THE X-RAY SPECTRUM OF THE COOLING-FLOW QUASAR H1821+643: A MASSIVE BLACK HOLE FEEDING OFF THE INTRACLUSTER MEDIUM

M32 is the nearest dwarf elliptical galaxy. Its center is known to have a mass concentration of 3 × 106 M⊙, which is usually interpreted as an evidence of a super massive black hole. We observed M32 with ASCA two times in July and August of 1996. An X-ray source was detected at the center of M32 and its first broad-band X-ray spectra were obtained. ASCA observations of M32 limit the activity of the central black hole to be less than 10−6 times of the Eddington limit. We also found two other bright sources within 12 arcmin from the M32 center. One is the newly appeared X-ray source and the other is G144. In this paper, we summarize the results on the new source and G144. For M32, please refer to the publication (Loewenstein et al. 1997).

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X-ray Flux and Spectral Variability of the TeV Blazars Mrk 421 and PKS 2155-304

Galaxies ◽

10.3390/galaxies8030064 ◽

2020 ◽

Vol 8 (3) ◽

pp. 64

Author(s):

Alok C. Gupta

Keyword(s):

Black Hole ◽

Time Series Data ◽

Series Data ◽

Physical Parameters ◽

Electromagnetic Spectrum ◽

Black Hole Mass ◽

Spectral Variability ◽

Massive Black Hole ◽

X Ray ◽

Northern And Southern Hemispheres

We reviewed X-ray flux and spectral variability properties studied to date by various X-ray satellites for Mrk 421 and PKS 2155-304, which are TeV emitting blazars. Mrk 421 and PKS 2155-304 are the most X-ray luminous blazars in the northern and southern hemispheres, respectively. Blazars show flux and spectral variabilities in the complete electromagnetic spectrum on diverse timescales ranging from a few minutes to hours, days, weeks, months and even several years. The flux and spectral variability on different timescales can be used to constrain the size of the emitting region, estimate the super massive black hole mass, find the dominant emission mechanism in the close vicinity of the super massive black hole, search for quasi-periodic oscillations in time series data and several other physical parameters of blazars. Flux and spectral variability is also a dominant tool to explain jet as well as disk emission from blazars at different epochs of observations.

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Flows of X-ray gas reveal the disruption of a star by a massive black hole

Nature ◽

10.1038/nature15708 ◽

2015 ◽

Vol 526 (7574) ◽

pp. 542-545 ◽

Cited By ~ 82

Author(s):

Jon M. Miller ◽

Jelle S. Kaastra ◽

M. Coleman Miller ◽

Mark T. Reynolds ◽

Gregory Brown ◽

...

Keyword(s):

Black Hole ◽

Massive Black Hole ◽

X Ray

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Precessing AGN jets, bubbles and cooling flows

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311014839 ◽

2010 ◽

Vol 6 (S275) ◽

Author(s):

D. Falceta-Gonçalves ◽

A. Caproni ◽

Z. Abraham ◽

E. M. de Gouveia Dal Pino ◽

D. M. Teixeira

Keyword(s):

Galaxy Clusters ◽

Flow Problem ◽

X Rays ◽

Intracluster Medium ◽

X Ray ◽

Cooling Flows ◽

Cooling Flow ◽

Central Regions ◽

Multiple Bubbles ◽

Hydrodynamical Simulations

AbstractSeveral galaxy clusters are known to present multiple and misaligned pairs of cavities seen in X-rays, as well as twisted kiloparsec-scale jets at radio wavelengths. It suggests that the AGN precessing jets play a role in the formation of the misaligned bubbles. Also, X-ray spectra reveal that typically these systems are also able to supress cooling flows, predicted theoretically. The absence of cooling flows in galaxy clusters has been a mistery for many years since numerical simulations and analytical studies suggest that AGN jets are highly energetic, but are unable to redistribute it at all directions. We performed 3D hydrodynamical simulations of the interaction between a precessing AGN jet and the warm intracluster medium plasma, in which dynamics is coupled to a NFW dark matter gravitational potential. Radiative cooling has been taken into account and the cooling flow problem was studied. We found that precession is responsible for multiple pairs of bubbles, as observed. The misaligned bubbles rise up to scales of tens of kiloparsecs, where the thermal energy released by the jets are redistributed. After ~150 Myrs, the temperature of the gas within the cavities is kept of order of ~107 K, while the denser plasma of the intracluster medium at the central regions reaches T ~ 105 K. The existence of multiple bubbles, at diferent directions, results in an integrated temperature along the line of sight much larger than the simulations of non-precessing jets. This result is in agreement with the observations. The simulations reveal that the cooling flows cessed ~50–70 Myr after the AGN jets are started.

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Observational Progress in Identifying and Characterizing Tidal Disruption Flares

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317001764 ◽

2016 ◽

Vol 12 (S324) ◽

pp. 93-98

Author(s):

S. Bradley Cenko

Keyword(s):

Black Hole ◽

Optical Spectra ◽

Starburst Galaxies ◽

Electromagnetic Spectrum ◽

Speed Of Light ◽

Tidal Disruption ◽

Massive Black Hole ◽

X Ray ◽

Tidal Forces

AbstractI present an overview of observational efforts across the electromagnetic spectrum to identify and study tidal disruption flares (TDFs), when a star wanders too close to a super-massive black hole and is torn apart by tidal forces. In particular I will focus on four unexpected surprises that challenge the most basic analytic picture of these events: 1) large inferred radii for the optical/UV-emitting material; 2) the ubiquity of outflows, detected at radio, X-ray, and UV wavelengths, ranging from speeds of 100 km/s to near the speed of light; 3) the peculiar atomic abundances observed in the UV and optical spectra of these objects; and, 4) the preference for these events to occur in post-starburst galaxies.

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Gravitational Waves and X‐Ray Signals from Stellar Disruption by a Massive Black Hole

The Astrophysical Journal ◽

10.1086/424684 ◽

2004 ◽

Vol 615 (2) ◽

pp. 855-865 ◽

Cited By ~ 91

Author(s):

Shiho Kobayashi ◽

Pablo Laguna ◽

E. Sterl Phinney ◽

Peter Meszaros

Keyword(s):

Black Hole ◽

Gravitational Waves ◽

Massive Black Hole ◽

X Ray

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Potential Black Hole Seeding of the Spiral Galaxy NGC 4424 via an Infalling Star Cluster

The Astrophysical Journal ◽

10.3847/1538-4357/ac235b ◽

2021 ◽

Vol 923 (2) ◽

pp. 146

Author(s):

Alister W. Graham ◽

Roberto Soria ◽

Bogdan C. Ciambur ◽

Benjamin L. Davis ◽

Douglas A. Swartz

Keyword(s):

Black Hole ◽

Spiral Galaxy ◽

Near Infrared ◽

High Energy ◽

Star Cluster ◽

The Body ◽

Stellar Structure ◽

Massive Black Hole ◽

X Ray ◽

Low Mass

Abstract Galaxies can grow through their mutual gravitational attraction and subsequent union. While orbiting a regular high-surface-brightness galaxy, the body of a low-mass galaxy can be stripped away. However, the stellar heart of the infalling galaxy, if represented by a tightly bound nuclear star cluster, is more resilient. From archival Hubble Space Telescope images, we have discovered a red, tidally stretched star cluster positioned ∼5″ (∼400 pc in projection) from, and pointing toward the center of, the post-merger spiral galaxy NGC 4424. The star cluster, which we refer to as “Nikhuli,” has a near-infrared luminosity of (6.88 ± 1.85) × 106 L ⊙,F160W and likely represents the nucleus of a captured/wedded galaxy. Moreover, from our Chandra X-ray Observatory image, Nikhuli is seen to contain a high-energy X-ray point source, with L 0.5 − 8 keV = 6.31 − 3.77 + 7.50 × 10 38 erg s−1 (90% confidence). We argue that this is more likely to be an active massive black hole than an X-ray binary. Lacking an outward-pointing comet-like appearance, the stellar structure of Nikhuli favors infall rather than the ejection from a gravitational-wave recoil event. A minor merger with a low-mass early-type galaxy may have sown a massive black hole, aided an X-shaped pseudobulge, and be sewing a small bulge. The stellar mass and the velocity dispersion of NGC 4424 predict a central black hole of (0.6–1.0) × 105 M ⊙, similar to the expected intermediate-mass black hole in Nikhuli, and suggestive of a black hole supply mechanism for bulgeless late-type galaxies. We may potentially be witnessing black hole seeding by capture and sinking, with a nuclear star cluster the delivery vehicle.

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X-ray flares from the stellar tidal disruption by a candidate supermassive black hole binary

Nature Communications ◽

10.1038/s41467-020-19675-z ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Xinwen Shu ◽

Wenjie Zhang ◽

Shuo Li ◽

Ning Jiang ◽

Liming Dou ◽

...

Keyword(s):

Black Hole ◽

X Rays ◽

Tidal Disruption ◽

Massive Black Hole ◽

Ultraviolet Emission ◽

X Ray ◽

Black Hole Binaries ◽

Supermassive Black Hole ◽

Black Hole Binary

AbstractOptical transient surveys have led to the discovery of dozens of stellar tidal disruption events (TDEs) by massive black hole in the centers of galaxies. Despite extensive searches, X-ray follow-up observations have produced no or only weak X-ray detections in most of them. Here we report the discovery of delayed X-ray brightening around 140 days after the optical outburst in the TDE OGLE16aaa, followed by several flux dips during the decay phase. These properties are unusual for standard TDEs and could be explained by the presence of supermassive black hole binary or patchy obscuration. In either scenario, the X-rays can be produced promptly after the disruption but are blocked in the early phase, possibly by a radiation-dominated ejecta which leads to the bulk of optical and ultraviolet emission. Our findings imply that the reprocessing is important in the TDE early evolution, and X-ray observations are promising in revealing supermassive black hole binaries.

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Reprocessing of Uv and Line Emission in AGN Accretion Discs

Symposium - International Astronomical Union ◽

10.1017/s007418090017665x ◽

1994 ◽

Vol 159 ◽

pp. 489-489

Author(s):

Evlabia Rokaki ◽

Catherine Boisson

Keyword(s):

Black Hole ◽

Accretion Rate ◽

Line Emission ◽

Line Spectrum ◽

Physical Parameters ◽

Spectral Features ◽

Physical Processes ◽

Massive Black Hole ◽

X Ray ◽

The Continuum

It is commonly admitted that AGN contain a massive black hole fuelled most likely by an accretion disc. Several spectral features of the AGN, as the continuum excess in the UV and the broad line spectrum, involving different physical processes of emission (thermal for the UV continuum, photoionisation for the line spectrum) have been proposed as signatures of the disc. Physical parameters of the nucleus (as the mass of the black hole, M, the disc inclination, i, and accretion rate, Ṁ) are better determined when these two spectral features are modelled simultaneously. Here, we present results from the disc modelling (see) of the UV and broad Hβ emission of the 22 Seyfert 1 galaxies in a complete AGN sample selected in a hard X-ray survey.

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High Frequency Observations of a Large Faraday Rotation Galaxy in a Cluster

Symposium - International Astronomical Union ◽

10.1017/s0074180900190953 ◽

1990 ◽

Vol 140 ◽

pp. 486-486

Author(s):

M. Inoue ◽

H. Tabara ◽

T. Kato ◽

K. Aizu

Keyword(s):

Faraday Rotation ◽

Hot Spots ◽

High Frequency ◽

Intracluster Medium ◽

X Ray ◽

Cooling Flow ◽

Radio Jets ◽

Rotation Measure ◽

Dominant Member

We present 22 and 49 GHz interferometric observations of Hyd A (3C218). The source was found to have a very large Faraday rotation measure (RM) (Kato et al. 1987), and to be a dominant member of a luminous X-ray cluster with a large cooling flow (David et al. 1988). These characteristics are very similar to those of Cyg A which is suggested to produce a large RM within a dense sheath around the radio lobes as a result of somehow an interaction between dense intracluster medium (ICM) and radio jets and/or lobes (Dreher et al. 1987). Hyd A is the second example of Cyg A type source. In case of Cyg A, hot spots are the place where the interaction between jets and ICM occurs (Carilli et al. 1988). We then expect in Hyd A that similar interaction also occurs to form hot spots, and consequently that high frequency observations reveal structures of the interaction.

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