Suzaku observations of active galactic nuclei detected in the SWIFT BAT survey: Discovery of a "new type" of buried supermassive black holes

Yoshihiro Ueda, Satoshi Eguchi, Yuichi Terashima, Richard Muschotzky, Jack Tueller, Craig Markwardt, Neil Gehrels, Yasuhiro Hashimoto, Stephen Potter

Research output: Contribution to journalArticle

124 Citations (Scopus)

Abstract

We present the Suzaku broadband observations of two AGNs detected by the Swift BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, SWIFT J0601.9-8636 and SWIFT J0138.6-4001. The Suzaku spectra reveal in both objects a heavily absorbed power-law component with a column density of N H ≃ 1023.5-1024 cm-2 that dominates above 10 keV and an intense reflection component with a solid angle ≳27π from a cold, optically thick medium. We find that these AGNs have an extremely small fraction of scattered light from the nucleus, ≲0.5% with respect to the intrinsic power-law component. This indicates that they are buried in a very geometrically thick torus with a small opening angle and/or have an unusually small amount of gas responsible for scattering. In the former case, the geometry of SWIFT J0601.9-8636 should be nearly face-on as inferred from the small absorption for the reflection component. The discovery of two such objects in this small sample implies that there must be a significant number of yet unrecognized, very Compton thick AGNs viewed at larger inclination angles in the local universe, which are difficult to detect even in the currently most sensitive optical or hard X-ray surveys.

Original languageEnglish
Pages (from-to)L79-L82
JournalAstrophysical Journal
Volume664
Issue number2 II
DOIs
Publication statusPublished - 2007 Aug 1

Fingerprint

active galactic nuclei
power law
x rays
scattering
inclination
geometry
universe
broadband
gas
nuclei
gases
cold

Keywords

  • Galaxies: active
  • Gamma rays: observations
  • X-rays: galaxies
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Ueda, Y., Eguchi, S., Terashima, Y., Muschotzky, R., Tueller, J., Markwardt, C., ... Potter, S. (2007). Suzaku observations of active galactic nuclei detected in the SWIFT BAT survey: Discovery of a "new type" of buried supermassive black holes. Astrophysical Journal, 664(2 II), L79-L82. https://doi.org/10.1086/520576

Suzaku observations of active galactic nuclei detected in the SWIFT BAT survey : Discovery of a "new type" of buried supermassive black holes. / Ueda, Yoshihiro; Eguchi, Satoshi; Terashima, Yuichi; Muschotzky, Richard; Tueller, Jack; Markwardt, Craig; Gehrels, Neil; Hashimoto, Yasuhiro; Potter, Stephen.

In: Astrophysical Journal, Vol. 664, No. 2 II, 01.08.2007, p. L79-L82.

Research output: Contribution to journalArticle

Ueda, Y, Eguchi, S, Terashima, Y, Muschotzky, R, Tueller, J, Markwardt, C, Gehrels, N, Hashimoto, Y & Potter, S 2007, 'Suzaku observations of active galactic nuclei detected in the SWIFT BAT survey: Discovery of a "new type" of buried supermassive black holes', Astrophysical Journal, vol. 664, no. 2 II, pp. L79-L82. https://doi.org/10.1086/520576
Ueda, Yoshihiro ; Eguchi, Satoshi ; Terashima, Yuichi ; Muschotzky, Richard ; Tueller, Jack ; Markwardt, Craig ; Gehrels, Neil ; Hashimoto, Yasuhiro ; Potter, Stephen. / Suzaku observations of active galactic nuclei detected in the SWIFT BAT survey : Discovery of a "new type" of buried supermassive black holes. In: Astrophysical Journal. 2007 ; Vol. 664, No. 2 II. pp. L79-L82.
@article{4fb696988ce04b1da8be7dc63a36778e,
title = "Suzaku observations of active galactic nuclei detected in the SWIFT BAT survey: Discovery of a {"}new type{"} of buried supermassive black holes",
abstract = "We present the Suzaku broadband observations of two AGNs detected by the Swift BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, SWIFT J0601.9-8636 and SWIFT J0138.6-4001. The Suzaku spectra reveal in both objects a heavily absorbed power-law component with a column density of N H ≃ 1023.5-1024 cm-2 that dominates above 10 keV and an intense reflection component with a solid angle ≳27π from a cold, optically thick medium. We find that these AGNs have an extremely small fraction of scattered light from the nucleus, ≲0.5{\%} with respect to the intrinsic power-law component. This indicates that they are buried in a very geometrically thick torus with a small opening angle and/or have an unusually small amount of gas responsible for scattering. In the former case, the geometry of SWIFT J0601.9-8636 should be nearly face-on as inferred from the small absorption for the reflection component. The discovery of two such objects in this small sample implies that there must be a significant number of yet unrecognized, very Compton thick AGNs viewed at larger inclination angles in the local universe, which are difficult to detect even in the currently most sensitive optical or hard X-ray surveys.",
keywords = "Galaxies: active, Gamma rays: observations, X-rays: galaxies, X-rays: general",
author = "Yoshihiro Ueda and Satoshi Eguchi and Yuichi Terashima and Richard Muschotzky and Jack Tueller and Craig Markwardt and Neil Gehrels and Yasuhiro Hashimoto and Stephen Potter",
year = "2007",
month = "8",
day = "1",
doi = "10.1086/520576",
language = "English",
volume = "664",
pages = "L79--L82",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 II",

}

TY - JOUR

T1 - Suzaku observations of active galactic nuclei detected in the SWIFT BAT survey

T2 - Discovery of a "new type" of buried supermassive black holes

AU - Ueda, Yoshihiro

AU - Eguchi, Satoshi

AU - Terashima, Yuichi

AU - Muschotzky, Richard

AU - Tueller, Jack

AU - Markwardt, Craig

AU - Gehrels, Neil

AU - Hashimoto, Yasuhiro

AU - Potter, Stephen

PY - 2007/8/1

Y1 - 2007/8/1

N2 - We present the Suzaku broadband observations of two AGNs detected by the Swift BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, SWIFT J0601.9-8636 and SWIFT J0138.6-4001. The Suzaku spectra reveal in both objects a heavily absorbed power-law component with a column density of N H ≃ 1023.5-1024 cm-2 that dominates above 10 keV and an intense reflection component with a solid angle ≳27π from a cold, optically thick medium. We find that these AGNs have an extremely small fraction of scattered light from the nucleus, ≲0.5% with respect to the intrinsic power-law component. This indicates that they are buried in a very geometrically thick torus with a small opening angle and/or have an unusually small amount of gas responsible for scattering. In the former case, the geometry of SWIFT J0601.9-8636 should be nearly face-on as inferred from the small absorption for the reflection component. The discovery of two such objects in this small sample implies that there must be a significant number of yet unrecognized, very Compton thick AGNs viewed at larger inclination angles in the local universe, which are difficult to detect even in the currently most sensitive optical or hard X-ray surveys.

AB - We present the Suzaku broadband observations of two AGNs detected by the Swift BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, SWIFT J0601.9-8636 and SWIFT J0138.6-4001. The Suzaku spectra reveal in both objects a heavily absorbed power-law component with a column density of N H ≃ 1023.5-1024 cm-2 that dominates above 10 keV and an intense reflection component with a solid angle ≳27π from a cold, optically thick medium. We find that these AGNs have an extremely small fraction of scattered light from the nucleus, ≲0.5% with respect to the intrinsic power-law component. This indicates that they are buried in a very geometrically thick torus with a small opening angle and/or have an unusually small amount of gas responsible for scattering. In the former case, the geometry of SWIFT J0601.9-8636 should be nearly face-on as inferred from the small absorption for the reflection component. The discovery of two such objects in this small sample implies that there must be a significant number of yet unrecognized, very Compton thick AGNs viewed at larger inclination angles in the local universe, which are difficult to detect even in the currently most sensitive optical or hard X-ray surveys.

KW - Galaxies: active

KW - Gamma rays: observations

KW - X-rays: galaxies

KW - X-rays: general

UR - http://www.scopus.com/inward/record.url?scp=34547977849&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547977849&partnerID=8YFLogxK

U2 - 10.1086/520576

DO - 10.1086/520576

M3 - Article

AN - SCOPUS:34547977849

VL - 664

SP - L79-L82

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 II

ER -