<i>Chandra</i>Study of X‐Ray Point Sources in the Early‐Type Galaxy NGC 4552 (M89)

Xu, Yujie; Xu, Haiguang; Zhang, Zhongli; Kundu, Arunav; Wang, Yu; Wu, Xiang-Ping

doi:10.1086/432636

Cited by 40 publications

(38 citation statements)

References 41 publications

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“…The GregoryLoredo analysis failed to find any statistically significant evidence for variability on shorter timescales, i.e., in the m > 2 moments. Thus, we find no statistical evidence in these data to support the claim by Xu et al (2005) that was based on their ''visual inspection of the light curve,'' for X-ray variability on 1 hr timescales.…”

Section: The Nuclear Regioncontrasting

confidence: 95%

ChandraObservations of Nuclear Outflows in the Elliptical Galaxy NGC 4552 in the Virgo Cluster

Macháček

Nulsen

Jones

et al. 2006

ApJ

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We use a 54.4 ks Chandra observation to study nuclear outflow activity in NGC 4552 (M89), an elliptical galaxy in the Virgo Cluster. Chandra images in the 0.5Y2 keV band show two ringlike features $1.7 kpc in diameter in the core of NGC 4552, as reported previously by Filho et al. We use spherically symmetric point explosion shock models to argue that the shape of the surface brightness profile across the rims of the rings and the temperature of hot gas in the rings are consistent with a Mach 1.7 shock carrying mean mechanical power L shock $ 3 ; 10 41 ergs s À1 produced by a $1:4 ; 10 55 ergs nuclear outburst $1Y2 Myr ago. We find the gas temperature in the central $100 pc of the galaxy to be 1:0 AE 0:2 keV, hotter than elsewhere in the galaxy, suggesting that we may be directly observing the reheating of the galaxy ISM by the outburst.

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Section: The Nuclear Regioncontrasting

confidence: 95%

ChandraObservations of Nuclear Outflows in the Elliptical Galaxy NGC 4552 in the Virgo Cluster

Macháček

Nulsen

Jones

et al. 2006

ApJ

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“…Both sources in NGC 4472, (+12:29:42.33, +08:00:07.96) and (+12:29:41.00, +07:57:44.46) were previously reported by Maccarone et al (2003Maccarone et al ( , 2011, respectively. Of the two sources in NGC 4552, one (+12:35:45.77, +12:33:02.46) was previously known (Xu et al 2005), while the other (+12:35:41.22, +12:34:51.43) is, to our knowledge, a new identification.…”

Section: Nature Of (Ultra-) Luminous X-ray Sourcesmentioning

confidence: 66%

Dependence of the low-mass X-ray binary population on stellar age

Zhang

Gilfanov

Bogdán

2012

A&A

128

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Aims. We investigate the dependence of the low-mass X-ray binary (LMXB) population in early-type galaxies on stellar age. Methods. We selected 20 massive nearby early-type galaxies from the Chandra archive occupying a relatively narrow range of masses and spanning a broad range of ages, from 1.6 Gyr to more than 10 Gyr, with the median value of 6 Gyr. With the ∼2000 X-ray point sources detected in total, we correlated the specific number of LMXBs in each galaxy with its stellar age and globular cluster (GC) content.Results. We found a correlation between the LMXB population and stellar age: older galaxies tend to possess about ≈50% more LMXBs (per unit stellar mass) than the younger ones. The interpretation of this dependence is complicated by large scatter and a rather strong correlation between stellar age and GC content of galaxies in our sample. We present evidence suggesting that the more important factor may be the evolution of the LMXB population with time. Its effect is further amplified by the larger GC content of older galaxies and correspondingly, the larger numbers of dynamically formed binaries in them. We also found clear evolution of the X-ray luminosity function (XLF) with age, i.e., that younger galaxies have more bright sources and fewer faint sources per unit stellar mass. The XLF of LMXBs in younger galaxies appears to extend significantly beyond 10 39 erg/s. Such bright sources seem to be less frequent in older galaxies. We found that 6 out of ≈12 (ultra-) luminous sources are located in GCs.

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“…However, three of the Chandra observations are not public yet, so the only reported results came from Chandra Obs ID 2072 (Filho et al 2004;Xu et al 2005;González-Martín et al 2009b;Grier et al 2011;Boroson et al 2011). Filho et al (2004 and González-Martín et al (2009b) In the UV, Cappellari et al (1999) studied this LINER with both HST imaging (FOC) and spectroscopy (FOS), with images taken in 1991, 1993, and 1996, showing long-term variability. This agrees with Maoz et al (2005), who used HST-ACS observations with its HRC mode and found a 20% variation of the nuclear flux in both F250W and F330W bands.…”

Section: Appendix A: Notes and Comparisons With Previous Results For mentioning

confidence: 99%

X-ray spectral variability of seven LINER nuclei withXMM-NewtonandChandradata

Hernández-García

González‐Martín

Márquez

et al. 2013

A&A

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Context. One of the most distinctive features in active galactic nuclei (AGN) is the variability of their emission. Variability has been discovered at X-ray, UV, and radio frequencies on timescales from hours to years. Among the AGN family and according to theoretical studies, low-ionization nuclear emission line region (LINER) nuclei would be objects variable on long timescales. Aims. Our purpose is to investigate spectral X-ray variability in LINERs and to understand the nature of these types of objects, as well as their accretion mechanism. Methods. Chandra and XMM-Newton public archives were used to compile X-ray spectra of seven LINER nuclei at different epochs with timescales of years. To search for variability we fit all spectra from the same object with a set of models to identify the parameters responsible for the variability pattern. We also analyzed the light curves to search for short timescale (from hours to days) variability. Whenever possible, UV variability was also studied. Results. We found spectral variability in four objects (NGC 1052, NGC 3226, NGC 4278, and NGC 4552), with variations mostly related to hard energies (2-10 keV). These variations are generated by several possible changes that act either alone or in combination: changes in the soft excess or in the absorber. Added to this can be intrinsic variations of the source, which may also be responsible by themselves for the spectral variability. These variations occurred within years, the shortest timescale being found for NGC 4278 (two months). Another two galaxies (NGC 4261 and NGC 5846) apparently do not vary. No short timescale variations during individual observations were found. Our analysis confirms the previously reported anticorrelation between the X-ray spectral index, Γ, and the Eddington ratio, L bol /L Edd , and also the correlation between the X-ray to UV flux ratio, α ox , and the Eddington ratio, L bol /L Edd . These results support an advection dominated accretion flow as the accretion mechanism in LINERs.

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ChandraStudy of X‐Ray Point Sources in the Early‐Type Galaxy NGC 4552 (M89)

Cited by 40 publications

References 41 publications

ChandraObservations of Nuclear Outflows in the Elliptical Galaxy NGC 4552 in the Virgo Cluster

ChandraObservations of Nuclear Outflows in the Elliptical Galaxy NGC 4552 in the Virgo Cluster

Dependence of the low-mass X-ray binary population on stellar age

X-ray spectral variability of seven LINER nuclei withXMM-NewtonandChandradata

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