scholarly journals Limits on the Accretion Rates onto Massive Black Holes in Nearby Galaxies

2001 ◽  
Vol 547 (2) ◽  
pp. 731-739 ◽  
Author(s):  
T. Di Matteo ◽  
C. L. Carilli ◽  
A. C. Fabian
Keyword(s):  
Black Holes ◽  
Massive Black Holes ◽  
Accretion Rates ◽  
Nearby Galaxies

scholarly journals 10.9. Dynamical constraints on alternatives to massive black holes in galactic nuclei

1998 ◽  
Vol 184 ◽  
pp. 447-448
Author(s):  
Eyal Maoz
Keyword(s):  
Black Holes ◽  
Galactic Nuclei ◽  
Compelling Evidence ◽  
Massive Black Holes ◽  
Nearby Galaxies ◽  
Dynamical Constraints

There is now compelling evidence for massive dark objects at the centers of severals galaxies. The possibility that these are black holes (BHs) fits well into the picture where quasars and AGNs are powered by accretion onto a massive BH, so that dead quasar engines should be hiding in many nearby galaxies.

scholarly journals 9.8. Bars and black holes

1998 ◽  
Vol 184 ◽  
pp. 397-398
Author(s):  
Eric Emsellem
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galaxies ◽  
Significant Fraction ◽  
Massive Black Hole ◽  
Central Mass ◽  
Massive Black Holes ◽  
Dark Object ◽  
Nearby Galaxies ◽  
Gas Accretion

Massive black holes are now thought to be present at the centre of a fair fraction of nearby galaxies. The origin of these central dark masses is still unknown, although tentative explanations have been proposed in an attempt to reconcile non-active galaxies with AGNs and quasars. The activity of a galaxy may then mostly depend on the efficiency of gas accretion onto the central dark object. It is important to note that many of the galaxies which are today candidates for the presence of a massive black hole are spirals. In this context, bars should play an important role in the evolution (and formation?) of a central mass, since (1) they are present in a significant fraction of spirals, (2) they may be efficient drivers of gas accretion. If indeed most of present day galaxies hosts a central dark mass, then bars and black holes should coexist in a significant fraction of them. We examine here the cases of 3 edge-on galaxies which are candidates for the presence of a central black holes: NGC 4570, NGC 3115 and M 104.

scholarly journals Relativistic Fe Kα line and ensemble spins of black holes in narrow-line Seyfert 1 galaxies

2014 ◽  
Vol 10 (S312) ◽  
pp. 39-42
Author(s):  
Weimin Yuan ◽  
Zhu Liu ◽  
Youjun Lu ◽  
Xin-Lin Zhou
Keyword(s):  
Black Holes ◽  
Seyfert Galaxies ◽  
Emission Feature ◽  
Narrow Line ◽  
Massive Black Holes ◽  
X Ray ◽  
Accretion Rates ◽  
Black Hole Growth ◽  
Average Spin ◽  
Hole Growth

AbstractWhile a broad line of the Fe Kα emission is commonly found in the X-ray spectra of typical Seyfert galaxies, the situation is unclear in the case of Narrow Line Seyfert 1 galaxies (NLS1s)—an extreme subset which are generally thought to harbor less massive black holes with higher accretion rates. We report results of our study of the assemble property of the Fe K line in NLS1s by stacking the X-ray spectra of a large sample of 51 NLS1s observed with XMM-Newton. We find in the stacked X-ray spectra a prominent, broad emission feature over 4–7 keV, which is characteristic of the broad Fe Kα line. Our results suggest that a relativistic broad Fe line may in fact be common in NLS1s. The line profile is used to study the average spin of the black holes in the sample. We find, for the first time, that their black holes are constrained to be likely spinning at averagely low or moderate rates as a population. The implications of the results are discussed in the context of the black hole growth in NLS1 galaxies.

scholarly journals On the Way AGN's Turn Off

1994 ◽  
Vol 159 ◽  
pp. 504-504
Author(s):  
D. Friedli
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Central Mass ◽  
Massive Black Holes ◽  
Present Epoch ◽  
Nearby Galaxies ◽  
The Way

Observations of nearby galaxies indicate non-negligible (dark) mass in their nuclei, interpreted either as very dense clusters or Massive Black Holes (MBH's). The latter hypothesis is supported by the widespread idea that MBH's can be the engine powering Active Galactic Nuclei (AGN's), and that interaction- or bar-induced central mass accretion can feed MBH's with large scale, plentiful fuel. However, there are fewer AGN's at the present time than at high redshifts, although many if not all bright galaxies must harbour relics of central active MBH's. How can we explain the fact that some AGN's are now turned off? Is it only due to the exhaustion or evaporation of the available fuel, and/or to the lower rate of interactions at the present epoch?

scholarly journals Emission from the Nuclei of Nearby Galaxies: Evidence for Massive Black Holes?

1978 ◽  
Vol 77 ◽  
pp. 237-244 ◽  
Author(s):  
M.J. Rees
Keyword(s):  
Black Holes ◽  
Physical Mechanism ◽  
Residual Activity ◽  
Galactic Nuclei ◽  
Slow Motion ◽  
Stellar Activity ◽  
Massive Black Holes ◽  
Low Level ◽  
Nearby Galaxies

The non-stellar activity in the nuclei of nearby galaxies poses problems of its own. But it gains added interest insofar as it may provide clues to the nature of quasars and the unusually energetic nuclei of some more remote galaxies. The evident qualitative resemblance between these spectacular phenomena and some of the nearby galactic nuclei discussed at this symposium suggests that we may be witnessing a scaled-down or slow-motion version of the same physical mechanism; and the likelihood that dead quasars vastly outnumber living ones suggests that defunct remnants - perhaps displaying some low-level residual activity - may lurk in the centres of most large galaxies.

Models for galaxy and massive black hole formation and early evolution

2020 ◽  
Vol 15 (S359) ◽  
pp. 11-16
Author(s):  
Rainer Weinberger
Keyword(s):  
Black Holes ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Accretion Rate ◽  
High Redshift ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Complex Processes ◽  
Accretion Rates ◽  
Eddington Limit

AbstractModels for massive black holes are a key ingredient for modern cosmological simulations of galaxy formation. The necessity of efficient AGN feedback in these simulations makes it essential to model the formation, growth and evolution of massive black holes, and parameterize these complex processes in a simplified fashion. While the exact formation mechanism is secondary for most galaxy formation purposes, accretion modeling turns out to be crucial. It can be informed by the properties of the high redshift quasars, accreting close to their Eddington limit, by the quasar luminosity function at peak activity and by low-redshift scaling relations. The need for halo-wide feedback implies a feedback-induced reduction of the accretion rate towards low redshift, amplifying the cosmological trend towards lower accretion rates at low redshift.

Black holes in stars and galaxies

2002 ◽  
Vol 10 (2) ◽  
pp. 205-220
Author(s):  
PHIL CHARLES
Keyword(s):  
Black Holes ◽  
Binary Stars ◽  
Unknown Origin ◽  
Gravitational Effect ◽  
Primary Energy ◽  
X Rays ◽  
Massive Black Holes ◽  
Accurate Mass Measurements ◽  
Nearby Stars ◽  
Nearby Galaxies

For 200 years, black holes have been a solution looking for a problem. In the last two decades they have moved to become a real scientific phenomenon. Black holes exist both as stars in our own Galaxy (identifiable as members of binary stars that emit X-rays) and as the centres of energetic galaxies (‘active galactic nuclei’). The last decade has seen the first accurate mass measurements of these black holes, which lie in the range from five times the mass of our own Sun to many million times. We also have clear evidence for the way that black holes accrete material as their primary energy source. Furthermore, the presence of super-massive black holes has been established in some nearby galaxies, and in the centre of our own Galaxy, from their gravitational effect on nearby stars. Some observations show processes that occur very close to the black hole, where the field of gravity is strong enough to test General Relativity. Recent observations suggest the existence of intermediate mass black holes of an as yet unknown origin.

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