60 research outputs found
Spectroscopy of broad absorption line quasars at -- I: evidence for quasar winds shaping broad/narrow emission line regions
We present an observational study of 22 broad absorption line quasars (BAL
QSOs) at based on optical/near-IR spectroscopy, aiming
to investigate quasar winds and their effects. The near-IR spectroscopy covers
the \hb\ and/or \mgii\ broad emission lines (BELs) for these quasars, allowing
us to estimate their central black hole (BH) masses in a robust way. We found
that our BAL QSOs on average do not have a higher Eddington ratio than that
from non-BAL QSOs matched in redshift and/or luminosity. In a subset consisting
of seven strong BAL QSOs possessing sub-relativistic BAL outflows, we see the
prevalence of large \civ-BEL blueshift (3100 km s) and weak \oiii\
emission (particularly the narrow \oiii5007 component), indicative of
nuclear outflows affecting the narrow emission-line (NEL) regions. In another
subset consisting of thirteen BAL QSOs having simultaneous observations of
\mgii\ and \hb, we found a strong correlation between 3000~\AA\ and 5000~\AA\
monochromatic luminosity, consistent with that from non-BAL QSOs matched in
redshift and luminosity; however, there is no correlation between \mgii\ and
\hb\ in FWHM, likely due to nuclear outflows influencing the BEL regions. Our
spectroscopic investigations offer strong evidence that the presence of nuclear
outflows plays an important role in shaping the BEL/NEL regions of these
quasars and possibly, regulating the growth of central supermassive black holes
(SMBHs). We propose that BEL blueshift and BAL could be different
manifestations of the same outflow system viewed at different sightlines and/or
phases.Comment: 13 pages, 10 figures. Accepted for publication in Ap
Black Hole Mass Estimates and Rapid Growth of Supermassive Black Holes in Luminous 3.5 Quasars
We present new near-infrared (IR) observations of the H
and MgII lines for 32 luminous quasars with using the
Palomar Hale 200 inch telescope and the Large Binocular Telescope. We find that
the MgII Full Width at Half Maximum (FWHM) is well correlated with the H
FWHM, confirming itself as a good substitute for the H FWHM in the black
hole mass estimates. The continuum luminosity at 5100 \AA\ well correlates with
the continuum luminosity at 3000 \AA\ and the broad emission line luminosities
(H and MgII). With simultaneous near-IR spectroscopy of the H and
MgII lines to exclude the influences of flux variability, we are able to
evaluate the reliability of estimating black hole masses based on the MgII line
for high redshift quasars. With the reliable H line based black hole
mass and Eddington ratio estimates, we find that the quasars in our
sample have black hole masses , with a median of and are accreting at Eddington ratios between 0.30 and 3.05, with a
median of . Assuming a duty cycle of 1 and a seed black hole mass of
, we show that the quasars in this sample can grow
to their estimated black hole masses within the age of the Universe at their
redshifts.Comment: 38 pages, 6 figures, accepted for publication in Ap
Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-Infrared Photometric Data
We present a new algorithm to estimate quasar photometric redshifts
(photo-s), by considering the asymmetries in the relative flux distributions
of quasars. The relative flux models are built with multivariate Skew-t
distributions in the multi-dimensional space of relative fluxes as a function
of redshift and magnitude. For 151,392 quasars in the SDSS, we achieve a
photo- accuracy, defined as the fraction of quasars with the difference
between the photo- and the spectroscopic redshift , within 0.1, of 74%. Combining the WISE W1 and W2 infrared
data with the SDSS data, the photo- accuracy is enhanced to 87%. Using the
Pan-STARRS1 or DECaLS photometry with WISE W1 and W2 data, the photo-
accuracies are 79% and 72%, respectively. The prior probabilities as a function
of magnitude for quasars, stars and galaxies are calculated respectively based
on (1) the quasar luminosity function; (2) the Milky Way synthetic simulation
with the Besan\c{c}on model; (3) the Bayesian Galaxy Photometric Redshift
estimation. The relative fluxes of stars are obtained with the Padova
isochrones, and the relative fluxes of galaxies are modeled through galaxy
templates. We test our classification method to select quasars using the DECaLS
, , , and WISE W1 and W2 photometry. The quasar selection completeness
is higher than 70% for a wide redshift range , and a wide magnitude
range mag. Our photo- regression and classification method has
the potential to extend to future surveys. The photo- code will be publicly
available.Comment: 22 pages, 17 figure, accepted by AJ. The code is available at
https://doi.org/10.5281/zenodo.101440
An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30
So far, roughly 40 quasars with redshifts greater than z=6 have been
discovered. Each quasar contains a black hole with a mass of about one billion
solar masses (). The existence of such black holes when the
Universe was less than 1 billion years old presents substantial challenges to
theories of the formation and growth of black holes and the coevolution of
black holes and galaxies. Here we report the discovery of an ultra-luminous
quasar, SDSS J010013.02+280225.8, at redshift z=6.30. It has an optical and
near-infrared luminosity a few times greater than those of previously known z>6
quasars. On the basis of the deep absorption trough on the blue side of the Ly
emission line in the spectrum, we estimate the proper size of the
ionized proximity zone associated with the quasar to be 26 million light years,
larger than found with other z>6.1 quasars with lower luminosities. We estimate
(on the basis of a near-infrared spectrum) that the black hole has a mass of
, which is consistent with the derived by assuming an Eddington-limited accretion rate.Comment: 24 pages, 4 figures plus 4 extended data figures, published in Nature
on 26 February 201
Unshifted Metastable He I* Mini-Broad Absorption Line System in the Narrow Line Type 1 Quasar SDSS J080248.18551328.9
We report the identification of an unusual absorption line system in the
quasar SDSS J080248.18551328.9 and present a detailed study of the system,
incorporating follow-up optical and NIR spectroscopy. A few tens of absorption
lines are detected, including He I*, Fe II* and Ni II* that arise from
metastable or excited levels, as well as resonant lines in Mg I, Mg II, Fe II,
Mn II, and Ca II. All of the isolated absorption lines show the same profile of
width km s centered at a common redshift as that of
the quasar emission lines, such as [O II], [S II], and hydrogen Paschen and
Balmer series. With narrow Balmer lines, strong optical Fe II multiplets, and
weak [O III] doublets, its emission line spectrum is typical for that of a
narrow-line Seyfert 1 galaxy (NLS1). We have derived reliable measurements of
the gas-phase column densities of the absorbing ions/levels. Photoionization
modeling indicates that the absorber has a density of and a column density of , and is located at
pc from the central super-massive black hole. The location of the absorber, the
symmetric profile of the absorption lines, and the coincidence of the
absorption and emission line centroid jointly suggest that the absorption gas
is originated from the host galaxy and is plausibly accelerated by stellar
processes, such as stellar winds \zhy{and/or} supernova explosions. The
implications for the detection of such a peculiar absorption line system in an
NLS1 are discussed in the context of co-evolution between super-massive black
hole growth and host galaxy build-up.Comment: 28 pages, 16 figures; accepted for publication in Astrophysical
Journa
CIV emission line properties and uncertainties in black hole mass estimates of z ~ 3.5 quasars
Using a high luminosity ( erg
s), high redshift () quasar sample of 19 quasars with
optical and near-infrared spectroscopy, we investigate the reliability of the
CIV-based black hole mass estimates (). The median logarithm of the
CIV- and H-based ratios is 0.110 dex with the scatter of
0.647 dex. The CIV-to-H BH mass differences are significantly correlated
with the CIV FWHMs, blueshifts and asymmetries. Corrections of the CIV FWHM
using the blueshift and asymmetry reduce the scatter of the mass differences by
0.04-0.2 dex. Quasars in our sample accrete at the Eddington ratio
and cover a considerable range of blueshifts, with 18/19 of
the quasars showing CIV blueshifts (with the median value of 1126 km s)
and 14/19 of the quasars showing CIV blueshifts larger than 500 km s. It
suggests that not all quasars with high Eddington ratios show large blueshifts.
The Baldwin effect between the CIV rest-frame equivalent width (REW) and the
continuum luminosity at 1350 \overset{\lower.5em\circ}{\mathrm{A}} is not
seen, likely due to the limited luminosity range of our sample. We find a lack
of flux in the red wing of the composite spectrum with larger CIV blueshift,
and detect a higher ratio of [OIII] quasars with REW
\overset{\lower.5em\circ}{\mathrm{A}} in the subsample with lower CIV
blueshift. It is more likely that they are caused by the combination of the
Eddington ratio and the orientation effect.Comment: 17 pages, 12 figures with additional 6 pages and 2 figures in the
appendix. Accepted for publication in Ap
An ultra-luminous quasar at z=5.363 with a ten billion solar mass black hole and a Metal-Rich DLA at z~5
We report the discovery of an ultra-luminous quasar J030642.51+185315.8
(hereafter J0306+1853) at redshift 5.363, which hosts a super-massive black
hole (SMBH) with . With an
absolute magnitude and bolometric luminosity
, J0306+1853 is one of the most luminous
objects in the early Universe. It is not likely to be a beamed source based on
its small flux variability, low radio loudness and normal broad emission lines.
In addition, a Damped Ly system (DLA) with , among the most metal rich DLAs at , is detected
in the absorption spectrum of this quasar. This ultra-luminous quasar puts
strong constraint on the bright-end of quasar luminosity function and
massive-end of black hole mass function. It will provide a unique laboratory to
the study of BH growth and the co-evolution between BH and host galaxy with
multi-wavelength follow-up observations. The future high resolution spectra
will give more insights to the DLA and other absorption systems along the
line-of-sight of J0306+1853.Comment: 5 pages, 3 figures, accepted for publication in ApJ
Official Reports of the Town of Wayland for Its One Hundred and Forty-Third Municipal Year From January 1,1922 To January 1, 1923
We study the relation between the metallicity of quasar broad line region (BLR) and black hole (BH) mass (10(7.5)-10(10) M-circle dot) and quasar bolometric luminosity (10(44.6)-10(48) erg s(-1)) using a sample of similar to 130000 quasars at 2.25 <= z <= 5.25 from Sloan Digital Sky Survey Data Release 12 (DR12). We generate composite spectra by stacking individual spectra in the same BH mass (bolometric luminosity) and redshift bins and then estimate the metallicity of quasar BLR using metallicity-sensitive broad emission-line flux ratios based on the photoionization models. We find a significant correlation between quasar BLR metallicity and BH mass (bolometric luminosity) but no correlation between quasar BLR metallicity and redshift. We also compare the metallicity of quasar BLR and that of host galaxies inferred from the mass metallicity relation of star-forming galaxy at z similar to 2.3 and 3.5. We find quasar BLR metallicity is 0.3 similar to 1.0 dex higher than their host galaxies. This discrepancy cannot be interpreted by the uncertainty due to different metallicity diagnostic methods, mass metallicity relation of galaxy, metallicity gradient in quasar host galaxies, BH mass estimation, the effect of different spectral energy distribution models, and a few other potential sources of uncertainties. We propose a possibility that the high metallicity in quasar BLR might be caused by metal enrichment from massive star formation in the nucleus region of quasars or even the accretion disc
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