A5101682710- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Astronomical Observations and Instrumentation
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Superconducting Materials and Applications
- History and Developments in Astronomy
- Numerical methods in inverse problems
- Earthquake Detection and Analysis
- Spectral Theory in Mathematical Physics
- Black Holes and Theoretical Physics
- Cosmology and Gravitation Theories
- Engineering Applied Research
- Solar and Space Plasma Dynamics
- Advanced Chemical Sensor Technologies
- Relativity and Gravitational Theory
- Neutrino Physics Research
Shanghai Astronomical Observatory
2014-2024
Peking University
2010-2015
University of Arizona
2015
We investigate the optical variability of 7658 quasars from SDSS Stripe 82. Taking advantage a larger sample and relatively more data points for each quasar, we estimate amplitudes divide into small bins redshift, rest-frame wavelength, black hole mass, Eddington ratio bolometric luminosity respectively, to relationships between these parameters. An anti-correlation wavelength is found. The amplitude radio-quiet shows almost no cosmological evolution, but that radio-loud ones may weakly...
This is the second paper in a series on new luminous z ~ 5 quasar survey using optical and near-infrared colors. Here we present determination of bright end luminosity function (QLF) at 5. Combined our 45 quasars with previously known that satisfy selections, construct largest uniform sample to date, 99 range 4.7 <= < 5.4 -29 M1450 -26.8, within Sloan Digital Sky Survey (SDSS) footprint. We use modified 1/Va method including flux limit correction derive binned QLF, model parametric QLF...
High-redshift quasars are important tracers of structure and evolution in the early universe. However, they very rare difficult to find when using color selection because contamination from late-type dwarfs. quasar surveys based on only optical colors suffer incompleteness low identification efficiency, especially at $z\gtrsim4.5$. We have developed a new method select $4.7\lesssim z \lesssim 5.4$ with both high efficiency completeness by combining mid-IR Wide-field Infrared Survey Explorer...
Abstract Using nearly simultaneous radio, near-infrared, optical, and ultraviolet (UV) data collected since 2009, we constructed 106 spectral energy distributions (SEDs) of the blazar OJ 287. These SEDs are well fitted by a log-parabolic model. By classifying into “flare” “quiescent” segments, find that median flux at peak frequency during flare segments is 0.37 ± 0.22 dex higher compared to quiescent while no significant differences observed in values curvature parameter b or <mml:math...
Abstract We present the first multiband centimeter detection of POX 52, a nearby dwarf galaxy believed to harbor robust intermediate-mass black hole. conducted deep observations using Australia Telescope Compact Array (ATCA), spanning frequencies from 4.5 10 GHz, as well sensitive Karl G. Jansky Very Large (VLA) operating in its most extended A configuration at S band (2–4 GHz) and C (4–8 GHz). In ATCA observations, source shows compact morphology, with only one direction marginally...
We present new near-infrared (IR) observations of the Hβ λ4861 and Mg ii λ2798 lines for 32 luminous quasars with 3.2 < z 3.9 using Palomar Hale 200 inch telescope Large Binocular Telescope. find that FWHM is well correlated FWHM, confirming itself as a good substitute in black hole mass estimates. The continuum luminosity at 5100 Å correlates 3000 broad emission line luminosities (Hβ ii). With simultaneous near-IR spectroscopy to exclude influences flux variability, we are able evaluate...
We study the relation between metallicity of quasar broad line region (BLR) and black hole (BH) mass (|$\rm 10^{7.5}{-}10^{10}\, M_{\odot }$|) bolometric luminosity 10^{44.6}{-}10^{48} {\rm \, erg\, s^{-1}}$|) using a sample ∼130 000 quasars at 2.25 ≤ |$z$| 5.25 from Sloan Digital Sky Survey Data Release 12 (DR12). generate composite spectra by stacking individual in same BH (bolometric luminosity) redshift bins then estimate BLR metallicity-sensitive emission-line flux ratios based on...
We report the discovery of an ultra-luminous quasar J030642.51+185315.8 (hereafter J0306+1853) at redshift 5.363, which hosts a supermassive black hole with . With absolute magnitude and bolometric luminosity , J0306+1853 is one most luminous objects in early universe. It not likely to be beamed source based on its small flux variability, low radio loudness, normal broad emission lines. In addition, damped Lyα system (DLA) among metal-rich DLAs detected absorption spectrum this quasar. This...
We present preliminary results of the quasar survey in Large Sky Area Multi- Object Fiber Spectroscopic Telescope (LAMOST) first data release (DR1), which includes pilot and year regular survey. There are 3921 quasars identified with reliability, among 1180 new discovered These at low to median redshifts, highest z 4.83. compile emission line measurements around H{\alpha}, H{\beta}, Mg II, C IV regions for quasars. The continuum luminosities inferred from SDSS photo- metric model fitting as...
Very few of the z > 5 quasars discovered to date have been radio-loud, with radio-to-optical flux ratios (radio-loudness parameters) higher than 10. Here we report discovery an optically luminous radio-loud quasar, SDSS J013127.34−032100.1 (J0131−0321 in short), at = 5.18 ± 0.01 using Lijiang 2.4 m and Magellan telescopes. J0131−0321 has a spectral energy distribution consistent that quasars. With i-band magnitude 18.47 radio density 33 mJy, its radio-loudness parameter is ∼100. The optical...
We report the discovery of eight new quasars in one extragalactic field (five degree centered at RA=$08^h58^m08.2^s$, Dec=$01^o32'29.7''$) with LAMOST commissioning observations on December 18, 2009. These quasars, $i$ magnitudes from 16.44 to 19.34 and redshifts 0.898 2.773, were not identified SDSS spectroscopic survey, though six them less than 2.5 selected as quasar targets SDSS. Except source without near-IR $Y$-band data, seven these meet a newly proposed selection criterion involving...
We report the identification of an unusual absorption line system in quasar SDSS J080248.18$+$551328.9 and present a detailed study system, incorporating follow-up optical NIR spectroscopy. A few tens lines are detected, including He I*, Fe II* Ni that arise from metastable or excited levels, as well resonant Mg I, II, Mn Ca II. All isolated show same profile width $\Delta v\sim 1,500$km s$^{-1}$ centered at common redshift emission lines, such [O II], [S hydrogen Paschen Balmer series. With...
Using a high luminosity ($L_{\rm bol} \sim 10^{47.5} - 10^{48.3}$ erg s$^{-1}$), redshift ($3.2 < z 3.8$) quasar sample of 19 quasars with optical and near-infrared spectroscopy, we investigate the reliability CIV-based black hole mass estimates ($M_{\rm BH}$). The median logarithm CIV- H$\beta$-based $M_{\rm BH}$ ratios is 0.110 dex scatter 0.647 dex. CIV-to-H$\beta$ BH differences are significantly correlated CIV FWHMs, blueshifts asymmetries. Corrections FWHM using blueshift asymmetry...
Abstract We present a new algorithm to estimate quasar photometric redshifts (photo- z s), by considering the asymmetries in relative flux distributions of quasars. The models are built with multivariate Skew-t multidimensional space fluxes as function redshift and magnitude. For 151,392 quasars SDSS, we achieve photo- accuracy, defined fraction difference between p spectroscopic s , <?CDATA $| {\rm{\Delta }}z| =| {z}_{s}-{z}_{p}| /(1+{z}_{s})$?> within 0.1, 74%. Combining WISE W 1 2...
To investigate the short-term variability and determine size of optical continuum emitting intermediate-mass black holes (IMBHs), we carried out high-cadence, multi-band photometric monitoring a Seyfert 1 galaxy J0249-0815 across two nights, together with one-night single-band preliminary test. The presence broad Ha component in our target was confirmed by recent Palomar/P200 spectroscopic observations, 23 years after Sloan Digital Sky Survey, ruling supernovae origin line. experiment...
Abstract Based on the magnetization, an accretion disk with a large-scale magnetic field can be separated into either standard and normal evolution or magnetically arrested (MAD), which are difficult to identify from observations. It is still unclear whether all radio-loud active galactic nuclei (RLAGNs) thin strong radio emissions contain MAD. We investigate this issue by utilizing 3CRR catalog. compile sample of 35 quasars 14 high-excitation galaxies powered disk. In order consistently...
Abstract To investigate the short-term variability and determine size of optical continuum emitting region intermediate-mass black holes (IMBHs), we carried out high-cadence, multiband photometric monitoring a Seyfert 1 galaxy J0249−0815 across two nights, together with one-night single-band preliminary test. The presence broad H α component in our target was confirmed by recent Palomar/P200 spectroscopic observations, 23 yr after Sloan Digital Sky Survey, ruling supernovae origin line....
Abstract We present near-IR spectroscopy of 22 luminous low-ionization broad absorption line quasars (LoBAL QSOs) at redshift <?CDATA $1.3\lt z\lt 2.5$?> , with 12 objects z ∼ 1.5 and 10 2.3. The spectra cover the rest-frame H α β regions, allowing us to obtain robust black hole mass estimates based on line. use these data, augmented by a lower-redshift sample from Sloan Digital Sky Survey, test proposed youth scenario for LoBALs, which suggests that LoBALs constitute an early short-lived...
The redshift range from 2.2 to 3 is known as the 'redshift desert' of quasars because with redshifts in this have similar optical colors normal stars and are thus difficult find sky surveys. A quasar candidate, SDSS J085543.40–001517.7, which was selected by a recently proposed criterion involving near-IR Y – K g z colors, identified spectroscopically new 2.427 Guoshoujing Telescope (LAMOST) commissioning observation 2009 December confirmed made NAOC/Xinglong 2.16 m telescope 2010 March....
We present the discovery of strong Balmer line absorption in H$α$ to H$γ$ two luminous low-ionization broad quasars (LoBAL QSOs) at z~1.5, with black hole masses around $10^{10}$ $M_\odot$ from near-IR spectroscopy. There are only previously known z>1 showing absorption. SDSS J1019+0225 shows blueshifted by ~1400 km/s an rest-frame equivalent width 13 Å. In J0859+4239 we find redshifted ~500 7 The could indicate inflow high density gas onto hole, though cannot rule out alternative...
We present an observational study of 22 broad absorption line quasars (BAL QSOs) at $3\lesssim z \lesssim5$ based on optical/near-IR spectroscopy, aiming to investigate quasar winds and their effects. The near-IR spectroscopy covers the \hb\ and/or \mgii\ emission lines (BELs) for these quasars, allowing us estimate central black hole (BH) masses in a robust way. found that our BAL QSOs average do not have higher Eddington ratio than from non-BAL matched redshift luminosity. In subset...
Abstract Very few low-ionization broad absorption line (LoBAL) QSOs have been found at high redshifts, to date. One high-redshift LoBAL QSO, J0122+1216, was recently discovered by the Lijiang 2.4 m Telescope, with an initial redshift determination of 4.76. Aiming investigate its physical properties, we carried out follow-up observations in optical and near-IR spectroscopy. Near-IR spectra from UKIRT P200 confirm that it is a LoBAL, new 4.82 ± 0.01 based on Mg ii emission-line. The reveals...
Abstract The existence of black holes with masses about one billion solar in quasars at redshifts z > 6 presents significant challenges to theories the formation and growth hole/galaxy co-evolution early Universe. Here we report a recent discovery an ultra-luminous quasar redshift = 6.30, which has observed optical near-infrared luminosity few times greater than those previously known quasars. With spectroscopy, obtain hole mass 12 masses, is well consistent derived by assuming...