THE MURMUR OF THE HIDDEN MONSTER:
                    <i>CHANDRA</i>
                    'S DECADAL VIEW OF THE SUPERMASSIVE BLACK HOLE IN M31

Li, Zhiyuan; Garcia, M. R.; Forman, W.; Jones, Christine; Kraft, Ralph; Lal, D.; Murray, Stephen S.; Wang, Q. Daniel

doi:10.1088/2041-8205/728/1/l10

Cited by 36 publications

(39 citation statements)

References 40 publications

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“…Again, the Galactic clouds of Nishimura et al (2015) lie on the right hand side of this figure and are difficult to compare with M31 measurements. Our measurements are not compatible with Seyfert galaxies, which makes sense because there is no sign of active galactic nuclei (AGN) in M31 (Li et al 2011). Interestingly, on the one hand, the HCN/HCO+ line ratio detected here is compatible with the value (1.5) measured by Liu et al (2013) in infrared dark clouds.…”

Section: Observed Line Ratioscontrasting

confidence: 82%

“…There is a significant continuum flux at 3.6 cm and 6.2 cm, and a weak polarised component (∼10%). There is a relatively flat spectral index (ν β = −0.4 ), while the contribution from the black hole is very weak and localised (Li et al 2011). This flat spectral index cannot be accounted for by an inverted synchrotron emission due to a present AGN, but we cannot exclude relic emission from past AGN activity (e.g.…”

Section: Gas Componentsmentioning

confidence: 99%

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Dense gas tracing the collisional past of Andromeda

Melchior

Combes

2015

A&A

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The central kiloparsec region of the Andromeda galaxy is relatively gas poor, while the interstellar medium appears to be concentrated in a ring-like structure at about 10 kpc radius. The central gas depletion has been attributed to a possible head-on collision 200 Myr ago, supported by the existence of an offset inner ring of warm dust. We present new IRAM 30 m radio telescope observations of the molecular gas in the central region, and the detection of CO and its isotopes 13 CO(2−1) and C 18 O(2−1), together with the dense gas tracers, HCN(1−0) and HCO+(1−0). A systematic study of the observed peak temperatures with non-local thermal equilibrium simulations shows that the detected lines trace dense regions with n H 2 in the range 2.5 × 10 4 −5.6 × 10 5 cm −3 , while the gas is very clumpy with a beam filling factor of 0.5−2 × 10 −2 . This is compatible with the dust mass derived from the far-infrared emission, assuming a dust-to-gas mass ratio of 0.01 with a typical clump size of 2 pc. We also show that the gas is optically thin in all lines except for 12 CO(1-0) and 12 CO(2-1), CO lines are close to their thermal equilibrium condition at 17-20 K, the molecular hydrogen density is larger than critical, and HCN and HCO+ lines have a subthermal excitation temperature of 9 K with a density smaller than critical. The average 12 CO/ 13 CO line ratio is high (∼21), and close to the 12 CO/C 18 O ratio (∼30) that was measured in the north-western region and estimated in the south-east stacking. The fact that the optically thin 13 CO and C 18 O lines have comparable intensities means that the secondary element 13 C is depleted with respect to the primary 12 C, as is expected just after a recent star formation. This suggests that there has been a recent starburst in the central region, supporting the head-on collision scenario.

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Section: Observed Line Ratioscontrasting

confidence: 82%

Section: Gas Componentsmentioning

confidence: 99%

Dense gas tracing the collisional past of Andromeda

Melchior

Combes

2015

A&A

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“…This circum-nuclear environment is discussed as a region of very high star density around a central black hole in Bender et al (2005) and Li et al (2009). Li et al (2011) recently discussed No. 164 as the X-ray source of the central super-massive black hole (M 31*) and provided a detailed Chandra light curve with an outburst in X-rays.…”

Section: Corementioning

confidence: 99%

X-ray source variability study of the M 31 central field usingChandraHRC-I

Pietsch¹,

Henze²,

Haberl³

et al. 2013

A&A

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Context. The central field of the Andromeda galaxy (M 31) was monitored from 2006 to 2012 using the Chandra HRC-I detector (about 0.1−10 keV energy range) with the main aim of detecting X-rays from optical novae. We present a systematic analysis of all X-ray sources found in the 41 nova monitoring observations, along with 23 M 31 central field HRC-I observations available from the Chandra data archive starting in December 1999. Aims. Based on these observations, we studied the X-ray long-term variability of the source population and especially of X-ray binaries in M 31. Methods. We created a catalogue of sources detected in the 64 available observations that adds up to a total exposure time of about 1 Ms. To study the variability, we developed a processing pipeline to derive long-term Chandra HRC-I light curves for each source over the 13 years of observations. We also searched for extended X-ray sources in the merged images.Results. We present a point-source catalogue containing 318 X-ray sources with detailed long-term variability information, 28 of which are published for the first time. The spatial and temporal resolution of the catalogue allows us to classify 115 X-ray binary candidates showing high X-ray variability or even outbursts, as well as 14 globular cluster X-ray binary candidates showing no significant variability. The analysis may suggest that outburst sources are less frequent in globular clusters than in the field of M 31. We detected seven supernova remnants, one of which is a new candidate, and also resolved the first X-rays from a known radio supernova remnant. In addition to 33 known optical nova/X-ray source correlations, we discovered one previously unknown super-soft X-ray outburst and several new nova candidates. Conclusions. The catalogue contains a large sample of detailed long-term X-ray light curves in the M 31 central field, which helps in understanding the X-ray population of our neighbouring spiral galaxy M 31.

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“…Therefore, we employed a two-dimensional image fitting method (Li et al 2011) to simultaneously determine the observed fluxes of X1 and X3, which not only maximizes the counting statistics, but also accounts for the propagation of the dominating error arising from the mutual point-spread function (PSF) scattering. Briefly, we fitted the 0.5-8 keV image of the central 60 60 ´ field with a three-component model convolved with the PSF.…”

Section: Revisiting the X-ray Nucleusmentioning

confidence: 99%

Detection of a Compact Nuclear Radio Source in the Local Group Elliptical Galaxy M32

Yang

Sjouwerman

et al. 2015

ApJ

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The Local Group compact elliptical galaxy M32 hosts one of the nearest candidate supermassive black holes (SMBHs), which has a previously suggested X-ray counterpart. Based on sensitive observations taken with the Karl G. Jansky Very Large Array (VLA), we detect for the first time a compact radio source coincident with the nucleus of M32, which exhibits an integrated flux density of 47.3 6.1 Jy m  at 6.6 GHz. We discuss several possibilities for the nature of this source, favoring an origin of the long-sought radio emission from the central SMBH, for which we also revisit the X-ray properties based on recently acquired Chandra and XMM-Newton data. Our VLA observations also discover radio emission from three previously known optical planetary nebulae in the inner region of M32.

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THE MURMUR OF THE HIDDEN MONSTER: CHANDRA 'S DECADAL VIEW OF THE SUPERMASSIVE BLACK HOLE IN M31

Cited by 36 publications

References 40 publications

Dense gas tracing the collisional past of Andromeda

Dense gas tracing the collisional past of Andromeda

X-ray source variability study of the M 31 central field usingChandraHRC-I

Detection of a Compact Nuclear Radio Source in the Local Group Elliptical Galaxy M32

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