Host Galaxies of Hard X‐Ray–Selected Type 2 Active Galactic Nuclei at Intermediate Redshifts

Kiuchi, Gaku; Ohta, Kouji; Akiyama, Masayuki; Aoki, Kentaro; Ueda, Yoshihiro

doi:10.1086/505108

Cited by 7 publications

(7 citation statements)

References 34 publications

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“…The studies in Pellegrini (2005) are based on the Chandra observations down to a luminosity L 2−10keV ∼ 10 38 ergs s −1 . Kiuchi et al (2006) used the broad-line AGN sample detected by the ASCA Large Sky Survey (ALSS) and ASCA Medium Sensitivity Survey in the northern sky (AMSSn) with a detection limit of a few ×10 −13 ergs s −1 cm −2 in 2-10keV bandpass. As discussed above, it is worthy noting that the correlation most likely does not reflect the physics but a selection effect of the surveys.…”

Section: Black Hole Mass and Eddington Ratiomentioning

confidence: 99%

ACCRETION PROPERTIES OF A SAMPLE OF HARD X-RAY (<60 keV) SELECTED SEYFERT 1 GALAXIES

Wang

Mao

Wei

2009

The Astronomical Journal

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We examine the accretion properties in a sample of 42 hard (3-60keV) X-ray selected nearby broad-line AGNs. The energy range in the sample is harder than that usually used in the similar previous studies. These AGNs are mainly complied from the RXTE All Sky Survey (XSS), and complemented by the released INTEGRAL AGN catalog. The black hole masses, bolometric luminosities of AGN, and Eddington ratios are derived from their optical spectra in terms of the broad Hβ emission line. The tight correlation between the hard X-ray (3-20keV) and bolometric/line luminosity is well identified in our sample. Also identified is a strong inverse Baldwin relationship of the Hβ emission line. In addition, all these hard X-ray AGNs are biased toward luminous objects with high Eddington ratio (mostly between 0.01 to 0.1) and low column density (< 10 22 cm −2 ), which is most likely due to the selection effect of the surveys. The hard X-ray luminosity is consequently found to be strongly correlated with the black hole mass. We believe the sample completeness will be improved in the next few years by the ongoing Swift and INTEGRAL missions, and by the next advanced missions, such as NuSTAR, Simbol-X, and NeXT. Finally, the correlation between RFe (=optical Fe II/Hβ) and disk temperature as assessed by T ∝ (L/L Edd )M −1 BH leads us to suggest that the strength of the Fe II emission is mainly determined by the shape of the ionizing spectrum.

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Section: Black Hole Mass and Eddington Ratiomentioning

confidence: 99%

ACCRETION PROPERTIES OF A SAMPLE OF HARD X-RAY (<60 keV) SELECTED SEYFERT 1 GALAXIES

Wang

Mao

Wei

2009

The Astronomical Journal

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“…, without evidence for past major mergers). 98 , 99 ) Most of those models, however, over-predict the space density of low luminosity AGNs at high redshifts ( z > 1–2) compared with the observations. 63 ) The reason is yet unclear; some important physics would still be missed.…”

Section: Discussionmentioning

confidence: 98%

Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations

Ueda

2015

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

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We review the current understanding of the cosmological evolution of supermassive black holes in galactic centers elucidated by X-ray surveys of active galactic nuclei (AGNs). Hard X-ray observations at energies above 2 keV are the most efficient and complete tools to find “obscured” AGNs, which are dominant populations among all AGNs. Combinations of surveys with various flux limits and survey area have enabled us to determine the space number density and obscuration properties of AGNs as a function of luminosity and redshift. The results have essentially solved the origin of the X-ray background in the energy band below ∼10 keV. The downsizing (or anti-hierarchical) evolution that more luminous AGNs have the space-density peak at higher redshifts has been discovered, challenging theories of galaxy and black hole formation. Finally, we summarize unresolved issues on AGN evolution and prospects for future X-ray missions.

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“…Along with the lack of cosmic evolution (Shields et al 2003;Kiuchi et al 2006; but also see Akiyama 2005;Woo et al 2006;Borys et al 2005), the tightness of the correlation indicates that the growth of the spheroid mass and of the BH mass (M BH ) occurs almost simultaneously.…”

Section: Introductionmentioning

confidence: 92%

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Kawaguchi¹,

Nakanishi²,

Kohno³

et al. 2008

ApJ

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In order to investigate how the growth of galactic bulges progresses with the growth of central black holes (BHs), we observed molecular gas (fuel for the coming star formation) in possibly young active galaxies: narrow-line Seyfert 1 galaxies ( NLS1s). We present the results of radio observations of 12 CO(1 ! 0) using the Nobeyama Millimeter Array (with 2Y 4 kpc spatial resolution) for two FIR-bright NLS1s, yielding the first detection of their CO emission. Corresponding molecular gas masses M(H 2 ) of (1Y3) ; 10 9 M are the second and fourth largest among NLS1s. By estimating dynamical masses and bulge masses M bulge for these two NLS1s using CO channel maps and CO line widths, we found that M(H 2 ) amounted to 13%Y35% of these masses. Taking into account the star formation efficiency ($0.1), the increase in M bulge in those NLS1s in the near future (P10 7.5 yr) is not expected to be a huge fraction (1%Y5% of the preexisting stars). Bulge growth may have finished before BH growth, or bulge-BH coevolution may proceed with many occasionally discrete events, where one coevolution event produces only a small amount of mass growth of BHs and bulges. We also discuss the ratios of star formation rate to gas accretion rate onto BHs, finding that two NLS1s have very small ratios (%1) compared with the M bulge /M BH ratios found in active and inactive galaxies (%700). This huge difference suggests either nonoverlapped coevolution, a long star formation duration, or a temporarily high accretion rate during the NLS1 phase.

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Host Galaxies of Hard X‐Ray–Selected Type 2 Active Galactic Nuclei at Intermediate Redshifts

Cited by 7 publications

References 34 publications

ACCRETION PROPERTIES OF A SAMPLE OF HARD X-RAY (<60 keV) SELECTED SEYFERT 1 GALAXIES

ACCRETION PROPERTIES OF A SAMPLE OF HARD X-RAY (<60 keV) SELECTED SEYFERT 1 GALAXIES

Cosmological evolution of supermassive black holes in galactic centers unveiled by hard X-ray observations

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