scholarly journals Properties of radio-loud quasars in the Sloan Digital Sky Survey

2019 ◽  
Vol 631 ◽  
pp. A46 ◽  
Author(s):  
H. Gaur ◽  
M. Gu ◽  
S. Ramya ◽  
H. Guo
Keyword(s):  
Spectral Index ◽  
Spectral Properties ◽  
Sloan Digital Sky Survey ◽  
Spectrum Radio ◽  
Sky Survey ◽  
Spectroscopic Feature ◽  
Stellar Velocity ◽  
Local Relation ◽  
Line Widths ◽  
Velocity Dispersions

We present a study of a sample of 223 radio-loud quasars (up to redshift < 0.3) in order to investigate their spectral properties. Twenty-six of these radio-loud quasars are identified as flat-spectrum radio quasars (FSRQs), and 54 are identified as steep-spectrum radio quasars (SSRQs) based on their radio spectral index. We study the [O III] line properties of these quasars to investigate the origin and properties of blue wings (shift of the profile toward lower wavelengths) and blue outliers (shift of the whole spectroscopic feature). Most of the quasars show blue wings with velocities of up to 420 km s−1. We find that about 17% of the quasars show outliers whose velocities span from 419 to −315 km s−1. Finally, we revisit the MBH − σ relation of our sample using the [S II]λ 6716,6731 and [O III] line widths as surrogates for stellar velocity dispersions, σ, to investigate their location on the MBH − σ relation for quiescent galaxies. Because [S II] is strongly blended with Hα, we were able to estimate σ[S II] for only 123 quasars. We find that the radio-loud quasars do not show a relationship between MBH and σ[S II]/[O III] up to a redshift of 0.3, although they cluster around the local relation. We find an overall offset of 0.12 ± 0.05 dex of our sample of radio-loud quasars from the MBH − σ relation of quiescent galaxies. Quasars in our highest redshift bin (z = 0.25 − 0.3) show a deviation of ∼0.33 ± 0.06 dex from the local relation. Implications of the results are discussed.

Environmental dependence of stellar velocity dispersion in the Main galaxy sample of SDSS DR10

Open Physics ◽  
2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Xin-Fa Deng
Keyword(s):  
Velocity Dispersion ◽  
Selection Effect ◽  
Sloan Digital Sky Survey ◽  
Apparent Magnitude ◽  
Main Galaxy ◽  
Sky Survey ◽  
Stellar Velocity ◽  
Galaxy Sample ◽  
Velocity Dispersions ◽  
Environmental Dependence

AbstractThe aim of this work is to examine the environmental dependence of stellar velocity dispersion in local galaxies. In studies that likely suffer from the radial selection effect, one has a preference for the use of volumelimited samples. Two volume-limited samples with different redshift and luminosity ranges were constructed from the Main galaxy data of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10). Considering some drawbacks of volume-limited samples, the apparent magnitude-limited Main galaxy sample was also applied. Statistical analyses in these different galaxy samples can reach the same conclusion: galaxies with large stellar velocity dispersions exist preferentially in high density regimes, while galaxies with small stellar velocity dispersions are located preferentially in low density regions, which is inconsistent with that obtained at intermediate redshifts.

scholarly journals Black hole masses in type II AGNs from the Sloan Digital Sky Survey

2006 ◽  
Vol 2 (S238) ◽  
pp. 325-326
Author(s):  
W. Bian ◽  
Q. Gu ◽  
Y. Zhao
Keyword(s):  
Synthesis Method ◽  
Sloan Digital Sky Survey ◽  
Type Ii ◽  
Population Synthesis ◽  
Sky Survey ◽  
Stellar Population Synthesis ◽  
Stellar Velocity ◽  
Velocity Dispersions ◽  
Black Hole Masses ◽  
Absorption Features

AbstractThe stellar population synthesis method is used to model the stellar contribution for a sample of 209 type II AGNs at 0.3>z>0.83 from the Sloan Digital Sky Survey. The reliable stellar velocity dispersions are obtained for 33 type II AGNs with significant stellar absorption features. We use the formula of Greene & Ho to obtain the corrected stellar velocity dispersions (σ*c). 20 of which can be classified as type II quasars. The SMBHs masses and the Eddington ratios are calculated. We measure the gas velocity dispersion (σg) from NLRs, and find that the relation between σg and σ*c becomes much weaker at higher redshifts than at smaller redshifts. We find that the deviation of σg from σ*c is correlated with the Eddington ratio.

scholarly journals Characterisation of the continuum and kinematical properties of nearby NLS1

2019 ◽  
Vol 629 ◽  
pp. A50
Author(s):  
Gabriel A. Oio ◽  
Luis R. Vega ◽  
Eduardo O. Schmidt ◽  
Diego Ferreiro
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Velocity Dispersion ◽  
Spectral Synthesis ◽  
Sloan Digital Sky Survey ◽  
Black Hole Mass ◽  
Composite Spectra ◽  
Sky Survey ◽  
Stellar Velocity ◽  
Gaussian Decomposition

Aims. In order to study the slope and strength of the non-stellar continuum, we analysed a sample from nearby Narrow Line Seyfert 1 (NLS1). Also, we re-examined the location of NLS1 galaxies on the MBH − σ⋆ relation, using the stellar velocity dispersion and the [OIII]λ5007 emission line as a surrogate of the former. Methods. We studied spectra of a sample of 131 NLS1 galaxies taken from the Sloan Digital Sky Survey (SDSS) DR7. We approached determining the non-stellar continuum by employing the spectral synthesis technique, which uses the code STARLIGHT, and by adopting a power-law base to model the non-stellar continuum. Composite spectra of NLS1 galaxies were also obtained based on the sample. In addition, we obtained the stellar velocity dispersion from the code and by measuring Calcium II Triplet absorption lines and [OIII] emission lines. From Gaussian decomposition of the Hβ profile we calculated the black hole mass. Results. We obtained a median slope of β = −1.6 with a median fraction of contribution of the non-stellar continuum to the total flux of 0.64. We determined black hole masses in the range of log(MBH/M⊙) = 5.6–7.5, which is in agreement with previous works. We found a correlation between the luminosity of the broad component of Hβ and black hole mass with the fraction of a power-law component. Finally, according to our results, NLS1 galaxies in our sample are located mostly underneath the MBH − σ⋆ relation, both considering the stellar velocity dispersion (σ⋆) and the core component of [OIII]λ5007.

Stellar and gaseous velocity dispersions in type II AGNs at 0.3

2006 ◽  
Vol 372 (2) ◽  
pp. 876-884 ◽  
Author(s):  
W. Bian ◽  
Q. Gu ◽  
Y. Zhao ◽  
L. Chao ◽  
Q. Cui
Keyword(s):  
Sloan Digital Sky Survey ◽  
Type Ii ◽  
Sky Survey ◽  
Velocity Dispersions

scholarly journals Spectral properties of AGN with very weak [O III] lines

2011 ◽  
pp. 17-24 ◽  
Author(s):  
J. Kovacevic
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
High Density ◽  
Sloan Digital Sky Survey ◽  
Physical Reason ◽  
Narrow Component ◽  
Sky Survey

The spectral properties of a sample of 58 Active Galactic Nuclei (AGN) spectra, in which emission [O III] ??4959, 5007 ? lines are weak or totally absent, are analyzed. In order to investigate the physical reason for the [O III] emission suppression, the spectral properties of the weak [O III] spectra sample are compared with the same properties of a sample of 269 spectra with the strong [O III] lines. The spectra are obtained from Sloan Digital Sky Survey (SDSS) Database. It is found that the objects with the weak or absent [O III] ??4959, 5007 ? lines generally have the high continuum luminosities (log(?L5100) > 45), that they are very rare at smaller redshifts (z < 0.3) and that they usually have strong starburst influence. From the sample with weak or absent [O III] lines, two boundary subgroups may be distinguished: the subgroup with a strong H? narrow component and subgroup with a very weak or negligible H? narrow component. The physical causes for the [O III] lines suppressing are probably different in these two subgroups: the [O III] lines are absent in objects with strong narrow H? probably because of strong starburst (SB) activity, which produces high density of the gas, while in the objects with the negligible narrow H?, the reason for [O III] and narrow H? suppression may be a low covering factor.

scholarly journals Radio galaxies in the Sloan Digital Sky Survey: spectral index-environment correlations

2010 ◽  
Vol 406 (1) ◽  
pp. 197-207 ◽  
Author(s):  
Carlos G. Bornancini ◽  
Ana Laura O'Mill ◽  
Sebastián Gurovich ◽  
Diego García Lambas
Keyword(s):  
Spectral Index ◽  
Radio Galaxies ◽  
Sloan Digital Sky Survey ◽  
Sky Survey

scholarly journals Subaru Hyper Suprime-Cam view of quasar host galaxies at z < 1

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Toru Ishino ◽  
Yoshiki Matsuoka ◽  
Shuhei Koyama ◽  
Yuya Saeda ◽  
Michael A Strauss ◽  
...  
Keyword(s):  
Sample Selection ◽  
Stellar Mass ◽  
Small Sample ◽  
Sloan Digital Sky Survey ◽  
Host Galaxy ◽  
Mass Relation ◽  
Host Galaxies ◽  
Sky Survey ◽  
Local Relation

Abstract Active galactic nuclei (AGNs) are key in understanding the coevolution of galaxies and supermassive black holes (SMBHs). AGN activity is thought to affect the properties of their host galaxies via a process called “AGN feedback,” which drives the coevolution. From a parent sample of 1151 z &lt; 1 type-1 quasars from the Sloan Digital Sky Survey quasar catalog, we detected the host galaxies of 862 of them in the high-quality grizy images of the Subaru Hyper Suprime-Cam survey. The unprecedented combination of the survey area and depth allowed us to perform a statistical analysis of the quasar host galaxies, with small sample variance. We fitted the radial image profile of each quasar as a linear combination of the point spread function and the Sérsic function, decomposing the images into the quasar nucleus and the host galaxy components. We found that the host galaxies are massive, with stellar mass Mstar ≳ 1010 $M_\odot$, and are mainly located on the green valley. This trend is consistent with a scenario in which star formation in the host galaxies is suppressed by AGN feedback, that is, AGN activity may be responsible for the transition of these galaxies from the blue cloud to the red sequence. We also investigated the SMBH mass to stellar mass relation of the z &lt; 1 quasars, and found a consistent slope with the local relation, while the SMBHs may be slightly undermassive. However, the above results are subject to our sample selection, which biases against host galaxies with low masses and/or large quasar-to-host flux ratios.

scholarly journals Calibration of the virial factor f in supermassive black hole masses of reverberation-mapped AGNs

2019 ◽  
Vol 488 (2) ◽  
pp. 1519-1534 ◽  
Author(s):  
Li-Ming Yu ◽  
Wei-Hao Bian ◽  
Chan Wang ◽  
Bi-Xuan Zhao ◽  
Xue Ge
Keyword(s):  
Black Hole ◽  
High Redshift ◽  
Sloan Digital Sky Survey ◽  
Time Lags ◽  
Broad Line ◽  
Reverberation Mapping ◽  
Supermassive Black Hole ◽  
Stellar Velocity ◽  
The Mean ◽  
Velocity Dispersions

ABSTRACT Using a compiled sample of 34 broad-line active galactic nuclei (AGNs) with measured H β time lags from the reverberation mapping (RM) method and measured bulge stellar velocity dispersions σ*, we calculate the virial factor f by assuming that the RM AGNs intrinsically obey the same MBH−σ* relation as quiescent galaxies, where MBH is the mass of the supermassive black hole (SMBH). Considering four tracers of the velocity of the broad-line regions (BLRs), i.e. the H β line width or line dispersion from the mean or rms spectrum, there are four kinds of the factor f. Using the H β full width at half-maximum (FWHM) to trace the BLRs velocity, we find significant correlations between the factor f and some observational parameters, e.g. FWHM, the line dispersion. Using the line dispersion to trace the BLRs velocity, these relations disappear or become weaker. It implies the effect of inclination in BLRs geometry. It also suggests that the variable f in MBH estimated from luminosity and FWHM in a single-epoch spectrum is not negligible. Using a simple model of thick-disc BLRs, we also find that, as the tracer of the BLRs velocity, H β FWHM has some dependence on the inclination, while the line dispersion σH β is insensitive to the inclination. Considering the calibrated FWHM-based factor f from the mean spectrum, the scatter of the SMBH mass is 0.39 dex for our sample of 34 low-redshift RM AGNs. For a high-redshift sample of 30 Sloan Digital Sky Survey RM AGNs with measured stellar velocity dispersions, we find that the SMBH mass scatter is larger than that for our sample of 34 low-redshift RM AGNs. It implies the possibility of evolution of the MBH−σ* relation from high-redshift to low-redshift AGNs.

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