1,701 research outputs found
Supermassive Black Hole Mass Regulated by Host Galaxy Morphology
We investigated the relationship between supermassive black hole (SMBH) mass
and host starburst luminosity in Seyfert galaxies and Palomar-Green QSOs,
focusing on the host galaxy morphology. Host starburst luminosity was derived
from the 11.3 micron polycyclic aromatic hydrocarbon luminosity. We found that
the SMBH masses of elliptical-dominated host galaxies are more massive than
those of disk-dominated host galaxies statistically. We also found that the
SMBH masses of disk-dominated host galaxies seem to be suppressed even under
increasing starburst luminosity. These findings imply that final SMBH mass is
strongly regulated by host galaxy morphology. This can be understood by
considering the radiation drag model as the SMBH growth mechanism, taking into
account the radiation efficiency of the host galaxy.Comment: 6 pages, 1 figure; accepted for publication in MNRA
The X-ray emission from Young Stellar Objects in the rho Ophiuchi cloud core as seen by XMM-Newton
We observed the main core F of the rho Ophiuchi cloud, an active star-forming
region located at ~140 pc, using XMM-Newton with an exposure of 33 ks. We
detect 87 X-ray sources within the 30' diameter field-of-view of the it EPIC
imaging detector array. We cross-correlate the positions of XMM-Newton X-ray
sources with previous X-ray and infrared (IR) catalogs: 25 previously unknown
X-ray sources are found from our observation; 43 X-ray sources are detected by
both XMM-Newton and Chandra; 68 XMM-Newton X-ray sources have 2MASS near-IR
counterparts. We show that XMM-Newton and Chandra have comparable sensitivity
for point source detection when the exposure time is set to ~30 ks for both. We
detect X-ray emission from 7 Class I sources, 26 Class II sources, and 17 Class
III sources. The X-ray detection rate of Class I sources is very high (64 %),
which is consistent with previous Chandra observations in this area. We propose
that 15 X-ray sources are new class III candidates, which doubles the number of
known Class III sources, and helps to complete the census of YSOs in this area.
We also detect X-ray emission from two young bona fide brown dwarfs, GY310 and
GY141, out of three known in the field of view. GY141 appears brighter by
nearly two orders of magnitude than in the Chandra observation. We extract
X-ray light curves and spectra from these YSOs, and find some of them showed
weak X-ray flares. We observed an X-ray flare from the bona fide brown dwarf
GY310. We find as in the previous Chandra observation of this region that Class
I sources tend to have higher temperatures and heavier X-ray absorptions than
Class II and III sources.Comment: 17 pages, 13 figures, 4 tables, accepted by A&
Hyperlink Management System and ID Converter System: enabling maintenance-free hyperlinks among major biological databases
Hyperlink Management System (HMS) is a system for automatically updating and maintaining hyperlinks among major public databases in the field of life science. We daily create corresponding tables of data IDs of major databases for human genes and proteins, and provide a CGI-program that returns correct and up-to-date URLs for showing data of various databases that correspond to user-specified IDs. The HMS can deal with various IDs: accession numbers of International Nucleotide Sequence Databases, HUGO Gene Symbols and IDs of UniProt, PDB, H-InvDB and others, and it can return URLs of various databases: H-InvDB, HUGO Gene Nomenclature Committee Database, NCBI Entrez Gene, UniProt, PDB and others. For example, 23 297 pages of Locus view of H-InvDB are reachable by using HUGO Gene Symbols through the HMS. Not only the CGI-program, the HMS provides a Web page for finding and opening URLs of these databases. Although hyperlinking is an effective way of relating biological data among different databases, updating hyperlinks has been a laborious work. The HMS fully automates the job, enabling maintenance-free hyperlinks. We also developed the ID Converter System (ICS) for simply converting data IDs by using corresponding tables in the HMS. The HMS and ICS are freely available at http://biodb.jp/
Subaru Spectroscopy and Spectral Modeling of Cygnus A
We present high angular resolution (0.5) MIR spectra
of the powerful radio galaxy, Cygnus A, obtained with the Subaru telescope. The
overall shape of the spectra agree with previous high angular resolution MIR
observations, as well as previous Spitzer spectra. Our spectra, both on and off
nucleus, show a deep silicate absorption feature. The absorption feature can be
modeled with a blackbody obscured by cold dust or a clumpy torus. The deep
silicate feature is best fit by a simple model of a screened blackbody,
suggesting foreground absorption plays a significant, if not dominant role, in
shaping the spectrum of Cygnus A. This foreground absorption prevents a clear
view of the central engine and surrounding torus, making it difficult to
quantify the extent the torus attributes to the obscuration of the central
engine, but does not eliminate the need for a torus in Cygnus A
The structure of the Au(111)/methylthiolate interface : new insights from near-edge X-ray absorption spectroscopy and X-ray standing waves
The local structure of the Au(111)([square root of]3Ă[square root of]3)R30°-methylthiolate surface phase has been investigated by S K-edge near-edge s-ray absorption fine structure (NEXAFS) both experimentally and theoretically and by experimental normal-incidence x-ray standing waves (NIXSW) at both the C and S atomic sites. NEXAFS shows not only excitation into the intramolecular sigma* SâC resonance but also into a sigma* SâAu orbital perpendicular to the surface, clearly identifying the local S headgroup site as atop a Au atom. Simulations show that it is not possible, however, to distinguish between the two possible adatom reconstruction models; a single thiolate species atop a hollow-site Au adatom or a dithiolate moiety comprising two thiolate species bonded to a bridge-bonded Au adatom. Within this dithiolate moiety a second sigma* SâAu orbital that lies near parallel to the surface has a higher energy that overlaps that of the sigma* SâC resonance. The new NIXSW data show the SâC bond to be tilted by 61° relative to the surface normal, with a preferred azimuthal orientation in , corresponding to the intermolecular nearest-neighbor directions. This azimuthal orientation is consistent with the thiolate being atop a hollow-site Au adatom, but not consistent with the originally proposed Au-adatom-dithiolate moiety. However, internal conformational changes within this species could, perhaps, render this model also consistent with the experimental data
A Study of the Populations of X-ray Sources in the Small Magellanic Cloud with ASCA
The Advanced Satellite for Cosmology and Astrophysics (ASCA) has made
multiple observations of the Small Magellanic Cloud (SMC). X-ray mosaic images
in the soft (0.7--2.0 keV) and hard (2.0--7.0 keV) bands are separately
constructed, and the latter provides the first hard X-ray view of the SMC. We
extract 39 sources from the two-band images with a criterion of S/N>5, and
conduct timing and spectral analyses for all of these sources. Coherent
pulsations are detected from 12 X-ray sources; five of which are new
discoveries. Most of the 12 X-ray pulsars are found to exhibit long-term flux
variabilities, hence they are likely to be X-ray binary pulsars (XBPs). On the
other hand, we classify four supernova remnants (SNRs) as thermal SNRs, because
their spectra exhibit emission lines from highly ionized atoms. We find that
XBPs and thermal SNRs in the SMC can be clearly separated by their hardness
ratio (the ratio of the count rate between the hard and soft bands). Using this
empirical grouping, we find many XBP candidates in the SMC, although no
pulsations have yet been detected from these sources. Possible implications on
the star-formation history and evolution of the SMC are presented by a
comparison of the source populations in the SMC and our Galaxy.Comment: 11 pages, 39 Figures, to be published in ApJ Supplement. Tables (body
and figures also) are available at
http://www-cr.scphys.kyoto-u.ac.jp/member/jun/job
Spectral decomposition of starbursts and AGNs in 5-8 micron Spitzer IRS spectra of local ULIRGs
We present an analysis of the 5-8 micron Spitzer-IRS spectra of a sample of
68 local Ultraluminous Infrared Galaxies (ULIRGs). Our diagnostic technique
allows a clear separation of the active galactic nucleus (AGN) and starburst
(SB) components in the observed mid-IR emission, and a simple analytic model
provides a quantitative estimate of the AGN/starburst contribution to the
bolometric luminosity. We show that AGNs are ~30 times brighter at 6 micron
than starbursts with the same bolometric luminosity, so that even faint AGNs
can be detected. Star formation events are confirmed as the dominant power
source for extreme infrared activity, since ~85% of ULIRG luminosity arises
from the SB component. Nonetheless an AGN is present in the majority (46/68) of
our sources.Comment: 5 Pages, 3 figures. MNRAS Letters, Accepte
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