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X-ray emission from the nucleus of the dwarf elliptical galaxy NGC 3226
被引:12
作者:
George, IM
Mushotzky, RF
Yaqoob, T
Turner, TJ
Kraemer, S
Ptak, AF
Nandra, K
Crenshaw, DM
Netzer, H
机构:
[1] NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA
[2] Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA
[3] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[4] NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA
[5] Catholic Univ Amer, Inst Astrophys & Computat Sci, Washington, DC 20064 USA
[6] Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA
[7] Univ Space Res Assoc, Washington, DC USA
[8] Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel
[9] Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Wise Observ, IL-69978 Tel Aviv, Israel
关键词:
galaxies : active;
galaxies : dwarf;
galaxies : individual (NGC 3226);
galaxies : nuclei;
X-rays : binaries;
X-rays : galaxies;
D O I:
10.1086/322389
中图分类号:
P1 [天文学];
学科分类号:
0704 ;
摘要:
We present the first high-resolution X-ray image of the dwarf elliptical galaxy NGC 3226. The data were obtained during an observation of the nearby Seyfert Galaxy NGC 3227 using the Chandra X-Ray Observatory. We detect a point X-ray source spatially consistent with the optical nucleus of NGC 3226 and a recently detected, compact, flat-spectrum radio source. The X-ray spectrum can be measured up to similar to 10 keV and is consistent with a power law with a photon index 1.7 less than or similar to Gamma less than or similar to 2.2 or thermal bremsstrahlung emission with 4 keV less than or similar to kT less than or similar to 10 keV. In both cases, the luminosity in the 2-10 keV band similar or equal to 10(40) h(75)(-1) ergs s(-1). We find marginal evidence that the nucleus varies within the observation. These characteristics support evidence from other wave bands that NGC 3226 harbors a low-luminosity active nucleus. We also comment on two previously unknown, fainter X-ray sources less than or similar to 15" from the nucleus of NGC 3226. Their proximity to the nucleus (with projected distances of less than or similar to 1.3 h(75)(-1) kpc) suggests both are within NGC 3226 and thus have luminosities (approximately a few times 10(38) to a few times 10(39) ergs s(-1)) consistent with black hole binary systems.
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页码:167 / 172
页数:6
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