Spectral properties of X-ray binaries in Centaurus a

Mark J. Burke; Somak Raychaudhury; Ralph P. Kraft; Thomas J. Maccarone; Nicola J. Brassington; Martin J. Hardcastle; Jouni Kainulainen; Kristin A. Woodley; Joanna L. Goodger; Gregory R. Sivakoff; William R. Forman; Christine Jones; Stephen S. Murray; Mark Birkinshaw; Judith H. Croston; Daniel A. Evans; Marat Gilfanov; Andrés Jordán; Craig L. Sarazin; Rasmus Voss; Diana M. Worrall; Zhongli Zhang

doi:10.1088/0004-637X/766/2/88

Spectral properties of X-ray binaries in Centaurus a

Mark J. Burke, Somak Raychaudhury, Ralph P. Kraft, Thomas J. Maccarone, Nicola J. Brassington, Martin J. Hardcastle, Jouni Kainulainen, Kristin A. Woodley, Joanna L. Goodger, Gregory R. Sivakoff, William R. Forman, Christine Jones, Stephen S. Murray, Mark Birkinshaw, Judith H. Croston, Daniel A. Evans, Marat Gilfanov, Andrés Jordán, Craig L. Sarazin, Rasmus VossDiana M. Worrall, Zhongli Zhang

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6 Scopus citations

Abstract

We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states based on the behavior of the fitted absorption column N _H, and present the spectral parameters of sources with L_x ≳ 2 × 10 ³⁷ erg s^-1. The majority of sources are consistent with being neutron star low-mass X-ray binaries (NS LMXBs) and we identify three transient black hole (BH) LMXB candidates coincident with the dust lane, which is the remnant of a small late-type galaxy. Our results also provide tentative support for the apparent "gap" in the mass distribution of compact objects between ∼2-5 M _⊙. We propose that BH LMXBs are preferentially found in the dust lane, and suggest this is because of the younger stellar population. The majority (∼70%-80%) of potential Roche lobe filling donors in the Cen A halo are ≳ 12 Gyr old, while BH LMXBs require donors ≳ 1 M _⊙ to produce the observed peak luminosities. This requirement for more massive donors may also explain recent results that claim a steepening of the X-ray luminosity function with age at L_x ≥ 5 × 10³⁸ erg s^-1 for the XB population of early-type galaxies; for older stellar populations, there are fewer stars ≳ 1 M _⊙, which are required to form the more luminous sources.

Original language	English
Article number	88
Journal	Astrophysical Journal
Volume	766
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/766/2/88
State	Published - 1 Apr 2013
Externally published	Yes

Keywords

X-rays: binaries
X-rays: galaxies
black hole physics
galaxies: elliptical and lenticular, cD
galaxies: individual (Centaurus A, NGC 5128)

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10.1088/0004-637X/766/2/88

Cite this

Burke, M. J., Raychaudhury, S., Kraft, R. P., Maccarone, T. J., Brassington, N. J., Hardcastle, M. J., Kainulainen, J., Woodley, K. A., Goodger, J. L., Sivakoff, G. R., Forman, W. R., Jones, C., Murray, S. S., Birkinshaw, M., Croston, J. H., Evans, D. A., Gilfanov, M., Jordán, A., Sarazin, C. L., ... Zhang, Z. (2013). Spectral properties of X-ray binaries in Centaurus a. Astrophysical Journal, 766(2), Article 88. https://doi.org/10.1088/0004-637X/766/2/88

@article{af7a494f74db43e39af92b761e91b3d8,

title = "Spectral properties of X-ray binaries in Centaurus a",

abstract = "We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states based on the behavior of the fitted absorption column N H, and present the spectral parameters of sources with Lx ≳ 2 × 10 37 erg s-1. The majority of sources are consistent with being neutron star low-mass X-ray binaries (NS LMXBs) and we identify three transient black hole (BH) LMXB candidates coincident with the dust lane, which is the remnant of a small late-type galaxy. Our results also provide tentative support for the apparent {"}gap{"} in the mass distribution of compact objects between ∼2-5 M ⊙. We propose that BH LMXBs are preferentially found in the dust lane, and suggest this is because of the younger stellar population. The majority (∼70%-80%) of potential Roche lobe filling donors in the Cen A halo are ≳ 12 Gyr old, while BH LMXBs require donors ≳ 1 M ⊙ to produce the observed peak luminosities. This requirement for more massive donors may also explain recent results that claim a steepening of the X-ray luminosity function with age at Lx ≥ 5 × 1038 erg s-1 for the XB population of early-type galaxies; for older stellar populations, there are fewer stars ≳ 1 M ⊙, which are required to form the more luminous sources.",

keywords = "X-rays: binaries, X-rays: galaxies, black hole physics, galaxies: elliptical and lenticular, cD, galaxies: individual (Centaurus A, NGC 5128)",

author = "Burke, {Mark J.} and Somak Raychaudhury and Kraft, {Ralph P.} and Maccarone, {Thomas J.} and Brassington, {Nicola J.} and Hardcastle, {Martin J.} and Jouni Kainulainen and Woodley, {Kristin A.} and Goodger, {Joanna L.} and Sivakoff, {Gregory R.} and Forman, {William R.} and Christine Jones and Murray, {Stephen S.} and Mark Birkinshaw and Croston, {Judith H.} and Evans, {Daniel A.} and Marat Gilfanov and Andr{\'e}s Jord{\'a}n and Sarazin, {Craig L.} and Rasmus Voss and Worrall, {Diana M.} and Zhongli Zhang",

year = "2013",

month = apr,

day = "1",

doi = "10.1088/0004-637X/766/2/88",

language = "English",

volume = "766",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2",

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Burke, MJ, Raychaudhury, S, Kraft, RP, Maccarone, TJ, Brassington, NJ, Hardcastle, MJ, Kainulainen, J, Woodley, KA, Goodger, JL, Sivakoff, GR, Forman, WR, Jones, C, Murray, SS, Birkinshaw, M, Croston, JH, Evans, DA, Gilfanov, M, Jordán, A, Sarazin, CL, Voss, R, Worrall, DM & Zhang, Z 2013, 'Spectral properties of X-ray binaries in Centaurus a', Astrophysical Journal, vol. 766, no. 2, 88. https://doi.org/10.1088/0004-637X/766/2/88

TY - JOUR

T1 - Spectral properties of X-ray binaries in Centaurus a

AU - Burke, Mark J.

AU - Raychaudhury, Somak

AU - Kraft, Ralph P.

AU - Maccarone, Thomas J.

AU - Brassington, Nicola J.

AU - Hardcastle, Martin J.

AU - Kainulainen, Jouni

AU - Woodley, Kristin A.

AU - Goodger, Joanna L.

AU - Sivakoff, Gregory R.

AU - Forman, William R.

AU - Jones, Christine

AU - Murray, Stephen S.

AU - Birkinshaw, Mark

AU - Croston, Judith H.

AU - Evans, Daniel A.

AU - Gilfanov, Marat

AU - Jordán, Andrés

AU - Sarazin, Craig L.

AU - Voss, Rasmus

AU - Worrall, Diana M.

AU - Zhang, Zhongli

PY - 2013/4/1

Y1 - 2013/4/1

N2 - We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states based on the behavior of the fitted absorption column N H, and present the spectral parameters of sources with Lx ≳ 2 × 10 37 erg s-1. The majority of sources are consistent with being neutron star low-mass X-ray binaries (NS LMXBs) and we identify three transient black hole (BH) LMXB candidates coincident with the dust lane, which is the remnant of a small late-type galaxy. Our results also provide tentative support for the apparent "gap" in the mass distribution of compact objects between ∼2-5 M ⊙. We propose that BH LMXBs are preferentially found in the dust lane, and suggest this is because of the younger stellar population. The majority (∼70%-80%) of potential Roche lobe filling donors in the Cen A halo are ≳ 12 Gyr old, while BH LMXBs require donors ≳ 1 M ⊙ to produce the observed peak luminosities. This requirement for more massive donors may also explain recent results that claim a steepening of the X-ray luminosity function with age at Lx ≥ 5 × 1038 erg s-1 for the XB population of early-type galaxies; for older stellar populations, there are fewer stars ≳ 1 M ⊙, which are required to form the more luminous sources.

AB - We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states based on the behavior of the fitted absorption column N H, and present the spectral parameters of sources with Lx ≳ 2 × 10 37 erg s-1. The majority of sources are consistent with being neutron star low-mass X-ray binaries (NS LMXBs) and we identify three transient black hole (BH) LMXB candidates coincident with the dust lane, which is the remnant of a small late-type galaxy. Our results also provide tentative support for the apparent "gap" in the mass distribution of compact objects between ∼2-5 M ⊙. We propose that BH LMXBs are preferentially found in the dust lane, and suggest this is because of the younger stellar population. The majority (∼70%-80%) of potential Roche lobe filling donors in the Cen A halo are ≳ 12 Gyr old, while BH LMXBs require donors ≳ 1 M ⊙ to produce the observed peak luminosities. This requirement for more massive donors may also explain recent results that claim a steepening of the X-ray luminosity function with age at Lx ≥ 5 × 1038 erg s-1 for the XB population of early-type galaxies; for older stellar populations, there are fewer stars ≳ 1 M ⊙, which are required to form the more luminous sources.

KW - X-rays: binaries

KW - X-rays: galaxies

KW - black hole physics

KW - galaxies: elliptical and lenticular, cD

KW - galaxies: individual (Centaurus A, NGC 5128)

UR - http://www.scopus.com/inward/record.url?scp=84875465181&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/766/2/88

DO - 10.1088/0004-637X/766/2/88

M3 - Article

AN - SCOPUS:84875465181

SN - 0004-637X

VL - 766

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 88

ER -

Spectral properties of X-ray binaries in Centaurus a

Abstract

Keywords

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