A Catalog of Quasar Properties From Sloan Digital Sky Survey Data Release 7

Shen, Yue; Richards, Gordon T.; Strauss, Michael A.; Hall, Patrick B.; Schneider, Donald P.; Snedden, Stephanie A.; Bizyaev, Dmitry; Brewington, H.; Malanushenko, Viktor; Malanushenko, Elena; Oravetz, D.; Pan, Kaike; Simmons, Audrey

doi:10.1088/0067-0049/194/2/45

Cited by 1,435 publications

(3,019 citation statements)

References 100 publications

Supporting

160

Mentioning

2,847

Contrasting

Order By: Relevance

“…Our sample is composed by 229 blazars detected by Fermi/LAT 31,33 for which broad emission lines have been measured 12,13,32 . This sample does not include several bright and famous blazars with historical spectroscopic classifications in the literature.…”

Section: Methodsmentioning

confidence: 99%

The power of relativistic jets is larger than the luminosity of their accretion disks

Ghisellini

Tavecchio

Maraschi

et al. 2014

Nature

437

521

View full text Add to dashboard Cite

Theoretical models for the production of relativistic jets from active galactic nuclei predict that jet power arises from the spin and mass of the central black hole, as well as the magnetic field near the event horizon 1 . The physical mechanism mechanism underlying the contribution from the magnetic field is the torque exerted on the rotating black hole by the field amplified by the accreting material. If the squared magnetic field is proportional to the accretion rate, then there will be a correlation between jet power and accretion luminosity. There is evidence for such a correlation 2-8 , but inadequate knowledge of the accretion luminosity of the limited and inhomogeneous used samples prevented a firm conclusion. Here we report an analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations. We find a clear correlation between jet power as measured through the γ-ray luminosity, and accretion luminosity as measured by the broad emission lines, with the jet power dominating over the disk luminosity, in agreement with numerical simulations 9 . This implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter 10 .The jet power is predicted 1 to depend on (aMB) 2 , where a and M are respectively the spin and mass of the black hole and B is the magnetic field at its horizon. Seed magnetic fields are amplified by the accretion disk up to equipartition with the mass energy density ∼ ρc 2 of the matter accreting at the rateṀ . A greaterṀ implies a larger ρ, that can sustain a larger magnetic field, which in turn can tap a larger amount of the black hole rotational energy. The magnetic field is thus a catalyst for the process. Increasing the spin of the black hole shrinks the innermost stable orbit, increasing the accretion efficiency η (defined by η = L disk /Ṁc 2 ) (L disk accretion disk luminosity) to a maximum value 11 η = 0.3.We use a well designed sample of blazars that have been detected in the γ-ray band by the Fermi Large Area Telescope (LAT) that have been spectroscopically observed in the optical 12, 13 (see Methods). They have been classified as BL Lac objects or Flat Spectrum Radio Quasars (FSRQs) according if the rest frame equivalent width of their broad emission lines was greater (FSRQ) or smaller (BL Lacs) than 5Å (rest frame). The sample contains 229 FSRQs, and 475 BL Lacs. Of the latter, 209 have a spectroscopically measured redshift. We considered all FSRQs with enough multi-wavelength data to have a Spectral Energy Distribution (SED) that allows to establish the bolometric luminosity. The considered FSRQs amount to 191 objects. Instead, for BL Lacs, we consider only the 26 sources with detected broad emission lines. This makes them the low disk luminosity tail of of the full 1 blazar sample. This choice is dictated by our will to measure the accretion luminosity, together with the jet power. Through the visible broad emission lines we reconstruct, through a t...

show abstract

Section: Methodsmentioning

confidence: 99%

The power of relativistic jets is larger than the luminosity of their accretion disks

Ghisellini

Tavecchio

Maraschi

et al. 2014

Nature

437

521

View full text Add to dashboard Cite

show abstract

“…This handy shortcut provides a means for taking large spectroscopic surveys and producing catalogs full of black hole mass estimates (e.g., Shen et al 2011). Of course, as one might expect, the devil is in the details.…”

Section: Black Hole Scaling Relationshipsmentioning

confidence: 99%

AGN Reverberation Mapping

Bentz

2016

Astronomy at High Angular Resolution

View full text Add to dashboard Cite

Reverberation mapping is now a well-established technique for investigating spatially-unresolved structures in the nuclei of distant galaxies with activelyaccreting supermassive black holes. Structural parameters for the broad emissionline region, with angular sizes of microarcseconds, can be constrained through the substitution of time resolution for spatial resolution. Many reverberation experiments over the last 30 years have led to a practical understanding of the requirements necessary for a successful program. With reverberation measurements now in hand for 60 active galaxies, and more on the horizon, we are able to directly constrain black hole masses, derive scaling relationships that allow large numbers of black hole mass estimates throughout the observable Universe, and begin investigating the detailed geometry and kinematics of the broad line region. Reverberation mapping is therefore one of the few techniques available that will allow a deeper understanding of the physical mechanisms involved in AGN feeding and feedback at very small scales, as well as constraints on the growth and evolution of black holes across cosmic time. In this contribution, I will briefly review the background, implementation, and major results derived from this high angular resolution technique.

show abstract

“…Black hole masses, bolometric luminosities and Eddington ratios are obtained from the quasar catalog in Shen et al (2011), where the black hole masses of quasars were settled by fiducial virial mass estimates: Hβ (Vestergaard & Wilkes 2006) estimates for z < 0.7, [MgII] (Shen & Kelly 2010) estimates for 0.7 ≤ z < 1.9 and CIV] (Vestergaard & Wilkes 2006) estimates for z ≥ 1.9. If more than one emission line are available, we still adopt the fiducial virial black hole mass in Shen & Kelly (2010).…”

Section: Samplementioning

confidence: 99%

“…Here radio loudness is defined as the ratio of the observed radio flux density at rest-frame 6 cm and the optical flux density at rest-frame 2500Å (Becker et al 1995;Shen et al 2011). 416 radio-loud sources and 7242 radio-quiet sources are obtained for the study in the following sections.…”

Section: Variability Distribution and Color Changesmentioning

confidence: 99%

The correlations between optical variability and physical parameters of quasars in SDSS Stripe 82

Zuo¹,

Wu²,

Liu³

et al. 2012

Proc. IAU

View full text Add to dashboard Cite

We investigate the optical variability of 7658 quasars from SDSS Stripe 82. Taking advantage of a larger sample and relatively more data points for each quasar, we estimate variability amplitudes and divide the sample into small bins of redshift, rest-frame wavelength, black hole mass, Eddington ratio and bolometric luminosity respectively, to investigate the relationships between variability and these parameters. An anti-correlation between variability and rest-frame wavelength is found. The variability amplitude of radio-quiet quasars shows almost no cosmological evolution, but that of radio-loud ones may weakly anticorrelate with redshift. In addition, variability increases as either luminosity or Eddington ratio decreases. However, the relationship between variability and black hole mass is uncertain; it is negative when the influence of Eddington ratio is excluded, but positive when the influence of luminosity is excluded. The intrinsic distribution of variability amplitudes for radio-loud and radio-quiet quasars are different. Both radio-loud and radio-quiet quasars exhibit a bluer-whenbrighter chromatism. Assuming that quasar variability is caused by variations of accretion rate, the Shakura-Sunyaev disk model can reproduce the tendencies of observed correlations between variability and rest-frame wavelength, luminosity as well as Eddington ratio, supporting that changes of accretion rate plays an important role in producing the observed optical variability. However, the predicted positive correlation between variability and black hole mass seems to be inconsistent with the observed negative correlation between them in small bins of Eddington ratio, which suggests that other physical mechanisms may still need to be considered in modifying the simple accretion disk model.

show abstract

A Catalog of Quasar Properties From Sloan Digital Sky Survey Data Release 7

Cited by 1,435 publications

References 100 publications

The power of relativistic jets is larger than the luminosity of their accretion disks

The power of relativistic jets is larger than the luminosity of their accretion disks

AGN Reverberation Mapping

The correlations between optical variability and physical parameters of quasars in SDSS Stripe 82

Contact Info

Product

Resources

About