Detection of a primitive hydrogen cloud

Bian, Yulin; Cui, Zhen-xing; Chen, Jiansheng

doi:10.1016/0275-1062(83)90012-7

Cited by 2 publications

(2 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Shemmer et al (2006) studied the correlation between X-ray spectral slope and accretion rate (L bol /L Edd ) for AGNs up to z ≈ 2, increasing the luminosity range to more than 3 orders of magnitude, almost twice as large as previous studies (e.g. Porquet et al 2004, Wang et al 2004, Bian 2005. Despite having a much lower mass than any of sources used in the Shemmer et al study (M BH ≈ 10 7 − 10 10 M ⊙ ), POX 52 falls among the majority of objects in the sample when plotting Γ versus L bol /L Edd , making it consistent with this correlation, and suggests this relationship is independent of black hole mass.…”

Section: Accretion Luminositymentioning

confidence: 86%

The Host Galaxy and Central Engine of the Dwarf Active Galactic Nucleus POX 52

Thornton

Barth

et al. 2008

Astrophysical Journal

102

132

View full text Add to dashboard Cite

We present new multi-wavelength observations of the dwarf Seyfert 1 galaxy POX 52 in order to investigate the properties of the host galaxy and the active nucleus, and to examine the mass of its black hole, previously estimated to be ∼ 10 5 M ⊙ . Hubble Space Telescope ACS/HRC images show that the host galaxy has a dwarf elliptical morphology (M I = −18.4 mag, Sérsic index n = 4.3) with no detected disk component or spiral structure, confirming previous results from ground-based imaging. X-ray observations from both Chandra and XMM-Newton show strong (factor of 2) variability over timescales as short as 500 s, as well as a dramatic decrease in the absorbing column density over a 9 month period. We attribute this change to a partial covering absorber, with a 94% covering fraction and N H = 58 +8.4 −9.2 × 10 21 cm −2 , that moved out of the line of sight in between the XMM-Newton and Chandra observations. Combining these data with observations from the VLA, Spitzer, and archival data from 2MASS and GALEX, we examine the spectral energy distribution (SED) of the active nucleus. Its shape is broadly similar to typical radio-quiet quasar SEDs, despite the very low bolometric luminosity of L bol = 1.3 × 10 43 ergs s −1 . Finally, we compare black hole mass estimators including methods based on X-ray variability, and optical scaling relations using the broad Hβ line width and AGN continuum luminosity, finding a range of black hole mass from all methods to be M BH = (2.2 − 4.2) × 10 5 M ⊙ , with an Eddington ratio of L bol /L Edd ≈ 0.2 − 0.5.

show abstract

Section: Accretion Luminositymentioning

confidence: 86%

The Host Galaxy and Central Engine of the Dwarf Active Galactic Nucleus POX 52

Thornton

Barth

et al. 2008

Astrophysical Journal

102

132

View full text Add to dashboard Cite

show abstract

“…In our models the intrinsic shape of the energy flux emitted by the accreting source is controlled by the photon index parameter (Γ), which can provide information about the accretion efficiency. For instance, Eddington ratios (f Edd = L Bol /L Edd , where L Bol is the bolometric luminosity and L Edd is the Eddington luminosity) of luminous (L X > 10 41 erg s −1 ) SMBHs and IMBHs are observed to positively correlate with Γ such that more efficiently accreting sources have softer X-ray spectra (larger values of Γ), corresponding to a higher fraction of soft X-ray and far-UV photons produced in the inner portion of the accretion disk (Bian 2005;Shemmer et al 2006;Greene & Ho 2007).…”

Section: Spectral Shapementioning

confidence: 99%

A Catalog of Hyper-luminous X-Ray Sources and Intermediate-mass Black Hole Candidates out to High Redshifts

Barrows

Mezcua

Comerford

2019

ApJ

View full text Add to dashboard Cite

Hyper-luminous X-ray sources (HLXs; L X > 10 41 erg s −1 ) are off-nuclear X-ray sources in galaxies and strong candidates for intermediate-mass black holes (IMBHs). We have constructed a sample of 169 HLX candidates by combining X-ray detections from the Chandra Source Catalog (Version 2) with galaxies from the Sloan Digital Sky Survey and registering individual images for improved relative astrometric accuracy. The spatial resolution of Chandra allows for the sample to extend out to z ∼ 0.9. Optical counterparts are detected among one-fourth of the sample, one-third of which are consistent with dwarf galaxy stellar masses. The average intrinsic X-ray spectral slope indicates efficient accretion, potentially driven by galaxy mergers, and the column densities suggest one-third of the sample has significant X-ray absorption. We find that 144 of the HLX candidates have X-ray emission that is significantly in excess of the expected contribution from star formation and hot gas, strongly suggesting that they are produced by accretion onto black holes more massive than stars. After correcting for an average background or foreground contamination rate of 8%, we estimate that at least ∼20 of the HLX candidates are consistent with IMBH masses, and this estimate is potentially several times higher assuming more efficient accretion. This catalog currently represents the largest sample of uniformly-selected, off-nuclear IMBH candidates. These sources may represent scenarios in which a low-mass galaxy hosting an IMBH has merged with a more massive galaxy and provide an excellent sample for testing models of low-mass BH formation and merger-driven growth.

show abstract

Detection of a primitive hydrogen cloud

Cited by 2 publications

References 3 publications

The Host Galaxy and Central Engine of the Dwarf Active Galactic Nucleus POX 52

The Host Galaxy and Central Engine of the Dwarf Active Galactic Nucleus POX 52

A Catalog of Hyper-luminous X-Ray Sources and Intermediate-mass Black Hole Candidates out to High Redshifts

Contact Info

Product

Resources

About