74 research outputs found
Outflow and hot dust emission in high redshift quasars
Correlations of hot dust emission with outflow properties are investigated,
based on a large z~2 non-broad absorption lines quasar sample built from the
Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We
use the near infrared slope and the infrared to UV luminosity ratio to indicate
the hot dust emission relative to the emission from the accretion disk. In our
luminous quasars, these hot dust emission indicators are almost independent of
the fundamental parameters, such as luminosity, Eddington ratio and black hole
mass, but moderately dependent on the blueshift and asymmetry index (BAI) and
full width at half-maximum (FWHM) of CIV lines. Interestingly, the latter two
correlations dramatically strengthen with increasing Eddington ratio. We
suggest that, in high Eddington ratio quasars, CIV regions are dominated by
outflows so the BAI and FWHM(CIV) can reliably reflect the general properties
and velocity of outflows, respectively. While in low Eddington ratio quasars,
CIV lines are primarily emitted by virialized gas so the BAI and FWHM(CIV)
become less sensitive to outflows. Therefore, the correlations for the highest
Eddington ratio quasars are more likely to represent the true dependence of hot
dust emission on outflows and the correlations for the entire sample are
significantly diluted by the low Eddington ratio quasars. Our results show that
an outflow with a large BAI or velocity can double the hot dust emission on
average. We suggest that outflows either contain hot dust in themselves or
interact with the dusty interstellar medium or torus.Comment: 14 page, 4 figures, accepted for publication in ApJ
Obscured Binary Quasar Cores in SDSS J104807.74+005543.5?
We report the discovery of a possible close binary system of quasars in SDSS
J1048+0055. The [OIII]4959,5007 emission lines are clearly double-peaked, and
two discrete radio sources with a projected physical separation of ~20 pc are
found in the VLBA milliarcsec resolution image at 8.4 GHz. Each of the [O
III]4959,5007 doublets and Hbeta can be well modelled by two Gaussians and the
line ratio, [O III]5007/Hbeta ~7, is typical of Seyfert 2 galaxies. No broad
component of Hbeta was detected and its [O III]5007 luminosity, L_[OIII] ~ 9.2
times 10^42 erg s^-1, is comparable to luminous quasars and is a few ten times
more luminous than typical Seyfert galaxies. One natural interpretation is that
SDSS J1048+0055 contains two close quasar-like nuclei and the BLR around them
are obscured. Other possible models are also discussed. We suggest that
double-peaked narrow emission line profile may be an effective way of selecting
candidates of binary black holes with intermediate separation
Outflow and hot dust emission in broad absorption line quasars
We have investigated a sample of 2099 broad absorption line (BAL) quasars
with z=1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and
the Wide-field Infrared Survey. This sample is collected from two BAL quasar
samples in the literature, and refined by our new algorithm. Correlations of
outflow velocity and strength with hot dust indicator (beta_NIR) and other
quasar physical parameters, such as Eddington ratio, luminosity and UV
continuum slope, are explored in order to figure out which parameters drive
outflows. Here beta_NIR is the near-infrared continuum slope, a good indicator
of the amount of hot dust emission relative to accretion disk emission. We
confirm previous findings that outflow properties moderately or weakly depends
on Eddington ratio, UV slope and luminosity. For the first time, we report
moderate and significant correlations of outflow strength and velocity with
beta_NIR in BAL quasars. It is consistent with the behavior of blueshifted
broad emission lines in non-BAL quasars. The statistical analysis and composite
spectra study both reveal that outflow strength and velocity are more strongly
correlated with beta_NIR than Eddington ratio, luminosity and UV slope. In
particular, the composites show that the entire C IV absorption profile shifts
blueward and broadens as beta_NIR increases, while Eddington ratio and UV slope
only affect the high and low velocity part of outflows, respectively. We
discuss several potential processes and suggest that dusty outflow scenario,
i.e. dust is intrinsic to outflows and may contribute to the outflow
acceleration, is most likely. The BAL quasar catalog is available from the
authors upon request.Comment: 16 pages, 10 figures, 2 tables; Accepted for publication in The
Astrophysical Journa
Criteria for SLOCC and LU Equivalence of Generic Multi-qudit States
In this paper, we study the stochastic local operation and classical
communication (SLOCC) and local unitary (LU) equivalence for multi-qudit states
by mode- matricization of the coefficient tensors. We establish a new scheme
of using the CANDECOMP/PARAFAC (CP) decomposition of tensors to find necessary
and sufficient conditions between the mode- unfolding and SLOCC\&LU
equivalence for pure multi-qudit states. For multipartite mixed states, we
present a necessary and sufficient condition for LU equivalence and necessary
condition for SLOCC equivalence
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