A Possible X-Ray Periodicity at Several Tens of Hours of an Ultraluminous Compact X-Ray Source in IC 342

Sugiho, Masahiko; Kotoku, J.; Makishima, Kazuo; Kubota, Aya; Mizuno, T.; Fukazawa, Yasushi; Tashiro, M.

doi:10.1086/324456

Cited by 33 publications

(29 citation statements)

References 31 publications

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“…The period is 27:0 AE 0:7 ks, and Bauer et al (2001) argue against the notion that this source is a foreground Galactic AM Her type system based primarily on the low surface density of Galactic X-ray sources in this direction (l ¼ 311 , b ¼ À3=8). Another IXO in IC 342 is possibly periodic, with a period of 31 or 41 hr, in agreement with that expected for a semidetached binary consisting of a black hole and a mainsequence star of tens of solar masses (Sugiho et al 2001).…”

Section: Introductionsupporting

confidence: 81%

AChandraX‐Ray Study of NGC 1068. II. The Luminous X‐Ray Source Population

Smith

Wilson

2003

ApJ

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We present an analysis of the compact X-ray source population in the Seyfert 2 galaxy NGC 1068, imaged with a $50 ks Chandra observation. We find a total of 84 compact sources on the S3 chip, of which 66 are located within the 25.0 B-mag arcsec À2 isophote of the galactic disk of NGC 1068. Spectra have been obtained for the 21 sources with at least 50 counts and modeled with both multicolor disk blackbody and power-law models. The power-law model provides the better description of the spectrum for 18 of these sources. For fainter sources, the spectral index has been estimated from the hardness ratio. Five sources have 0.4-8 keV intrinsic luminosities greater than 10 39 ergs s À1 , assuming that their emission is isotropic and that they are associated with NGC 1068. We refer to these sources as intermediate-luminosity X-ray objects (IXOs). If these five sources are X-ray binaries accreting with luminosities that are both sub-Eddington and isotropic, then the implied source masses are e7 M , and so they are inferred to be black holes. Most of the spectrally modeled sources have spectral shapes similar to Galactic black hole candidates. However, the brightest compact source in NGC 1068 has a spectrum that is much harder than that found in Galactic black hole candidates and other IXOs. The brightest source also shows large amplitude variability on both shortterm and long-term timescales, with the count rate possibly decreasing by a factor of 2 in $2 ks during our Chandra observation, and the source flux decreasing by a factor of 5 between our observation and the grating observations taken just over 9 months later. The ratio of the number of sources with luminosities greater than 2:1 Â 10 38 ergs s À1 in the 0.4-8 keV band to the rate of massive (>5 M ) star formation is the same, to within a factor of 2, for NGC 1068, the Antennae, NGC 5194 (the main galaxy in M51), and the Circinus galaxy. This suggests that the rate of production of X-ray binaries per massive star is approximately the same for galaxies with currently active star formation, including '' starbursts.''

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Section: Introductionsupporting

confidence: 81%

AChandraX‐Ray Study of NGC 1068. II. The Luminous X‐Ray Source Population

Smith

Wilson

2003

ApJ

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“…For the source Circinus CGX-1, Bauer et al (2001) claim periodic variations of 7.5 hours, and argue against it being a foreground galactic binary because of the absence of an optical counterpart to m v > 25.3 magnitudes, and on general statistical grounds. The other possibly periodic ULX is in the galaxy IC342 (Sugiho et al 2001) and has a suggested period of 31 hours or 41 hours, which is consistent with the orbital period of a semidetached binary with a BH and a main-sequence star of several tens of solar masses. Recently Terashima & Wilson (2003) reported a ULX in M51 with a > 50% variation separated by about two hours.…”

Section: Do Intermediate Mass Black Holes Exist?supporting

confidence: 63%

Do intermediate mass black holes exist?

Ward

2004

Proc. IAU

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“…The second possibility is that the X-rays are beamed, and we happen to be in the beam, the right interpretation for many of these sources, according to Georganopoulos et al (2002). Beaming leads one to expect rapid variability, as is indeed the case for some, perhaps most, of them (Sugiho et al 2001;Strickland et al 2001).…”

Section: Intermediate Mass Black Holesmentioning

confidence: 99%

Astrophysics in 2002

Trimble

Aschwanden

2003

PUBL ASTRON SOC PAC

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ABSTRACT. This has been the Year of the Baryon. Some low temperature ones were seen at high redshift, some high temperature ones were seen at low redshift, and some cooling ones were (probably) reheated. Astronomers saw the back of the Sun (which is also made of baryons), a possible solution to the problem of ejection of material by Type II supernovae (in which neutrinos push out baryons), the production of R Coronae Borealis stars (previously-owned baryons), and perhaps found the missing satellite galaxies (whose failing is that they have no baryons). A few questions were left unanswered for next year, and an attempt is made to discuss these as well.

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A Possible X-Ray Periodicity at Several Tens of Hours of an Ultraluminous Compact X-Ray Source in IC 342

Cited by 33 publications

References 31 publications

AChandraX‐Ray Study of NGC 1068. II. The Luminous X‐Ray Source Population

AChandraX‐Ray Study of NGC 1068. II. The Luminous X‐Ray Source Population

Do intermediate mass black holes exist?

Astrophysics in 2002

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