustering Measurements of broad-line AGNs: Review and Future
Despite substantial effort, the precise physical processes that lead to the growth of super-massive black holes in the centers of galaxies are still not well understood. These phases of black hole growth are thought to be of key importance in understanding galaxy evolution. Forthcoming missions such as eROSITA, HETDEX, eBOSS, BigBOSS, LSST, and Pan-STARRS will compile by far the largest ever Active Galactic Nuclei (AGNs) catalogs which will allow us to measure the spatial distribution of AGNs in the universe with unprecedented accuracy. For the first time, AGN clustering measurements will reach a level of precision that will not only allow for an alternative approach to answering open questions in AGN and galaxy co-evolution but will open a new frontier, allowing us to precisely determine cosmological parameters. This paper reviews large-scale clustering measurements of broad line AGNs. We summarize how clustering is measured and which constraints can be derived from AGN clustering measurements, we discuss recent developments, and we briefly describe future projects that will deliver extremely large AGN samples which will enable AGN clustering measurements of unprecedented accuracy. In order to maximize the scientific return on the research fields of AGN and galaxy evolution and cosmology, we advise that the community develops a full understanding of the systematic uncertainties which will, in contrast to today’s measurement, be the dominant source of uncertainty
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