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Sample records for accreting massive black

  1. MASSIVE BLACK HOLES IN STELLAR SYSTEMS: 'QUIESCENT' ACCRETION AND LUMINOSITY

    SciTech Connect

    Volonteri, M.; Campbell, D.; Mateo, M.; Dotti, M.

    2011-04-01

    Only a small fraction of local galaxies harbor an accreting black hole, classified as an active galactic nucleus. However, many stellar systems are plausibly expected to host black holes, from globular clusters to nuclear star clusters, to massive galaxies. The mere presence of stars in the vicinity of a black hole provides a source of fuel via mass loss of evolved stars. In this paper, we assess the expected luminosities of black holes embedded in stellar systems of different sizes and properties, spanning a large range of masses. We model the distribution of stars and derive the amount of gas available to a central black hole through a geometrical model. We estimate the luminosity of the black holes under simple, but physically grounded, assumptions on the accretion flow. Finally, we discuss the detectability of 'quiescent' black holes in the local universe.

  2. Retrograde binaries of massive black holes in circumbinary accretion discs

    NASA Astrophysics Data System (ADS)

    Amaro-Seoane, Pau; Maureira-Fredes, Cristián; Dotti, Massimo; Colpi, Monica

    2016-06-01

    Context. We explore the hardening of a massive black hole binary embedded in a circumbinary gas disc under a specific circumstance: when the binary and the gas are coplanar and the gas is counter-rotating. The binary has unequal mass and the interaction of the gas with the lighter secondary black hole is the main cause of the braking torque on the binary that shrinks with time. The secondary black hole, revolving in the direction opposite to the gas, experiences a drag from gas-dynamical friction and from direct accretion of part of it. Aims: In this paper, using two-dimensional (2D) hydrodynamical grid simulations we investigate the effect of changing the accretion prescriptions on the dynamics of the secondary black hole, which in turn affect the binary hardening and eccentricity evolution. Methods: We find that realistic accretion prescriptions lead to results that differ from those inferred assuming accretion of all the gas within the Roche Lobe of the secondary black hole. Results: When considering gas accretion within the gravitational influence radius of the secondary black hole (which is smaller than the Roche Lobe radius) to better describe gas inflows, the shrinking of the binary is slower. In addition, in this case, a smaller amount of accreted mass is required to reduce the binary separation by the same amount. Different accretion prescriptions result in different discs' surface densities, which alter the black hole's dynamics back. Full 3D Smoothed-particle hydrodynamics realizations of a number of representative cases, run over a shorter interval of time, validate the general trends observed in the less computationally demanding 2D simulations. Conclusions: Initially circular black hole binaries increase their eccentricity only slightly, which then oscillates around small values (<0.1) while they harden. By contrast, initially eccentric binaries become more and more eccentric. A semi-analytical model describing the black hole's dynamics under

  3. Quasi-stars: accreting black holes inside massive envelopes

    NASA Astrophysics Data System (ADS)

    Begelman, Mitchell C.; Rossi, Elena M.; Armitage, Philip J.

    2008-07-01

    We study the structure and evolution of `quasi-stars', accreting black holes embedded within massive hydrostatic gaseous envelopes. These configurations may model the early growth of supermassive black hole seeds. The accretion rate on to the black hole adjusts so that the luminosity carried by the convective envelope equals the Eddington limit for the total mass, M* + MBH ~ M*. This greatly exceeds the Eddington limit for the black hole mass alone, leading to rapid growth of the black hole. We use analytic models and numerical stellar structure calculations to study the structure and evolution of quasi-stars. We show that the photospheric temperature of the envelope scales as Tph ~ M-2/5BHM7/20*, and decreases with time while the black hole mass increases. Once Tph < 104 K, the photospheric opacity drops precipitously and Tph hits a limiting value, analogous to the Hayashi track for red giants and protostars, below which no hydrostatic solution for the convective envelope exists. For metal-free (Population III) opacities, this limiting temperature is approximately 4000 K. After a quasi-star reaches this limiting temperature, it is rapidly dispersed by radiation pressure. We find that black hole seeds with masses between 103 and 104Msolar could form via this mechanism in less than a few Myr.

  4. Hyper-Eddington accretion flows on to massive black holes

    NASA Astrophysics Data System (ADS)

    Inayoshi, Kohei; Haiman, Zoltán; Ostriker, Jeremiah P.

    2016-07-01

    We study very high rate, spherically symmetric accretion flows on to massive black holes (BHs; 102 ≲ MBH ≲ 106 M⊙) embedded in dense metal-poor clouds, performing one-dimensional radiation hydrodynamical simulations. We find solutions from outside the Bondi radius at hyper-Eddington rates, unimpeded by radiation feedback when (n∞/105 cm-3) > (MBH/104 M⊙)-1(T∞/104 K)3/2, where n∞ and T∞ are the density and temperature of ambient gas. Accretion rates in this regime are steady, and larger than 5000LEdd/c2, where LEdd is the Eddington luminosity. At lower Bondi rates, the accretion is episodic due to radiative feedback and the average rate is below the Eddington rate. In the hyper-Eddington case, the solution consists of a radiation-dominated central core, where photon trapping due to electron scattering is important, and an accreting envelope which follows a Bondi profile with T ≃ 8000 K. When the emergent luminosity is limited to ≲ LEdd because of photon trapping, radiation from the central region does not affect the gas dynamics at larger scales. We apply our result to the rapid formation of massive BHs in protogalaxies with a virial temperature of Tvir ≳ 104K. Once a seed BH forms at the centre of the galaxy, it can grow to a maximum ˜105(Tvir/104 K) M⊙ via gas accretion independent of the initial BH mass. Finally, we discuss possible observational signatures of rapidly accreting BHs with/without allowance for dust. We suggest that these systems could explain Lyα emitters without X-rays and nearby luminous infrared sources with hot dust emission, respectively.

  5. Hyper-Eddington accretion flows onto massive black holes

    NASA Astrophysics Data System (ADS)

    Inayoshi, Kohei; Haiman, Zoltán; Ostriker, Jeremiah P.

    2016-04-01

    We study very-high rate, spherically symmetric accretion flows onto massive black holes (BH; 10^2 ⪉ M_BH ⪉ 10^6~M_⊙) embedded in dense metal-poor clouds, performing one-dimensional radiation hydrodynamical simulations. We find solutions from outside the Bondi radius at hyper-Eddington rates, unimpeded by radiation feedback when (n∞/105~cm-3) > (MBH/104~M⊙)-1(T∞/104~K)3/2, where n∞ and T∞ are the density and temperature of ambient gas. Accretion rates in this regime are steady, and larger than 5000~LEdd/c2, where LEdd is the Eddington luminosity. At lower Bondi rates, the accretion is episodic due to radiative feedback and the average rate is below the Eddington rate. In the hyper-Eddington case, the solution consists of a radiation-dominated central core, where photon trapping due to electron scattering is important, and an accreting envelope which follows a Bondi profile with T ≃ 8000~K. When the emergent luminosity is limited to ⪉ L_Edd because of photon trapping, radiation from the central region does not affect the gas dynamics at larger scales. We apply our result to the rapid formation of massive BHs in protogalaxies with a virial temperature of T_vir⪆ 10^4~K. Once a seed BH forms at the center of the galaxy, it can grow to a maximum ˜105~(Tvir/104~K)~M⊙ via gas accretion independent of the initial BH mass. Finally, we discuss possible observational signatures of rapidly accreting BHs with/without allowance for dust. We suggest that these systems could explain Lyα emitters without X-rays and nearby luminous infrared sources with hot dust emission, respectively.

  6. An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10.

    PubMed

    Reines, Amy E; Sivakoff, Gregory R; Johnson, Kelsey E; Brogan, Crystal L

    2011-02-01

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first 'seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize 2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize 2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize 2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids. PMID:21217688

  7. An actively accreting massive black hole in the dwarf starburst galaxy Henize2-10

    NASA Astrophysics Data System (ADS)

    Reines, Amy E.; Sivakoff, Gregory R.; Johnson, Kelsey E.; Brogan, Crystal L.

    2011-02-01

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first `seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids.

  8. Growing massive black holes through supercritical accretion of stellar-mass seeds

    NASA Astrophysics Data System (ADS)

    Lupi, A.; Haardt, F.; Dotti, M.; Fiacconi, D.; Mayer, L.; Madau, P.

    2016-03-01

    The rapid assembly of the massive black holes that power the luminous quasars observed at z ˜ 6-7 remains a puzzle. Various direct collapse models have been proposed to head-start black hole growth from initial seeds with masses ˜105 M⊙, which can then reach a billion solar mass while accreting at the Eddington limit. Here, we propose an alternative scenario based on radiatively inefficient supercritical accretion of stellar-mass holes embedded in the gaseous circumnuclear discs (CNDs) expected to exist in the cores of high-redshift galaxies. Our sub-pc resolution hydrodynamical simulations show that stellar-mass holes orbiting within the central 100 pc of the CND bind to very high density gas clumps that arise from the fragmentation of the surrounding gas. Owing to the large reservoir of dense cold gas available, a stellar-mass black hole allowed to grow at super-Eddington rates according to the `slim-disc' solution can increase its mass by three orders of magnitudes within a few million years. These findings are supported by simulations run with two different hydro codes, RAMSES based on the Adaptive Mesh Refinement technique and GIZMO based on a new Lagrangian Godunov-type method, and with similar, but not identical, sub-grid recipes for star formation, supernova feedback, black hole accretion and feedback. The low radiative efficiency of supercritical accretion flows are instrumental to the rapid mass growth of our black holes, as they imply modest radiative heating of the surrounding nuclear environment.

  9. Super-Eddington accreting massive black holes as long-lived cosmological standards.

    PubMed

    Wang, Jian-Min; Du, Pu; Valls-Gabaud, David; Hu, Chen; Netzer, Hagai

    2013-02-22

    Super-Eddington accreting massive black holes (SEAMBHs) reach saturated luminosities above a certain accretion rate due to photon trapping and advection in slim accretion disks. We show that these SEAMBHs could provide a new tool for estimating cosmological distances if they are properly identified by hard x-ray observations, in particular by the slope of their 2-10 keV continuum. To verify this idea we obtained black hole mass estimates and x-ray data for a sample of 60 narrow line Seyfert 1 galaxies that we consider to be the most promising SEAMBH candidates. We demonstrate that the distances derived by the new method for the objects in the sample get closer to the standard luminosity distances as the hard x-ray continuum gets steeper. The results allow us to analyze the requirements for using the method in future samples of active black holes and to demonstrate that the expected uncertainty, given large enough samples, can make them into a useful, new cosmological ruler. PMID:23473126

  10. The Torquing of Circumnuclear Accretion Disks by Stars and the Evolution of Massive Black Holes

    NASA Astrophysics Data System (ADS)

    Bregman, Michal; Alexander, Tal

    2012-03-01

    An accreting massive black hole (MBH) in a galactic nucleus is surrounded by a dense stellar cluster. We analyze and simulate numerically the evolution of a thin accretion disk due to its internal viscous torques, due to the frame-dragging torques of a spinning MBH (the Bardeen-Petterson effect), and due to the orbit-averaged gravitational torques by the stars (resonant relaxation). We show that the evolution of the MBH mass accretion rate, the MBH spin growth rate, and the covering fraction of the disk relative to the central ionizing continuum source, are all strongly coupled to the stochastic fluctuations of the stellar potential via the warps that the stellar torques excite in the disk. These lead to fluctuations by factors of up to a few in these quantities over a wide range of timescales, with most of the power on timescales >~ (M •/Md )P(Rd ), where M • and Md are the masses of the MBH and disk, and P is the orbital period at the disk's mass-weighted mean radius Rd . The response of the disk is stronger the lighter it is and the more centrally concentrated the stellar cusp. As proof of concept, we simulate the evolution of the low-mass maser disk in NGC 4258 and show that its observed O(10°) warp can be driven by the stellar torques. We also show that the frame dragging of a massive active galactic nucleus disk couples the stochastic stellar torques to the MBH spin and can excite a jitter of a few degrees in its direction relative to that of the disk's outer regions.

  11. Effects of high-energy particles on accretion flows onto a super massive black hole

    NASA Astrophysics Data System (ADS)

    Kimura, Shigeo

    We study effects of high-energy particles on the accretion flow onto a supermassive black hole and luminosities of escaping particles such as protons, neutrons, gamma-rays, and neutrinos. We formulate a one-dimensional model of the two-component accretion flow consisting of thermal particles and high-energy particles, supposing that some fraction of viscous dissipation energy is converted to the acceleration of high-energy particles. The thermal component is governed by fluid dynamics while the high-energy particles obey the moment equations of the diffusion-convection equation. By solving the time evolution of these equations, we obtain advection dominated flows as steady state solutions. Effects of the high-energy particles on the flow structure turn out to be very small because the compressional heating is so effective that the thermal component always provides the major part of the pressure. We calculate luminosities of escaping particles for these steady solutions. For a broad range of mass accretion rates, escaping particles can extract the energy about one-thousandth of the accretion energy. We also discuss some implications on relativistic jet production by escaping particles.

  12. THE OBSERVED M-{sigma} RELATIONS IMPLY THAT SUPER-MASSIVE BLACK HOLES GROW BY COLD CHAOTIC ACCRETION

    SciTech Connect

    Nayakshin, Sergei; King, Andrew R.; Power, Chris

    2012-07-01

    We argue that current observations of M-{sigma} relations for galaxies can be used to constrain theories of super-massive black holes (SMBHs) feeding. In particular, assuming that SMBH mass is limited only by the feedback on the gas that feeds it, we show that SMBHs fed via a planar galaxy-scale gas flow, such as a disk or a bar, should be much more massive than their counterparts fed by quasi-spherical inflows. This follows from the relative inefficiency of active galactic nucleus feedback on a flattened inflow. We find that even under the most optimistic conditions for SMBH feedback on flattened inflows, the mass at which the SMBH expels the gas disk and terminates its own growth is a factor of several higher than the one established for quasi-spherical inflows. Any beaming of feedback away from the disk and any disk self-shadowing strengthen this result further. Contrary to this theoretical expectation, recent observations have shown that SMBHs in pseudobulge galaxies (which are associated with barred galaxies) are typically under- rather than overmassive when compared with their classical bulge counterparts at a fixed value of {sigma}. We conclude from this that SMBHs are not fed by large (100 pc to many kpc) scale gas disks or bars, most likely because such planar flows are turned into stars too efficiently to allow any SMBH growth. Based on this and other related observational evidence, we argue that most SMBHs grow by chaotic accretion of gas clouds with a small and nearly randomly distributed direction of angular momentum.

  13. Evolution of Massive Protostars Via Disk Accretion

    NASA Astrophysics Data System (ADS)

    Hosokawa, Takashi; Yorke, Harold W.; Omukai, Kazuyuki

    2010-09-01

    Mass accretion onto (proto-)stars at high accretion rates \\dot{M}_* > 10^{-4} M_{⊙} yr^{-1} is expected in massive star formation. We study the evolution of massive protostars at such high rates by numerically solving the stellar structure equations. In this paper, we examine the evolution via disk accretion. We consider a limiting case of "cold" disk accretion, whereby most of the stellar photosphere can radiate freely with negligible backwarming from the accretion flow, and the accreting material settles onto the star with the same specific entropy as the photosphere. We compare our results to the calculated evolution via spherically symmetric accretion, the opposite limit, whereby the material accreting onto the star contains the entropy produced in the accretion shock front. We examine how different accretion geometries affect the evolution of massive protostars. For cold disk accretion at 10-3 M sun yr-1, the radius of a protostar is initially small, R *sime a few R sun. After several solar masses have accreted, the protostar begins to bloat up and for M * ~= 10 M sun the stellar radius attains its maximum of 30-400 R sun. The large radius ~100 R sun is also a feature of spherically symmetric accretion at the same accreted mass and accretion rate. Hence, expansion to a large radius is a robust feature of accreting massive protostars. At later times, the protostar eventually begins to contract and reaches the zero-age main sequence (ZAMS) for M * ~= 30 M sun, independent of the accretion geometry. For accretion rates exceeding several 10-3 M sun yr-1, the protostar never contracts to the ZAMS. The very large radius of several hundreds R sun results in the low effective temperature and low UV luminosity of the protostar. Such bloated protostars could well explain the existence of bright high-mass protostellar objects, which lack detectable H II regions.

  14. Super- and sub-Eddington accreting massive black holes: a comparison of slim and thin accretion discs through study of the spectral energy distribution

    NASA Astrophysics Data System (ADS)

    Castelló-Mor, N.; Netzer, H.; Kaspi, S.

    2016-05-01

    We employ optical and ultraviolet (UV) observations to present spectral energy distributions (SEDs) for two reverberation-mapped samples of super-Eddington and sub-Eddington active galactic nuclei (AGN) with similar luminosity distributions. The samples are fitted with accretion disc (AD) models in order to look for SED differences that depend on the Eddington ratio. The fitting takes into account measured black hole (BH) mass and accretion rates, BH spin and intrinsic reddening of the sources. All objects in both groups can be fitted by thin AD models over the range 0.2-1 μm with reddening as a free parameter. The intrinsic reddening required to fit the data are relatively small, E(B - V) ≤ 0.2 mag, except for one source. Super-Eddington AGN seems to require more reddening. The distribution of E(B - V) is similar to what is observed in larger AGN samples. The best-fitting disc models recover very well the BH mass and accretion for the two groups. However, the SEDs are very different, with super-Eddington sources requiring much more luminous far-UV continuum. The exact amount depends on the possible saturation of the UV radiation in slim discs. In particular, we derive for the super-Eddington sources a typical bolometric correction at 5100 Å of 60-150 compared with a median of ˜20 for the sub-Eddington AGN. The measured torus luminosity relative to λLλ(5100 Å) are similar in both groups. The αOX distribution is similar too. However, we find extremely small torus covering factors for super-Eddington sources, an order of magnitude smaller than those of sub-Eddington AGN. The small differences between the groups regarding the spectral range 0.2-22 μm, and the significant differences related to the part of the SED that we cannot observe may be consistent with some slim disc models. An alternative explanation is that present day slim-disc models overestimate the far-UV luminosity of such objects by a large amount.

  15. Black hole accretion disc impacts

    NASA Astrophysics Data System (ADS)

    Pihajoki, P.

    2016-04-01

    We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength λ = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.

  16. Massive star formation by accretion. I. Disc accretion

    NASA Astrophysics Data System (ADS)

    Haemmerlé, L.; Eggenberger, P.; Meynet, G.; Maeder, A.; Charbonnel, C.

    2016-01-01

    Context. Massive stars likely form by accretion and the evolutionary track of an accreting forming star corresponds to what is called the birthline in the Hertzsprung-Russell (HR) diagram. The shape of this birthline is quite sensitive to the evolution of the entropy in the accreting star. Aims: We first study the reasons why some birthlines published in past years present different behaviours for a given accretion rate. We then revisit the question of the accretion rate, which allows us to understand the distribution of the observed pre-main-sequence (pre-MS) stars in the HR diagram. Finally, we identify the conditions needed to obtain a large inflation of the star along its pre-MS evolution that may push the birthline towards the Hayashi line in the upper part of the HR diagram. Methods: We present new pre-MS models including accretion at various rates and for different initial structures of the accreting core. We compare them with previously published equivalent models. From the observed upper envelope of pre-MS stars in the HR diagram, we deduce the accretion law that best matches the accretion history of most of the intermediate-mass stars. Results: In the numerical computation of the time derivative of the entropy, some treatment leads to an artificial loss of entropy and thus reduces the inflation that the accreting star undergoes along the birthline. In the case of cold disc accretion, the existence of a significant swelling during the accretion phase, which leads to radii ≳ 100 R⊙ and brings the star back to the red part of the HR diagram, depends sensitively on the initial conditions. For an accretion rate of 10-3M⊙ yr-1, only models starting from a core with a significant radiative region evolve back to the red part of the HR diagram. We also obtain that, in order to reproduce the observed upper envelope of pre-MS stars in the HR diagram with an accretion law deduced from the observed mass outflows in ultra-compact HII regions, the fraction of the

  17. Accretion disks around black holes

    NASA Technical Reports Server (NTRS)

    Abramowicz, M. A.

    1994-01-01

    The physics of accretion flow very close to a black hole is dominated by several general relativistic effects. It cannot be described by the standard Shakura Sunyaev model or by its relativistic version developed by Novikov and Thome. The most important of these effects is a dynamical mass loss from the inner edge of the disk (Roche lobe overflow). The relativistic Roche lobe overflow induces a strong advective cooling, which is sufficient to stabilize local, axially symmetric thermal and viscous modes. It also stabilizes the non-axially-symmetric global modes discovered by Papaloizou and Pringle. The Roche lobe overflow, however, destabilizes sufficiently self-gravitating accretion disks with respect to a catastrophic runaway of mass due to minute changes of the gravitational field induced by the changes in the mass and angular momentum of the central black hole. One of the two acoustic modes may become trapped near the inner edge of the disk. All these effects, absent in the standard model, have dramatic implications for time-dependent behavior of the accretion disks around black holes.

  18. Massive black holes in galactic halos?

    NASA Technical Reports Server (NTRS)

    Lacey, C. G.; Ostriker, J. P.

    1985-01-01

    In the present attempt to resolve the problems posed by the composition of dark halos and the heating of stellar disks, under the assumption that galaxy halos are composed of massive black holes, it is noted that the black holes must have masses of the order of one million solar masses. The heating mechanism proposed yields predictions for the dependence of the velocity dispersion on time, and for the shape of the velocity ellipsoid, which are in good agreement with observations. Attention is given to the constraints set by dynamical friction causing black holes to spiral to the Galactic center, by the possible presence of dark matter in dwarf spheroidal galaxies, and by the accretion of interstellar gas by the black holes that produce luminous objects in the Galaxy.

  19. Accretion flows govern black hole jet properties

    NASA Astrophysics Data System (ADS)

    Koljonen, K.; Russell, D.; Fernández Ontiveros, J.; Miller-Jones, J.; Russell, T.; Curran, P.; Soria, R.; Markoff, S.; van der Horst, A.; Casella, P.

    2015-07-01

    The process of jet formation in accreting black holes, and the conditions under which it occurs is currently hotly debated, with competing models predicting the jet power to be governed by black hole spin, the magnetic field strength, the location of the jet base, the mass accretion rate and/or the properties of the inner accretion flow. We present new results that show empirical correlations between the accretion flow properties and the spectral energy distribution of the jets launched from accreting black holes. The X-ray power law is directly related to the particle energy distribution in the hot accretion flow. We find that the photon index of this power law correlates with the characteristic break frequency in the jet spectrum emitted near the jet base, and the jet luminosity up to the break frequency. The observed correlations can be explained by the energy distribution of electrons in the hot accretion flow being subsequently channeled into the jet. These correlations represent a new inflow--outflow connection in accreting black holes, and demonstrate that the spectral properties of the jet rely most critically on the conditions in the inner accretion flow, rather than other parameters such as the black hole mass or spin.

  20. Accretion onto the first stellar mass black holes

    SciTech Connect

    Alvarez, Marcelo A.; Wise, John H.; Abel, Tom

    2009-08-05

    The first stars, forming at redshifts z > 15 in minihalos with M {approx} 10{sup 5-6} M{sub {circle_dot}} may leave behind remnant black holes, which could conceivably have been the 'seeds' for the supermassive black holes observed at z {approx}< 7. We study remnant black hole growth through accretion, including for the first time the radiation emitted due to accretion, with adaptive mesh refinement cosmological radiation-hydrodynamical simulations. The effects of photo-ionization and heating dramatically affect the large-scale inflow, resulting in negligible mass growth. We compare cases with accretion luminosity included and neglected to show that accretion radiation drastically changes the environment within 100 pc of the black hole, increasing gas temperatures by an order of magnitude. Gas densities are reduced and further star formation in the same minihalo is prevented for the two hundred million years we followed. Without radiative feedback included most seed black holes do not gain mass as efficiently as has been hoped for in previous theories, implying that black hole remnants of Pop III stars in minihalos are not likely to be miniquasars. Most importantly, however, our calculations demonstrate that if these black holes are indeed accreting close to the Bondi-Hoyle rate with ten percent radiative efficiency they have a dramatic local effect in regulating star formation in the first galaxies. This suggests a novel mechanism for massive black hole formation - stellar-mass black holes may have suppressed fragmentation and star formation after falling into halos with virial temperatures {approx} 10{sup 4} K, facilitating intermediate mass black hole formation at their centers.

  1. Bondi accretion onto cosmological black holes

    NASA Astrophysics Data System (ADS)

    Karkowski, Janusz; Malec, Edward

    2013-02-01

    In this paper we investigate a steady accretion within the Einstein-Straus vacuole, in the presence of the cosmological constant. The dark energy damps the mass accretion rate and—above a certain limit—completely stops the steady accretion onto black holes, which, in particular, is prohibited in the inflation era and after (roughly) 1012 years from the big bang (assuming the presently known value of the cosmological constant). Steady accretion would not exist in the late phases of the Penrose’s scenario—known as the Weyl curvature hypothesis—of the evolution of the Universe.

  2. Accretion of Ghost Condensate by Black Holes

    SciTech Connect

    Frolov, A

    2004-06-02

    The intent of this letter is to point out that the accretion of a ghost condensate by black holes could be extremely efficient. We analyze steady-state spherically symmetric flows of the ghost fluid in the gravitational field of a Schwarzschild black hole and calculate the accretion rate. Unlike minimally coupled scalar field or quintessence, the accretion rate is set not by the cosmological energy density of the field, but by the energy scale of the ghost condensate theory. If hydrodynamical flow is established, it could be as high as tenth of a solar mass per second for 10MeV-scale ghost condensate accreting onto a stellar-sized black hole, which puts serious constraints on the parameters of the ghost condensate model.

  3. Quasistationary solutions of scalar fields around accreting black holes

    NASA Astrophysics Data System (ADS)

    Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Izquierdo, Paula; Font, José A.; Montero, Pedro J.

    2016-08-01

    Massive scalar fields can form long-lived configurations around black holes. These configurations, dubbed quasibound states, have been studied both in the linear and nonlinear regimes. In this paper, we show that quasibound states can form in a dynamical scenario in which the mass of the black hole grows significantly due to the capture of infalling matter. We solve the Klein-Gordon equation numerically in spherical symmetry, mimicking the evolution of the spacetime through a sequence of analytic Schwarzschild black hole solutions of increasing mass. It is found that the frequency of oscillation of the quasibound states decreases as the mass of the black hole increases. In addition, accretion leads to an increase of the exponential decay of the scalar field energy. We compare the black hole mass growth rates used in our study with estimates from observational surveys and extrapolate our results to values of the scalar field masses consistent with models that propose scalar fields as dark matter in the universe. We show that, even for unrealistically large mass accretion rates, quasibound states around accreting black holes can survive for cosmological time scales. Our results provide further support to the intriguing possibility of the existence of dark matter halos based on (ultralight) scalar fields surrounding supermassive black holes in galactic centers.

  4. Dynamical structure of magnetized dissipative accretion flow around black holes

    NASA Astrophysics Data System (ADS)

    Sarkar, Biplob; Das, Santabrata

    2016-06-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several super-massive black hole sources and the observational implications of our present analysis are discussed.

  5. Birth of Massive Black Hole Binaries

    SciTech Connect

    Colpi, M.; Dotti, M.; Mayer, L.; Kazantzidis, S.; /KIPAC, Menlo Park

    2007-11-19

    If massive black holes (BHs) are ubiquitous in galaxies and galaxies experience multiple mergers during their cosmic assembly, then BH binaries should be common albeit temporary features of most galactic bulges. Observationally, the paucity of active BH pairs points toward binary lifetimes far shorter than the Hubble time, indicating rapid inspiral of the BHs down to the domain where gravitational waves lead to their coalescence. Here, we review a series of studies on the dynamics of massive BHs in gas-rich galaxy mergers that underscore the vital role played by a cool, gaseous component in promoting the rapid formation of the BH binary. The BH binary is found to reside at the center of a massive self-gravitating nuclear disc resulting from the collision of the two gaseous discs present in the mother galaxies. Hardening by gravitational torques against gas in this grand disc is found to continue down to sub-parsec scales. The eccentricity decreases with time to zero and when the binary is circular, accretion sets in around the two BHs. When this occurs, each BH is endowed with it own small-size ({approx}< 0.01 pc) accretion disc comprising a few percent of the BH mass. Double AGN activity is expected to occur on an estimated timescale of {approx}< 1 Myr. The double nuclear point-like sources that may appear have typical separation of {approx}< 10 pc, and are likely to be embedded in the still ongoing starburst. We note that a potential threat of binary stalling, in a gaseous environment, may come from radiation and/or mechanical energy injections by the BHs. Only short-lived or sub-Eddington accretion episodes can guarantee the persistence of a dense cool gas structure around the binary necessary for continuing BH inspiral.

  6. Chaotic Accretion and Merging Supermassive Black Holes

    NASA Astrophysics Data System (ADS)

    Nixon, Christopher James

    2012-09-01

    The main driver of the work in this thesis is the idea of chaotic accretion in galaxy centres. Most research in this area focuses on orderly or coherent accretion where supermassive black holes or supermassive black hole binaries are fed with gas always possessing the same sense of angular momentum. If instead gas flows in galaxies are chaotic, feeding occurs through randomly oriented depositions of gas. Previous works show that this chaotic mode of feeding can explain some astrophysical phenomena, such as the lack of correlation between host galaxy structure and the direction of jets. It has also been shown that by keeping the black hole spin low this feeding mechanism can grow supermassive black holes from stellar mass seeds. In this thesis I show that it also alleviates the "final parsec problem" by facilitating the merger of two supermassive black holes, and the growth of supermassive black holes through rapid accretion. I also develop the intriguing possibility of breaking a warped disc into two or more distinct planes.

  7. Gravitomagnetic acceleration from black hole accretion disks

    NASA Astrophysics Data System (ADS)

    Poirier, J.; Mathews, G. J.

    2016-05-01

    We demonstrate how the motion of the neutral masses in an accretion disk orbiting a black hole creates a general-relativistic magnetic-like (gravitomagnetic) field that vertically accelerates neutral particles near an accretion disk upward and then inward toward the axis of the accretion disk. Even though this gravitomagnetic field is not the only mechanism contributing to the production of jets, it presents a novel means to identify one general relativistic effect from a much more complicated problem. In addition, as the accelerated material above or below the accretion disk nears the axis with a nearly vertical direction, a frame-dragging effect twists the trajectories around the axis thus contributing to the collimation of the jet.

  8. Limiting Accretion onto Massive Stars by Fragmentation-Induced Starvation

    SciTech Connect

    Peters, Thomas; Klessen, Ralf S.; Mac Low, Mordecai-Mark; Banerjee, Robi; /ZAH, Heidelberg

    2010-08-25

    Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly understood. Two widely discussed models are monolithic collapse of molecular cloud cores and competitive accretion. To learn more about massive star formation, we perform simulations of the collapse of rotating, massive, cloud cores including radiative heating by both non-ionizing and ionizing radiation using the FLASH adaptive mesh refinement code. These simulations show fragmentation from gravitational instability in the enormously dense accretion flows required to build up massive stars. Secondary stars form rapidly in these flows and accrete mass that would have otherwise been consumed by the massive star in the center, in a process that we term fragmentation-induced starvation. This explains why massive stars are usually found as members of high-order stellar systems that themselves belong to large clusters containing stars of all masses. The radiative heating does not prevent fragmentation, but does lead to a higher Jeans mass, resulting in fewer and more massive stars than would form without the heating. This mechanism reproduces the observed relation between the total stellar mass in the cluster and the mass of the largest star. It predicts strong clumping and filamentary structure in the center of collapsing cores, as has recently been observed. We speculate that a similar mechanism will act during primordial star formation.

  9. LIMITING ACCRETION ONTO MASSIVE STARS BY FRAGMENTATION-INDUCED STARVATION

    SciTech Connect

    Peters, Thomas; Klessen, Ralf S.; Banerjee, Robi; Low, Mordecai-Mark Mac

    2010-12-10

    Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly understood. Two widely discussed models are monolithic collapse of molecular cloud cores and competitive accretion. To learn more about massive star formation, we perform and analyze simulations of the collapse of rotating, massive, cloud cores including radiative heating by both non-ionizing and ionizing radiation using the FLASH adaptive-mesh refinement code. These simulations show fragmentation from gravitational instability in the enormously dense accretion flows required to build up massive stars. Secondary stars form rapidly in these flows and accrete mass that would have otherwise been consumed by the massive star in the center, in a process that we term fragmentation-induced starvation. This explains why massive stars are usually found as members of high-order stellar systems that themselves belong to large clusters containing stars of all masses. The radiative heating does not prevent fragmentation, but does lead to a higher Jeans mass, resulting in fewer and more massive stars than would form without the heating. This mechanism reproduces the observed relation between the total stellar mass in the cluster and the mass of the largest star. It predicts strong clumping and filamentary structure in the center of collapsing cores, as has recently been observed. We speculate that a similar mechanism will act during primordial star formation.

  10. The formation of massive star systems by accretion.

    PubMed

    Krumholz, Mark R; Klein, Richard I; McKee, Christopher F; Offner, Stella S R; Cunningham, Andrew J

    2009-02-01

    Massive stars produce so much light that the radiation pressure they exert on the gas and dust around them is stronger than their gravitational attraction, a condition that has long been expected to prevent them from growing by accretion. We present three-dimensional radiation-hydrodynamic simulations of the collapse of a massive prestellar core and find that radiation pressure does not halt accretion. Instead, gravitational and Rayleigh-Taylor instabilities channel gas onto the star system through nonaxisymmetric disks and filaments that self-shield against radiation while allowing radiation to escape through optically thin bubbles. Gravitational instabilities cause the disk to fragment and form a massive companion to the primary star. Radiation pressure does not limit stellar masses, but the instabilities that allow accretion to continue lead to small multiple systems. PMID:19150809

  11. Small Seed Black Hole Growth in Various Accretion Regimes

    NASA Astrophysics Data System (ADS)

    Gerling-Dunsmore, Hannalore J.; Hopkins, Philip F.

    2016-03-01

    Observational evidence indicates a population of super massive black holes (SMBHs) (~109 -1010M⊙) formed within 1 Gyr after the Big Bang. One proposed means of SMBH formation is accretion onto small seed black holes (BHs) (~ 100M⊙). However, the existence of SMBHs within 1 Gyr requires rapid growth, but conventional models of accretion fail to grow the seed BHs quickly enough. Super Eddington accretion (Ṁ >ṀEddington) may aid in improving growth efficiency. We study small seed BH growth via accretion in 3D, using the magneto-hydrodynamics+gravity code GIZMO. In particular, we consider a BH in a high density turbulent star-forming cloud, and ask whether or not the BH can capture sufficient gas to grow rapidly. We consider both Eddington-limited and super Eddington regimes, and resolve physics on scales from 0.1 pc to 1 kpc while including detailed models for stellar feedback physics, including stellar winds, supernovae, radiation pressure, and photo-ionization. We present results on the viability of different small seed BHs growing into SMBH candidates.

  12. Chaotic cold accretion on to black holes

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Ruszkowski, M.; Oh, S. Peng

    2013-07-01

    Bondi theory is often assumed to adequately describe the mode of accretion in astrophysical environments. However, the Bondi flow must be adiabatic, spherically symmetric, steady, unperturbed, with constant boundary conditions. Using 3D adaptive mesh refinement simulations, linking the 50 kpc to the sub-parsec (sub-pc) scales over the course of 40 Myr, we systematically relax the classic assumptions in a typical galaxy hosting a supermassive black hole. In the more realistic scenario, where the hot gas is cooling, while heated and stirred on large scales, the accretion rate is boosted up to two orders of magnitude compared with the Bondi prediction. The cause is the non-linear growth of thermal instabilities, leading to the condensation of cold clouds and filaments when tcool/tff ≲ 10. The clouds decouple from the hot gas, `raining' on to the centre. Subsonic turbulence of just over 100 km s-1 (M > 0.2) induces the formation of thermal instabilities, even in the absence of heating, while in the transonic regime turbulent dissipation inhibits their growth (tturb/tcool ≲ 1). When heating restores global thermodynamic balance, the formation of the multiphase medium is violent, and the mode of accretion is fully cold and chaotic. The recurrent collisions and tidal forces between clouds, filaments and the central clumpy torus promote angular momentum cancellation, hence boosting accretion. On sub-pc scales the clouds are channelled to the very centre via a funnel. In this study, we do not inject a fixed initial angular momentum, though vorticity is later seeded by turbulence. A good approximation to the accretion rate is the cooling rate, which can be used as subgrid model, physically reproducing the boost factor of 100 required by cosmological simulations, while accounting for the frequent fluctuations. Since our modelling is fairly general (turbulence/heating due to AGN feedback, galaxy motions, mergers, stellar evolution), chaotic cold accretion may be common in

  13. Normal Modes of Black Hole Accretion Disks

    SciTech Connect

    Ortega-Rodriguez, Manuel; Silbergleit, Alexander S.; Wagoner, Robert V.; /Stanford U., Phys. Dept. /KIPAC, Menlo Park

    2006-11-07

    This paper studies the hydrodynamical problem of normal modes of small adiabatic oscillations of relativistic barotropic thin accretion disks around black holes (and compact weakly magnetic neutron stars). Employing WKB techniques, we obtain the eigen frequencies and eigenfunctions of the modes for different values of the mass and angular momentum of the central black hole. We discuss the properties of the various types of modes and examine the role of viscosity, as it appears to render some of the modes unstable to rapid growth.

  14. Superextremal spinning black holes via accretion

    NASA Astrophysics Data System (ADS)

    Bode, Tanja; Laguna, Pablo; Matzner, Richard

    2011-09-01

    A Kerr black hole with mass M and angular momentum J satisfies the extremality inequality |J|≤M2. In the presence of matter and/or gravitational radiation, this bound needs to be reformulated in terms of local measurements of the mass and the angular momentum directly associated with the black hole. The isolated and dynamical horizon framework provides such quasilocal characterization of black hole mass and angular momentum. With this framework, it is possible in axisymmetry to reformulate the extremality limit as |J|≤2MH2, with MH the irreducible mass of the black hole computed from its apparent horizon area and J obtained using a rotational Killing vector field on the apparent horizon. The |J|≤2MH2 condition is also equivalent to requiring a non-negative black hole surface gravity. We present numerical experiments of an accreting black hole that temporarily violates this extremality inequality. The initial configuration consists of a single, rotating black hole surrounded by a thick, shell cloud of negative energy density. For these numerical experiments, we introduce a new matter-without-matter evolution method.

  15. Observational constraints on black hole accretion disks

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.

    1994-01-01

    We review the empirical constraints on accretion disk models of stellar-mass black holes based on recent multiwavelength observational results. In addition to time-averaged emission spectra, the time evolutions of the intensity and spectrum provide critical information about the structure, stability, and dynamics of the disk. Using the basic thermal Keplerian disk paradigm, we consider in particular generalizations of the standard optically thin disk models needed to accommodate the extremely rich variety of dynamical phenomena exhibited by black hole candidates ranging from flares of electron-positron annihilations and quasiperiodic oscillations in the X-ray intensity to X-ray novae activity. These in turn provide probes of the disk structure and global geometry. The goal is to construct a single unified framework to interpret a large variety of black hole phenomena. This paper will concentrate on the interface between basic theory and observational data modeling.

  16. Gas Accretion and Mergers in Massive Galaxies at z ~ 2

    NASA Astrophysics Data System (ADS)

    Conselice, C. J.; Ownsworth, Jamie; Mortlock, Alice; Bluck, Asa F. L.

    2013-07-01

    Galaxy assembly is an unsolved problem, with ΛCDM theoretical models unable to easily account for among other things, the abundances of massive galaxies, and the observed merger history. We show here how the problem of galaxy formation can be addressed in an empirical way without recourse to models. We discuss how galaxy assembly occurs at 1.5 < z < 3 examining the role of major and minor mergers, and gas accretion from the intergalactic medium in forming massive galaxies with log M* > 11 found within the GOODS NICMOS Survey (GNS). We find that major mergers, minor mergers and gas accretion are roughly equally important in the galaxy formation process during this epoch, with 64% of the mass assembled through merging and 36% through accreted gas which is later converted to stars, while 58% of all new star formation during this epoch arises from gas accretion. We also discuss how the total gas accretion rate is measured as Ṁ = 90+/-40 M⊙ yr-1 at this epoch, a value close to those found in some hydrodynamical simulations.

  17. The lamppost model of accreting black holes

    NASA Astrophysics Data System (ADS)

    Zdziarski, A.

    2016-06-01

    Niedzwiecki, Zdziarski & Szanecki (2016, ApJL, submitted) have studied the lamppost model, in which the X-ray source in accreting black-hole systems is located on the rotation axis close to the horizon. We point out a number of inconsistencies in the widely used lamppost model relxilllp. They appear to invalidate those model fitting results for which the source distances from the horizon are within several gravitational radii. Furthermore, we note that if those results were correct, most of the photons produced in the lamppost would be trapped by the black hole, and the source luminosity as measured at infinity would be much larger than that observed. This appears to be in conflict with the observed smooth state transitions between the hard and soft states of X-ray binaries. The required increase of the accretion rate and the associated efficiency reduction present also a problem for AGNs. Then, those models imply the luminosity measured in the local frame much higher than the dissipated power due to time dilation and redshift, and the electron temperature significantly higher than that observed. We show that these conditions imply that the fitted sources would be out of the pair equilibrium.

  18. Black Hole Phase Transition in Massive Gravity

    NASA Astrophysics Data System (ADS)

    Ning, Shou-Li; Liu, Wen-Biao

    2016-07-01

    In massive gravity, some new phenomena of black hole phase transition are found. There are more than one critical points under appropriate parameter values and the Gibbs free energy near critical points also has some new properties. Moreover, the Maxwell equal area rule is also investigated and the coexistence curve of the black hole is given.

  19. Tidal disruption events by a massive black hole binary

    NASA Astrophysics Data System (ADS)

    Ricarte, Angelo; Natarajan, Priyamvada; Dai, Lixin; Coppi, Paolo

    2016-05-01

    Massive black hole binaries (MBHBs) are a natural byproduct of galaxy mergers. Previous studies have shown that flares from stellar tidal disruption events (TDEs) are modified by the presence of a secondary perturber, causing interruptions in the light curve. We study the dynamics of TDE debris in the presence of a milliparsec-separated MBHB by integrating ballistic particle orbits in the time-varying potential of the binary. We find that gaps in the light curve appear when material misses the accretion radius on its first return to pericentre. Subsequent recurrences can be decomposed into `continuous' and `delayed' components, which exhibit different behaviour. We find that this potential can substantially alter the locations of stream self-intersections. When debris is confined to the plane, we find that close encounters with the secondary massive black hole (MBH) leave noticeable signatures on the fallback rate and can result in significant accretion on to the secondary MBH. Tight, equal-mass MBHBs accrete equally, periodically trading the infalling stream.

  20. Accretion onto some well-known regular black holes

    NASA Astrophysics Data System (ADS)

    Jawad, Abdul; Shahzad, M. Umair

    2016-03-01

    In this work, we discuss the accretion onto static spherically symmetric regular black holes for specific choices of the equation of state parameter. The underlying regular black holes are charged regular black holes using the Fermi-Dirac distribution, logistic distribution, nonlinear electrodynamics, respectively, and Kehagias-Sftesos asymptotically flat regular black holes. We obtain the critical radius, critical speed, and squared sound speed during the accretion process near the regular black holes. We also study the behavior of radial velocity, energy density, and the rate of change of the mass for each of the regular black holes.

  1. Star Formation in Massive Clusters via Bondi Accretion

    NASA Astrophysics Data System (ADS)

    Murray, Norman; Chang, Philip

    2012-02-01

    Essentially all stars form in giant molecular clouds (GMCs). However, inside GMCs, most of the gas does not participate in star formation; rather, denser gas accumulates in clumps in the GMC, with the bulk of the stars in a given GMC forming in a few of the most massive clumps. In the Milky Way, these clumps have masses M cl <~ 5 × 10-2 of the GMC, radii r cl ~ 1 pc, and free-fall times τcl ~ 2 × 105 yr. We show that clumps inside GMCs should accrete at a modified Bondi accretion rate, which depends on clump mass as \\dot{M}_{cl}\\sim M_{cl}^{5/4}. This rate is initially rather slow, usually slower than the initial star formation rate inside the clump (we adopt the common assumption that inside the clump, \\dot{M}_*=\\epsilon _ffM_{cl}/\\tau _{cl}, with epsilonff ≈ 0.017). However, after ~2 GMC free-fall times τGMC, the clump accretion rate accelerates rapidly; formally, the clump can accrete the entire GMC in ~3τGMC. At the same time, the star formation rate accelerates, tracking the Bondi accretion rate. If the GMC is disrupted by feedback from the largest clump, half the stars in that clump form in the final τGMC before the GMC is disrupted. The theory predicts that the distribution of effective star formation rates, measured per GMC free-fall time, is broad, ranging from ~0.001 up to 0.1 or larger and that the mass spectrum of star clusters is flatter than that of clumps, consistent with observations.

  2. Accretion onto a charged higher-dimensional black hole

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Iftikhar, Sehrish

    2016-03-01

    This paper deals with the steady-state polytropic fluid accretion onto a higher-dimensional Reissner-Nordström black hole. We formulate the generalized mass flux conservation equation, energy flux conservation and relativistic Bernoulli equation to discuss the accretion process. The critical accretion is investigated by finding the critical radius, the critical sound velocity, and the critical flow velocity. We also explore gas compression and temperature profiles to analyze the asymptotic behavior. It is found that the results for the Schwarzschild black hole are recovered when q=0 in four dimensions. We conclude that the accretion process in higher dimensions becomes slower in the presence of charge.

  3. Phantom energy accretion onto black holes in a cyclic universe

    SciTech Connect

    Sun Chengyi

    2008-09-15

    Black holes pose a serious problem in cyclic or oscillating cosmology. It is speculated that, in the cyclic universe with phantom turnarounds, black holes will be torn apart by phantom energy prior to turnaround before they can create any problems. In this paper, using the mechanism of phantom accretion onto black holes, we find that black holes do not disappear before phantom turnaround. But the remanent black holes will not cause any problems due to Hawking evaporation.

  4. Accretion driven outflows across the black hole mass scale

    NASA Astrophysics Data System (ADS)

    King, Ashley L.

    2016-04-01

    Pumping highly relativistic particles and radiation into their environment, accreting black holes co-evolve with their surroundings through their powerful outflows. These outflows are divided into highly collimated, relativistic jets and wide-angle winds, and are primarily associated with a particular accretion states. Understanding just how these outflows couple to the accretion flow will enable us to assess the amount of energy and feedback that is injected into the vicinity of a black hole. During this talk, I will discuss our studies of both stellar-mass and supermassive black hole outlfows, and how the similarities of these flows across the mass scale may point to common driving mechanisms.

  5. Neutrino oscillation above a black hole accretion disk

    SciTech Connect

    Malkus, A.; Kneller, J. P.; McLaughlin, G. C.; Surman, R.

    2015-05-15

    We examine neutrino oscillations in the context of an accretion disk surrounding a black hole. Because accretion disks produce large quantities of neutrinos, they may be home to interesting neutrino oscillation as well. We model accretion disks associated with stellar collapse for the sake of understanding neutrino oscillations. We find that the neutrino oscillations include phenomena seen in the protoneutron star setting as well as phenomena not seen elsewhere.

  6. Alignments Of Black Holes with Their Warped Accretion Disks and Episodic Lifetimes of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Li, Yan-Rong; Wang, Jian-Min; Cheng, Cheng; Qiu, Jie

    2015-05-01

    Warped accretion disks have attracted intense attention because of their critical role in shaping the spin of supermassive massive black holes (SMBHs) through the Bardeen-Petterson effect, a general relativistic effect that leads to final alignments or anti-alignments between black holes and warped accretion disks. We study such alignment processes by explicitly taking into account the finite sizes of accretion disks and the episodic lifetimes of active galactic nuclei (AGNs) that delineate the duration of gas fueling onto accretion disks. We employ an approximate global model to simulate the evolution of accretion disks, allowing us to determine the gravitomagnetic torque that drives the alignments in a simple way. We then track down the evolutionary paths for mass and spin of black holes both in a single activity episode and over a series of episodes. Given with randomly and isotropically oriented gas fueling over episodes, we calculate the spin evolution with different episodic lifetimes and find that it is quite sensitive to the lifetimes. We therefore propose that the spin distribution of SMBHs can place constraints on the episodic lifetimes of AGNs and vice versa. The applications of our results on the observed spin distributions of SMBHs and the observed episodic lifetimes of AGNs are discussed, although both measurements at present are too ambiguous for us to draw a firm conclusion. Our prescription can be easily incorporated into semi-analytic models for black hole growth and spin evolution.

  7. Dwarf Galaxies with Active Massive Black Holes

    NASA Astrophysics Data System (ADS)

    Reines, Amy E.; Greene, J. E.; Geha, M. C.

    2014-01-01

    Supermassive black holes (BHs) live at the heart of essentially all massive galaxies with bulges, power AGN, and are thought to be important agents in the evolution of their hosts. However, the birth and growth of the first supermassive BH "seeds" is far from understood. While direct observations of these distant BHs in the infant Universe are unobtainable with current capabilities, massive BHs in present-day dwarf galaxies can place valuable constraints on the masses, formation path, and hosts of supermassive BH seeds. Using optical spectroscopy from the SDSS, we have systematically assembled the largest sample of dwarf galaxies hosting active massive BHs to date. These dwarf galaxies have stellar masses comparable to the Magellanic Clouds and contain some of the least-massive supermassive BHs known.

  8. Accretion of a ghost condensate by black holes

    SciTech Connect

    Frolov, Andrei V.

    2004-09-15

    The intent of this paper is to point out that the accretion of a ghost condensate by black holes could be extremely efficient. We analyze steady-state spherically symmetric flows of the ghost fluid in the gravitational field of a Schwarzschild black hole and calculate the accretion rate. Unlike minimally coupled scalar field or quintessence, the accretion rate is set not by the cosmological energy density of the field, but by the energy scale of the ghost condensate theory. If hydrodynamical flow is established, it could be as high as a tenth of a solar mass per second for 10 MeV scale ghost condensate accreting onto a stellar-sized black hole, which puts serious constraints on the parameters of the ghost condensate model.

  9. Dynamically important magnetic fields near accreting supermassive black holes.

    PubMed

    Zamaninasab, M; Clausen-Brown, E; Savolainen, T; Tchekhovskoy, A

    2014-06-01

    Accreting supermassive black holes at the centres of active galaxies often produce 'jets'--collimated bipolar outflows of relativistic particles. Magnetic fields probably play a critical role in jet formation and in accretion disk physics. A dynamically important magnetic field was recently found near the Galactic Centre black hole. If this is common and if the field continues to near the black hole event horizon, disk structures will be affected, invalidating assumptions made in standard models. Here we report that jet magnetic field and accretion disk luminosity are tightly correlated over seven orders of magnitude for a sample of 76 radio-loud active galaxies. We conclude that the jet-launching regions of these radio-loud galaxies are threaded by dynamically important fields, which will affect the disk properties. These fields obstruct gas infall, compress the accretion disk vertically, slow down the disk rotation by carrying away its angular momentum in an outflow and determine the directionality of jets. PMID:24899311

  10. Massive Binary Black Holes in the Cosmic Landscape

    NASA Astrophysics Data System (ADS)

    Colpi, Monica; Dotti, Massimo

    2011-02-01

    Binary black holes occupy a special place in our quest for understanding the evolution of galaxies along cosmic history. If massive black holes grow at the center of (pre-)galactic structures that experience a sequence of merger episodes, then dual black holes form as inescapable outcome of galaxy assembly, and can in principle be detected as powerful dual quasars. But, if the black holes reach coalescence, during their inspiral inside the galaxy remnant, then they become the loudest sources of gravitational waves ever in the universe. The Laser Interferometer Space Antenna is being developed to reveal these waves that carry information on the mass and spin of these binary black holes out to very large look-back times. Nature seems to provide a pathway for the formation of these exotic binaries, and a number of key questions need to be addressed: How do massive black holes pair in a merger? Depending on the properties of the underlying galaxies, do black holes always form a close Keplerian binary? If a binary forms, does hardening proceed down to the domain controlled by gravitational wave back reaction? What is the role played by gas and/or stars in braking the black holes, and on which timescale does coalescence occur? Can the black holes accrete on flight and shine during their pathway to coalescence? After outlining key observational facts on dual/binary black holes, we review the progress made in tracing their dynamics in the habitat of a gas-rich merger down to the smallest scales ever probed with the help of powerful numerical simulations. N-Body/hydrodynamical codes have proven to be vital tools for studying their evolution, and progress in this field is expected to grow rapidly in the effort to describe, in full realism, the physics of stars and gas around the black holes, starting from the cosmological large scale of a merger. If detected in the new window provided by the upcoming gravitational wave experiments, binary black holes will provide a deep view

  11. Hot accretion flows onto binary and single black holes

    NASA Astrophysics Data System (ADS)

    Gold, Roman; Paschalidis, Vasileios; Ruiz, Milton; Shapiro, Stuart; Etienne, Zachariah; Pfeiffer, Harald; McKinney, Jonathan

    2015-04-01

    Accreting black holes (BHs) are at the core of relativistic astrophysics as messengers of the strong-field regime of General Relativity and prime targets of several observational campaigns, including imaging the black hole shadow in SagA* and M87 with the Event Horizon Telescope. Binary Black Holes are one of the most promising gravitational wave sources for adLIGO and Pulsar Timing Arrays and - if accreting - can provide a strong electromagnetic counterpart. I will present results from global GRMHD simulations of both single and binary BHs embedded in a hot, magnetized disk, highlighting differences in their observational appearance including their gravitational and electromagnetic radiation.

  12. Constraints on black hole spins with a general relativistic accretion disk corona model

    NASA Astrophysics Data System (ADS)

    You, Bei; Cao, Xin-Wu; Yuan, Ye-Fei

    2016-04-01

    The peaks in the spectra of the accretion disks surrounding massive black holes in quasars are in the far-UV or soft X-ray band, which are usually not observed. However, in the disk corona model, soft photons from the disk are Comptonized to high energy in the hot corona, and the hard X-ray spectra (luminosity and spectral shape) contain information on the incident spectra from the disk. The values of black hole spin parameter a* are inferred from the spectral fitting, which are spread over a large range, ∼ ‑0.94 to 0.998. We find that the inclination angles and mass accretion rates are well determined by the spectral fitting, but the results are sensitive to the accuracy of black hole mass estimates. No tight constraints on the black hole spins are achieved, if the uncertainties in black hole mass measurements are a factor of four, which are typical for the single-epoch reverberation mapping method. Recently, the accuracy of black hole mass measurement has been significantly improved to 0.2 – 0.4 dex with the velocity resolved reverberation mapping method. The black hole spin can be well constrained if the mass measurement accuracy is ≲ 50%. In the accretion disk corona scenario, a fraction of power dissipated in the disk is transported into the corona, and therefore the accretion disk is thinner than a bare disk for the same mass accretion rate, because the radiation pressure in the disk is reduced. We find that the thin disk approximation, H/R ≲ 0.1, is still valid if 0.3 < ṁ < 0.5, provided half of the dissipated power is radiated in the corona above the disk.

  13. Domination of black hole accretion in brane cosmology.

    PubMed

    Majumdar, A S

    2003-01-24

    We consider the evolution of primordial black holes formed during the high energy phase of the braneworld scenario. We show that the effect of accretion from the surrounding radiation bath is dominant compared to evaporation for such black holes. This feature lasts till the onset of matter (or black hole) domination of the total energy density which could occur either in the high energy phase or later. We find that the black hole evaporation times could be significantly large even for black holes with small initial mass to survive until several cosmologically interesting eras. PMID:12570481

  14. Megaparsec relativistic jets launched from an accreting supermassive black hole in an extreme spiral galaxy

    SciTech Connect

    Bagchi, Joydeep; Vivek, M.; Srianand, Raghunathan; Gopal-Krishna; Vikram, Vinu; Hota, Ananda; Biju, K. G.; Sirothia, S. K.; Jacob, Joe

    2014-06-20

    The radio galaxy phenomenon is directly connected to mass-accreting, spinning supermassive black holes found in the active galactic nuclei. It is still unclear how the collimated jets of relativistic plasma on hundreds to thousands of kiloparsec scales form and why they are nearly always launched from the nuclei of bulge-dominated elliptical galaxies and not flat spirals. Here we present the discovery of the giant radio source J2345–0449 (z = 0.0755), a clear and extremely rare counterexample where relativistic jets are ejected from a luminous and massive spiral galaxy on a scale of ∼1.6 Mpc, the largest known so far. Extreme physical properties observed for this bulgeless spiral host, such as its high optical and infrared luminosity, large dynamical mass, rapid disk rotation, and episodic jet activity, are possibly the results of its unusual formation history, which has also assembled, via gas accretion from a disk, its central black hole of mass >2 × 10{sup 8} M {sub ☉}. The very high mid-IR luminosity of the galaxy suggests that it is actively forming stars and still building a massive disk. We argue that the launch of these powerful jets is facilitated by an advection-dominated, magnetized accretion flow at a low Eddington rate onto this unusually massive (for a bulgeless disk galaxy) and possibly fast spinning central black hole. Therefore, J2345–0449 is an extremely rare, unusual galactic system whose properties challenge the standard paradigms for black hole growth and the formation of relativistic jets in disk galaxies. Thus, it provides fundamental insight into accretion disk-relativistic jet coupling processes.

  15. Accretion disks and particle emission from black holes

    NASA Astrophysics Data System (ADS)

    Saifullah, Khalid

    2014-07-01

    Black holes are among the most interesting predictions of the general theory of relativity. The Thirty Meter Telescope will extend our ability to measure the masses of central black holes more accurately and to study the orbits of stars in the vicinity of these supermassive dark objects and warping of spacetime around them. Thus they will provide further evidence in favour of general relativity. This will help us resolve the accretion disks for these black holes also. The study of interaction of these accretion disks and the production and emission of particles from black holes is significant from the point of view of investigating the environment surrounding the dark objects hosted in the centre of many galaxies. The emission probabilities of particles including scalars and Dirac particles from black holes are calculated.

  16. Observational Signatures of Tilted Black Hole Accretion Disks from Simulations

    NASA Astrophysics Data System (ADS)

    Dexter, Jason; Fragile, P. Chris

    2011-03-01

    Geometrically thick accretion flows may be present in black hole X-ray binaries observed in the low/hard state and in low-luminosity active galactic nuclei. Unlike in geometrically thin disks, the angular momentum axis in these sources is not expected to align with the black hole spin axis. We compute images from three-dimensional general relativistic magnetohydrodynamic simulations of misaligned (tilted) accretion flows using relativistic radiative transfer and compare the estimated locations of the radiation edge with expectations from their aligned (untilted) counterparts. The radiation edge in the tilted simulations is independent of black hole spin for a tilt of 15°, in stark contrast to the results for untilted simulations, which agree with the monotonic dependence on spin expected from thin accretion disk theory. Synthetic emission line profiles from the tilted simulations depend strongly on the observer's azimuth and exhibit unique features such as broad "blue wings." Coupled with precession, the azimuthal variation could generate time fluctuations in observed emission lines, which would be a clear "signature" of a tilted accretion flow. Finally, we evaluate the possibility that the observed low- and high-frequency quasi-periodic oscillations (QPOs) from black hole binaries could be produced by misaligned accretion flows. Although low-frequency QPOs from precessing, tilted disks remains a viable option, we find little evidence for significant power in our light curves in the frequency range of high-frequency QPOs.

  17. Rapidly Accreting Supergiant Protostars: Embryos of Supermassive Black Holes?

    NASA Astrophysics Data System (ADS)

    Hosokawa, Takashi; Omukai, Kazuyuki; Yorke, Harold W.

    2012-09-01

    Direct collapse of supermassive stars (SMSs) is a possible pathway for generating supermassive black holes in the early universe. It is expected that an SMS could form via very rapid mass accretion with \\dot{M}_*\\sim 0.1{--}1 \\,M_\\odot \\,yr^{-1} during the gravitational collapse of an atomic-cooling primordial gas cloud. In this paper, we study how stars would evolve under such extreme rapid mass accretion, focusing on the early evolution until the stellar mass reaches 103 M ⊙. To this end, we numerically calculate the detailed interior structure of accreting stars with primordial element abundances. Our results show that for accretion rates higher than 10-2 M ⊙ yr-1, stellar evolution is qualitatively different from that expected at lower rates. While accreting at these high rates, the star always has a radius exceeding 100 R ⊙, which increases monotonically with the stellar mass. The mass-radius relation for stellar masses exceeding ~100 M ⊙ follows the same track with R *vpropM 1/2 * in all cases with accretion rates >~ 10-2 M ⊙ yr-1 at a stellar mass of 103 M ⊙, the radius is ~= 7000 R ⊙ (sime 30 AU). With higher accretion rates, the onset of hydrogen burning is shifted toward higher stellar masses. In particular, for accretion rates exceeding \\dot{M}_*\\gtrsim 0.1 \\,M_\\odot \\,yr^{-1}, there is no significant hydrogen burning even after 103 M ⊙ have accreted onto the protostar. Such "supergiant" protostars have effective temperatures as low as T eff ~= 5000 K throughout their evolution and because they hardly emit ionizing photons, they do not create an H II region or significantly heat their immediate surroundings. Thus, radiative feedback is unable to hinder the growth of rapidly accreting stars to masses in excess of 103 M ⊙ as long as material is accreted at rates \\dot{M}_*\\gtrsim 10^{-2} \\,M_\\odot \\,yr^{-1}.

  18. The role of stellar relaxation in the formation and evolution of the first massive black holes

    NASA Astrophysics Data System (ADS)

    Yajima, Hidenobu; Khochfar, Sadegh

    2016-04-01

    We present calculations on the formation of massive black holes of 105 M⊙ at z > 6, which can be the seeds of supermassive black holes at z ≳ 6. Under the assumption of compact star cluster formation in merging galaxies, star clusters in haloes of ˜ 108-109 M⊙ can undergo rapid core collapse, leading to the formation of very massive stars (VMSs) of ˜ 1000 M⊙ that collapse directly into black holes with similar masses. Star clusters in haloes of ≳ 109 M⊙ experience Type II supernovae before the formation of VMSs, due to long core-collapse time-scales. We also model the subsequent growth of black holes via accretion of residual stars in clusters. Two-body relaxation refills the loss cones of stellar orbits efficiently at larger radii and resonant relaxation at small radii is the main driver for accretion of stars on to black holes. As a result, more than 90 percent of stars in the initial cluster are swallowed by the central black holes before z = 6. Using dark matter merger trees, we derive black hole mass functions at z = 6-20. The mass function ranges from 103-105 M⊙ at z ≲ 15. Major merging of galaxies of ≳ 4 × 108 M⊙ at z ˜ 20 leads successfully to the formation of ≳ 105 M⊙ black holes by z ≳ 10, which could be the potential seeds of supermassive black holes seen today.

  19. A GENERAL RELATIVISTIC MODEL OF ACCRETION DISKS WITH CORONAE SURROUNDING KERR BLACK HOLES

    SciTech Connect

    You Bei; Cao Xinwu; Yuan Yefei E-mail: cxw@shao.ac.cn

    2012-12-20

    We calculate the structure of a standard accretion disk with a corona surrounding a massive Kerr black hole in the general relativistic frame, in which the corona is assumed to be heated by the reconnection of the strongly buoyant magnetic fields generated in the cold accretion disk. The emergent spectra of accretion disk-corona systems are calculated by using the relativistic ray-tracing method. We propose a new method to calculate the emergent Comptonized spectra from the coronae. The spectra of disk-corona systems with a modified {alpha}-magnetic stress show that both the hard X-ray spectral index and the hard X-ray bolometric correction factor L{sub bol}/L{sub X,2-10keV} increase with the dimensionless mass accretion rate, which is qualitatively consistent with the observations of active galactic nuclei. The fraction of the power dissipated in the corona decreases with increasing black hole spin parameter a, which leads to lower electron temperatures of the coronae for rapidly spinning black holes. The X-ray emission from the coronae surrounding rapidly spinning black holes becomes weak and soft. The ratio of the X-ray luminosity to the optical/UV luminosity increases with the viewing angle, while the spectral shape in the X-ray band is insensitive to the viewing angle. We find that the spectral index in the infrared waveband depends on the mass accretion rate and the black hole spin a, which deviates from the f{sub {nu}}{proportional_to}{nu}{sup 1/3} relation expected by the standard thin disk model.

  20. Gamma rays from accretion onto rotating black holes

    NASA Technical Reports Server (NTRS)

    Collins, M. S.

    1978-01-01

    Ionized matter falling onto an isolated, rotating black hole will be heated sufficiently that proton-proton collisions will produce mesons, including neutral pions, which decay into gamma rays. For massive (1000 M sub circled dot), black holes, the resulting gamma-ray luminosity may exceed 10 to the 36th power engs/s, with a spectrum peaked near 20 MeV.

  1. Gamma rays from accretion onto rotating black holes

    NASA Technical Reports Server (NTRS)

    Collins, M. S.

    1979-01-01

    Ionized matter falling onto an isolated rotating black hole will be heated sufficiently that proton-proton collisions will produce mesons, including neutral pions, which decay into gamma rays. For massive (1000-solar mass) black holes, the resulting gamma-ray luminosity may exceed 10 to the 36th erg/s with a spectrum peaked near 20 MeV.

  2. Properties of optically thick coronae around accreting black holes

    NASA Astrophysics Data System (ADS)

    Belmont, R.; Różańska, A.; Malzac, J.; Czerny, B.; Petrucci, P.-O.

    2015-12-01

    Accreting black holes are complex sources exhibiting several spectral components (disc, jet, hot corona etc). The exact nature and the interplay between these components is still uncertain, and constraining the accretion flow in the vicinity of the compact object has become a key problem to understand the general physics of accretion and ejection. In the past years, the X-ray spectra of several X-ray binaries and AGN have suggested the existence of a new type of coronae in the inner part of their accretion disk. These coronae are warm (about 1 keV) and have Thomson optical depths of about τ ≈ 10, much larger than the standard comptonizing medium inferred in black hole systems. However, simple radiative models based on the diffusion approximation are unable to sustain a large temperature over such high optical depths, therefore questioning existence of these thick coronae. Here we investigate the radiative and hydrostatic properties of slabs, thick coronae covering a standard accretion disc. A precise modelling of the radiation transfer shows that the observed temperature inversion can be reproduced, provided that most of the accretion power is dissipated in this upper layer and that the medium is strongly magnetised.

  3. Dynamical structure of magnetized dissipative accretion flow around black holes

    NASA Astrophysics Data System (ADS)

    Sarkar, Biplob; Das, Santabrata

    2016-09-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several supermassive black hole sources and the observational implications of our present analysis are discussed.

  4. Linking the Spin Evolution of Massive Black Holes to Galaxy Kinematics

    NASA Astrophysics Data System (ADS)

    Sesana, A.; Barausse, E.; Dotti, M.; Rossi, E. M.

    2014-10-01

    We present the results of a semianalytical model that evolves the masses and spins of massive black holes together with the properties of their host galaxies across the cosmic history. As a consistency check, our model broadly reproduces a number of observations, e.g., the cosmic star formation history; the black hole mass, luminosity, and galaxy mass functions at low redshift; the black hole-bulge mass relation; and the morphological distribution at low redshift. For the first time in a semianalytical investigation, we relax the simplifying assumptions of perfect coherency or perfect isotropy of the gas fueling the black holes. The dynamics of gas is instead linked to the morphological properties of the host galaxies, resulting in different spin distributions for black holes hosted in different galaxy types. We compare our results with the observed sample of spin measurements obtained through broad Kα iron line fitting. The observational data disfavor both accretion along a fixed direction and isotropic fueling. Conversely, when the properties of the accretion flow are anchored to the kinematics of the host galaxy, we obtain a good match between theoretical expectations and observations. A mixture of coherent accretion and phases of activity in which the gas dynamics is similar to that of the stars in bulges (i.e., with a significant velocity dispersion superimposed to a net rotation) best describes the data, adding further evidence in support of the coevolution of massive black holes and their hosts.

  5. Linking the spin evolution of massive black holes to galaxy kinematics

    SciTech Connect

    Sesana, A.; Barausse, E.; Dotti, M.; Rossi, E. M. E-mail: barausse@iap.fr E-mail: emr@strw.leidenuniv.nl

    2014-10-20

    We present the results of a semianalytical model that evolves the masses and spins of massive black holes together with the properties of their host galaxies across the cosmic history. As a consistency check, our model broadly reproduces a number of observations, e.g., the cosmic star formation history; the black hole mass, luminosity, and galaxy mass functions at low redshift; the black hole-bulge mass relation; and the morphological distribution at low redshift. For the first time in a semianalytical investigation, we relax the simplifying assumptions of perfect coherency or perfect isotropy of the gas fueling the black holes. The dynamics of gas is instead linked to the morphological properties of the host galaxies, resulting in different spin distributions for black holes hosted in different galaxy types. We compare our results with the observed sample of spin measurements obtained through broad Kα iron line fitting. The observational data disfavor both accretion along a fixed direction and isotropic fueling. Conversely, when the properties of the accretion flow are anchored to the kinematics of the host galaxy, we obtain a good match between theoretical expectations and observations. A mixture of coherent accretion and phases of activity in which the gas dynamics is similar to that of the stars in bulges (i.e., with a significant velocity dispersion superimposed to a net rotation) best describes the data, adding further evidence in support of the coevolution of massive black holes and their hosts.

  6. Resolving the Bondi Accretion Flow toward the Supermassive Black Hole of NGC 3115 with Chandra

    NASA Astrophysics Data System (ADS)

    Wong, Ka-Wah; Irwin, J.; Million, E.; Yukita, M.; Mathews, W.; Bregman, J.

    2011-09-01

    Gas undergoing Bondi accretion on to a supermassive black hole (SMBH) becomes hotter toward smaller radii. We searched for this signature with a Chandra observation of the hot gas in NGC 3115, which optical observation show has a very massive SMBH. Our observations show that the gas temperature rises toward the galaxy center as expected in all accretion models in which the black hole is gravitationally capturing the ambient gas. The data support that the Bondi radius is at least about 4-5 arcsec (188-235 pc), suggesting a supermassive blackhole of two billion solar masses that is consistent with the upper end of the optical results. The density profile within the Bondi radius has a power law index of 1.03, and we will discuss the interpretations of the results.

  7. Cold, clumpy accretion onto an active supermassive black hole

    NASA Astrophysics Data System (ADS)

    Tremblay, Grant R.; Oonk, J. B. Raymond; Combes, Françoise; Salomé, Philippe; O'Dea, Christopher P.; Baum, Stefi A.; Voit, G. Mark; Donahue, Megan; McNamara, Brian R.; Davis, Timothy A.; McDonald, Michael A.; Edge, Alastair C.; Clarke, Tracy E.; Galván-Madrid, Roberto; Bremer, Malcolm N.; Edwards, Louise O. V.; Fabian, Andrew C.; Hamer, Stephen; Li, Yuan; Maury, Anaëlle; Russell, Helen R.; Quillen, Alice C.; Urry, C. Megan; Sanders, Jeremy S.; Wise, Michael W.

    2016-06-01

    Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of very hot gas. Recent theory and simulations instead predict that accretion can be dominated by a stochastic, clumpy distribution of very cold molecular clouds—a departure from the ‘hot mode’ accretion model—although unambiguous observational support for this prediction remains elusive. Here we report observations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift z = 0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma. Under the right conditions, thermal instabilities produce a rain of cold clouds that fall towards the galaxy’s centre, sustaining star formation amid a kiloparsec-scale molecular nebula that is found at its core. The observations show that these cold clouds also fuel black hole accretion, revealing ‘shadows’ cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole, which serves as a bright backlight. Corroborating evidence from prior observations of warmer atomic gas at extremely high spatial resolution, along with simple arguments based on geometry and probability, indicate that these clouds are within the innermost hundred parsecs of the black hole, and falling closer towards it.

  8. Cold, clumpy accretion onto an active supermassive black hole.

    PubMed

    Tremblay, Grant R; Oonk, J B Raymond; Combes, Françoise; Salomé, Philippe; O'Dea, Christopher P; Baum, Stefi A; Voit, G Mark; Donahue, Megan; McNamara, Brian R; Davis, Timothy A; McDonald, Michael A; Edge, Alastair C; Clarke, Tracy E; Galván-Madrid, Roberto; Bremer, Malcolm N; Edwards, Louise O V; Fabian, Andrew C; Hamer, Stephen; Li, Yuan; Maury, Anaëlle; Russell, Helen R; Quillen, Alice C; Urry, C Megan; Sanders, Jeremy S; Wise, Michael W

    2016-06-01

    Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless largely unconstrained by observations, and is instead routinely simplified as a smooth, spherical inflow of very hot gas. Recent theory and simulations instead predict that accretion can be dominated by a stochastic, clumpy distribution of very cold molecular clouds--a departure from the 'hot mode' accretion model--although unambiguous observational support for this prediction remains elusive. Here we report observations that reveal a cold, clumpy accretion flow towards a supermassive black hole fuel reservoir in the nucleus of the Abell 2597 Brightest Cluster Galaxy (BCG), a nearby (redshift z = 0.0821) giant elliptical galaxy surrounded by a dense halo of hot plasma. Under the right conditions, thermal instabilities produce a rain of cold clouds that fall towards the galaxy's centre, sustaining star formation amid a kiloparsec-scale molecular nebula that is found at its core. The observations show that these cold clouds also fuel black hole accretion, revealing 'shadows' cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole, which serves as a bright backlight. Corroborating evidence from prior observations of warmer atomic gas at extremely high spatial resolution, along with simple arguments based on geometry and probability, indicate that these clouds are within the innermost hundred parsecs of the black hole, and falling closer towards it. PMID:27279215

  9. Accretion of radiation and rotating primordial black holes

    NASA Astrophysics Data System (ADS)

    Mahapatra, S.; Nayak, B.

    2016-02-01

    We consider rotating primordial black holes (PBHs) and study the effect of accretion of radiation in the radiation-dominated era. The central part of our analysis deals with the role of the angular momentum parameter on the evolution of PBHs. We find that both the accretion and evaporation rates decrease with an increase in the angular momentum parameter, but the rate of evaporation decreases more rapidly than the rate of accretion. This shows that the evaporation time of PBHs is prolonged with an increase in the angular momentum parameter. We also note that the lifetime of rotating PBHs increases with an increase in the accretion efficiency of radiation as in the case of nonrotating PBHs.

  10. The innermost extremes of black hole accretion

    NASA Astrophysics Data System (ADS)

    Fabian, A. C.

    2016-05-01

    The inner 20 gravitational radii around the black hole at the centre of luminous active galactic nuclei and stellar mass black hole binaries are now being routinely mapped by X-ray spectral-timing techniques. Spectral blurring and reverberation of the reflection spectrum are key tools in this work. In the most extreme AGN cases with high black hole spin, when the source appears in a low state, observations probe the region within 1 gravitational radius of the event horizon. The location, size, and operation of the corona which generates the power-law X-ray continuum is also being revealed.

  11. Stellar winds near massive black holes - the case of the S-stars

    NASA Astrophysics Data System (ADS)

    Lützgendorf, N.; Helm, E. van der; Pelupessy, F. I.; Portegies Zwart, S.

    2016-03-01

    The Galactic Centre provides a unique laboratory to study the interaction of a supermassive black hole (SMBH) with its gaseous and stellar environment. Simulations to determine the accretion of stellar winds from the surrounding O-stars on to the black hole have been performed earlier, but in those the presence of the S-star system was ignored. The S-stars are a group of young massive B-stars in relatively close orbits around the black hole. Here, we simulate those stars in order to study their contribution to the accretion rate, without taking the more distant and massive O-stars into account. We use the Astrophysical Multipurpose Software Environment to combine gravitational physics, stellar evolution and hydrodynamics in a single simulation of the S-stars orbiting the SMBH, and use this framework to determine the amount of gas that is accreted on to the black hole. We find that the accretion rate is sensitive to the wind properties of the S-stars (rate of mass-loss and terminal velocity). Our simulations are consistent with the observed accretion rate of the black hole only if the stars exhibit high wind mass-loss rates that are comparable with those of evolved 7-10 Myr old stars with masses of M = 19-25 M⊙. This is in contrast with observations that have shown that these stars are rather young, main-sequence B-stars. We therefore conclude that the S-stars cannot account for the accretion rate alone.

  12. SUPER-CRITICAL GROWTH OF MASSIVE BLACK HOLES FROM STELLAR-MASS SEEDS

    SciTech Connect

    Madau, Piero; Haardt, Francesco; Dotti, Massimo

    2014-04-01

    We consider super-critical accretion with angular momentum onto stellar-mass black holes as a possible mechanism for growing billion-solar-mass black holes from light seeds at early times. We use the radiatively inefficient ''slim disk'' solution—advective, optically thick flows that generalize the standard geometrically thin disk model—to show how mildly super-Eddington intermittent accretion may significantly ease the problem of assembling the first massive black holes when the universe was less than 0.8 Gyr old. Because of the low radiative efficiencies of slim disks around non-rotating as well as rapidly rotating black holes, the mass e-folding timescale in this regime is nearly independent of the spin parameter. The conditions that may lead to super-critical growth in the early universe are briefly discussed.

  13. Black hole spin influence on accretion disk neutrino detection

    NASA Astrophysics Data System (ADS)

    Caballero, O. L.; Zielinski, T.; McLaughlin, G. C.; Surman, R.

    2016-06-01

    Neutrinos are copiously emitted from neutrino-cooled black hole accretion disks playing a fundamental role in their evolution, as well as in the production of gamma ray bursts and r-process nucleosynthesis. The black hole generates a strong gravitational field able to change the properties of the emerging neutrinos. We study the influence of the black hole spin on the structure of the neutrino surfaces, neutrino luminosities, average neutrino energies, and event counts at SuperK. We consider several disk models and provide estimates that cover different black hole efficiency scenarios. We discuss the influence of the detector's inclination with respect to the axis of the torus on neutrino properties. We find that tori around spinning black holes have larger luminosities, energies, and rates compared to tori around static black holes and that the inclination of the observer causes a reduction in the luminosities and detection rates but an increase in the average energies.

  14. Hyper massive black holes in evolved galaxies

    NASA Astrophysics Data System (ADS)

    Romero-Cruz, Fernando J.

    2015-09-01

    From the SDSS DR7 we took a sample of 16733 galaxies which do not show all of the emission lines required to classify their activity according to the classical BPT diagram (Baldwin et al. 1981 PASP). Since they do not show these emission lines they are thought to be evolved enough so to host Hyper Massive Black holes. We compared their statistical properties with other galaxies from the SDSS DR7 which do show emission lines and confirmed that their M-sigma relationship correspond to HMBHs (Gutelkin et al. 2009 ApJ) and also that their SFH confirms evolution. We also analyzed them with a new Diagnostic Diagram in the IR (Coziol et al. 2015 AJ) and found that their position in the IR color space (W3W4 vs W2W3) correspond to AGN activity with current low SF, another confirmation of an evolved galaxy. The position of our final sample in the IR diagram is in the same region in which Holm 15A lies, this galaxy is considered to host the most massive BHs in the nearby universe (Lopez-Cruz et al. 2014 ApJL). The morphology of these galaxies (all of them are classified as elliptical) confirms that they are very evolved. We claim that the hyper massive BH lie in galaxies very evolved and with very low SF and without clear AGN activity in the BPT diagram.

  15. Where do Accretion Disks Around Black Holes End?

    NASA Astrophysics Data System (ADS)

    Asmus, D.; Duschl, W. J.

    2010-10-01

    Accretion disks around (supermassive) black holes act as "machines" which extract gravitational energy. In fact, the observed radiation allows to sample the physical conditions very close to the event horizon. For a test particle, the innermost stable circular orbit (ISCO) is located at 3 rS for a non-rotating hole (Schwarzschild metrics; at smaller radii for a rotating black hole). This ISCO is usually identified with the inner edge of the accretion disk. For a given black hole mass, it allows, in principle, to determine the Kerr parameter. In "real life," however, we deal not with test particles but with a viscous flow, which introduces additional forces. We have calculated the location of the inner edge in a more realistic environment. The results show that the true inner edge of the disk is no longer located at the ISCO, when radial advection of energy is taken into account with a careful treatment of the transonic nature of the flow.

  16. Lorentz Symmetric Aether and Its Accretion Onto Black Holes

    NASA Astrophysics Data System (ADS)

    Mirbabayi, Mehrdad

    Finding a consistent formulation of Lorentz-invariant massive gravity, with the right number of five degrees of freedom has been a long-standing problem in theoretical physics. A two-parameter family of candidate models has been recently proposed by de Rham, Gabadadze, and Tolley who provided considerable evidence for the absence of any extra degree of freedom. Meanwhile, it has been shown that massive gravity can be thought of as a generally covariant theory of a medium described by four scalar fields -- the aether . In the first part of the thesis, I study this theory of four scalar fields and show that de Rham-Gabadadze-Tolley massive gravity is the unique theory in which one of the scalar fields remains non-dynamical, and the full gravitational theory propagates five degrees of freedom, thereby proving the conjecture. The second part of the thesis deals with black holes in massive electrodynamics and massive gravity. In particular, the sense in which black hole solutions approach their counterparts in massless theories as the photon (graviton) mass is taken to zero. I will introduce and calculate the discharge mode for a Schwarzschild black hole in massive electrodynamics. For small photon mass, the discharge mode describes the decay of the electric field of a charged star collapsing into a black hole. I will then argue that a similar ``discharge of mass'' occurs in massive gravity and leads to a process of black hole disappearance. The zero-mass limit is, nevertheless, smooth in that the discharge (disappearance) rate vanishes in the limit: it scales as m2rg where m is the photon (graviton) mass and rg is the Schwarzschild radius of the black hole.

  17. Radial accretion flows on static spherically symmetric black holes

    NASA Astrophysics Data System (ADS)

    Chaverra, Eliana; Sarbach, Olivier

    2015-08-01

    We analyze the steady radial accretion of matter into a nonrotating black hole. Neglecting the self-gravity of the accreting matter, we consider a rather general class of static, spherically symmetric and asymptotically flat background spacetimes with a regular horizon. In addition to the Schwarzschild metric, this class contains certain deformation of it, which could arise in alternative gravity theories or from solutions of the classical Einstein equations in the presence of external matter fields. Modeling the ambient matter surrounding the black hole by a relativistic perfect fluid, we reformulate the accretion problem as a dynamical system, and under rather general assumptions on the fluid equation of state, we determine the local and global qualitative behavior of its phase flow. Based on our analysis and generalizing previous work by Michel, we prove that for any given positive particle density number at infinity, there exists a unique radial, steady-state accretion flow which is regular at the horizon. We determine the physical parameters of the flow, including its accretion and compression rates, and discuss their dependency on the background metric.

  18. Black hole accretion disks with coronae

    NASA Technical Reports Server (NTRS)

    Svensson, Roland; Zdziarski, Andrzej A.

    1994-01-01

    Observations suggest the existence of both hot and cold dark matter in the centers of active galactic nuclei. Recent spectral models require a major fraction of power to be dissipated in the hot matter. We study the case when the hot matter forms a corona around a standard cold alpha-disk. In particular, we investigate the case when a major fraction, f, of the power released when the cold matter accretes is transported to and dissipated in the corona. This has major effects on the cold disk, making it colder, more geometrically thin, denser, and having larger optical depths. One important consequence is the disappearance of the effectively optically thin zone as well as of the radiation pressure dominated zone for values of f sufficiently closed to unity. The disappearance of the radiation pressure dominated zone will result in a cold disk with only a gas pressure dominated zone that is stable against thermal and viscous instabilities. We also show that the pressure ( and the radiation) from the corona will only affect the surface layers of the cold disk. Our results disagree with those of other recent work on accretion disks with coronae. We find those works to be based on unphysical assumptions.

  19. Measuring Massive Black Hole Binaries with LISA

    NASA Technical Reports Server (NTRS)

    Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

    2009-01-01

    The coalescence of two massive black holes produces gravitational waves (GWs) which can be detected by the space-based detector LISA. By measuring these waves, LISA can determine the various parameters which characterize the source. Measurements of the black hole masses and spins will provide information about the growth of black holes and their host galaxies over time. Measurements of a source's sky position and distance may help astronomers identify an electromagnetic counterpart to the GW event. The counterpart's redshift, combined with the GW-measured luminosity distance, can then be used to measure the Hubble constant and the dark energy parameter $w$. Because the potential science output is so high, it is useful to know in advance how well LISA can measure source parameters for a wide range of binaries. We calculate expected parameter estimation errors using the well-known Fisher matrix method. Our waveform model includes the physics of spin precession, as well as subleading harmonics. When these higher-order effects are not included, strong degeneracies between some parameters cause them to be poorly determined by a GW measurement. When precession and subleading harmonics are properly included, the degeneracies are broken, reducing parameter errors by one to several orders of magnitude.

  20. X-ray and gamma-ray emission of Sagittarius A* as a wind-accreting black hole

    NASA Technical Reports Server (NTRS)

    Mastichiadis, A.; Ozernoy, L. M.

    1994-01-01

    If, as many believe, Sgr A* is a massive black hole at the Galactic center, one should expect it to be a source of X-ray and gamma-ray activity, behaving basically as a scaled-down active galactic nucleus. An unavoidable source of accretion is the wind from IRS 16, a nearby group of hot, massive stars. Since the density and velocity of the accreting matter are known from observations, the accretion rate is basically a function of the putative black hole mass, M(sub h), only; this value represents a reliable lower limit to a real rate, given the other possible sources of accreting matter. Based on this and on the theories about shock acceleration in active galactic nuclei, we have estimated the expected production of relativistic particles and their hard radiation. These values turn out to be a function of M(sub h) as well. Comparing our results with available X-ray and gamma-ray observations which show Sgr A* to have a relatively low activity level, we conclude tentatively that the putative black hole in the Galactic center cannot have a mass greater than approximately 6 x 10(exp 3) solar mass. This conclusion is consistent with the upper limits to the black hole mass found by different methods earlier, although much more work is needed to make calculations of shock acceleration around black holes more reliable.

  1. DWARF GALAXIES WITH OPTICAL SIGNATURES OF ACTIVE MASSIVE BLACK HOLES

    SciTech Connect

    Reines, Amy E.; Greene, Jenny E.; Geha, Marla

    2013-10-01

    We present a sample of 151 dwarf galaxies (10{sup 8.5} ∼< M{sub *} ∼< 10{sup 9.5} M{sub ☉}) that exhibit optical spectroscopic signatures of accreting massive black holes (BHs), increasing the number of known active galaxies in this stellar-mass range by more than an order of magnitude. Utilizing data from the Sloan Digital Sky Survey Data Release 8 and stellar masses from the NASA-Sloan Atlas, we have systematically searched for active BHs in ∼25,000 emission-line galaxies with stellar masses comparable to the Magellanic Clouds and redshifts z < 0.055. Using the narrow-line [O III]/Hβ versus [N II]/Hα diagnostic diagram, we find photoionization signatures of BH accretion in 136 galaxies, a small fraction of which also exhibit broad Hα emission. For these broad-line active galactic nucleus (AGN) candidates, we estimate BH masses using standard virial techniques and find a range of 10{sup 5} ∼< M{sub BH} ∼< 10{sup 6} M{sub ☉} and a median of M{sub BH} ∼ 2 × 10{sup 5} M{sub ☉}. We also detect broad Hα in 15 galaxies that have narrow-line ratios consistent with star-forming galaxies. Follow-up observations are required to determine if these are true type 1 AGN or if the broad Hα is from stellar processes. The median absolute magnitude of the host galaxies in our active sample is M{sub g} = –18.1 mag, which is ∼1-2 mag fainter than previous samples of AGN hosts with low-mass BHs. This work constrains the smallest galaxies that can form a massive BH, with implications for BH feedback in low-mass galaxies and the origin of the first supermassive BH seeds.

  2. Black Hole Event Horizons and Advection-Dominated Accretion

    NASA Technical Reports Server (NTRS)

    McClintock, Jeffrey; Mushotzky, Richard F. (Technical Monitor)

    2001-01-01

    The XMM data on black-hole X-ray novae are only now becoming available and they have so far not been included in any publications. This work is part of a larger project that makes use of both XMM and Chandra data. Our first publication on the Chandra results is the following: "New Evidence for Black Hole Event Horizons from Chandra" by M.R. Garcia, J.E. McClintock, R. Narayan, P. Callanan, D. Barret and S. Murray (2001, ApJ, 553, L47). Therein we present the luminosities of the two black-hole X-ray novae, GRO J0422+22 and 4U1 543-47, which were observed by Chandra. These results are combined with the luminosities of four additional black-hole X-ray novae, which were observed as part of a Chandra GTO program (PI: S. Murray). The very low, but nonzero, quiescent X-ray luminosities of these black hole binaries is very difficult to understand in the context of standard viscous accretion disk theory. The principal result of this work is that X-ray novae that contain black hole primaries are about 100 times fainter that X-ray novae that contain neutron star primaries. This result had been suggested in earlier work, but the present work very firmly establishes this large luminosity difference. The result is remarkable because the black-hole and the neutron-star systems are believed to be similar in many respects. Most importantly, the mass transfer rate from the secondary star is believed to be very comparable for the two kinds of systems for similar orbital periods. The advection-dominated accretion flow (ADAF) model provides a natural framework for understanding the extraordinarily low luminosities of the black hole systems and the hundred-fold greater luminosities of the neutron star systems. The chief feature of an ADAF is that the heat energy in the accreting gas is trapped in the gas and travels with it, rather than being radiated promptly. Thus the accreting gas reaches the central object with a huge amount of thermal energy. If the accretor is a black hole, the

  3. RESOLVING THE BONDI ACCRETION FLOW TOWARD THE SUPERMASSIVE BLACK HOLE OF NGC 3115 WITH CHANDRA

    SciTech Connect

    Wong, Ka-Wah; Irwin, Jimmy A.; Yukita, Mihoko; Million, Evan T.; Mathews, William G.

    2011-07-20

    Gas undergoing Bondi accretion onto a supermassive black hole (SMBH) becomes hotter toward smaller radii. We searched for this signature with a Chandra observation of the hot gas in NGC 3115, which optical observations show has a very massive SMBH. Our analysis suggests that we are resolving, for the first time, the accretion flow within the Bondi radius of an SMBH. We show that the temperature is rising toward the galaxy center as expected in all accretion models in which the black hole is gravitationally capturing the ambient gas. There is no hard central point source that could cause such an apparent rise in temperature. The data support that the Bondi radius is at about 4''-5'' (188-235 pc), suggesting an SMBH of 2 x 10{sup 9} M{sub sun} that is consistent with the upper end of the optical results. The density profile within the Bondi radius has a power-law index of 1.03{sup +0.23}{sub -0.21}, which is consistent with gas in transition from the ambient medium and the accretion flow. The accretion rate at the Bondi radius is determined to be M-dot{sub B} = 2.2x10{sup -2} M{sub sun} yr{sup -1}. Thus, the accretion luminosity with 10% radiative efficiency at the Bondi radius (10{sup 44} erg s{sup -1}) is about six orders of magnitude higher than the upper limit of the X-ray luminosity of the nucleus.

  4. Torque-limited Growth of Massive Black Holes in Galaxies across Cosmic Time

    NASA Astrophysics Data System (ADS)

    Anglés-Alcázar, Daniel; Özel, Feryal; Davé, Romeel; Katz, Neal; Kollmeier, Juna A.; Oppenheimer, Benjamin D.

    2015-02-01

    We combine cosmological hydrodynamic simulations with analytic models to evaluate the role of galaxy-scale gravitational torques on the evolution of massive black holes at the centers of star-forming galaxies. We confirm and extend our earlier results to show that torque-limited growth yields black holes and host galaxies evolving on average along the M BH-M bulge relation from early times down to z = 0 and that convergence onto the scaling relation occurs independent of the initial conditions and with no need for mass averaging through mergers or additional self-regulation processes. Smooth accretion dominates the long-term evolution, with black hole mergers with mass ratios gsim 1:5 representing typically a small fraction of the total growth. Winds from the accretion disk are required to eject significant mass to suppress black hole growth, but there is no need for coupling this wind to galactic-scale gas to regulate black holes in a nonlinear feedback loop. Torque-limited growth yields a close-to-linear < \\dot{M}_BH > \\propto star formation rate (SFR) relation for the black hole accretion rate averaged over galaxy evolution timescales. However, the SFR-AGN connection has significant scatter owing to strong variability of black hole accretion at all resolved timescales. Eddington ratios can be described by a broad lognormal distribution with median value evolving roughly as λMSvprop(1 + z)1.9, suggesting a main sequence for black hole growth similar to the cosmic evolution of specific SFRs. Our results offer an attractive scenario consistent with available observations in which cosmological gas infall and transport of angular momentum in the galaxy by gravitational instabilities regulate the long-term co-evolution of black holes and star-forming galaxies.

  5. Black Hole Accretion and Feedback Driven by Thermal Instability

    NASA Astrophysics Data System (ADS)

    Gaspari, M.; Ruszkowski, M.; Oh, S. P.; Churazov, E.; Brighenti, F.; Ettori, S.; Sharma, P.; Temi, P.

    2013-03-01

    Multiwavelength data indicate that the cores of several galaxy clusters are moderately cooling, though not catastrophically, showing signs of filamentary extended multiphase gas. Through 3D AMR hydrodynamic simulations, we study the impact of thermal instability in the evolution of the intracluster medium. Common moderate turbulence of just over 100 km/s leads to the growth of nonlinear thermal instability within the central few tens kpc. In the presence of a global counterbalancing heating, the condensation of extended filamentary cold gas is violent, occurring when the cooling time falls below 10 times the free-fall time. The frequent stochastic collisions, fragmentations and shearing motions between the cold clouds, filaments and the central torus, efficiently reduce angular momentum. Tracking the accreting gas with a dynamical range of 10 million, we find that the accretion rate is boosted up to 100 times with respect to the Bondi rate. In a commonly turbulent and quasi-stable atmosphere, the mode of black accretion is cold and chaotic, substantially different from the classic idealized scenario. Only in the transonic regime, turbulent dissipation starts to inhibit thermal instability. On sub-parsec scales the cold phase is channeled via a funnel, triggering the black hole feedback likely linked to mechanical jets/outflows. As shown by long-term self-regulated simulations, the interplay of chaotic cold accretion and AGN feedback is crucial in order to avoid the cooling catastrophe and to reproduce the key thermodynamical features of observed clusters.

  6. Structure and Spectroscopy of Black Hole Accretion Disks

    SciTech Connect

    Liedahl, D; Mauche, C

    2005-02-14

    The warped spacetime near black holes is one of the most exotic observable environments in the Universe. X-ray spectra from active galaxies obtained with the current generation of X-ray observatories reveal line emission that is modified by both special relativistic and general relativistic effects. The interpretation is that we are witnessing X-ray irradiated matter orbiting in an accretion disk around a supermassive black hole, as it prepares to cross the event horizon. This interpretation, however, is based upon highly schematized models of accretion disk structure. This report describes a project to design a detailed computer model of accretion disk atmospheres, with the goal of elucidating the high radiation density environments associated with mass flows in the curved spacetime near gravitationally collapsed objects. We have evolved the capability to generate realistic theoretical X-ray line spectra of accretion disks, thereby providing the means for a workable exploration of the behavior of matter in the strong-field limit of gravitation.

  7. Super-Extremal Spinning Black Holes via Accretion

    NASA Astrophysics Data System (ADS)

    Laguna, Pablo; Bode, Tanja; Matzner, Richard

    2011-04-01

    A Kerr black hole with mass M and angular momentum J satisfies the extremality inequality J <=M2 . In the presence of matter and/or gravitational radiation, the bound needs to be reformulated in terms of local measurements of M and J directly associated with the black hole. The isolated and dynamical horizons framework provides such natural quasi-local characterization of M and J, making possible in axi-symmetry to reformulate the extremality limit as J <= 2M2 , with M the irreducible mass computed from the apparent horizon area and J obtained using approximate rotational Killing vectors on the apparent horizon. This condition is also equivalent to requiring a non-negative black hole surface gravity. We present numerical experiments of an accreting black hole that temporarily violates this extremality inequality.

  8. X-ray properties of accreting black holes

    SciTech Connect

    White, N.E.

    1984-01-01

    The X-ray signatures of Cyg X-1 and IMC X-3 have been taken as templates of binary systems which include a black hole component. Cyg X-1 exhibits rapid flickering on a time scale varying from 0.001-1 sec and bimodal spectral behavior in its X-ray emissions. Similar emissions from IMC X-3 have been detected, along with an absence of X-ray eclipses. Taking three characteristics, i.e., flickering, bimodal spectra and the estimated masses of the X ray components, of assumed black hole companions for Cyg X-1 and IMC X-3, an estimate is made of the number of black holes a whole sky survey would reveal, based on data from the HEAO-1 and Einstein Observatory satellites. Cin X-1, BX 339-4 and LMC X-1 are concluded to probably be accreting black holes. Eleven other objects are identified as possible candidates, as are active galactic nuclei.

  9. Ubiquitous equatorial accretion disc winds in black hole soft states

    NASA Astrophysics Data System (ADS)

    Ponti, G.; Fender, R. P.; Begelman, M. C.; Dunn, R. J. H.; Neilsen, J.; Coriat, M.

    2012-05-01

    High-resolution spectra of Galactic black holes (GBHs) reveal the presence of highly ionized absorbers. In one GBH, accreting close to the Eddington limit for more than a decade, a powerful accretion disc wind is observed to be present in softer X-ray states and it has been suggested that it can carry away enough mass and energy to quench the radio jet. Here we report that these winds, which may have mass outflow rates of the order of the inner accretion rate or higher, are a ubiquitous component of the jet-free soft states of all GBHs. We furthermore demonstrate that these winds have an equatorial geometry with opening angles of few tens of degrees, and so are only observed in sources in which the disc is inclined at a large angle to the line of sight. The decrease in Fe XXV/Fe XXVI line ratio with Compton temperature, observed in the soft state, suggests a link between higher wind ionization and harder spectral shapes. Although the physical interaction between the wind, accretion flow and jet is still not fully understood, the mass flux and power of these winds and their presence ubiquitously during the soft X-ray states suggest they are fundamental components of the accretion phenomenon.

  10. Geometrothermodynamics of black holes in Lorentz noninvariant massive gravity

    NASA Astrophysics Data System (ADS)

    Sánchez, Alberto

    2016-07-01

    We analyze a static and spherically symmetric hairy black hole solution in noninvariant massive gravity. The formalism of geometrothermodynamics is used to describe the thermodynamic characteristics of this black hole in a Legendre invariant way. For a black hole in massive gravity, the geometry of the space of equilibrium states is computed showing that it contains information about the thermodynamic interaction, critical points, and phase transitions structure.

  11. Revealing accretion onto black holes through X-ray reflection

    NASA Astrophysics Data System (ADS)

    Plant, D.; Fender, R.; Ponti, G.; Munoz-Darias, T.; Coriat, M.

    2014-07-01

    Understanding the dynamics behind black hole state transitions and the changes they reflect in outbursts has become long-standing problem. The X-ray reflection spectrum describes the interaction between the hard X-ray source (the power-law continuum) and the cool accretion disc it illuminates, and thus permits an indirect view of how the two evolve. We present a systematic analysis of the reflection spectrum throughout three outbursts (500+ RXTE observations) of the black hole binary GX 339-4, representing the largest study applying a self-consistent treatment of reflection to date. Particular attention is payed to the coincident evolution of the power-law and reflection, which can be used to determine the accretion geometry. The hard state is found to be distinctly reflection weak, however the ratio of reflection to power-law gradually increases as the source luminosity rises. In contrast the reflection is found dominate the power-law throughout most of the soft state, with increasing supremacy as the source decays. Using results from archival and AO-12 observations of GX 339-4 with XMM-Newton we reveal the dynamics driving this evolution and the nature of accretion onto black holes in outburst.

  12. Unveiling Gargantua: A new search strategy for the most massive central cluster black holes

    NASA Astrophysics Data System (ADS)

    Brockamp, M.; Baumgardt, H.; Britzen, S.; Zensus, A.

    2016-01-01

    Aims: We aim to unveil the most massive central cluster black holes in the Universe. Methods: We present a new search strategy, which is based on a black hole mass gain sensitive calorimeter and which links the innermost stellar density profile of a galaxy to the adiabatic growth of its central supermassive black hole (SMBH). As a first step we convert observationally inferred feedback powers into SMBH growth rates using reasonable energy conversion efficiency parameters, ɛ. In the main part of this paper we use these black hole growth rates, sorted in logarithmically increasing steps encompassing our whole parameter space, to conduct N-body computations of brightest cluster galaxies (BCGs) with the newly developed Muesli software. For the initial setup of galaxies, we use core-Sérsic models to account for SMBH scouring. Results: We find that adiabatically driven core regrowth is significant at the highest accretion rates. As a result, the most massive black holes should be located in BCGs with less pronounced cores when compared to the predictions of empirical scaling relations, which are usually calibrated in less extreme environments. For efficiency parameters ɛ< 0.1, BCGs in the most massive, relaxed, and X-ray luminous galaxy clusters might even develop steeply rising density cusps. Finally, we discuss several promising candidates for follow-up investigations, among them the nuclear black hole in the Phoenix cluster. Based on our results, its central black hole might have a mass of the order of 1011 M⊙.

  13. ROTATING ACCRETION FLOWS: FROM INFINITY TO THE BLACK HOLE

    SciTech Connect

    Li, Jason; Ostriker, Jeremiah; Sunyaev, Rashid

    2013-04-20

    Accretion onto a supermassive black hole of a rotating inflow is a particularly difficult problem to study because of the wide range of length scales involved. There have been broadly utilized analytic and numerical treatments of the global properties of accretion flows, but detailed numerical simulations are required to address certain critical aspects. We use the ZEUS code to run hydrodynamical simulations of rotating, axisymmetric accretion flows with Bremsstrahlung cooling, considering solutions for which the centrifugal balance radius significantly exceeds the Schwarzschild radius, with and without viscous angular momentum transport. Infalling gas is followed from well beyond the Bondi radius down to the vicinity of the black hole. We produce a continuum of solutions with respect to the single parameter M-dot{sub B}/ M-dot{sub Edd}, and there is a sharp transition between two general classes of solutions at an Eddington ratio of M-dot{sub B}/M-dot{sub Edd}{approx}few Multiplication-Sign 10{sup -2}. Our high inflow solutions are very similar to the standard Shakura and Sunyaev results. But our low inflow results are to zeroth order the stationary Papaloizou and Pringle solution, which has no accretion. To next order in the small, assumed viscosity they show circulation, with disk and conical wind outflows almost balancing inflow. These solutions are characterized by hot, vertically extended disks, and net accretion proceeds at an extremely low rate, only of order {alpha} times the inflow rate. Our simulations have converged with respect to spatial resolution and temporal duration, and they do not depend strongly on our choice of boundary conditions.

  14. Theoretical Researches on Hot Accretion Flows around Black Holes

    NASA Astrophysics Data System (ADS)

    Xie, F. G.

    2010-10-01

    Black hole accretion systems, which are widely believed to be harbored in the central regions of active galactic nuclei (AGNs), low-luminosity AGNs (LLAGNs) as well as some X-ray binaries (XRBs), are the key physical processes to understand their observational phenomena, like spectral energy distribution, radiative variability, etc. In this thesis, we focus on the hot accretion flow models, including advection-dominated accretion flow (ADAF) and luminous hot accretion flow (LHAF). These models are the foundations to explain the observations of LLAGNs and XRBs in hard state. In Chapter 1, a detailed description of the background is presented. First the astrophysical black holes and the systems in which they reside are discussed. Then, an extensive discussion on the accretion process is presented. The basic concepts, 4 well-known accretion models and the mechanism of the transition between ADAF and standard thin disk are focused on. After this, we further describe the properties of ADAF - the basic model of this thesis, e.g., the dynamics, the radiative processes and several recent progresses: outflow, direct turbulent heating to the electrons, as well as LHAF at relatively high accretion rate. In Chapter 2, the influences of outflow on the dynamics of inflow are explored. As indicated through observations (e.g., towards the Galactic center), theoretical researches and (magneto-) hydrodynamical simulations, outflow is a common phenomenon in accretion systems. However, most researches in this field, especially when aiming at explaining/fitting observational data, incline to only include the mass loss due to the existence of outflow, while all the other effects like the angular momentum transport are totally neglected. This obviously conflicts with the results from simulations. Since outflow is not fully understood currently, we here parameterize its properties. Our results are shown as follows: (1) under current status of observations and theories, it is acceptable to

  15. Tilted Thick-Disk Accretion onto a Kerr Black Hole

    SciTech Connect

    Fragile, P C; Anninos, P

    2003-12-12

    We present the first results from fully general relativistic numerical studies of thick-disk accretion onto a rapidly-rotating (Kerr) black hole with a spin axis that is tilted (not aligned) with the angular momentum vector of the disk. We initialize the problem with the solution for an aligned, constant angular momentum, accreting thick disk around a black hole with spin a/M = J/M{sup 2} = +0.9 (prograde disk). The black hole is then instantaneously tilted, through a change in the metric, by an angle {beta}{sub 0}. In this Letter we report results with {beta}{sub 0} = 0, 15, and 30{sup o}. The disk is allowed to respond to the Lense-Thirring precession of the tilted black hole. We find that the disk settles into a quasi-static, twisted, warped configuration with Lense-Thirring precession dominating out to a radius analogous to the Bardeen-Petterson transition in tilted Keplerian disks.

  16. Accretion onto black holes: The power generating mechanism

    SciTech Connect

    Colgate, S.A.; Hills, J.G.; Miller, W.A.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The physical relationships among accretion disks, quasars, black holes, collimated radio sources and galactic dynamos previously has been only weakly related without explicit cause and effect. We have constructed a physical evolution from large, primordial density perturbations to {open_quotes}damped Lyman alpha clouds,{close_quotes} to galaxy formation, to black holes, jets, and the the galactic dynamo. We have derived the general relativistic distortions of radiation emitted from close to the black hole and thereby have a new observational test of the central engine. The physics of accretion disks, the astrophysical dynamo, and magnetic reconnection are the least understood physical phenomena in astrophysics. They are still less understood in the general relativity (GR) field close to the black hole. This lack of physical understanding frustrates a quantitative evaluation of observations that define the evolution from the early universe to star formation. We have made progress in this understanding.

  17. EDDINGTON-LIMITED ACCRETION AND THE BLACK HOLE MASS FUNCTION AT REDSHIFT 6

    SciTech Connect

    Willott, Chris J.; Crampton, David; Hutchings, John B.; Schade, David; Albert, Loic; Arzoumanian, Doris; Bergeron, Jacqueline; Omont, Alain; Delorme, Philippe; Reyle, Celine

    2010-08-15

    We present discovery observations of a quasar in the Canada-France High-z Quasar Survey (CFHQS) at redshift z = 6.44. We also use near-infrared spectroscopy of nine CFHQS quasars at z {approx} 6 to determine black hole masses. These are compared with similar estimates for more luminous Sloan Digital Sky Survey quasars to investigate the relationship between black hole mass and quasar luminosity. We find a strong correlation between Mg II FWHM and UV luminosity and that most quasars at this early epoch are accreting close to the Eddington limit. Thus, these quasars appear to be in an early stage of their life cycle where they are building up their black hole mass exponentially. Combining these results with the quasar luminosity function, we derive the black hole mass function at z = 6. Our black hole mass function is {approx}10{sup 4} times lower than at z = 0 and substantially below estimates from previous studies. The main uncertainties which could increase the black hole mass function are a larger population of obscured quasars at high redshift than is observed at low redshift and/or a low quasar duty cycle at z = 6. In comparison, the global stellar mass function is only {approx}10{sup 2} times lower at z = 6 than at z = 0. The difference between the black hole and stellar mass function evolution is due to either rapid early star formation which is not limited by radiation pressure as is the case for black hole growth or inefficient black hole seeding. Our work predicts that the black hole mass-stellar mass relation for a volume-limited sample of galaxies declines rapidly at very high redshift. This is in contrast to the observed increase at 4 < z < 6 from the local relation if one just studies the most massive black holes.

  18. Numerical relativity simulations of thick accretion disks around tilted Kerr black holes

    NASA Astrophysics Data System (ADS)

    Mewes, Vassilios; Font, José A.; Galeazzi, Filippo; Montero, Pedro J.; Stergioulas, Nikolaos

    2016-03-01

    In this paper we present 3D numerical relativity simulations of thick accretion disks around tilted Kerr black holes. We investigate the evolution of three different initial disk models with a range of initial black hole spin magnitudes and tilt angles. For all the disk-to-black hole mass ratios considered (0.044-0.16) we observe significant black hole precession and nutation during the evolution. This indicates that for such mass ratios, neglecting the self-gravity of the disks by evolving them in a fixed background black hole spacetime is not justified. We find that the two more massive models are unstable against the Papaloizou-Pringle (PP) instability and that those PP-unstable models remain unstable for all initial spins and tilt angles considered, showing that the development of the instability is a very robust feature of such PP-unstable disks. Our lightest model, which is the most astrophysically favorable outcome of mergers of binary compact objects, is stable. The tilt between the black hole spin and the disk is strongly modulated during the growth of the PP instability, causing a partial global realignment of black hole spin and disk angular momentum in the most massive model with constant specific angular momentum l . For the model with nonconstant l -profile we observe a long-lived m =1 nonaxisymmetric structure which shows strong oscillations of the tilt angle in the inner regions of the disk. This effect might be connected to the development of Kozai-Lidov oscillations. Our simulations also confirm earlier findings that the development of the PP instability causes the long-term emission of large amplitude gravitational waves, predominantly for the l =m =2 multipole mode. The imprint of the black hole (BH) precession on the gravitational waves from tilted BH-torus systems remains an interesting open issue that would require significantly longer simulations than those presented in this paper.

  19. The galactic center: is it a massive black hole?

    PubMed

    Lo, K Y

    1986-09-26

    Studies of active galactic nuclei constitute one of the major efforts in astronomy. Massive black holes are the most likely source for the enormous energy radiated from such nuclei. Observations reviewed here suggest unusual activity and the possible existence of a massive black hole in the nucleus of our galaxy. Because of its proximity to Earth, our galactic nucleus can be observed in unsurpassed detail and may serve as the Rosetta stone both for deciphering active galactic nuclei and for confirming the existence of a massive black hole. PMID:17830738

  20. MASSIVE BLACK HOLES IN CENTRAL CLUSTER GALAXIES

    SciTech Connect

    Volonteri, Marta; Ciotti, Luca

    2013-05-01

    We explore how the co-evolution of massive black holes (MBHs) and galaxies is affected by environmental effects, addressing in particular MBHs hosted in the central cluster galaxies (we will refer to these galaxies in general as ''CCGs''). Recently, the sample of MBHs in CCGs with dynamically measured masses has increased, and it has been suggested that these MBH masses (M{sub BH}) deviate from the expected correlations with velocity dispersion ({sigma}) and mass of the bulge (M{sub bulge}) of the host galaxy: MBHs in CCGs appear to be ''overmassive''. This discrepancy is more pronounced when considering the M{sub BH}-{sigma} relation than the M{sub BH}-M{sub bulge} one. We show that this behavior stems from a combination of two natural factors: (1) CCGs experience more mergers involving spheroidal galaxies and their MBHs and (2) such mergers are preferentially gas poor. We use a combination of analytical and semi-analytical models to investigate the MBH-galaxy co-evolution in different environments and find that the combination of these two factors is in accordance with the trends observed in current data sets.

  1. Black holes in Born-Infeld extended new massive gravity

    SciTech Connect

    Ghodsi, Ahmad; Yekta, Davood Mahdavian

    2011-05-15

    In this paper we find different types of black holes for the Born-Infeld extended new massive gravity. Our solutions include (un)charged warped (anti-)de Sitter black holes for four and six derivative expanded action. We also look at the black holes in unexpanded Born-Infeld action. In each case we calculate the entropy, angular momentum and mass of the black holes. We also find the central charges for the conformal field theory duals.

  2. Formation of Massive Primordial Stars: Intermittent UV Feedback with Episodic Mass Accretion

    NASA Astrophysics Data System (ADS)

    Hosokawa, Takashi; Hirano, Shingo; Kuiper, Rolf; Yorke, Harold W.; Omukai, Kazuyuki; Yoshida, Naoki

    2016-06-01

    We present coupled stellar evolution (SE) and 3D radiation-hydrodynamic (RHD) simulations of the evolution of primordial protostars, their immediate environment, and the dynamic accretion history under the influence of stellar ionizing and dissociating UV feedback. Our coupled SE RHD calculations result in a wide diversity of final stellar masses covering 10 {M}ȯ ≲ M * ≲ 103 {M}ȯ . The formation of very massive (≳250 {M}ȯ ) stars is possible under weak UV feedback, whereas ordinary massive (a few ×10 {M}ȯ ) stars form when UV feedback can efficiently halt the accretion. This may explain the peculiar abundance pattern of a Galactic metal-poor star recently reported by Aoki et al., possibly the observational signature of very massive precursor primordial stars. Weak UV feedback occurs in cases of variable accretion, in particular when repeated short accretion bursts temporarily exceed 0.01 {M}ȯ {{{yr}}}-1, causing the protostar to inflate. In the bloated state, the protostar has low surface temperature and UV feedback is suppressed until the star eventually contracts, on a thermal adjustment timescale, to create an H ii region. If the delay time between successive accretion bursts is sufficiently short, the protostar remains bloated for extended periods, initiating at most only short periods of UV feedback. Disk fragmentation does not necessarily reduce the final stellar mass. Quite the contrary, we find that disk fragmentation enhances episodic accretion as many fragments migrate inward and are accreted onto the star, thus allowing continued stellar mass growth under conditions of intermittent UV feedback. This trend becomes more prominent as we improve the resolution of our simulations. We argue that simulations with significantly higher resolution than reported previously are needed to derive accurate gas mass accretion rates onto primordial protostars.

  3. Black Hole Universe Model for Explaining GRBs, X-Ray Flares, and Quasars as Emissions of Dynamic Star-like, Massive, and Supermassive Black Holes

    NASA Astrophysics Data System (ADS)

    Zhang, Tianxi

    2014-01-01

    Slightly modifying the standard big bang theory, the author has recently developed a new cosmological model called black hole universe, which is consistent with Mach’s principle, governed by Einstein’s general theory of relativity, and able to explain all observations of the universe. Previous studies accounted for the origin, structure, evolution, expansion, cosmic microwave background radiation, and acceleration of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This study investigates the emissions of dynamic black holes according to the black hole universe model and provides a self-consistent explanation for the observations of gamma ray bursts (GRBs), X-ray flares, and quasars as emissions of dynamic star-like, massive, and supermassive black holes. It is shown that a black hole, when it accretes its ambient matter or merges with other black holes, becomes dynamic. Since the event horizon of a dynamic black hole is broken, the inside hot (or high-frequency) blackbody radiation leaks out. The leakage of the inside hot blackbody radiation leads to a GRB if it is a star-like black hole, an X-ray flare if it is a massive black hole like the one at the center of the Milky Way, or a quasar if it is a supermassive black hole like an active galactic nucleus (AGN). The energy spectra and amount of emissions produced by the dynamic star-like, massive, and supermassive black holes can be consistent with the measurements of GRBs, X-ray flares, and quasars.

  4. Searching with the Large Binocular Telescope for Accreting Supermassive Black Holes in Bulgeless Galaxies

    NASA Astrophysics Data System (ADS)

    Ferguson, Jason; Constantin, Anca; Satyapal, Shobita; Rothberg, Barry

    2016-01-01

    There is increasing evidence that supermassive black holes are created and evolve in bulgeless galaxies, revealing pathways for merger free, secular growth. Constraints on the fraction of bulgeless galaxies that host an AGN remain, however, extremely limited. Following the recent discovery of a large population of bulgeless galaxies with red mid-infrared colors, that are highly suggestive of heated dust by powerful accreting massive black holes, we have employed the Large Binocular Telescope to investigate the near-IR spectra of six of these systems. We present here the data and measurements of near-infrared hydrogen molecular and recombination lines. We find no evidence for broad components of the Paschen Alpha emission lines, suggesting the AGNs are either too weak or too absorbed to be detected. Based on new estimates of extinction and comparisons with optical measurements we discuss the likelihood of these systems being heavily obscured AGN or galactic nuclei with vigorous, yet dust embedded star formation.

  5. General Relativistic Magnetohydrodynamics Simulations of Tilted Black Hole Accretion Flows and Their Radiative Properties

    NASA Astrophysics Data System (ADS)

    Shiokawa, Hotaka; Gammie, C. F.; Dolence, J.; Noble, S. C.

    2013-01-01

    We perform global General Relativistic Magnetohydrodynamics (GRMHD) simulations of non-radiative, magnetized disks that are initially tilted with respect to the black hole's spin axis. We run the simulations with different size and tilt angle of the tori for 2 different resolutions. We also perform radiative transfer using Monte Carlo based code that includes synchrotron emission, absorption and Compton scattering to obtain spectral energy distribution and light curves. Similar work was done by Fragile et al. (2007) and Dexter & Fragile (2012) to model the super massive black hole SgrA* with tilted accretion disks. We compare our results of fully conservative hydrodynamic code and spectra that include X-ray, with their results.

  6. Star accretion onto supermassive black holes in axisymmetric galactic nuclei

    NASA Astrophysics Data System (ADS)

    Zhong, Shiyan; Berczik, Peter; Spurzem, Rainer

    2016-02-01

    Tidal Disruption (TD) of stars by supermassive central black holes from dense rotating star clusters is modeled by high-accuracy direct N-body simulation. We study the time evolution of the stellar tidal disruption rate and the origin of tidally disrupted stars. Compared with that in spherical systems, we found a higher TD rate in axisymmetric systems. The enhancement can be explained by an enlarged loss-cone in phase space which is raised from the fact that total angular momentum J is not conserved. As in the case of spherical systems, the distribution of the last apocenter distance of tidally accreted stars peaks at the classical critical radius. However, the angular distribution of the origin of the accreted stars reveals bimodal features. We show that the bimodal structure can be explained by the presence of two families of regular orbits, namely short axis tube and saucer orbits.

  7. Viscosity parameter values in accretion flows around black holes.

    NASA Astrophysics Data System (ADS)

    Nagarkoti, Shreeram; Chakrabarti, Sandip Kumar

    2016-07-01

    Viscosity is responsible for the transport of angular momentum in accretion processes. Assuming mixed stress prescription suitable for flow discontinuities, we draw parameter space of specific angular momentum and specific energy of flow at the inner sonic point for all possible values of viscosity parameter. Then, we identify the region which is capable of producing standard Rankine-Hugoniot shocks. From this analysis, it is found that a large range of values of viscosity parameter (0.0-0.3) is capable of producing shocks. At values larger than this, the parameter space allowing shock formation is negligible. The shock formation causes piling up of matter in the post-shock region which Comptonizes soft X-ray photons coming from the Keplerian accretion disk, creating the hard X-Ray radiation. Since numerical simulations generally produce alpha parameters very smaller as compared to this upper limit, we conclude that the shocks remain essential component to model black hole spectral and timing properties.

  8. Numerical Simulations of Viscous Accretion Flow around Black Holes

    NASA Astrophysics Data System (ADS)

    Lee, Seong-Jae; Chattopadhyay, Indranil; Kumar, Rajiv; Hyung, Siek; Ryu, Dongsu

    2016-06-01

    We present shocked viscous accretion flow onto a black hole in a two dimensional cylindrical geometry, where initial conditions were chosen from analytical solutions. The simulation code used the Lagrangian Total Variation Diminishing (LTVD) and remap routine, which enabled us to attain high accuracy in capturing shocks and to handle the angular momentum distribution correctly. The steady state shocked solution in the inviscid, as well as in the viscous regime, matched theoretical predictions well, but increasing viscosity renders the accretion shock unstable. Large amplitude shock oscillation is accompanied by intermittent, transient inner multiple shocks. Such oscillation of the inner part of disk is interpreted as the source of QPO in hard X-rays observed in microquasars; and strong shock oscillation induces strong episodic jet emission. The periodicity of jets and shock oscillation are similar. Our simulation shows that the jets for higher viscosity parameter are evidently stronger and faster than that for lower viscosity.

  9. Phase transitions of black holes in massive gravity

    NASA Astrophysics Data System (ADS)

    Fernando, Sharmanthie

    2016-05-01

    In this paper, we have studied thermodynamics of a black hole in massive gravity in the canonical ensemble. The massive gravity theory in consideration here has a massive graviton due to Lorentz symmetry breaking. The black hole studied here has a scalar charge due to the massive graviton and is asymptotically anti-de Sitter (AdS). We have computed various thermodynamical quantities such as temperature, specific heat and free energy. Both the local and global stability of the black hole are studied by observing the behavior of the specific heat and the free energy. We have observed that there is a first-order phase transition between small (SBH) and large black hole (LBH) for a certain range of the scalar charge. This phase transition is similar to the liquid/gas phase transition at constant temperature for a van der Waals fluid. The coexistence curves for the SBH and LBH branches are also discussed in detail.

  10. Physics-Based Spectra of Accretion Disks around Black Holes

    NASA Technical Reports Server (NTRS)

    Krolik, Julian H.

    2005-01-01

    The purpose of this grant was to begin the process of deriving the light output of accretion disks around black holes directly from the actual processes that inject heat into the accreting matter, rather than from guessed dependences of heating rate on physical parameters. At JHU, the effort has focussed so far on models of accretion onto "intermediate mass black holes", a possible class of black holes, examples of which may have recently been discovered in nearby galaxies. There, Krolik and his student (Yawei Hui) have computed stellar atmospheres for uniformly-heated disks around this class of black holes. Their models serve two purposes: they are the very first serious attempts to compute the spectrum from accreting black holes in this mass range; and a library of such models can be used later in this program as contrasts for those computed on the basis of real disk dynamics. The output from these local disk calculations has also been successfully coupled to a program that applies the appropriate relativistic transformations and computes photon trajectories in order to predict the spectrum received by observers located at different polar angles. The principal new result of these calculations is the discovery of potentially observable ionization edges of H-like C and O at frequencies near the peak in flux from these objects. Most of the grant money at UCSB was spent on supporting graduate student Shane Davis. In addition. some money was spent on supporting two other students: Ari Socrates (now a Hubble Fellow at Princeton), and Laura Melling. Davis spent the year constructing stellar atmosphere models of accretion disks appropriate for the high/soft (thermal) state of black hole X-ray binaries. As with AGN models published previously by our collaboration with NASA support. our models include a complete general relativistic treatment of both the disk structure and the propagation of photons from the disk to a distant observer. They also include all important

  11. Fe Kα Profiles from Simulations of Accreting Black Holes

    NASA Astrophysics Data System (ADS)

    Kinch, Brooks E.; Schnittman, Jeremy D.; Kallman, Timothy R.; Krolik, Julian H.

    2016-07-01

    We present the first results from a new technique for the prediction of Fe Kα profiles directly from general relativistic magnetohydrodynamic (GRMHD) simulations. Data from a GRMHD simulation are processed by a Monte Carlo global radiation transport code, which determines the X-ray flux irradiating the disk surface and the coronal electron temperature self-consistently. With that irradiating flux and the disk’s density structure drawn from the simulation, we determine the reprocessed Fe Kα emission from photoionization equilibrium and solution of the radiation transfer equation. We produce maps of the surface brightness of Fe Kα emission over the disk surface, which—for our example of a 10{M}ȯ Schwarzschild black hole accreting at 1% the Eddington value—rises steeply one gravitational radius outside the radius of the innermost stable circular orbit and then falls ∝r ‑2 at larger radii. We explain these features of the Fe Kα radial surface brightness profile as consequences of the disk’s ionization structure and an extended coronal geometry, respectively. We also present the corresponding Fe Kα line profiles as would be seen by distant observers at several inclinations. Both the shapes of the line profiles and the equivalent widths of our predicted Kα lines are qualitatively similar to those typically observed from accreting black holes. Most importantly, this work represents a direct link between theory and observation: in a fully self-consistent way, we produce observable results—iron fluorescence line profiles—from the theory of black hole accretion with almost no phenomenological assumptions.

  12. OMOSHI Effect: A New Mechanism for Mass Accretion under the Radiation Pressure in Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Tanaka, Kei; Nakamoto, Taishi

    2009-08-01

    In a massive-star formation process, a high-mass accretion rate is considered to be needed to overcome the strong radiation pressure at the dust sublimation front. We examined the accretion structure near the dust sublimation front and found a new mechanism to overcome this radiation pressure. The weight of the accumulated mass in a stagnant flow near the dust sublimation front helps with the mass accretion. We call this mechanism the ``OMOSHI effect,'' where OMOSHI is an acronym for ``One Mechanism for Overcoming Stellar High radiation pressure by weight.'' OMOSHI is also a Japanese noun meaning a weight that is put on something to prevent it from moving. This mechanism relaxes the condition for the massive star formation.

  13. EVOLUTION OF VERY MASSIVE POPULATION III STARS WITH MASS ACCRETION FROM PRE-MAIN SEQUENCE TO COLLAPSE

    SciTech Connect

    Ohkubo, Takuya; Nomoto, Ken'ichi; Umeda, Hideyuki; Yoshida, Naoki; Tsuruta, Sachiko E-mail: umeda@astron.s.u-tokyo.ac.j E-mail: naoki.yoshida@ipmu.j

    2009-12-01

    We calculate the evolution of zero-metallicity Population III (Pop III) stars whose mass grows from the initial mass of approx1 M{sub sun} by accreting the surrounding gases. Our calculations cover whole evolutionary stages from the pre-main sequence, via various nuclear burning stages, through the final core-collapse or pair-creation instability phases. We adopt two different sets of stellar mass accretion rates as our fiducial models. One is derived from a cosmological simulation of the first generation (PopIII.1) stars, and the other is derived from a simulation of the second generation stars that are affected by radiation from PopIII.1 stars. The latter represents one case of PopIII.2 stars. We also adopt additional models that include radiative feedback effects. We show that the final mass of Pop III.1 stars can be as large as approx1000 M {sub sun}, beyond the mass range (140-300 M{sub sun}) for the pair-instability supernovae. Such massive stars undergo core-collapse to form intermediate-mass black holes, which may be the seeds for merger trees to supermassive black holes. On the other hand, Pop III.2 stars become less massive (approx<40-60 M{sub sun}), being in the mass range of ordinary iron core-collapse stars. Such stars explode and eject heavy elements to contribute to chemical enrichment of the early universe as observed in the abundance patterns of extremely metal-poor stars in the Galactic halo. In view of the large range of possible accretion rates, further studies are important to see if these fiducial models are actually the cases.

  14. Evidence for a massive stellar black hole in x ray Nova Muscae

    NASA Technical Reports Server (NTRS)

    Chen, Wan; Gehrels, Neil; Cheng, F. H.

    1992-01-01

    We present evidence that the X-ray Nova Muscae system contains a massive, greater than 10 M solarmass, black hole. A recently measured photometric binary mass function gives the black hole mass for this system as a function of orbital inclination angle. From the spectral redshift and width of the positron annihilation gamma-ray line observed by GRANAT/SIGMA, we find the accretion disk inclination angle to be 22 deg plus or minus 18 deg. Assuming the accretion disk lies in the orbital plane of the system, the black hole mass is found to have a lower limit of 14 M solar mass although statistics are poor. This is supported by spectral modeling of combined optical/UV/x-ray/gamma-ray data and by a new Nova Muscae distance limit we derive of greater than 3 kpc. The large mass for this black hole and the high binary mass ratio it implies (greater than 20) raise a serious challenge to theoretical models of the formation and evolution of massive binaries. The gamma-ray line technique introduced here can give tight constraints on orbital parameters when high-sensitivity line measurements are made by such missions as GRO.

  15. Growth of black holes and dark matter accretion

    NASA Astrophysics Data System (ADS)

    Munyaneza, Faustin; Biermann, Peter L.

    2006-12-01

    We investigate the distribution of fermion dark matter in the Milky Way galaxy and find that dark matter could gravitationally condensate in a degenerate core of mass of 3 × 106Mdot o embedded in a dark matter halo of 3 × 1012Mdot o with a size of about 200 kpc. We then show that the galactic black hole of mass of about 3 × 106Mdot o might have grown from a stellar seed black hole by mainly accreting dark matter from the compact degenerate fermion core. This leads to a lower limit on the mass of the fermion dark matter of about (6 10) keV. It is then argued that the constrained dark matter could be a sterile neutrino.

  16. Time-dependent, optically thick accretion onto a black hole

    NASA Technical Reports Server (NTRS)

    Gilden, D. L.; Wheeler, J. C.

    1980-01-01

    A fully relativistic hydrodynamics code which incorporates diffusive radiation transport is used to study time-dependent, spherically symmetric, optically thick accretion onto a black hole. It is found that matter free-falls into the hole regardless of whether the diffusion time scale is longer or shorter than the dynamical time. Nonadiabatic heating due to magnetic field reconnection is included. The internal energy thus generated affects the flow in a purely relativistic way, again ensuring free-fall collapse of the inflowing matter. Any matter enveloping a black hole will thus be swallowed on a dynamical time scale with relatively small net release of energy. The inclusion of angular momentum will not necessarily affect this conclusion.

  17. Modeling the evolution of galaxies and massive black holes across cosmic time

    NASA Astrophysics Data System (ADS)

    Angles-Alcazar, Daniel

    I use cosmological hydrodynamic simulations to investigate different aspects of the evolution of galaxies and massive black holes across cosmic time. First, I present high resolution "zoom-in" simulations including various prescriptions for galactic outflows designed to explore the impact of star-formation driven winds on the morphological, dynamical, and structural properties of individual galaxies from early times down to z = 2. Simulations without winds produce massive, compact galaxies with low gas fractions, super-solar metallicities, high bulge fractions, and much of the star formation concentrated within the inner kpc. I show that strong winds are required to suppress early star formation, maintain high gas fractions, redistribute star-forming gas and metals over larger scales, and increase the velocity dispersion of simulated galaxies, more in agreement with the large, extended, turbulent disks typical of high-redshift star-forming galaxies. Next, I combine cosmological simulations with analytic models of black hole growth to investigate the physical mechanisms driving the observed connection between massive black holes and their host galaxies. I describe a plausible model consistent with available observations in which black hole growth is limited by galaxy-scale torques. In this torque-limited growth scenario, black holes and host galaxies evolve on average toward the observed scaling relations, regardless of the initial conditions, and with no need for mass averaging through mergers or additional self-regulation processes. Outflows from the accretion disk play a key role by providing significant mass loss, but there is no need for strong interaction with the inflowing gas in order to regulate black holes in a non-linear feedback loop. I discuss some of the main implications of this scenario in the context of current observations, including the distribution and evolution of Eddington ratios, the connection between major galaxy mergers, star formation, and

  18. ACCRETION ONTO INTERMEDIATE-MASS BLACK HOLES REGULATED BY RADIATIVE FEEDBACK. I. PARAMETRIC STUDY FOR SPHERICALLY SYMMETRIC ACCRETION

    SciTech Connect

    Park, Kwang Ho; Ricotti, Massimo E-mail: ricotti@astro.umd.edu

    2011-09-20

    We study the effect of radiative feedback on accretion onto intermediate-mass black holes (IMBHs) using the hydrodynamical code ZEUS-MP with a radiative transfer algorithm. In this paper, the first of a series, we assume accretion from a uniformly dense gas with zero angular momentum and extremely low metallicity. Our one-dimensional (1D) and 2D simulations explore how X-ray and UV radiation emitted near the black hole regulates the gas supply from large scales. Both 1D and 2D simulations show similar accretion rates and periods between peaks in accretion, meaning that the hydro-instabilities that develop in 2D simulations do not affect the mean flow properties. We present a suite of simulations exploring accretion across a large parameter space, including different radiative efficiencies and radiation spectra, black hole masses, density, and temperature, T{sub {infinity}}, of the neighboring gas. In agreement with previous studies, we find regular oscillatory behavior of the accretion rate, with duty cycle {approx}6%, mean accretion rate 3% (T{sub {infinity}}/10{sup 4} K){sup 2.5} of the Bondi rate and peak accretion {approx}10 times the mean for T{sub {infinity}} ranging between 3000 K and 15, 000 K. We derive parametric formulae for the period between bursts, the mean accretion rate, and the peak luminosity of the bursts and thus provide a formulation of how feedback-regulated accretion operates. The temperature profile of the hot ionized gas is crucial in determining the accretion rate, while the period of the bursts is proportional to the mean size of the Stroemgren sphere, and we find qualitatively different modes of accretion in the high versus low density regimes. We also find that a softer radiation spectrum produces a higher mean accretion rate. However, it is still unclear what the effect of a significant time delay is between the accretion rate at our inner boundary and the output luminosity. Such a delay is expected in realistic cases with non

  19. Tunneling Radiation of Massive Vector Bosons from Dilaton Black Holes

    NASA Astrophysics Data System (ADS)

    Li, Ran; Zhao, Jun-Kun; Wu, Xing-Hua

    2016-07-01

    It is well known that Hawking radiation can be treated as a quantum tunneling process of particles from the event horizon of black hole. In this paper, we attempt to apply the massive vector bosons tunneling method to study the Hawking radiation from the non-rotating and rotating dilaton black holes. Starting with the Proca field equation that govern the dynamics of massive vector bosons, we derive the tunneling probabilities and radiation spectrums of the emitted vector bosons from the static spherical symmetric dilatonic black hole, the rotating Kaluza—Klein black hole, and the rotating Kerr—Sen black hole. Comparing the results with the blackbody spectrum, we satisfactorily reproduce the Hawking temperatures of these dilaton black holes, which are consistent with the previous results in the literature. Supported by National Natural Science Foundation of China under Grant No. 11205048

  20. Diagnosing the Black Hole Accretion Physics of Sgr A*

    NASA Astrophysics Data System (ADS)

    Fazio, Giovanni; Ashby, Matthew; Baganoff, Frederick; Becklin, Eric; Carey, Sean; Gammie, Charles; Ghez, Andrea; Glaccum, William; Gurwell, Mark; Haggard, Daryl; Hora, Joseph; Ingalls, James; Marrone, Daniel; Meyer, Leo; Morris, Mark; Smith, Howard; Willner, Steven; Witzel, Gunther

    2016-08-01

    The Galactic center offers the closest opportunity for studying accretion onto supermassive black holes. The fluctuating source, Sgr A*, is detected across the electromagnetic spectrum and may originate in the accretion flow or jet. Recent general relativistic magneto-hydrodynamic (GRMHD) models indicate that variability can be produced by a tilted inner disk, gravitational lensing of bright spots in the disk by the hole, or particle acceleration in reconnection events. These models produce different flare characteristics, and in particular better characterization of flares may enable us to distinguish between strong and weakly magnetized disks. Disentangling the power source and emission mechanisms of the flares is a central challenge to our understanding of the Sgr A* accretion flow. Following our successful observations of the variability of Sgr A* with IRAC in 2013 and 2014, we propose simultaneous IRAC (4.5 micron) and Chandra (2-10 keV) observations to (1) probe the accretion physics of Sgr A* on event-horizon scales and (2) detect any effect of the object G2 on Sgr A*. Specifically, we propose six additional epochs of observation, each of 24 uninterrupted hours; four in 2017 July and two in 2018 July. In this proposal we request two 24-hour (86.4 ks) Chandra periods, and are requesting another four through the Chandra TAC to have simultaneous X-ray observations in each of the six Spitzer epochs. Independent of this proposal we will also request NuSTAR (3-79 keV), SMA/ALMA/APEX (0.8 mm), and Keck/Magellan NIR (2.2 micron) observations during the IRAC/Chandra epochs. Only such long-duration, continuous, multi-wavelength observations can achieve a comprehensive view of the dominant emission process(es) and quantify the physical properties near the event horizon. Theoretical models are increasing in physical sophistication, and our study will provide essential constraints for the next generation of models.

  1. UNDERSTANDING BLACK HOLE MASS ASSEMBLY VIA ACCRETION AND MERGERS AT LATE TIMES IN COSMOLOGICAL SIMULATIONS

    SciTech Connect

    Kulier, Andrea; Ostriker, Jeremiah P.; Lackner, Claire N.; Cen, Renyue; Natarajan, Priyamvada

    2015-02-01

    Accretion is thought to primarily contribute to the mass accumulation history of supermassive black holes (SMBHs) throughout cosmic time. While this may be true at high redshifts, at lower redshifts and for the most massive black holes (BHs) mergers themselves might add significantly to the mass budget. We explore this in two disparate environments—a massive cluster and a void region. We evolve SMBHs from 4 > z > 0 using merger trees derived from hydrodynamical cosmological simulations of these two regions, scaled to the observed value of the stellar mass fraction to account for overcooling. Mass gains from gas accretion proportional to bulge growth and BH-BH mergers are tracked, as are BHs that remain ''orbiting'' due to insufficient dynamical friction in a merger remnant, as well as those that are ejected due to gravitational recoil. We find that gas accretion remains the dominant source of mass accumulation in almost all SMBHs; mergers contribute 2.5% ± 0.1% for all SMBHs in the cluster and 1.0% ± 0.1% in the void since z = 4. However, mergers are significant for massive SMBHs. The fraction of mass accumulated from mergers for central BHs generally increases for larger values of the host bulge mass: in the void, the fraction is 2% at M {sub *,} {sub bul} = 10{sup 10} M {sub ☉}, increasing to 4% at M {sub *,} {sub bul} ≳ 10{sup 11} M {sub ☉}, and in the cluster it is 4% at M {sub *,} {sub bul} = 10{sup 10} M {sub ☉} and 23% at 10{sup 12} M {sub ☉}. We also find that the total mass in orbiting SMBHs is negligible in the void, but significant in the cluster, in which a potentially detectable 40% of SMBHs and ≈8% of the total SMBH mass (where the total includes central, orbiting, and ejected SMBHs) is found orbiting at z = 0. The existence of orbiting and ejected SMBHs requires modification of the Soltan argument. We estimate this correction to the integrated accreted mass density of SMBHs to be in the range 6%-21%, with a mean value of 11% ± 3

  2. Hydrodynamical simulations of the tidal stripping of binary stars by massive black holes

    NASA Astrophysics Data System (ADS)

    Mainetti, Deborah; Lupi, Alessandro; Campana, Sergio; Colpi, Monica

    2016-04-01

    In a galactic nucleus, a star on a low angular momentum orbit around the central massive black hole can be fully or partially disrupted by the black hole tidal field, lighting up the compact object via gas accretion. This phenomenon can repeat if the star, not fully disrupted, is on a closed orbit. Because of the multiplicity of stars in binary systems, also binary stars may experience in pairs such a fate, immediately after being tidally separated. The consumption of both the binary components by the black hole is expected to power a double-peaked flare. In this paper, we perform for the first time, with GADGET2, a suite of smoothed particle hydrodynamics simulations of binary stars around a galactic central black hole in the Newtonian regime. We show that accretion luminosity light curves from double tidal disruptions reveal a more prominent knee, rather than a double peak, when decreasing the impact parameter of the encounter and when elevating the difference between the mass of the star which leaves the system after binary separation and the mass of the companion. The detection of a knee can anticipate the onset of periodic accretion luminosity flares if one of the stars, only partially disrupted, remains bound to the black hole after binary separation. Thus knees could be precursors of periodic flares, which can then be predicted, followed up and better modelled. Analytical estimates in the black hole mass range 105-108 M⊙ show that the knee signature is enhanced in the case of black holes of mass 106-107 M⊙.

  3. The Origin of Galactic and Metagalactic Magnetic Fields: The Black Hole Accretion Disk Dynamo

    NASA Astrophysics Data System (ADS)

    Colgate, S.; Li, H.; Beckley, H.; Finn, J.; Pariev, V.

    1998-12-01

    The frequent star-disk collisions in the accretion disk forming the massive black hole of galaxies is an efficient, robust mechanism for generating the alpha -helicity in the alpha -Omega dynamo. In the rotating frame of the disk, these collisions result in axially directed, expanding plumes which "un-twist" due to their increased moment of inertia. We have demonstrated this flow field and its feasibility in the laboratory in preparation for a dynamo experiment using liquid sodium. The near-infinite number of rotations of the inner accretion disk and hence, amplification, ensures that this dynamo will saturate at the maximum accretion disk stress, where Bmax ~ 50 kG, corresponding to a luminosity, L ~ 10(46) ergs/s. The magnetic flux expelled as a collimated Poynting flux is sufficient to explain the magnetic flux of the galaxy as well as that of galactic clusters. The dissipation of a fraction of this magnetic energy is the likely source of the AGN/quasar phenomena.

  4. Testing black hole neutrino-dominated accretion discs for long-duration gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Song, Cui-Ying; Liu, Tong; Gu, Wei-Min; Tian, Jian-Xiang

    2016-05-01

    Long-duration gamma-ray bursts (LGRBs) are generally considered to originate from the massive collapsars. It is believed that the central engine of gamma-ray bursts (GRBs) is a neutrino-dominated accretion flow (NDAF) around a rotating stellar-mass black hole (BH). The neutrino annihilation above the NDAF is a feasible mechanism to power GRB. In this work, we analyse the distributions of the isotropic gamma-ray-radiated energy and jet kinetic energy of 48 LGRBs. According to the NDAF and fireball models, we estimate the mean accreted masses of LGRBs in our sample to investigate whether the NDAFs can power LGRBs with the reasonable BH parameters and conversion efficiency of neutrino annihilation. The results indicate that most of the values of the accreted masses are less than 5 M⊙ for the extreme Kerr BHs and high conversion efficiency. It suggests that the NDAFs may be suitable for most of LGRBs except for some extremely high energy sources.

  5. THE QUASAR ACCRETION DISK SIZE-BLACK HOLE MASS RELATION

    SciTech Connect

    Morgan, Christopher W.; Kochanek, C. S.; Morgan, Nicholas D.; Falco, Emilio E. E-mail: ckochanek@astronomy.ohio-state.ed E-mail: efalco@cfa.harvard.ed

    2010-04-01

    We use the microlensing variability observed for 11 gravitationally lensed quasars to show that the accretion disk size at a rest-frame wavelength of 2500 A is related to the black hole mass by log(R{sub 2500}/cm) = (15.78 +- 0.12) + (0.80 +- 0.17)log(M{sub BH}/10{sup 9} M{sub sun}). This scaling is consistent with the expectation from thin-disk theory (R {proportional_to} M {sup 2/3}{sub BH}), but when interpreted in terms of the standard thin-disk model (T {proportional_to} R {sup -3/4}), it implies that black holes radiate with very low efficiency, log(eta) = -1.77 +- 0.29 + log(L/L{sub E}), where eta=L/(M-dot c{sup 2}). Only by making the maximum reasonable shifts in the average inclination, Eddington factors, and black hole masses can we raise the efficiency estimate to be marginally consistent with typical efficiency estimates (eta {approx} 10%). With one exception, these sizes are larger by a factor of {approx}4 than the size needed to produce the observed 0.8 {mu}m quasar flux by thermal radiation from a thin disk with the same T {proportional_to} R {sup -3/4} temperature profile. While scattering a significant fraction of the disk emission on large scales or including a large fraction of contaminating line emission can reduce the size discrepancy, resolving it also appears to require that accretion disks have flatter temperature/surface brightness profiles.

  6. AN UPPER LIMIT TO THE VELOCITY DISPERSION OF RELAXED STELLAR SYSTEMS WITHOUT MASSIVE BLACK HOLES

    SciTech Connect

    Miller, M. Coleman; Davies, Melvyn B.

    2012-08-10

    Massive black holes have been discovered in all closely examined galaxies with high velocity dispersion. The case is not as clear for lower-dispersion systems such as low-mass galaxies and globular clusters. Here we suggest that above a critical velocity dispersion {approx}40 km s{sup -1}, massive central black holes will form in relaxed stellar systems at any cosmic epoch. This is because above this dispersion primordial binaries cannot support the system against deep core collapse. If, as previous simulations show, the black holes formed in the cluster settle to produce a dense subcluster, then given the extremely high densities reached during core collapse the holes will merge with each other. For low velocity dispersions and hence low cluster escape speeds, mergers will typically kick out all or all but one of the holes due to three-body kicks or the asymmetric emission of gravitational radiation. If one hole remains, it will tidally disrupt stars at a high rate. If none remain, one is formed after runaway collisions between stars, and then it tidally disrupts stars at a high rate. The accretion rate after disruption is many orders of magnitude above Eddington. If, as several studies suggest, the hole can accept matter at that rate because the generated radiation is trapped and advected, then it will grow quickly and form a massive central black hole.

  7. Linear stability of nonbidiagonal black holes in massive gravity

    NASA Astrophysics Data System (ADS)

    Babichev, Eugeny; Brito, Richard; Pani, Paolo

    2016-02-01

    We consider generic linear perturbations of a nonbidiagonal class of static black-hole solutions in massive (bi-)gravity. We show that the quasinormal spectrum of these solutions coincides with that of a Schwarzschild black hole in general relativity, thus proving that these solutions are mode stable. This is in contrast to the case of bidiagonal black-hole solutions which are affected by a radial instability. On the other hand, the full set of perturbation equations is generically richer than that of a Schwarzschild black hole in general relativity, and this affects the linear response of the black hole to external perturbations. Finally, we argue that the generalization of these solutions to the spinning case does not suffer from the superradiant instability, despite the fact that the theory describes a massive graviton.

  8. Rapid growth of black holes in massive star-forming galaxies.

    PubMed

    Alexander, D M; Smail, I; Bauer, F E; Chapman, S C; Blain, A W; Brandt, W N; Ivison, R J

    2005-04-01

    The tight relationship between the masses of black holes and galaxy spheroids in nearby galaxies implies a causal connection between the growth of these two components. Optically luminous quasars host the most prodigious accreting black holes in the Universe, and can account for greater than or approximately equal to 30 per cent of the total cosmological black-hole growth. As typical quasars are not, however, undergoing intense star formation and already host massive black holes (> 10(8)M(o), where M(o) is the solar mass), there must have been an earlier pre-quasar phase when these black holes grew (mass range approximately (10(6)-10(8))M(o)). The likely signature of this earlier stage is simultaneous black-hole growth and star formation in distant (redshift z > 1; >8 billion light years away) luminous galaxies. Here we report ultra-deep X-ray observations of distant star-forming galaxies that are bright at submillimetre wavelengths. We find that the black holes in these galaxies are growing almost continuously throughout periods of intense star formation. This activity appears to be more tightly associated with these galaxies than any other coeval galaxy populations. We show that the black-hole growth from these galaxies is consistent with that expected for the pre-quasar phase. PMID:15815623

  9. THERMAL EQUILIBRIA OF MAGNETICALLY SUPPORTED BLACK HOLE ACCRETION DISKS

    SciTech Connect

    Oda, H.; Machida, M.; Nakamura, K. E.; Matsumoto, R.

    2009-05-20

    We present new thermal equilibrium solutions for optically thin and optically thick disks incorporating magnetic fields. The purpose of this paper is to explain the bright hard state and the bright/slow transition observed in the rising phases of outbursts in black hole candidates. On the basis of the results of three-dimensional magnetohydrodynamic simulations, we assume that magnetic fields inside the disk are turbulent and dominated by the azimuthal component and that the azimuthally averaged Maxwell stress is proportional to the total (gas, radiation, and magnetic) pressure. We prescribe the magnetic flux advection rate to determine the azimuthal magnetic flux at a given radius. Local thermal equilibrium solutions are obtained by equating the heating, radiative cooling, and heat advection terms. We find magnetically supported ({beta} = (p {sub gas} + p {sub rad})/p {sub mag} < 1), thermally stable solutions for both optically thin disks and optically thick disks, in which the heating enhanced by the strong magnetic field balances the radiative cooling. The temperature in a low-{beta} disk (T {approx} 10{sup 7}-10{sup 11}K) is lower than that in an advection-dominated accretion flow (or radiatively inefficient accretion flow) but higher than that in a standard disk. We also study the radial dependence of the thermal equilibrium solutions. The optically thin, low-{beta} branch extends to M-dot{approx}>0.1 M-dot{sub Edd}, where M-dot is the mass accretion rate and M-dot{sub Edd} is the Eddington mass accretion rate, in which the temperature anticorrelates with the mass accretion rate. Thus, optically thin low-{beta} disks can explain the bright hard state. Optically thick, low-{beta} disks have the radial dependence of the effective temperature T {sub eff} {proportional_to} piv{sup -3/4}. Such disks will be observed as staying in a high/soft state. Furthermore, limit cycle oscillations between an optically thick low-{beta} disk and a slim disk will occur because

  10. Accretion and Feedback Processes in Supermassive Black Holes

    NASA Astrophysics Data System (ADS)

    Zubovas, Kastytis

    2012-10-01

    Supermassive black holes (SMBHs) have been gradually recognised as important elements of galaxy and cosmic structure evolution. Their connection with the large-scale environment is maintained via feedback processes - communication of a fraction of the accretion luminosity to the host galaxy. Feedback is conjectured to expel gas from galaxies, quench star formation and establish the observed correlations between SMBH mass and host galaxy properties. Efficient feedback requires rapid gas accretion and is therefore usually investigated within the context of quasar activity phases in SMBH evolution. In this Thesis, I investigate several implications of an SMBH wind feedback model, advancing our understanding of feedback processes and the immediate environment of SMBHs. I consider analytically the large-scale outflows and their observable properties. I find that rapidly accreting SMBHs may sweep galaxies clear of gas, turning them into red-and-dead spheroids. I apply the same feedback model to our Galaxy. Its SMBH, Sgr A*, is currently exceptionally quiescent, although it must have been more active in the past in order to have grown to its present size. I investigate, both analytically and numerically, a short burst of activity which may have occurred ∼ 6 million years ago, producing an outflow which formed two large γ-ray emitting bubbles perpendicular to the Galactic plane. The results show that dynamical footprints of outflows may persist for a long time and provide evidence of past AGN activity in quiescent galaxies. I also present a model for the short-timescale flares observed daily in Sgr A*, based on tidal disruption and evaporation of asteroids in the vicinity of the SMBH. The model explains some observed flare properties, and thus improves our understanding of the processes occurring close to the SMBH. It also provides predictions for observable effects as the quiescent luminosity of Sgr A* varies on long timescales.

  11. Supermassive black hole formation by the cold accretion shocks in the first galaxies

    NASA Astrophysics Data System (ADS)

    Inayoshi, K.; Omukai, K.

    2012-09-01

    We propose a new scenario for supermassive star (SMS; >~105Msolar) formation in shocked regions of colliding cold accretion flows near the centers of first galaxies. When the post-shock density is high enough for collisionally exciting H2 rovibrational levels (>~104cm-3), enhanced H2 collisional dissociation suppresses the gas to cool below 8000 K. In this case, the layer fragments into massive clouds (>~105Msolar), which collapse isothermally (~ 8000 K) by the Lyα cooling without subsequent fragmentation. As an outcome, SMSs are expected to form and evolve eventually to seeds of supermassive black holes. By calculating thermal evolution of the shocked gas, we delimit the range of post-shock conditions for the SMS formation. We also find that metal enrichment does not affect the SMS forming condition for <~10-3Zsolar if metals are in the gas phase.

  12. Quiescent accretion disks in black hole X-ray novae

    NASA Technical Reports Server (NTRS)

    Orosz, Jerome A.; Bailyn, Charles D.; Remillard, Ronald A.; Mcclintock, Jeffrey E.; Foltz, Craig B.

    1994-01-01

    We present detailed time-resolved spectroscopy of the Balmer emission lines from two black hole binary systems in quiescence, A0620-00 and Nova Muscae 1991. We find extraordinary similarities between the two systems. There are 30-40 km/s velocity variations of the emission lines over the orbital period, the phases of which are not aligned with the expected phase of the motion of the compact primary. Detailed modeling of both systems is complicated by variable hot spot components, regions of optical thickness, and intermittent excess emission in the blue line wings of the H-alpha lines. Both sources also display low velocities at the outer edge of the accretion disk, implying a large primary Roche lobe and extreme mass ratios. These complications suggest that although simple optically thin, Keplerian alpha-disk models provide a useful parameterization of emission lines from these systems, the straightforward physical models they imply should be treated with great caution.

  13. On the Lamppost Model of Accreting Black Holes

    NASA Astrophysics Data System (ADS)

    Niedźwiecki, Andrzej; Zdziarski, Andrzej A.; Szanecki, Michał

    2016-04-01

    We study the lamppost model, in which the X-ray source in accreting black hole (BH) systems is located on the rotation axis close to the horizon. We point out a number of inconsistencies in the widely used lamppost model relxilllp, e.g., neglecting the redshift of the photons emitted by the lamppost that are directly observed. They appear to invalidate those model fitting results for which the source distances from the horizon are within several gravitational radii. Furthermore, if those results were correct, most of the photons produced in the lamppost would be trapped by the BH, and the luminosity generated in the source as measured at infinity would be much larger than that observed. This appears to be in conflict with the observed smooth state transitions between the hard and soft states of X-ray binaries. The required increase of the accretion rate and the associated efficiency reduction also present a problem for active galactic nuclei. Then, those models imply the luminosity measured in the local frame is much higher than that produced in the source and measured at infinity, due to the additional effects of time dilation and redshift, and the electron temperature is significantly higher than that observed. We show that these conditions imply that the fitted sources would be out of the e± pair equilibrium. On the other hand, the above issues pose relatively minor problems for sources at large distances from the BH, where relxilllp can still be used.

  14. Warped black holes in 3D general massive gravity

    NASA Astrophysics Data System (ADS)

    Tonni, Erik

    2010-08-01

    We study regular spacelike warped black holes in the three dimensional general massive gravity model, which contains both the gravitational Chern-Simons term and the linear combination of curvature squared terms characterizing the new massive gravity besides the Einstein-Hilbert term. The parameters of the metric are found by solving a quartic equation, constrained by an inequality that imposes the absence of closed timelike curves. Explicit expressions for the central charges are suggested by exploiting the fact that these black holes are discrete quotients of spacelike warped AdS 3 and a known formula for the entropy. Previous results obtained separately in topological massive gravity and in new massive gravity are recovered as special cases.

  15. A NEW MECHANISM FOR MASS ACCRETION UNDER RADIATION PRESSURE IN MASSIVE STAR FORMATION

    SciTech Connect

    Tanaka, Kei E. I.; Nakamoto, Taishi

    2010-05-01

    During the formation of a massive star, strong radiation pressure from the central star acts on the dust sublimation front and tends to halt the accretion flow. To overcome this strong radiation pressure, it has been considered that a strong ram pressure produced by a high-mass accretion rate of 10{sup -3} M{sub sun} yr{sup -1} or more is needed. We reinvestigated the necessary condition to overcome the radiation pressure and found a new mechanism for overcoming it. Accumulated mass in a stagnant flow near the dust sublimation front helps the mass accretion by its weight. This mechanism relaxes the condition for the massive star formation. We call this mechanism the 'OMOSHI effect', where OMOSHI is an acronym for 'One Mechanism for Overcoming Stellar High radiation pressure by weIght'. Additionally, in Japanese, OMOSHI is a noun meaning a weight that is put on something to prevent it from moving. We investigate the generation of the OMOSHI effect using local one-dimensional radiation hydrodynamics simulations. The radiation pressure and the gravitational force are connected through the gas pressure, and to sum up, the radiation pressure is balanced or overcome by the gravitational force. We also discuss the global structure and temporal variation of the accretion flow.

  16. The formation of a massive protostar through the disk accretion of gas.

    PubMed

    Chini, Rolf; Hoffmeister, Vera; Kimeswenger, Stefan; Nielbock, Markus; Nürnberger, Dieter; Schmidtobreick, Linda; Sterzik, Michael

    2004-05-13

    The formation of low-mass stars like our Sun can be explained by the gravitational collapse of a molecular cloud fragment into a protostellar core and the subsequent accretion of gas and dust from the surrounding interstellar medium. Theoretical considerations suggest that the radiation pressure from the protostar on the in-falling material may prevent the formation of stars above ten solar masses through this mechanism, although some calculations have claimed that stars up to 40 solar masses can in principle be formed via accretion through a disk. Given this uncertainty and the fact that most massive stars are born in dense clusters, it was suggested that high-mass stars are the result of the runaway merging of intermediate-mass stars. Here we report observations that clearly show a massive star being born from a large rotating accretion disk. The protostar has already assembled about 20 solar masses, and the accretion process is still going on. The gas reservoir of the circumstellar disk contains at least 100 solar masses of additional gas, providing sufficient fuel for substantial further growth of the forming star. PMID:15141204

  17. A New Mechanism for Mass Accretion Under Radiation Pressure in Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Tanaka, Kei E. I.; Nakamoto, Taishi

    2010-05-01

    During the formation of a massive star, strong radiation pressure from the central star acts on the dust sublimation front and tends to halt the accretion flow. To overcome this strong radiation pressure, it has been considered that a strong ram pressure produced by a high-mass accretion rate of 10-3 M sun yr-1 or more is needed. We reinvestigated the necessary condition to overcome the radiation pressure and found a new mechanism for overcoming it. Accumulated mass in a stagnant flow near the dust sublimation front helps the mass accretion by its weight. This mechanism relaxes the condition for the massive star formation. We call this mechanism the "OMOSHI effect," where OMOSHI is an acronym for "One Mechanism for Overcoming Stellar High radiation pressure by weIght." Additionally, in Japanese, OMOSHI is a noun meaning a weight that is put on something to prevent it from moving. We investigate the generation of the OMOSHI effect using local one-dimensional radiation hydrodynamics simulations. The radiation pressure and the gravitational force are connected through the gas pressure, and to sum up, the radiation pressure is balanced or overcome by the gravitational force. We also discuss the global structure and temporal variation of the accretion flow.

  18. A Possible Relativistic Jetted Outburst from a Massive Black Hole Fed by a Tidally Disrupted Star

    NASA Astrophysics Data System (ADS)

    Bloom, Joshua S.; Giannios, Dimitrios; Metzger, Brian D.; Cenko, S. Bradley; Perley, Daniel A.; Butler, Nathaniel R.; Tanvir, Nial R.; Levan, Andrew J.; O'Brien, Paul T.; Strubbe, Linda E.; De Colle, Fabio; Ramirez-Ruiz, Enrico; Lee, William H.; Nayakshin, Sergei; Quataert, Eliot; King, Andrew R.; Cucchiara, Antonino; Guillochon, James; Bower, Geoffrey C.; Fruchter, Andrew S.; Morgan, Adam N.; van der Horst, Alexander J.

    2011-07-01

    Gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, but most MBHs are considered dormant. Occasionally, a star passing too near an MBH is torn apart by gravitational forces, leading to a bright tidal disruption flare (TDF). Although the high-energy transient Sw 1644+57 initially displayed none of the theoretically anticipated (nor previously observed) TDF characteristics, we show that observations suggest a sudden accretion event onto a central MBH of mass about 106 to 107 solar masses. There is evidence for a mildly relativistic outflow, jet collimation, and a spectrum characterized by synchrotron and inverse Compton processes; this leads to a natural analogy of Sw 1644+57 to a temporary smaller-scale blazar.

  19. THE MOST MASSIVE ACTIVE BLACK HOLES AT z ∼ 1.5-3.5 HAVE HIGH SPINS AND RADIATIVE EFFICIENCIES

    SciTech Connect

    Trakhtenbrot, Benny

    2014-07-01

    The radiative efficiencies (η) of 72 luminous unobscured active galactic nuclei at z ∼ 1.5-3.5, powered by some of the most massive black holes (BHs), are constrained. The analysis is based on accretion disk (AD) models, which link the continuum luminosity at rest-frame optical wavelengths and the BH mass (M {sub BH}) to the accretion rate through the AD, M-dot {sub AD}. The data are gathered from several literature samples with detailed measurements of the Hβ emission line complex, observed at near-infrared bands. When coupled with standard estimates of bolometric luminosities (L {sub bol}), the analysis suggests high radiative efficiencies, with most of the sources showing η > 0.2, that is, higher than the commonly assumed value of 0.1, and the expected value for non-spinning BHs (η = 0.057). Even under more conservative assumptions regarding L {sub bol} (i.e., L {sub bol} = 3 × L {sub 5100}), most of the extremely massive BHs in the sample (i.e., M {sub BH} ≳ 3 × 10{sup 9} M {sub ☉}) show radiative efficiencies which correspond to very high BH spins (a {sub *}), with typical values well above a {sub *} ≅ 0.7. These results stand in contrast to the predictions of a ''spin-down'' scenario, in which a series of randomly oriented accretion episodes leads to a {sub *} ∼ 0. Instead, the analysis presented here strongly supports a ''spin-up'' scenario, which is driven by either prolonged accretion or a series of anisotropically oriented accretion episodes. Considering the fact that these extreme BHs require long-duration or continuous accretion to account for their high masses, it is argued that the most probable scenario for the super-massive black holes under study is that of an almost continuous sequence of randomly yet not isotropically oriented accretion episodes.

  20. Energy flows in thick accretion discs and their consequences for black hole feedback

    NASA Astrophysics Data System (ADS)

    Sądowski, Aleksander; Lasota, Jean-Pierre; Abramowicz, Marek A.; Narayan, Ramesh

    2016-03-01

    We study energy flows in geometrically thick accretion discs, both optically thick and thin, using general relativistic, three-dimensional simulations of black hole accretion flows. We find that for non-rotating black holes the efficiency of the total feedback from thick accretion discs is 3 per cent - roughly half of the thin disc efficiency. This amount of energy is ultimately distributed between outflow and radiation, the latter scaling weakly with the accretion rate for super-critical accretion rates, and returned to the interstellar medium. Accretion on to rotating black holes is more efficient because of the additional extraction of rotational energy. However, the jet component is collimated and likely to interact only weakly with the environment, whereas the outflow and radiation components cover a wide solid angle.

  1. Tunneling of massive particles from noncommutative inspired Schwarzschild black hole

    NASA Astrophysics Data System (ADS)

    Miao, Yan-Gang; Xue, Zhao; Zhang, Shao-Jun

    2012-02-01

    We apply the generalization of the Parikh-Wilczek method to the tunneling of massive particles from noncommutative inspired Schwarzschild black holes. By deriving the equation of radial motion of the tunneling particle directly, we calculate the emission rate which is shown to be dependent on the noncommutative parameter besides the energy and mass of the tunneling particle. After equating the emission rate to the Boltzmann factor, we obtain the modified Hawking temperature which relates to the noncommutativity and recovers the standard Hawking temperature in the commutative limit. We also discuss the entropy of the noncommutative inspired Schwarzschild black hole and its difference after and before a massive particle's emission.

  2. THE RATE OF GAS ACCRETION ONTO BLACK HOLES DRIVES JET VELOCITY

    SciTech Connect

    King, Ashley L.; Miller, Jon M.; Gültekin, Kayhan; Reynolds, Mark; Bietenholz, Michael; Bartel, Norbert; Mioduszewski, Amy; Rupen, Michael

    2015-01-20

    Accreting black holes are observed to launch relativistic, collimated jets of matter and radiation. In some sources, discrete ejections have been detected with highly relativistic velocities. These particular sources typically have very high mass accretion rates, while sources lower knot velocities are predominantly associated with black holes with relatively low mass accretion rates. We quantify this behavior by examining knot velocity with respect to X-ray luminosity, a proxy for mass accretion rate onto the black hole. We find a positive correlation between the mass-scaled X-ray luminosity and jet knot velocity. In addition, we find evidence that the jet velocity is also a function of polar angle, supporting the ''spine-sheath'' model of jet production. Our results reveal a fundamental aspect of how accretion shapes mechanical feedback from black holes into their host environments.

  3. X-Ray Iron Line Constraints on the Inner Accretion Disk and Black Hole Spin

    NASA Technical Reports Server (NTRS)

    Reynolds, C. S.

    2000-01-01

    The broad iron line, seen in the X-ray spectra of many AGN, is thought to originate from the inner regions of the black hole accretion disk. I will summarize recent developments in using this line to probe the accretion disk structure, as well as the mass and spin of black holes n Seyfert galaxies. In particular, I will present observational evidence suggesting that the inner regions of the accretion disks in low-luminosity AGN (LLAGN) are distinctly different from those in higher-luminosity AGN. This tentative result lends support models of LLAGN based upon advective accretion disks.

  4. Magneto centrifugal winds from accretion discs around black hole binaries

    NASA Astrophysics Data System (ADS)

    Chakravorty, S.; Petrucci, P.; Ferreira, J.; Henri, G.

    2015-07-01

    X-ray observations of black hole X-ray binaries (BHBs) suggest that disc winds occur in the softer (disk-dominated) states of the outburst and are less prominent or absent in the harder (power-law dominated) states, which are more characterized by radio-loud jets. We investigate the presence/absence and physical characteristics of disk winds in BHBs through the use of the magneto-hydrodynamic (MHD) solutions of Ferreira (1997). These models treat accretion and ejection self-consistently within a self-similar ansatz that allows to solve the full set of dynamical MHD equations without neglecting any term. As a consequence the ejection efficiency is not a free parameter but depends on the global structure of the disk. By testing different sets of solutions with varying disk aspect ratio and ejection efficiency, we attempt to reproduce the observed state dependent prevalence of the winds. With no a priori theoretical assumption about the state of the black hole, we recover this observed bias of the winds for the softer states. In this talk I shall detail the methods employed by us, followed by the results.

  5. Gravitational Rocket from the Merging Massive Black Hole Binaries

    NASA Technical Reports Server (NTRS)

    Choi, Dale

    2006-01-01

    Coalescing massive black hole binaries are expected to be among the most fascinating gravitational wave sources, observable by the NASA/ESA LISA detector. Not only will the merger events reveal the rich phenomenology of extremely strong and dynamical gravity deep inside the potential wells at the centers of galaxies (thus providing an excellent testing ground for general relativity), it will also make important contributions to the astrophysics of massive black hole evolutions. Typical black hole mergers involve asymmetric radiation of gravitational waves and lose linear momentum as well as energy and angular momentum. As a result, the merger remnant receives a kick from the GW emission: a gravitational rocket effect. High kick velocities (higher than the escape velocities of the host structure) would have a strong impact on our understanding of how massive black holes have evolved over time and, in particular, on the estimates of the merger rate for LISA. The main difficulties in calculations of the kick velocities has been in the last moments of the merger where the full theory of general relativity must be employed to accurately model the black hole dynamics. I describe a recent calculation of the kick velocities from numerical relativity simulations of the merging black hole binaries.

  6. Gravitational Rocket from the Merging Massive Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Choi, D.

    2005-12-01

    Coalescing massive black hole binaries are expected to be among the most fascinating gravitational wave sources, observable by the NASA/ESA LISA detector. Not only will the merger events reveal the rich phenomenology of extremely strong and dynamical gravity deep inside the potential wells at the centers of galaxies (thus providing an excellent testing ground for general relativity), it will also make important contributions to the astrophysics of massive black hole evolutions. Typical black hole mergers involve asymmetric radiation of gravitational waves and lose linear momentum as well as energy and angular momentum. As a result, the merger remnant receives a kick from the GW emission: a gravitational rocket effect. High kick velocities (higher than the escape velocites of the host structure) would have a strong impact on our understanding of how massive black holes have evolved over time and, in particular, on the estimates of the merger rate for LISA. The main difficulties in calculations of the kick velocities has been in the last moments of the merger where the full theory of general relativity must be employed to accurately model the black hole dynamics. I describe a recent calculation of the kick velocities from numerical relativity simulations of the merging black hole binaries. Support from NASA ATP#02-0043-0056 is greatly appreciated.

  7. A Hot and Massive Accretion Disk around the High-mass Protostar IRAS 20126+4104

    NASA Astrophysics Data System (ADS)

    Chen, Huei-Ru Vivien; Keto, Eric; Zhang, Qizhou; Sridharan, T. K.; Liu, Sheng-Yuan; Su, Yu-Nung

    2016-06-01

    We present new spectral line observations of the CH3CN molecule in the accretion disk around the massive protostar IRAS 20126+4104 with the Submillimeter Array, which, for the first time, measure the disk density, temperature, and rotational velocity with sufficient resolution (0.″37, equivalent to ∼600 au) to assess the gravitational stability of the disk through the Toomre-Q parameter. Our observations resolve the central 2000 au region that shows steeper velocity gradients with increasing upper state energy, indicating an increase in the rotational velocity of the hotter gas nearer the star. Such spin-up motions are characteristics of an accretion flow in a rotationally supported disk. We compare the observed data with synthetic image cubes produced by three-dimensional radiative transfer models describing a thin flared disk in Keplerian motion enveloped within the centrifugal radius of an angular-momentum-conserving accretion flow. Given a luminosity of 1.3 × 104 L ⊙, the optimized model gives a disk mass of 1.5 M ⊙ and a radius of 858 au rotating about a 12.0 M ⊙ protostar with a disk mass accretion rate of 3.9 × 10‑5 M ⊙ yr‑1. Our study finds that, in contrast to some theoretical expectations, the disk is hot and stable to fragmentation with Q > 2.8 at all radii which permits a smooth accretion flow. These results put forward the first constraints on gravitational instabilities in massive protostellar disks, which are closely connected to the formation of companion stars and planetary systems by fragmentation.

  8. Clumpy Accretion onto Black Holes. I. Clumpy-advection-dominated Accretion Flow Structure and Radiation

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Min; Cheng, Cheng; Li, Yan-Rong

    2012-04-01

    We investigate the dynamics of clumps embedded in and confined by the advection-dominated accretion flows (ADAFs), in which collisions among the clumps are neglected. We start from the collisionless Boltzmann equation and assume that interaction between the clumps and the ADAF is responsible for transporting the angular momentum of clumps outward. The inner edge of the clumpy-ADAF is set to be the tidal radius of the clumps. We consider strong- and weak-coupling cases, in which the averaged properties of clumps follow the ADAF dynamics and are mainly determined by the black hole potential, respectively. We propose the analytical solution of the dynamics of clumps for the two cases. The velocity dispersion of clumps is one magnitude higher than the ADAF for the strong-coupling case. For the weak-coupling case, we find that the mean radial velocity of clumps is linearly proportional to the coefficient of the drag force. We show that the tidally disrupted clumps would lead to an accumulation of the debris to form a debris disk in the Shakura-Sunyaev regime. The entire hot ADAF will be efficiently cooled down by photons from the debris disk, giving rise to a collapse of the ADAF, and quench the clumpy accretion. Subsequently, evaporation of the collapsed ADAF drives resuscitate of a new clumpy-ADAF, resulting in an oscillation of the global clumpy-ADAF. Applications of the present model are briefly discussed to X-ray binaries, low ionization nuclear emission regions, and BL Lac objects.

  9. CLUMPY ACCRETION ONTO BLACK HOLES. I. CLUMPY-ADVECTION-DOMINATED ACCRETION FLOW STRUCTURE AND RADIATION

    SciTech Connect

    Wang Jianmin; Cheng Cheng; Li Yanrong

    2012-04-01

    We investigate the dynamics of clumps embedded in and confined by the advection-dominated accretion flows (ADAFs), in which collisions among the clumps are neglected. We start from the collisionless Boltzmann equation and assume that interaction between the clumps and the ADAF is responsible for transporting the angular momentum of clumps outward. The inner edge of the clumpy-ADAF is set to be the tidal radius of the clumps. We consider strong- and weak-coupling cases, in which the averaged properties of clumps follow the ADAF dynamics and are mainly determined by the black hole potential, respectively. We propose the analytical solution of the dynamics of clumps for the two cases. The velocity dispersion of clumps is one magnitude higher than the ADAF for the strong-coupling case. For the weak-coupling case, we find that the mean radial velocity of clumps is linearly proportional to the coefficient of the drag force. We show that the tidally disrupted clumps would lead to an accumulation of the debris to form a debris disk in the Shakura-Sunyaev regime. The entire hot ADAF will be efficiently cooled down by photons from the debris disk, giving rise to a collapse of the ADAF, and quench the clumpy accretion. Subsequently, evaporation of the collapsed ADAF drives resuscitate of a new clumpy-ADAF, resulting in an oscillation of the global clumpy-ADAF. Applications of the present model are briefly discussed to X-ray binaries, low ionization nuclear emission regions, and BL Lac objects.

  10. Detectable MeV neutrinos from black hole neutrino-dominated accretion flows

    NASA Astrophysics Data System (ADS)

    Liu, Tong; Zhang, Bing; Li, Ye; Ma, Ren-Yi; Xue, Li

    2016-06-01

    Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes (BHs) have been theorized as the central engine of relativistic jets launched in massive star core collapse events or compact star mergers. In this work, we calculate the electron neutrino/antineutrino spectra of NDAFs by fully taking into account the general relativistic effects, and investigate the effects of viewing angle, BH spin, and mass accretion rate on the results. We show that even though a typical NDAF has a neutrino luminosity lower than that of a typical supernova (SN), it can reach 1050- 1051 erg s-1 peaking at ˜10 MeV , making NDAFs potentially detectable with the upcoming sensitive MeV neutrino detectors if they are close enough to Earth. Based on the observed gamma-ray burst (GRB) event rate in the local universe and requiring that at least three neutrinos are detected to claim a detection, we estimate a detection rate up to ˜(0.10 - 0.25 ) per century for GRB-related NDAFs by the Hyper-Kamiokande (Hyper-K) detector if one neglects neutrino oscillation. If one assumes that all type Ib/c SNe have an engine-driven NDAF, the Hyper-K detection rate would be ˜(1 - 3 ) per century. By considering neutrino oscillations, the detection rate may decrease by a factor of 2-3. Detecting one such event would establish the observational evidence of NDAFs in the Universe.

  11. Pathways to massive black holes and compact star clusters in pre-galactic dark matter haloes with virial temperatures >~10000K

    NASA Astrophysics Data System (ADS)

    Regan, John A.; Haehnelt, Martin G.

    2009-06-01

    Large dynamic range numerical simulations of atomic cooling driven collapse of gas in pre-galactic dark matter haloes with Tvir ~ 10000 K show that the gas loses 90 per cent and more of its angular momentum before rotational support sets in. In a fraction of these haloes where the metallicity is low and ultraviolet (UV) radiation suppresses H2 cooling, conditions are thus very favourable for the rapid build-up of massive black holes. Depending on the progression of metal enrichment, the continued suppression of H2 cooling by external and internal UV radiation and the ability to trap the entropy produced by the release of gravitational energy, the gas at the centre of the halo is expected to form a supermassive star, a stellar-mass black hole accreting at super-Eddington accretion rates or a compact star-cluster undergoing collisional run-away of massive stars at its centre. In all three cases, a massive black hole of initially modest mass finds itself at the centre of a rapid inflow of gas with inflow rates of >~1Msolaryr-1. The massive black hole will thus grow quickly to a mass of 105- 106Msolar until further inflow is halted either by consumption of gas by star formation or by the increasing energy and momentum feedback from the growing massive black hole. Conditions for the formation of massive seed black holes in this way are most favourable in haloes with Tvir ~ 15000K and Vvir ~ 20 km s-1 with less massive haloes not allowing collapse of gas by atomic cooling and more massive haloes being more prone to fragmentation. This should imprint a characteristic mass on the mass spectrum of an early population of massive black hole seeds in pre-galactic haloes which will later grow into the observed population of supermassive black holes in galactic bulges.

  12. COLLAPSE OF MOLECULAR CLOUD CORES WITH RADIATION TRANSFER: FORMATION OF MASSIVE STARS BY ACCRETION

    SciTech Connect

    Sigalotti, Leonardo Di G.; Daza-Montero, Judith; De Felice, Fernando

    2009-12-20

    Most early radiative transfer calculations of protostellar collapse have suggested an upper limit of approx40 M{sub sun} for the final stellar mass before radiation pressure can exceed the star's gravitational pull and halt the accretion. Here we perform further collapse calculations, using frequency-dependent radiation transfer coupled to a frequency-dependent dust model that includes amorphous carbon particles, silicates, and ice-coated silicates. The models start from pressure-bounded, logatropic spheres of mass between 5 M{sub sun} and 150 M{sub sun} with an initial nonsingular density profile. We find that in a logatrope the infall is never reversed by the radiative forces on the dust and that stars with masses approx>100 M{sub sun} may form by continued accretion. Compared to previous models that start the collapse with a rho propor to r{sup -2} density configuration, our calculations result in higher accretion times and lower average accretion rates with peak values of approx5.8 x 10{sup -5} M{sub sun} yr{sup -1}. The radii and bolometric luminosities of the produced massive stars (approx>90 M{sub sun}) are in good agreement with the figures reported for detected stars with initial masses in excess of 100 M{sub sun}. The spectral energy distribution from the stellar photosphere reproduces the observed fluxes for hot molecular cores with peaks of emission from mid- to near-infrared.

  13. A CANDIDATE MASSIVE BLACK HOLE IN THE LOW-METALLICITY DWARF GALAXY PAIR MRK 709

    SciTech Connect

    Reines, Amy E.; Condon, James J.; Plotkin, Richard M.; Russell, Thomas D.; Mezcua, Mar; Sivakoff, Gregory R.; Johnson, Kelsey E.

    2014-06-01

    The incidence and properties of present-day dwarf galaxies hosting massive black holes (BHs) can provide important constraints on the origin of high-redshift BH seeds. Here we present high-resolution X-ray and radio observations of the low-metallicity, star-forming, dwarf-galaxy system Mrk 709 with the Chandra X-ray Observatory and the Karl G. Jansky Very Large Array. These data reveal spatially coincident hard X-ray and radio point sources with luminosities suggesting the presence of an accreting massive BH (M {sub BH} ∼ 10{sup 5-7} M {sub ☉}). Based on imaging from the Sloan Digital Sky Survey (SDSS), we find that Mrk 709 consists of a pair of compact dwarf galaxies that appear to be interacting with one another. The position of the candidate massive BH is consistent with the optical center of the southern galaxy (Mrk 709 S), while no evidence for an active BH is seen in the northern galaxy (Mrk 709 N). We derive stellar masses of M {sub *} ∼ 2.5 × 10{sup 9} M {sub ☉} and M {sub *} ∼ 1.1 × 10{sup 9} M {sub ☉} for Mrk 709 S and Mrk 709 N, respectively, and present an analysis of the SDSS spectrum of the BH host Mrk 709 S. At a metallicity of just ∼10% solar, Mrk 709 is among the most metal-poor galaxies with evidence for an active galactic nucleus. Moreover, this discovery adds to the growing body of evidence that massive BHs can form in dwarf galaxies and that deep, high-resolution X-ray and radio observations are ideally suited to reveal accreting massive BHs hidden at optical wavelengths.

  14. The Chaotic Light Curves of Accreting Black Holes

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes

    2007-01-01

    We present model light curves for accreting Black Hole Candidates (BHC) based on a recently developed model of these sources. According to this model, the observed light curves and aperiodic variability of BHC are due to a series of soft photon injections at random (Poisson) intervals and the stochastic nature of the Comptonization process in converting these soft photons to the observed high energy radiation. The additional assumption of our model is that the Comptonization process takes place in an extended but non-uniform hot plasma corona surrounding the compact object. We compute the corresponding Power Spectral Densities (PSD), autocorrelation functions, time skewness of the light curves and time lags between the light curves of the sources at different photon energies and compare our results to observation. Our model reproduces the observed light curves well, in that it provides good fits to their overall morphology (as manifest by the autocorrelation and time skewness) and also to their PSDs and time lags, by producing most of the variability power at time scales 2 a few seconds, while at the same time allowing for shots of a few msec in duration, in accordance with observation. We suggest that refinement of this type of model along with spectral and phase lag information can be used to probe the structure of this class of high energy sources.

  15. X-RAY POLARIZATION FROM ACCRETING BLACK HOLES: CORONAL EMISSION

    SciTech Connect

    Schnittman, Jeremy D.; Krolik, Julian H. E-mail: jhk@pha.jhu.ed

    2010-04-01

    We present new calculations of X-ray polarization from accreting black holes (BHs), using a Monte Carlo ray-tracing code in full general relativity. In our model, an optically thick disk in the BH equatorial plane produces thermal seed photons with polarization oriented parallel to the disk surface. These seed photons are then inverse-Compton scattered through a hot (but thermal) corona, producing a hard X-ray power-law spectrum. We consider three different models for the corona geometry: a wedge 'sandwich' with aspect ratio H/R and vertically integrated optical depth tau{sub 0} constant throughout the disk; an inhomogeneous 'clumpy' corona with a finite number of hot clouds distributed randomly above the disk within a wedge geometry; and a spherical corona of uniform density, centered on the BH and surrounded by a truncated thermal disk with inner radius R{sub edge}. In all cases, we find a characteristic transition from horizontal polarization at low energies to vertical polarization above the thermal peak; the vertical direction is defined as the projection of the BH spin axis on the plane of the sky. We show how the details of the spectropolarization signal can be used to distinguish between these models and infer various properties of the corona and BH. Although the bulk of this paper focuses on stellar-mass BHs, we also consider the effects of coronal scattering on the X-ray polarization signal from supermassive BHs in active galactic nuclei.

  16. Are BL Lac-type objects nearby black holes. [gas accretion model

    NASA Technical Reports Server (NTRS)

    Shapiro, S. L.; Elliot, J. L.

    1974-01-01

    It is pointed out that isolated black holes accreting interstellar gas can account for the characteristic properties of the Lacertids. Emission spectra for various interstellar gas densities and black hole masses are compared with the data plotted by Strittmatter et al. (1972) for the BL Lac-type objects. Rough estimates indicate that there may indeed be a finite number of stellar-mass black holes close to the earth as required by the theory. If it is determined that the BL Lac-type objects lie outside of the galactic disk a black hole accretion model may still apply if certain conditions are satisfied.

  17. Flares from the Tidal Disruption of Stars by Massive Black Holes in Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Strubbe, Linda; Quataert, E.

    2011-01-01

    A star that wanders too close to a massive black hole (BH) gets shredded by the BH's tidal gravity. Stellar gas soon falls back to the BH at a rate initially exceeding the Eddington rate, releasing a flare of energy as gas accretes. How often this process occurs is uncertain at present, as is the physics of super-Eddington accretion (which is relevant for BH growth and feedback at high redshift as well). Excitingly, transient surveys like the Palomar Transient Factory (PTF), Pan-STARRS and LSST should shed light on these questions soon -- in anticipation, we predict observational properties of tidal flares. Early on, much of the falling-back gas should blow away in a wind, producing luminous optical emission that are likely imprinted with blueshifted UV absorption lines. If the gas shocking close to the BH is unable to reach thermal equilibrium, the emission will instead be hard X-rays with no optical/UV lines. At later times, the gas accretes in a disk; for MBH 105 - 106 Msun, 1-10% of the disk's emission is reprocessed by escaping stellar debris, producing a spectrum of very broad emission lines. We predict detection rates for PTF, Pan-STARRS and LSST, and discuss the substantial challenge of disentangling these events from supernovae. These surveys should significantly improve our knowledge of stellar dynamics in galactic nuclei, the physics of super-Eddington accretion, the demography of IMBHs, and the role of tidal disruption in the growth of massive BHs. We gratefully acknowledge support from the Miller Institute, UC Berkeley, NASA, and the Packard Foundation.

  18. Greybody factors for a black hole in massive gravity

    NASA Astrophysics Data System (ADS)

    Dong, Ruifeng; Stojkovic, Dejan

    2015-10-01

    An exact solution was recently found in the massive gravity theory having the form of Schwarzschild-de Sitter (dS) black holes with some additional background fields. Hawking radiation will occur at the event and cosmological horizons having the blackbody spectrum, which will be modified by the geometry outside the black hole. In this paper, we study the greybody factors of a test scalar, considering its minimal coupling with the background geometry. The case of small black holes with a horizon radius much smaller than the cosmological dS radius is studied numerically. The case of near-extremal black holes with the horizon radius comparable to the cosmological dS radius is studied analytically. In addition, we considered the coupling of the test field with the background Stückelberg fields, which in turn leads to reductions in particle emission and some nontrivial features (resonances) in the greybody factors.

  19. A SYSTEMATIC SEARCH FOR MASSIVE BLACK HOLE BINARIES IN THE SLOAN DIGITAL SKY SURVEY SPECTROSCOPIC SAMPLE

    SciTech Connect

    Tsalmantza, P.; Decarli, R.; Hogg, David W.; Dotti, M. E-mail: decarli@mpia.de

    2011-09-01

    We present the results of a systematic search for massive black hole binaries in the Sloan Digital Sky Survey (SDSS) spectroscopic database. We focus on bound binaries, under the assumption that one of the black holes is active. In this framework, the broad lines associated with the accreting black hole are expected to show systematic velocity shifts with respect to the narrow lines, which trace the rest frame of the galaxy. For a sample of 54,586 quasars and 3929 galaxies at redshifts 0.1 < z < 1.5, we brute-force model each spectrum as a mixture of two quasars at two different redshifts. The spectral model is a data-driven dimensionality reduction of the SDSS quasar spectra based on a matrix factorization. We identified 32 objects with peculiar spectra. Nine of them can be interpreted as black hole binaries. This doubles the number of known black hole binary candidates. We also report on the discovery of a new class of extreme double-peaked emitters with exceptionally broad and faint Balmer lines. For all the interesting sources, we present detailed analysis of the spectra and discuss possible interpretations.

  20. Super massive black hole in galactic nuclei with tidal disruption of stars

    SciTech Connect

    Zhong, Shiyan; Berczik, Peter; Spurzem, Rainer

    2014-09-10

    Tidal disruption of stars by super massive central black holes from dense star clusters is modeled by high-accuracy direct N-body simulation. The time evolution of the stellar tidal disruption rate, the effect of tidal disruption on the stellar density profile, and, for the first time, the detailed origin of tidally disrupted stars are carefully examined and compared with classic papers in the field. Up to 128k particles are used in simulation to model the star cluster around a super massive black hole, and we use the particle number and the tidal radius of the black hole as free parameters for a scaling analysis. The transition from full to empty loss-cone is analyzed in our data, and the tidal disruption rate scales with the particle number, N, in the expected way for both cases. For the first time in numerical simulations (under certain conditions) we can support the concept of a critical radius of Frank and Rees, which claims that most stars are tidally accreted on highly eccentric orbits originating from regions far outside the tidal radius. Due to the consumption of stars moving on radial orbits, a velocity anisotropy is found inside the cluster. Finally we estimate the real galactic center based on our simulation results and the scaling analysis.

  1. Super Massive Black Hole in Galactic Nuclei with Tidal Disruption of Stars

    NASA Astrophysics Data System (ADS)

    Zhong, Shiyan; Berczik, Peter; Spurzem, Rainer

    2014-09-01

    Tidal disruption of stars by super massive central black holes from dense star clusters is modeled by high-accuracy direct N-body simulation. The time evolution of the stellar tidal disruption rate, the effect of tidal disruption on the stellar density profile, and, for the first time, the detailed origin of tidally disrupted stars are carefully examined and compared with classic papers in the field. Up to 128k particles are used in simulation to model the star cluster around a super massive black hole, and we use the particle number and the tidal radius of the black hole as free parameters for a scaling analysis. The transition from full to empty loss-cone is analyzed in our data, and the tidal disruption rate scales with the particle number, N, in the expected way for both cases. For the first time in numerical simulations (under certain conditions) we can support the concept of a critical radius of Frank & Rees, which claims that most stars are tidally accreted on highly eccentric orbits originating from regions far outside the tidal radius. Due to the consumption of stars moving on radial orbits, a velocity anisotropy is found inside the cluster. Finally we estimate the real galactic center based on our simulation results and the scaling analysis.

  2. The formation of rare massive black holes at redshift 30

    NASA Astrophysics Data System (ADS)

    Tanaka, Takamitsu; Li, M.

    2014-01-01

    How supermassive black holes with billions of solar masses formed before redshift 7, when the Universe was less than 800 million years old, remains a theoretical puzzle. One hypothesis is that they grew from ~10^5 Msol black holes formed in the direct collapse of pristine, atomic-cooling (>8000 K) gas. A major uncertainty for this scenario is how the gas can be kept metal free, as dark matter haloes begin forming stars at a virial temperature of ~1000 K. We propose that baryonic streaming, the relative motion of baryons against dark matter at cosmological recombination, is a natural mechanism for delaying star formation and keeping the gas pristine until the halo potential can support conditions for direct collapse. In rare regions where the local streaming velocities are more than twice the rms value, direct-collapse black holes can form as early as 30. This scenario can explain the most massive and earliest known quasar black holes, even if only 1% of pristine atomic-cooling haloes form direct-collapse massive black holes.

  3. The formation and evolution of massive black holes.

    PubMed

    Volonteri, M

    2012-08-01

    The past 10 years have witnessed a change of perspective in the way astrophysicists think about massive black holes (MBHs), which are now considered to have a major role in the evolution of galaxies. This appreciation was driven by the realization that black holes of millions of solar masses and above reside in the center of most galaxies, including the Milky Way. MBHs also powered active galactic nuclei known to exist just a few hundred million years after the Big Bang. Here, I summarize the current ideas on the evolution of MBHs through cosmic history, from their formation about 13 billion years ago to their growth within their host galaxies. PMID:22859482

  4. Gas retention and accumulation in stellar clusters and galaxies: Implications for star formation and black hole accretion

    NASA Astrophysics Data System (ADS)

    Naiman, Jill

    Star formation cannot proceed without the existence of an extensive gas reservoir. In particular, the supply of gas to form stars in dwarf galaxies and star clusters requires overcoming a variety of difficulties - namely, the effectiveness of different feedback mechanisms in removing gas from these shallow gravitational potentials. In addition, the supply of external gas to these systems is determined by the large scale galactic structure in which they reside. This thesis employs computational hydrodynamics coupled with physically realistic subgrid feedback prescriptions to resolve the interplay between the small scale feedback mechanisms and larger scale gas flows to determine the amount of gas a shallow potential can accumulate. First, we consider the flow of gas external to dwarf galaxies and star clusters into their cores as a generalized accretion process. Second, we explore the enhancement of gas accretion rates onto the compact members of young star clusters when the flow of external gas into the cluster cores is large. Third, we discuss how external gas flows initiated by the presence of a massive nuclear star cluster can enhance central massive black hole accretion rates during galaxy mergers. Fourth, we change our focus to exploring internal stellar wind retention in proto-globular clusters as a mechanism to supply gas for multiple episodes of star formation. Finally, the implications of stellar wind retention on the current gas reservoir in globular clusters is discussed.

  5. Eccentricity boost of stars around shrinking massive black hole binaries

    NASA Astrophysics Data System (ADS)

    Iwasa, Mao; Seto, Naoki

    2016-06-01

    Based on a simple geometrical approach, we analyze the evolution of the Kozai-Lidov mechanism for stars around shrinking massive black hole binaries on circular orbits. We find that, due to a peculiar bifurcation pattern induced by the Newtonian potential of stellar clusters, the orbit of stars could become highly eccentric. This transition occurs abruptly for stars with small initial eccentricities. The approach presented in this paper may be useful for studying the Kozai-Lidov mechanism in various astrophysical contexts.

  6. Massive Black Holes and the Laser Interferometer Space Antenna (LISA)

    NASA Technical Reports Server (NTRS)

    Blender, Peter L.; Hils, Dieter; Stebbins, Robin T.

    1998-01-01

    The goals of the USA mission include both astrophysical investigations and fundamental physics tests. The main astrophysical questions concern the space density, growth, mass function, and surroundings of massive black holes. Thus the crucial issue for the USA mission is the likelihood of observing signals from such sources. Four possible sources of this kind are discussed briefly in this paper. It appears plausible, or even likely. that one or more of these types of sources can be detected and studied by LISA.

  7. The cosmic evolution of massive black holes in the Horizon-AGN simulation

    NASA Astrophysics Data System (ADS)

    Volonteri, M.; Dubois, Y.; Pichon, C.; Devriendt, J.

    2016-08-01

    We analyse the demographics of black holes (BHs) in the large-volume cosmological hydrodynamical simulation Horizon-AGN. This simulation statistically models how much gas is accreted on to BHs, traces the energy deposited into their environment and, consequently, the back-reaction of the ambient medium on BH growth. The synthetic BHs reproduce a variety of observational constraints such as the redshift evolution of the BH mass density and the mass function. Strong self-regulation via AGN feedback, weak supernova feedback, and unresolved internal processes result in a tight BH-galaxy mass correlation. Starting at z ˜ 2, tidal stripping creates a small population of BHs over-massive with respect to the halo. The fraction of galaxies hosting a central BH or an AGN increases with stellar mass. The AGN fraction agrees better with multi-wavelength studies, than single-wavelength ones, unless obscuration is taken into account. The most massive haloes present BH multiplicity, with additional BHs gained by ongoing or past mergers. In some cases, both a central and an off-centre AGN shine concurrently, producing a dual AGN. This dual AGN population dwindles with decreasing redshift, as found in observations. Specific accretion rate and Eddington ratio distributions are in good agreement with observational estimates. The BH population is dominated in turn by fast, slow, and very slow accretors, with transitions occurring at z = 3 and z = 2, respectively.

  8. The cosmic evolution of massive black holes in the Horizon-AGN simulation

    NASA Astrophysics Data System (ADS)

    Volonteri, M.; Dubois, Y.; Pichon, C.; Devriendt, J.

    2016-08-01

    We analyse the demographics of black holes (BHs) in the large-volume cosmological hydrodynamical simulation Horizon-AGN. This simulation statistically models how much gas is accreted onto BHs, traces the energy deposited into their environment and, consequently, the back-reaction of the ambient medium on BH growth. The synthetic BHs reproduce a variety of observational constraints such as the redshift evolution of the BH mass density and the mass function. Strong self-regulation via AGN feedback, weak supernova feedback, and unresolved internal processes result in a tight BH-galaxy mass correlation. Starting at z~2, tidal stripping creates a small population of BHs over-massive with respect to the halo. The fraction of galaxies hosting a central BH or an AGN increases with stellar mass. The AGN fraction agrees better with multi-wavelength studies, than single-wavelength ones, unless obscuration is taken into account. The most massive halos present BH multiplicity, with additional BHs gained by ongoing or past mergers. In some cases, both a central and an off-centre AGN shine concurrently, producing a dual AGN. This dual AGN population dwindles with decreasing redshift, as found in observations. Specific accretion rate and Eddington ratio distributions are in good agreement with observational estimates. The BH population is dominated in turn by fast, slow, and very slow accretors, with transitions occurring at z=3 and z=2 respectively.

  9. Simulating the Formation of Massive Protostars. I. Radiative Feedback and Accretion Disks

    NASA Astrophysics Data System (ADS)

    Klassen, Mikhail; Pudritz, Ralph E.; Kuiper, Rolf; Peters, Thomas; Banerjee, Robi

    2016-05-01

    We present radiation hydrodynamic simulations of collapsing protostellar cores with initial masses of 30, 100, and 200 M ⊙. We follow their gravitational collapse and the formation of a massive protostar and protostellar accretion disk. We employ a new hybrid radiative feedback method blending raytracing techniques with flux-limited diffusion for a more accurate treatment of the temperature and radiative force. In each case, the disk that forms becomes Toomre-unstable and develops spiral arms. This occurs between 0.35 and 0.55 freefall times and is accompanied by an increase in the accretion rate by a factor of 2–10. Although the disk becomes unstable, no other stars are formed. In the case of our 100 and 200 M ⊙ simulations, the star becomes highly super-Eddington and begins to drive bipolar outflow cavities that expand outwards. These radiatively driven bubbles appear stable, and appear to be channeling gas back onto the protostellar accretion disk. Accretion proceeds strongly through the disk. After 81.4 kyr of evolution, our 30 M ⊙ simulation shows a star with a mass of 5.48 M ⊙ and a disk of mass 3.3 M ⊙, while our 100 M ⊙ simulation forms a 28.8 M ⊙ mass star with a 15.8 M ⊙ disk over the course of 41.6 kyr, and our 200 M ⊙ simulation forms a 43.7 M ⊙ star with an 18 M ⊙ disk in 21.9 kyr. In the absence of magnetic fields or other forms of feedback, the masses of the stars in our simulation do not appear to be limited by their own luminosities.

  10. Strong Field Effects on Emission Line Profiles: Kerr Black Holes and Warped Accretion Disks

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Xiang-Dong

    2012-01-01

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.

  11. Strong Field Effects On Emission Line Profiles: Kerr Black Holes And Warped Accretion Disks

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, X.

    2012-01-01

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetry of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole. This work was supported by the Natural Science Foundation of China (under grant number 10873008), and the National Basic Research Program of China (973 Program 2009CB824800).

  12. STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS

    SciTech Connect

    Wang Yan; Li Xiangdong

    2012-01-10

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.

  13. Impact of black hole's spin to power the accretion/outflow phenomena

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Banibrata

    2016-07-01

    I plan to address how important role the spin of black hole is playing to determine various features of accretion and outflow/jet. I will also attempt to explore the relative importance among magnetic fields, viscous and cooling processes of accretion flows and the Kerr parameter of black holes to determine observed features. This will be done based on magnetohydrodynamical modelling of the flow in the pseudo-Newtonian framework. Finally, I will attempt to predict the spin of black holes in observed sources.

  14. Does the mass of a black hole decrease due to the accretion of phantom energy?

    SciTech Connect

    Gao Changjun; Chen Xuelei; Faraoni, Valerio; Shen Yougen

    2008-07-15

    According to Babichev et al., the accretion of a phantom test fluid onto a Schwarzschild black hole will induce the mass of the black hole to decrease, however the backreaction was ignored in their calculation. Using new exact solutions describing black holes in a background Friedmann-Robertson-Walker universe, we find that the physical black hole mass may instead increase due to the accretion of phantom energy. If this is the case, and the future universe is dominated by phantom dark energy, the black hole apparent horizon and the cosmic apparent horizon will eventually coincide and, after that, the black hole singularity will become naked in finite comoving time before the big rip occurs, violating the cosmic censorship conjecture.

  15. Accretion-induced variability links young stellar objects, white dwarfs, and black holes

    PubMed Central

    Scaringi, Simone; Maccarone, Thomas J.; Körding, Elmar; Knigge, Christian; Vaughan, Simon; Marsh, Thomas R.; Aranzana, Ester; Dhillon, Vikram S.; Barros, Susana C. C.

    2015-01-01

    The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained with Kepler/K2 and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies. PMID:26601307

  16. Accretion-induced variability links young stellar objects, white dwarfs, and black holes.

    PubMed

    Scaringi, Simone; Maccarone, Thomas J; Körding, Elmar; Knigge, Christian; Vaughan, Simon; Marsh, Thomas R; Aranzana, Ester; Dhillon, Vikram S; Barros, Susana C C

    2015-10-01

    The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained with Kepler/K2 and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies. PMID:26601307

  17. The coevolution of supermassive black holes and massive galaxies at high redshift

    SciTech Connect

    Lapi, A.; Raimundo, S.; Aversa, R.; Cai, Z.-Y.; Celotti, A.; De Zotti, G.; Danese, L.; Negrello, M.

    2014-02-20

    We exploit the recent, wide samples of far-infrared (FIR) selected galaxies followed up in X-rays and of X-ray/optically selected active galactic nuclei (AGNs) followed up in the FIR band, along with the classic data on AGNs and stellar luminosity functions at high redshift z ≳ 1.5, to probe different stages in the coevolution of supermassive black holes (BHs) and host galaxies. The results of our analysis indicate the following scenario: (1) the star formation in the host galaxy proceeds within a heavily dust-enshrouded medium at an almost constant rate over a timescale ≲ 0.5-1 Gyr and then abruptly declines due to quasar feedback, over the same timescale; (2) part of the interstellar medium loses angular momentum, reaches the circum-nuclear regions at a rate proportional to the star formation, and is temporarily stored in a massive reservoir/proto-torus wherefrom it can be promptly accreted; (3) the BH grows by accretion in a self-regulated regime with radiative power that can slightly exceed the Eddington limit L/L {sub Edd} ≲ 4, particularly at the highest redshifts; (4) for massive BHs, the ensuing energy feedback at its maximum exceeds the stellar one and removes the interstellar gas, thus stopping the star formation and the fueling of the reservoir; (5) afterward, if the latter has retained enough gas, a phase of supply-limited accretion follows, exponentially declining with a timescale of about two e-folding times. We also discuss how the detailed properties and the specific evolution of the reservoir can be investigated via coordinated, high-resolution observations of star-forming, strongly lensed galaxies in the (sub-)mm band with ALMA and in the X-ray band with Chandra and the next-generation X-ray instruments.

  18. A Very Massive Stellar Black Hole in the Milky Way Galaxy

    NASA Astrophysics Data System (ADS)

    2001-11-01

    VLT ISAAC Uncovers an Enigmatic Microquasar Summary One of the most enigmatic stellar systems in our Milky Way Galaxy has been shown to harbour a very massive black hole. With 14 times more mass than the Sun [1], this is the heaviest known stellar black hole in the Galaxy. Using the ISAAC instrument on the VLT 8.2-m ANTU telescope at the ESO Paranal Observatory , an international team of astronomers [2] peered into a remote area of the Milky Way to probe the binary system GRS 1915+105 , located almost 40,000 light-years away. They were able to identify the low-mass star that feeds the black hole by means of a steady flow of stellar material. A detailed follow-up study revealed how this star revolves around its hungry companion. The analysis of the orbital motion then made it possible to estimate the mass of the black hole. The observation of the heavy black hole in GRS 1915+105 is opening up fundamental questions about how massive stellar black holes form, and whether or not such objects rotate around their own axes. PR Photo 31a/01 : Schematic drawing of the GRS 1915+105 binary system . PR Photo 31b/01 : ISAAC spectrum of the companion star . PR Photo 31c/01 : The velocity curve from which the mass of the black hole was derived . Miniature Quasars in our Galaxy ESO PR Photo 31a/01 ESO PR Photo 31a/01 [Preview - JPEG: 400 x 399 pix - 44k] [Normal - JPEG: 800 x 797 pix - 192k] Caption : PR Photo 31a/01 shows an artist's impression of the binary stellar system GRS 1915+105 in which a heavy black hole is present. The distance between the donor star and the accreting black hole is about half the distance between the Earth and the Sun. The drawing illustrates how the donor star feeds the black hole via an accretion disk , and also the emergence of jets perpendicular to the disk. In the lower panel the blue colour denotes matter that spirals in the accretion disk, while in the orange region matter is freely falling radially into the black hole. Technical information

  19. The impact of non-thermal electrons on resolved black hole accretion disk images

    NASA Astrophysics Data System (ADS)

    Mao, Shengkai; Dexter, Jason; Quataert, Eliot

    2015-01-01

    Recent developments in radio astronomy (in particular, the Event Horizon Telescope) allow us for the first time to resolve length scales around the Milky Way's Sgr A* comparable to the event horizon radius. These observations are opening up new opportunities to study strong gravity and accretion physics in the vicinity of a supermassive black hole. However, the processes governing black hole accretion are not well understood. In particular, the electron thermodynamics in black hole accretion disks remain mysterious, and current models vary significantly from each other. The impact of these differences between current electron thermodynamics models on results obtained from EHT images is not well understood. Thus, in this work, we explore the effects of non-thermal electrons on black hole images and radio spectra in the context of both semi-analytic and numerical models of accretion flows. Using general relativistic ray-tracing and radiative transfer code, we simulate images of the accretion disk around Sgr A* and compare our simulations to observed radio data. We estimate the range of electron energy distribution functions permissible by the data. In so doing, we also explore the range and variety of black hole images obtained by varying the distribution function.

  20. Building massive, tightly packed planetary systems by in-situ accretion of pebbles

    NASA Astrophysics Data System (ADS)

    Moriarty, John; Fischer, Debra

    2015-01-01

    The distribution of mass in planetary systems is one of the most important constraints available for understanding the process of planet formation. One particularly interesting observation is the large number of super-Earth sized planets in short period orbits and tightly packed systems. The amount of mass in these systems is about ten times what would be expected if they had surface density disributions similar to the solar system (i.e. the minimum mass solar nebula) extrapolated inwards of half an AU. This observation raises the question: how and when did all that mass get there? In this work we explore the idea that the radial drift and eventual accretion of small, centimeter sized pebbles leads to massive inner planetary systems.

  1. Infalling clouds on to supermassive black hole binaries - I. Formation of discs, accretion and gas dynamics

    NASA Astrophysics Data System (ADS)

    Goicovic, F. G.; Cuadra, J.; Sesana, A.; Stasyszyn, F.; Amaro-Seoane, P.; Tanaka, T. L.

    2016-01-01

    There is compelling evidence that most - if not all - galaxies harbour a supermassive black hole (SMBH) at their nucleus; hence binaries of these massive objects are an inevitable product of the hierarchical evolution of structures in the Universe, and represent an important but thus-far elusive phase of galaxy evolution. Gas accretion via a circumbinary disc is thought to be important for the dynamical evolution of SMBH binaries, as well as in producing luminous emission that can be used to infer their properties. One plausible source of the gaseous fuel is clumps of gas formed due to turbulence and gravitational instabilities in the interstellar medium, that later fall towards and interact with the binary. In this context, we model numerically the evolution of turbulent clouds in near-radial infall on to equal-mass SMBH binaries, using a modified version of the SPH (smoothed particle hydrodynamics) code GADGET-3. We present a total of 12 simulations that explore different possible pericentre distances and relative inclinations, and show that the formation of circumbinary discs and discs around each SMBH (`mini-discs') depend on those parameters. We also study the dynamics of the formed discs, and the variability of the feeding rate on to the SMBHs in the different configurations.

  2. Electron thermodynamics in GRMHD simulations of low-luminosity black hole accretion

    NASA Astrophysics Data System (ADS)

    Ressler, S. M.; Tchekhovskoy, A.; Quataert, E.; Chandra, M.; Gammie, C. F.

    2015-12-01

    Simple assumptions made regarding electron thermodynamics often limit the extent to which general relativistic magnetohydrodynamic (GRMHD) simulations can be applied to observations of low-luminosity accreting black holes. We present, implement, and test a model that self-consistently evolves an entropy equation for the electrons and takes into account the effects of spatially varying electron heating and relativistic anisotropic thermal conduction along magnetic field lines. We neglect the backreaction of electron pressure on the dynamics of the accretion flow. Our model is appropriate for systems accreting at ≪10-5 of the Eddington accretion rate, so radiative cooling by electrons can be neglected. It can be extended to higher accretion rates in the future by including electron cooling and proton-electron Coulomb collisions. We present a suite of tests showing that our method recovers the correct solution for electron heating under a range of circumstances, including strong shocks and driven turbulence. Our initial applications to axisymmetric simulations of accreting black holes show that (1) physically motivated electron heating rates that depend on the local magnetic field strength yield electron temperature distributions significantly different from the constant electron-to-proton temperature ratios assumed in previous work, with higher electron temperatures concentrated in the coronal region between the disc and the jet; (2) electron thermal conduction significantly modifies the electron temperature in the inner regions of black hole accretion flows if the effective electron mean free path is larger than the local scaleheight of the disc (at least for the initial conditions and magnetic field configurations we study). The methods developed in this work are important for producing more realistic predictions for the emission from accreting black holes such as Sagittarius A* and M87; these applications will be explored in future work.

  3. Further Studies of Accretion onto Hot, Massive, White Dwarfs: The Growth to the Chandrasekhar Limit

    NASA Astrophysics Data System (ADS)

    Starrfield, S.; Timmes, F. X.; Hix, W. R.; Sion, E. M.; Sparks, W. M.; Dwyer, S.

    2004-05-01

    We report on further studies of accretion (Solar Composition material) at a variety of rates onto hot, massive white dwarfs (WDs: Starrfield et al. 2003, Atlanta Meeting, poster 45.10). Our initial models are 1.0 M⊙, 1.25 M⊙, and 1.35 M⊙ WDs with luminosities of 30 L⊙. We have now run evolutionary sequences with mass accretion rates varying from 1.6×10-10 M⊙ yr-1 to 3.5×10-7 M⊙ yr-1 and, in all cases, the WDs grow in mass to near the Chandrasekhar Limit. We use the 1D, hydrodynamic computer code as described in Starrfield et al. (APJS, 127,485, 2000) and have updated the nuclear reaction network, since the calculations reported at Atlanta, to that found at www.cococubed.com/code_pages/net_hhe.shtml. This network combines the pp + hot cno + rp breakout network used previously with an alpha-chain that runs to 56Ni. This will allow us to report on whether or not elements such as Si, S, and Ca are produced in the outer layers during the evolution to explosion so that they do not have to be produced by the explosion. We will also report on simulations done with a lower metallicity for the accreting material - characteristic of that of the LMC. S. Starrfield acknowledges support from NSF and NASA grants to ASU, FXT is supported by the National Security Fellow program at Los Alamos National Laboratory, WRH is partially supported by the National Science Foundation under contracts PHY-0244783 and AST-9877130 and by the Department of Energy, through the Scientific Discovery through Advanced Computing Program. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. EMS is supported by NASA ADP grant NAG5-11182.

  4. How do massive black holes get their gas?

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Quataert, Eliot

    2010-09-01

    We use multiscale smoothed particle hydrodynamic simulations to study the inflow of gas from galactic scales (~10kpc) down to <~ 0.1pc, at which point the gas begins to resemble a traditional, Keplerian accretion disc. The key ingredients of the simulations are gas, stars, black holes (BHs), self-gravity, star formation and stellar feedback (via a subgrid model); BH feedback is not included. We use ~100 simulations to survey a large parameter space of galaxy properties and subgrid models for the interstellar medium physics. We generate initial conditions for our simulations of galactic nuclei (<~ 300pc) using galaxy-scale simulations, including both major galaxy mergers and isolated bar-(un)stable disc galaxies. For sufficiently gas-rich, disc-dominated systems, we find that a series of gravitational instabilities generates large accretion rates of up to ~ 1-10 Msolar yr-1 on to the BH (i.e. at <~ 0.1pc) this is comparable to what is needed to fuel the most luminous quasars. The BH accretion rate is highly time variable for a given set of conditions in the galaxy at ~kpc. At radii of >rsim 10 pc, our simulations resemble the `bars-within-bars' model of Shlosman et al., but we show that the gas can have a diverse array of morphologies, including spirals, rings, clumps and bars; the duty cycle of these features is modest, complicating attempts to correlate BH accretion with the morphology of gas in galactic nuclei. At ~ 1-10 pc, the gravitational potential becomes dominated by the BH and bar-like modes are no longer present. However, we show that the gas can become unstable to a standing, eccentric disc or a single-armed spiral mode (m = 1), in which the stars and gas precess at different rates, driving the gas to sub-pc scales (again for sufficiently gas-rich, disc-dominated systems). A proper treatment of this mode requires including star formation and the self-gravity of both the stars and gas (which has not been the case in many previous calculations). Our

  5. Super-Eddington mechanical power of an accreting black hole in M83.

    PubMed

    Soria, R; Long, K S; Blair, W P; Godfrey, L; Kuntz, K D; Lenc, E; Stockdale, C; Winkler, P F

    2014-03-21

    Mass accretion onto black holes releases energy in the form of radiation and outflows. Although the radiative flux cannot substantially exceed the Eddington limit, at which the outgoing radiation pressure impedes the inflow of matter, it remains unclear whether the kinetic energy flux is bounded by this same limit. Here, we present the detection of a radio-optical structure, powered by outflows from a non-nuclear black hole. Its accretion disk properties indicate that this black hole is less than 100 solar masses. The optical-infrared line emission implies an average kinetic power of 3 × 10(40) erg second(-1), higher than the Eddington luminosity of the black hole. These results demonstrate kinetic power exceeding the Eddington limit over a sustained period, which implies greater ability to influence the evolution of the black hole's environment. PMID:24578533

  6. Super-Eddington Mechanical Power of an Accreting Black Hole in M83

    NASA Technical Reports Server (NTRS)

    Soria, R.; Long, K. S.; Blair, W. P.; Godfrey, L.; Kuntz, K. D.; Lenc, E.; Stockdale, C.; Winkler, P. F.

    2014-01-01

    Mass accretion onto black holes releases energy in the form of radiation and outflows. Although the radiative flux cannot substantially exceed the Eddington limit, at which the outgoing radiation pressure impedes the inflow of matter, it remains unclear whether the kinetic energy flux is bounded by this same limit. Here, we present the detection of a radio-optical structure, powered by outflows from a non-nuclear black hole. Its accretion disk properties indicate that this black hole is less than 100 solar masses. The optical-infrared line emission implies an average kinetic power of 3 × 10(exp 40) erg second(exp -1), higher than the Eddington luminosity of the black hole. These results demonstrate kinetic power exceeding the Eddington limit over a sustained period, which implies greater ability to influence the evolution of the black hole's environment.

  7. LAUNCHING AND QUENCHING OF BLACK HOLE RELATIVISTIC JETS AT LOW ACCRETION RATE

    SciTech Connect

    Pu, Hung-Yi; Chang, Hsiang-Kuang; Hirotani, Kouichi

    2012-10-20

    Relativistic jets are launched from black hole (BH) X-ray binaries and active galactic nuclei when the disk accretion rate is below a certain limit (i.e., when the ratio of the accretion rate to the Eddingtion accretion rate, m-dot , is below about 0.01) but quenched when above. We propose a new paradigm to explain this observed coupling between the jet and the accretion disk by investigating the extraction of the rotational energy of a BH when it is surrounded by different types of accretion disk. At low accretion rates (e.g., when m-dot {approx}<0.1), the accretion near the event horizon is quasi-spherical. The accreting plasmas fall onto the event horizon in a wide range of latitudes, breaking down the force-free approximation near the horizon. To incorporate the plasma inertia effect, we consider the magnetohydrodynamical (MHD) extraction of the rotational energy from BHs by the accreting MHD fluid, as described by the MHD Penrose process. It is found that the energy extraction operates, and hence a relativistic jet is launched, preferentially when the accretion disk consists of an outer Shakura-Sunyaev disk (SSD) and an inner advection-dominated accretion flow. When the entire accretion disk type changes into an SSD, the jet is quenched because the plasmas bring more rest-mass energy than what is extracted from the hole electromagnetically to stop the extraction. Several other issues related to observed BH disk-jet couplings, such as why the radio luminosity increases with increasing X-ray luminosity until the radio emission drops, are also explained.

  8. Episodic ejection from super-massive black holes

    NASA Astrophysics Data System (ADS)

    Saripalli, Lakshmi; Subrahmanyan, Ravi; Hunstead, Richard W.

    2007-04-01

    Episodic activity in super-massive black holes on timescales of a million years is confirmed by radio galaxies exhibiting `double-double' radio morphologies (Subrahmanyan et al, 1996; Schoenmakers et al, 2000). Spectacular examples showing a renewal of beam activity in the form of new beams emerging within relic radio lobes of previous activity have placed the phenomenon of recurrence in AGN outflows on a firm footing (Saripalli et al 2002; 2003). Using 25% of the Sydney University Molonglo Sky Survey we have compiled flux and volume limited samples of giant radio galaxies (Saripalli et al 2005) and herein we discuss the occurrence rates for the restarting of nuclear activity.

  9. Observing Massive Black Hole Binary Coalescences with LISA

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2005-01-01

    Massive black hole binary coalescences are among the most important astrophysical sources of gravitational waves to be observed by LISA. The ability to observe and characterize such sources with masses approximately equal to 105 M/odot and larger at high redshifts is strongly dependent on the sensitivity of LISA in the low frequency (0.1 mHz and below) regime. We examine LISA's ability to observe these systems at redshifts up to z approximately equal to 10 for various proposed values of the low frequency sensitivity, under current assumptions about the merger rates. The discussion will focus on the astrophysical information that can be gained by these observations.

  10. Tunneling of massive vector particles from rotating charged black strings

    NASA Astrophysics Data System (ADS)

    Jusufi, Kimet; Övgün, Ali

    2016-07-01

    We study the quantum tunneling of charged massive vector bosons from a charged static and a rotating black string. We apply the standard methods, first we use the WKB approximation and the Hamilton-Jacobi equation, and then we end up with a set of four linear equations. Finally, solving for the radial part by using the determinant of the metric equals zero, the corresponding tunneling rate and the Hawking temperature is recovered in both cases. The tunneling rate deviates from pure thermality and is consistent with an underlying unitary theory.

  11. Quantization of massive scalar fields over static black string backgrounds

    SciTech Connect

    Fernandez Piedra, Owen Pavel; Montes de Oca, Alejandro Cabo

    2007-05-15

    The renormalized mean value of the corresponding components of the energy-momentum tensor for massive scalar fields coupled to an arbitrary gravitational field configuration having cylindrical symmetry are analytically evaluated using the Schwinger-DeWitt approximation, up to second order in the inverse mass value. The general results are employed to explicitly derive compact analytical expressions for the energy-momentum tensor in the particular background of the black-string space-time. In the case of the black string considered in this work, we prove that a violation of the weak energy condition occurs at the horizon of the space-time for values of the coupling constant, which include as particular cases the most interesting of minimal and conformal coupling.

  12. Astrophysics of Super-Massive Black Hole Mergers

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy D.

    2013-01-01

    We present here an overview of recent work in the subject of astrophysical manifestations of super-massive black hole (SMBH) mergers. This is a field that has been traditionally driven by theoretical work, but in recent years has also generated a great deal of interest and excitement in the observational astronomy community. In particular, the electromagnetic (EM) counterparts to SMBH mergers provide the means to detect and characterize these highly energetic events at cosmological distances, even in the absence of a space-based gravitational-wave observatory. In addition to providing a mechanism for observing SMBH mergers, EM counterparts also give important information about the environments in which these remarkable events take place, thus teaching us about the mechanisms through which galaxies form and evolve symbiotically with their central black holes.

  13. Suppression of the accretion rate in thin discs around binary black holes.

    NASA Astrophysics Data System (ADS)

    Ragusa, Enrico; Lodato, Giuseppe; Price, Daniel J.

    2016-05-01

    We present three-dimensional Smoothed Particle Hydrodynamics (SPH) simulations investigating the dependence of the accretion rate on the disc thickness around an equal-mass, circular black hole binary system. We find that for thick/hot discs, with H/R ≳ 0.1, the binary torque does not prevent the gas from penetrating the cavity formed in the disc by the binary (in line with previous investigations). The situation drastically changes for thinner discs, in this case the mass accretion rate is suppressed, such that only a fraction (linearly dependent on H/R) of the available gas is able to flow within the cavity and accrete on to the binary. Extrapolating this result to the cold and thin accretion discs expected around supermassive black hole binary systems implies that this kind of systems accretes less material than predicted so far, with consequences not only for the electromagnetic and gravitational waves emissions during the late inspiral phase but also for the recoil speed of the black hole formed after binary coalescence, thus influencing also the evolutionary path both of the binary and of the host galaxy. Our results, being scale-free, are also applicable to equal mass, circular binaries of stellar mass black holes, such as the progenitor of the recently discovered gravitational wave source GW150914.

  14. Suppression of the accretion rate in thin discs around binary black holes

    NASA Astrophysics Data System (ADS)

    Ragusa, Enrico; Lodato, Giuseppe; Price, Daniel J.

    2016-08-01

    We present three-dimensional Smoothed Particle Hydrodynamics (SPH) simulations investigating the dependence of the accretion rate on the disc thickness around an equal-mass, circular black hole binary system. We find that for thick/hot discs, with H/R ≳ 0.1, the binary torque does not prevent the gas from penetrating the cavity formed in the disc by the binary (in line with previous investigations). The situation drastically changes for thinner discs; in this case the mass accretion rate is suppressed, such that only a fraction (linearly dependent on H/R) of the available gas is able to flow within the cavity and accrete on to the binary. Extrapolating this result to the cold and thin accretion discs expected around supermassive black hole binary systems implies that this kind of system accretes less material than predicted so far, with consequences not only for the electromagnetic and gravitational waves emissions during the late inspiral phase but also for the recoil speed of the black hole formed after binary coalescence, thus influencing also the evolutionary path both of the binary and of the host galaxy. Our results, being scale-free, are also applicable to equal-mass, circular binaries of stellar mass black holes, such as the progenitor of the recently discovered gravitational wave source GW150914.

  15. Charged black hole solutions in Gauss-Bonnet-massive gravity

    NASA Astrophysics Data System (ADS)

    Hendi, S. H.; Panahiyan, S.; Panah, B. Eslam

    2016-01-01

    Motivated by high interest in the close relation between string theory and black hole solutions, in this paper, we take into account the Einstein-Gauss-Bonnet Lagrangian in the context of massive gravity. We examine the possibility of black hole in this regard, and discuss the types of horizons. Next, we calculate conserved and thermodynamic quantities and check the validity of the first law of thermodynamics. In addition, we investigate the stability of these black holes in context of canonical ensemble. We show that number, type and place of phase transition points may be significantly affected by different parameters. Next, by considering cosmological constant as thermodynamical pressure, we will extend phase space and calculate critical values. Then, we construct thermodynamical spacetime by considering mass as thermodynamical potential. We study geometrical thermodynamics of these black holes in context of heat capacity and extended phase space. We show that studying heat capacity, geometrical thermodynamics and critical behavior in extended phase space lead to consistent results. Finally, we will employ a new method for obtaining critical values and show that the results of this method are consistent with those of other methods.

  16. Formation of new stellar populations from gas accreted by massive young star clusters.

    PubMed

    Li, Chengyuan; de Grijs, Richard; Deng, Licai; Geller, Aaron M; Xin, Yu; Hu, Yi; Faucher-Giguère, Claude-André

    2016-01-28

    Stars in clusters are thought to form in a single burst from a common progenitor cloud of molecular gas. However, massive, old 'globular' clusters--those with ages greater than ten billion years and masses several hundred thousand times that of the Sun--often harbour multiple stellar populations, indicating that more than one star-forming event occurred during their lifetimes. Colliding stellar winds from late-stage, asymptotic-giant-branch stars are often suggested to be triggers of second-generation star formation. For this to occur, the initial cluster masses need to be greater than a few million solar masses. Here we report observations of three massive relatively young star clusters (1-2 billion years old) in the Magellanic Clouds that show clear evidence of burst-like star formation that occurred a few hundred million years after their initial formation era. We show that such clusters could have accreted sufficient gas to form new stars if they had orbited in their host galaxies' gaseous disks throughout the period between their initial formation and the more recent bursts of star formation. This process may eventually give rise to the ubiquitous multiple stellar populations in globular clusters. PMID:26819043

  17. The binary systems IC 10 X-1 and NGC 300 X-1: Accretion of matter from an intense Wolf-Rayet stellar wind onto a black hole

    NASA Astrophysics Data System (ADS)

    Tutukov, A. V.; Fedorova, A. V.

    2016-01-01

    The current evolutionary stage of the binary systems IC 10 X-1 and NGC 300 X-1, which contain a massive black hole and a Wolf-Rayet star with a strong stellar wind that does not fill its Roche lobe, is considered. The high X-ray luminosity and X-ray properties testify to the presence of accretion disks in these systems. The consistency of the conditions for the existence of such a disk and the possibility of reproducing the observed X-ray luminosity in the framework of the Bondi-Hoyle-Littleton theory for a spherically symmetric stellar wind is analyzed. A brief review of information about the mass-loss rates of Wolf-Rayet stars and the speeds of their stellar winds is given. The evolution of these systems at the current stage is computed. Estimates made using the derived parameters show that it is not possible to achieve consistency, since the conditions for the existence of an accretion disk require that the speed of the Wolf-Rayetwind be appreciably lower than is required to reproduce the observedX-ray luminosity. Several explanations of this situation are possible: (1) the real pattern of the motion of the stellar-wind material in the binary is substantially more complex than is assumed in the Bondi-Hoyle-Littleton theory, changing the conditions for the formation of an accretion disk and influencing the accretion rate onto the black hole; (2) some of the accreting material leaves the accretor due to X-ray heating; (3) the accretion efficiency in these systems is nearly an order of magnitude lower than in the case of accretion through a thin disk onto a non-rotating black hole; (4) the intensity of the Wolf-Rayet wind is one to two orders of magnitude lower than has been suggested by modern studies.

  18. LOW-MASS AGNs AND THEIR RELATION TO THE FUNDAMENTAL PLANE OF BLACK HOLE ACCRETION

    SciTech Connect

    Gültekin, Kayhan; King, Ashley L.; Miller, Jon M.; Cackett, Edward M.; Pinkney, Jason

    2014-06-20

    We put active galactic nuclei (AGNs) with low-mass black holes on the fundamental plane of black hole accretion—the plane that relates X-ray emission, radio emission, and mass of an accreting black hole—to test whether or not the relation is universal for both stellar-mass and supermassive black holes. We use new Chandra X-ray and Very Large Array radio observations of a sample of black holes with masses less than 10{sup 6.3} M {sub ☉}, which have the best leverage for determining whether supermassive black holes and stellar-mass black holes belong on the same plane. Our results suggest that the two different classes of black holes both belong on the same relation. These results allow us to conclude that the fundamental plane is suitable for use in estimating supermassive black hole masses smaller than ∼10{sup 7} M {sub ☉}, in testing for intermediate-mass black holes, and in estimating masses at high accretion rates.

  19. Accreting supermassive black holes in the COSMOS field and the connection to their host galaxies

    NASA Astrophysics Data System (ADS)

    Bongiorno, A.; Merloni, A.; Brusa, M.; Magnelli, B.; Salvato, M.; Mignoli, M.; Zamorani, G.; Fiore, F.; Rosario, D.; Mainieri, V.; Hao, H.; Comastri, A.; Vignali, C.; Balestra, I.; Bardelli, S.; Berta, S.; Civano, F.; Kampczyk, P.; Le Floc'h, E.; Lusso, E.; Lutz, D.; Pozzetti, L.; Pozzi, F.; Riguccini, L.; Shankar, F.; Silverman, J.

    2012-12-01

    Using the wide multiband photometry available in the Cosmic Evolution Survey (COSMOS) field, we explore the host galaxy properties of a large sample of active galactic nuclei (AGNs; ˜1700 objects) with Lbol ranging from 1043 to 1047 erg s-1, obtained by combining X-ray and optical spectroscopic selections. Based on a careful study of their spectral energy distributions, which have been parametrized using a two-component (AGN+galaxy) model fit, we have derived dust-corrected rest-frame magnitudes, colours and stellar masses of the obscured and unobscured AGN hosts up to high redshift (z≲3). Moreover, for the sample of obscured AGNs, we have also derived reliable star formation rates (SFRs). We find that AGN hosts span a large range of stellar masses and SFRs. No colour-bimodality is seen at any redshift in the AGN hosts, which are found to be mainly massive, red galaxies. Once we have accounted for the colour-mass degeneracy in well-defined mass-matched samples, we find a residual (marginal) enhancement of the incidence of AGNs in redder galaxies with lower specific SFRs. We argue that this result might emerge because of our ability to properly account for AGN light contamination and dust extinction, compared to surveys with a more limited multiwavelength coverage. However, because these colour shifts are relatively small, systematic effects could still be considered responsible for some of the observed trends. Interestingly, we find that the probability for a galaxy to host a black hole that is growing at any given 'specific accretion rate' (i.e. the ratio of X-ray luminosity to the host stellar mass) is almost independent of the host galaxy mass, while it decreases as a power law with LX/M*. By analysing the normalization of such a probability distribution, we show how the incidence of AGNs increases with redshift as rapidly as (1 + z)4, which closely resembles the overall evolution of the specific SFR of the entire galaxy population. We provide analytical

  20. STUDIES OF THERMALLY UNSTABLE ACCRETION DISKS AROUND BLACK HOLES WITH ADAPTIVE PSEUDOSPECTRAL DOMAIN DECOMPOSITION METHOD. II. LIMIT-CYCLE BEHAVIOR IN ACCRETION DISKS AROUND KERR BLACK HOLES

    SciTech Connect

    Xue Li; Lu Jufu; Sadowski, Aleksander; Abramowicz, Marek A. E-mail: lujf@xmu.edu.cn

    2011-07-01

    For the first time ever, we derive equations governing the time evolution of fully relativistic slim accretion disks in the Kerr metric and numerically construct their detailed non-stationary models. We discuss applications of these general results to a possible limit-cycle behavior of thermally unstable disks. Our equations and numerical method are applicable in a wide class of possible viscosity prescriptions, but in this paper we use a diffusive form of the 'standard alpha prescription' that assumes that the viscous torque is proportional to the total pressure. In this particular case, we find that the parameters that dominate the limit-cycle properties are the mass-supply rate and the value of the alpha-viscosity parameter. Although the duration of the cycle (or the outburst) does not exhibit any clear dependence on the black hole spin, the maximal outburst luminosity (in the Eddington units) is positively correlated with the spin value. We suggest a simple method for a rough estimate of the black hole spin based on the maximal luminosity and the ratio of outburst to cycle durations. We also discuss a temperature-luminosity relation for the Kerr black hole accretion disk limit cycle. Based on these results, we discuss the limit-cycle behavior observed in microquasar GRS 1915+105. We also extend this study to several non-standard viscosity prescriptions, including a 'delayed heating' prescription recently addressed by the MHD simulations of accretion disks.

  1. Understanding X-ray Reflection as a Probe of Accreting Black Holes

    NASA Astrophysics Data System (ADS)

    Wilkins, Dan

    2014-01-01

    Active galactic nuclei (AGN) are some of the most luminous objects we see in the Universe, powered by the accretion of matter onto a supermassive black hole in the centre of a galaxy, yet many of the physical processes by which the energy is released and injected into the surroundings remain a mystery. X-rays are emitted from a ‘corona’ of energetic particles surrounding the black hole and as well as being observed directly, they are seen to be reflected from the accreting disc, producing a number of spectral features including emission lines that are broadened by relativistic effects in the proximity of the black hole. In my thesis, I develop methods through which detailed measurement of the reflected X-rays from the accretion disc can be used to probe the innermost regions of accretion flow and corona, right down to the innermost stable orbit and the event horizon. Novel spectral analysis techniques allow us to reconstruct, from the observed relativistic X-ray reflection spectrum the spatially resolved illumination pattern of the accretion disc and will discuss how comparing this to the results of systematic general relativistic ray tracing simulations I have developed, we are able to constrain the location and geometry of the X-ray emitting corona and understand the dramatic change of the narrow line Seyfert 1 galaxy 1H 0707-495 into an extremely low flux state in terms of a collapse in the corona. I will discuss how measurements of the X-ray variability, specifically the reverberation time lags that are observed between variability in the directly observed X-rays from the corona and those reflected from the accretion disc add a further dimension to the study of accreting black holes, letting us not only build up a three dimensional image of the immediate vicinity of the black hole but also to probe mechanisms by which the energy is released from the accretion flow; techniques that will let us exploit not just current instrumentation but future proposed X

  2. Supermassive black holes with high accretion rates in active galactic nuclei. II. The most luminous standard candles in the universe

    SciTech Connect

    Wang, Jian-Min; Du, Pu; Hu, Chen; Qiu, Jie; Li, Yan-Rong; Netzer, Hagai; Kaspi, Shai; Bai, Jin-Ming; Wang, Fang; Lu, Kai-Xing; Collaboration: SEAMBH collaboration

    2014-10-01

    This is the second in a series of papers reporting on a large reverberation mapping (RM) campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). The goal is to identify super-Eddington accreting massive black holes (SEAMBHs) and to use their unique properties to construct a new method for measuring cosmological distances. Based on theoretical models, the saturated bolometric luminosity of such sources is proportional to the BH mass, which can be used to obtain their distance. Here we report on five new RM measurements and show that in four of the cases, we can measure the BH mass and three of these sources are SEAMBHs. Together with the three sources from our earlier work, we now have six new sources of this type. We use a novel method based on a minimal radiation efficiency to identify nine additional SEAMBHs from earlier RM-based mass measurements. We use a Bayesian analysis to determine the parameters of the new distance expression and the method uncertainties from the observed properties of the objects in the sample. The ratio of the newly measured distances to the standard cosmological ones has a mean scatter of 0.14 dex, indicating that SEAMBHs can be use as cosmological distance probes. With their high luminosity, long period of activity, and large numbers at high redshifts, SEAMBHs have a potential to extend the cosmic distance ladder beyond the range now explored by Type Ia supernovae.

  3. Three-dimensional simulations of supercritical black hole accretion discs - luminosities, photon trapping and variability

    NASA Astrophysics Data System (ADS)

    Sądowski, Aleksander; Narayan, Ramesh

    2016-03-01

    We present a set of four three-dimensional, general relativistic, radiation magnetohydrodynamical simulations of black hole accretion at supercritical mass accretion rates, dot{M} > dot{M}_Edd. We use these simulations to study how disc properties are modified when we vary the black hole mass, the black hole spin, or the mass accretion rate. In the case of a non-rotating black hole, we find that the total efficiency is of the order of 3 per cent dot{M} c^2, approximately a factor of 2 less than the efficiency of a standard thin accretion disc. The radiation flux in the funnel along the axis is highly super-Eddington, but only a small fraction of the energy released by accretion escapes in this region. The bulk of the 3 per cent dot{M} c^2 of energy emerges farther out in the disc, either in the form of photospheric emission or as a wind. In the case of a black hole with a spin parameter of 0.7, we find a larger efficiency of about 8 per cent dot{M} c^2. By comparing the relative importance of advective and diffusive radiation transport, we show that photon trapping is effective near the equatorial plane. However, near the disc surface, vertical transport of radiation by diffusion dominates. We compare the properties of our fiducial three-dimensional run with those of an equivalent two-dimensional axisymmetric model with a mean-field dynamo. The latter simulation runs nearly 100 times faster than the three-dimensional simulation, and gives very similar results for time-averaged properties of the accretion flow, but does not reproduce the time-variability.

  4. Mass-loss from advective accretion disc around rotating black holes

    NASA Astrophysics Data System (ADS)

    Aktar, Ramiz; Das, Santabrata; Nandi, Anuj

    2015-11-01

    We examine the properties of the outflowing matter from an advective accretion disc around a spinning black hole. During accretion, rotating matter experiences centrifugal pressure-supported shock transition that effectively produces a virtual barrier around the black hole in the form of post-shock corona (hereafter PSC). Due to shock compression, PSC becomes hot and dense that eventually deflects a part of the inflowing matter as bipolar outflows because of the presence of extra thermal gradient force. In our approach, we study the outflow properties in terms of the inflow parameters, namely specific energy (E) and specific angular momentum (λ) considering the realistic outflow geometry around the rotating black holes. We find that spin of the black hole (ak) plays an important role in deciding the outflow rate R_{dot{m}} (ratio of mass flux of outflow to inflow); in particular, R_{dot{m}} is directly correlated with ak for the same set of inflow parameters. It is found that a large range of the inflow parameters allows global accretion-ejection solutions, and the effective area of the parameter space (E, λ) with and without outflow decreases with black hole spin (ak). We compute the maximum outflow rate (R^{max}_{dot{m}}) as a function of black hole spin (ak) and observe that R^{max}_{dot{m}} weakly depends on ak that lies in the range ˜10-18 per cent of the inflow rate for the adiabatic index (γ) with 1.5 ≥ γ ≥ 4/3. We present the observational implication of our approach while studying the steady/persistent jet activities based on the accretion states of black holes. We discuss that our formalism seems to have the potential to explain the observed jet kinetic power for several Galactic black hole sources and active galactic nuclei.

  5. Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Wu, Mao-Chun; Xie, Fu-Guo; Yuan, Ye-Fei; Gan, Zhaoming

    2016-06-01

    We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron self-Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value dot{M} ˜ 3α dot{M}_Edd, above which cold and dense clumpy/filamentary structures are formed, embedded within the hot gas. We argued this mode likely corresponds to the proposed two-phase accretion model, which may be responsible for the intermediate state of black hole X-ray binaries. When the accretion rate becomes sufficiently high, the clumpy/filamentary structures gradually merge and settle down on to the mid-plane. Eventually the accretion geometry transforms to a disc-corona configuration. In summary, our results are consistent with the truncated accretion scenario for the state transition.

  6. Inclusion of TCAF model in XSPEC to study accretion flow dynamics around black hole candidates

    NASA Astrophysics Data System (ADS)

    Debnath, Dipak; Chakrabarti, Sandip Kumar; Mondal, Santanu

    Spectral and Temporal properties of black hole candidates can be well understood with the Chakrabarti-Titarchuk solution of two component advective flow (TCAF). This model requires two accretion rates, namely, the Keplerian disk accretion rate and the sub-Keplerian halo accretion rate, the latter being composed of a low angular momentum flow which may or may not develop a shock. In this solution, the relevant parameter is the relative importance of the halo (which creates the Compton cloud region) rate with respect to the Keplerian disk rate (soft photon source). Though this model has been used earlier to manually fit data of several black hole candidates quite satisfactorily, for the first time we are able to create a user friendly version by implementing additive Table model FITS file into GSFC/NASA's spectral analysis software package XSPEC. This enables any user to extract physical parameters of accretion flows, such as two accretion rates, shock location, shock strength etc. for any black hole candidate. Most importantly, unlike any other theoretical model, we show that TCAF is capable of predicting timing properties from spectral fits, since in TCAF, a shock is responsible for deciding spectral slopes as well as QPO frequencies.

  7. The search for massive black hole binaries with LISA

    NASA Astrophysics Data System (ADS)

    Cornish, Neil J.; Porter, Edward K.

    2007-12-01

    In this work we focus on the search and detection of massive black hole binary (MBHB) systems, including systems at high redshift. As well as expanding on previous works where we used a variant of Markov chain Monte Carlo (MCMC), called Metropolis Hastings Monte Carlo, with simulated annealing, we introduce a new search method based on frequency annealing which leads to a more rapid and robust detection. We compare the two search methods on systems where we do and do not see the merger of the black holes. In the non-merger case, we also examine the posterior distribution exploration using a 7D MCMC algorithm. We demonstrate that this method is effective in dealing with the high correlations between parameters, has a higher acceptance rate than previously proposed methods and produces posterior distribution functions that are close to the prediction from the Fisher information matrix. Finally, after carrying out searches where there is only one binary in the data stream, we examine the case where two black hole binaries are present in the same data stream. We demonstrate that our search algorithm can accurately recover both binaries, and more importantly showing that we can safely extract the MBHB sources without contaminating the rest of the data stream.

  8. The stellar accretion origin of stellar population gradients at large radii in massive, early-type galaxies

    NASA Astrophysics Data System (ADS)

    Hirschmann, Michaela; Naab, Thorsten

    2015-08-01

    We investigate the differential impact of physical mechanisms, mergers (stellar accretion) and internal energetic phenomena, on the evolution of stellar population gradients in massive, present-day galaxies employing a set of high-resolved, cosmological zoom simulations. We demonstrate that negative metallicity and color gradients at large radii (>2Reff) originate from the accretion of metal-poor stellar systems. At larger radii, galaxies become typically more dominated by stars accreted from satellite galaxies in major and minor mergers. However, only strong galactic winds can sufficiently reduce the metallicity content of the accreted stars to realistically steepen the outer metallicity and colour gradients in agreement with present-day observations. In contrast, the gradients of the models without winds are inconsistent with observations (too flat). In the wind model, colour and metallicity gradients are significantly steeper for systems which have accreted stars in minor mergers, while galaxies with major mergers have relatively flat gradients, confirming previous results. This analysis greatly highlights the importance of both energetic processes and merger events for stellar population properties of massive galaxies at large radii. Our results are expected to significantly contribute to the interpretation of current and up-coming IFU surveys (like MaNGA and Califa), which in turn can help to constrain models for energetic processes in simulations.

  9. An analytic model of angular momentum transport by gravitational torques: from galaxies to massive black holes

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Quataert, Eliot

    2011-08-01

    We present analytic calculations of angular momentum transport and gas inflow in galaxies, from scales of ˜ kpc to deep inside the potential of a central massive black hole (BH). We compare these analytic calculations to numerical simulations and use them to develop a sub-grid model of BH growth that can be incorporated into semi-analytic calculations or cosmological simulations. Motivated by both analytic calculations and simulations of gas inflow in galactic nuclei, we argue that the strongest torque on gas arises when non-axisymmetric perturbations to the stellar gravitational potential produce orbit crossings and shocks in the gas. This is true both at large radii ˜0.01-1 kpc, where bar-like stellar modes dominate the non-axisymmetric potential, and at smaller radii ≲10 pc, where a lopsided/eccentric stellar disc dominates. The traditional orbit-crossing criterion is not always adequate to predict the locations of, and inflow due to, shocks in gas+stellar discs with finite sound speeds. We derive a modified criterion that predicts the presence of shocks in stellar-dominated systems even absent formal orbit crossing. We then derive analytic expressions for the loss of angular momentum and the resulting gas inflow rates in the presence of such shocks. We test our analytic predictions using hydrodynamic simulations at a range of galactic scales, and show that they successfully predict the mass inflow rates and quasi-steady gas surface densities with a small scatter ≃0.3 dex. We use our analytic results to construct a new estimate of the BH accretion rate given galaxy properties at larger radii, for use in galaxy and cosmological simulations and semi-analytic models. While highly simplified, this accretion rate predictor captures the key scalings in the numerical simulations. By contrast, alternate estimates such as the local viscous accretion rate or the spherical Bondi rate fail systematically to reproduce the simulations and have significantly larger

  10. Black hole accretion disks in brane gravity via a confining potential

    NASA Astrophysics Data System (ADS)

    Heydari-Fard, Malihe

    2010-12-01

    Accretion disks are among the most luminous and ubiquitous sources in astrophysics and they have drawn a good deal of attention from the observational and theoretical communities. In this paper, we study the process of matter forming thin accretion disks around black hole solutions in the context of the brane-world scenario where our universe is a three-brane embedded in an m-dimensional bulk and localization of matter on the brane is achieved by means of a confining potential. The physical properties of thin accretion disks including the time averaged energy flux, temperature distribution, the emission spectrum as well as the energy conversion efficiency are obtained, and the results are compared with the DMPR, CFM and BMD brane black holes and the standard general relativistic Schwarzschild solution.

  11. Limits on the spin up of stellar-mass black holes through a spiral stationary accretion shock instability

    NASA Astrophysics Data System (ADS)

    Moreno Méndez, Enrique; Cantiello, Matteo

    2016-04-01

    The spin of a number of black holes (BHs) in binary systems has been measured. In the case of BHs found in low-mass X-ray binaries (LMXBs) the observed values are in agreement with some theoretical predictions based on binary stellar evolution. However, using the same evolutionary models, the calculated spins of BHs in high-mass X-ray binaries (HMXBs) fall short compared to the observations. A possible solution to this conundrum is the accretion of high-specific-angular-momentum material after the formation of the BH, although this requires accretion above the Eddington limit. Another suggestion is that the observed high values of the BHs spin could be the result of an asymmetry during Core Collapse (CC). The only available energy to spin up the compact object during CC is its binding energy. A way to convert it to rotational kinetic energy is by using a Standing Accretion Shock Instability (SASI), which can develop during CC and push angular momentum into the central compact object through a spiral mode (m = 1). Here we study the CC-SASI scenario and discuss, in the case of LMXBs and HMXBs, the limits for the spin of a stellar-mass BHs. Our results predict a strong dichotomy in the maximum spin of low-mass compact objects and massive BHs found in HMXBs. The maximum spin value (|a⋆|) for a compact object near the mass boundary between BHs and NSs is found to be somewhere between 0.27 and 0.38, depending on whether secular or dynamical instabilities limit the efficiency of the spin up process. For more massive BHs, such as those found in HMXBs, the natal spin is substantially smaller and for MBH > 8M⊙ spin is limited to values |a⋆| ≲ 0.05. Therefore we conclude that the observed high spins of BHs in HMXBs cannot be the result of a CC-SASI spin up.

  12. Rapid growth of seed black holes in the early universe by supra-exponential accretion.

    PubMed

    Alexander, Tal; Natarajan, Priyamvada

    2014-09-12

    Mass accretion by black holes (BHs) is typically capped at the Eddington rate, when radiation's push balances gravity's pull. However, even exponential growth at the Eddington-limited e-folding time t(E) ~ few × 0.01 billion years is too slow to grow stellar-mass BH seeds into the supermassive luminous quasars that are observed when the universe is 1 billion years old. We propose a dynamical mechanism that can trigger supra-exponential accretion in the early universe, when a BH seed is bound in a star cluster fed by the ubiquitous dense cold gas flows. The high gas opacity traps the accretion radiation, while the low-mass BH's random motions suppress the formation of a slowly draining accretion disk. Supra-exponential growth can thus explain the puzzling emergence of supermassive BHs that power luminous quasars so soon after the Big Bang. PMID:25103410

  13. Rapid growth of seed black holes in the early universe by supra-exponential accretion

    NASA Astrophysics Data System (ADS)

    Alexander, Tal; Natarajan, Priyamvada

    2014-09-01

    Mass accretion by black holes (BHs) is typically capped at the Eddington rate, when radiation's push balances gravity's pull. However, even exponential growth at the Eddington-limited e-folding time tE ~ few × 0.01 billion years is too slow to grow stellar-mass BH seeds into the supermassive luminous quasars that are observed when the universe is 1 billion years old. We propose a dynamical mechanism that can trigger supra-exponential accretion in the early universe, when a BH seed is bound in a star cluster fed by the ubiquitous dense cold gas flows. The high gas opacity traps the accretion radiation, while the low-mass BH's random motions suppress the formation of a slowly draining accretion disk. Supra-exponential growth can thus explain the puzzling emergence of supermassive BHs that power luminous quasars so soon after the Big Bang.

  14. Magneto centrifugal winds from accretion discs around black hole binaries

    NASA Astrophysics Data System (ADS)

    Chakravorty, S.; Petrucci, P.-O.; Ferreira, J.; Henri, G.; Belmont, R.; Clavel, M.; Corbel, S.; Rodriguez, J.; Coriat, M.; Drappeau, S.; Malzac, J.

    2016-05-01

    We want to test if self-similar magneto-hydrodynamic (MHD) accretion-ejection models can explain the observational results for accretion disk winds in BHBs. In our models, the density at the base of the outflow from the accretion disk is not a free parameter but is determined by solving the full set of dynamical MHD equations without neglecting any physical term. Different MHD solutions were generated for different values of (a) the disk aspect ratio (ǎrepsilon) and (b) the ejection efficiency (p). We generated two kinds of MHD solutions depending on the absence (cold solution) or presence (warm solution) of heating at the disk surface. The cold MHD solutions are found to be inadequate to account for winds due to their low ejection efficiency. The warm solutions can have sufficiently high values of p (\\gtrsim 0.1) which is required to explain the observed physical quantities in the wind. The heating (required at the disk surface for the warm solutions) could be due to the illumination which would be more efficient in the Soft state. We found that in the Hard state a range of ionisation parameter is thermodynamically unstable, which makes it impossible to have any wind at all, in the Hard state. Our results would suggest that a thermo-magnetic process is required to explain winds in BHBs.

  15. An Accretion Model for the Growth of Black Hole in Quasars

    NASA Technical Reports Server (NTRS)

    Lu, Ye; Cheng, K. S.; Zhang, S. N.

    2003-01-01

    A possible accretion model associated with the ionization instability of quasar disks is proposed to address the growth of the central black hole harbored in the host galaxy. The evolution of quasars in cosmic time is assumed to change from a highly active state to a quiescent state triggered by the S-shaped ionization instability of the quasar accretion disk. For a given external mass transfer rate ionization instability can modify accretion rate in the disk and separates the accretion flows of the disk into three different phases like a S-shape. We suggest that the bright quasars observed today are those quasars with disks in the upper branch of S-shaped instability and the dormant quasars are the system in the lower branch. The disk is assumed to evolve as ADIOS configuration in the lower branch. The mass ratio between black hole and its host galactic bulge is a nature consequence of ADIOS. Our model also demonstrates that a seed black hole 2 x 10(exp 6) solar masses similar to those found in spiral galaxies today is needed to produce a black hole with a final mass 2 x 10(exp 8) solar masses.

  16. The truncated and evolving inner accretion disc of the black hole GX 339-4

    NASA Astrophysics Data System (ADS)

    Plant, D. S.; Fender, R. P.; Ponti, G.; Muñoz-Darias, T.; Coriat, M.

    2015-01-01

    The nature of accretion onto stellar mass black holes in the low/hard state remains unresolved, with some evidence suggesting that the inner accretion disc is truncated and replaced by a hot flow. However, the detection of relativistic broadened Fe emission lines, even at relatively low luminosities, seems to require an accretion disc extending fully to its innermost stable circular orbit. Modelling such features is, however, highly susceptible to degeneracies, which could easily bias any interpretation. We present the first systematic study of the Fe line region to track how the inner accretion disc evolves in the low/hard state of the black hole GX 339-4. Our four observations display increased broadening of the Fe line over two magnitudes in luminosity, which we use to track any variation of the disc inner radius. We find that the disc extends closer to the black hole at higher luminosities, but is consistent with being truncated throughout the entire low/hard state, a result which renders black hole spin estimates inaccurate at these stages of the outburst. Furthermore, we show that the evolution of our spectral inner disc radius estimates corresponds very closely to the trend of the break frequency in Fourier power spectra, supporting the interpretation of a truncated and evolving disc in the hard state.

  17. Accretion of gaseous clumps from the Galactic Centre Mini-spiral onto Milky Way's supermassive black hole

    NASA Astrophysics Data System (ADS)

    Karas, Vladimir; Kunneriath, Devaky; Czerny, Bozena; Rozanska, Agata; Adhikari, Tek P.

    2016-07-01

    Evidence for reflection of X-rays on molecular clouds in the vicinity of Sagittarius A* super-massive black hole (Sgr A* SMBH) suggests that the center of Galaxy was active in its recent history. We investigate the idea of gaseous Mini-spiral pattern as the origin of material triggering this enhanced activity. Collisions between clumps of gas in the Mini-spiral can reduce their angular momentum and set some of the clumps on a plunging trajectory towards Sgr A* SMBH. It turns out that the amount of material in the Mini-spiral region is sufficient to sustain the required level of luminosity. We examine a possibility of Thermal Instability onset to describe the mechanism for elevated accretion during the past period. Our contribution extends a recent paper by including the effect of the Nuclear Star Cluster, which provides additional important contribution to the energy balance of the inter-stellar medium.

  18. Magnetohydrodynamic Accretion Around Supermassive Black Holes : Short-Length Disc for Stronger Field

    NASA Astrophysics Data System (ADS)

    Biswas, Ritabrata

    2016-07-01

    Thin accretion flow, i.e., geometrically thin accretion disc was first studied by Shakura and Sunyaev. Relativistic fluid flows around a black hole produce enormous energy on the cost of permanent lost of the gravitational potential due to the fall into a infinitely sloped gravitational well or to be specific, into a space time singularity. This energy is actually observed in different wavelengths and we specify the source as Active Galactic Nuclei, quasars, Gamma-ray burst sources etc. Eventually, two popular kind of accretion disc models are there. The first one is advection dominated, known as geometrically thin optically thick accretion disc. The other is geometrically thick but optically thin as it does not capture photons inside! The jets formed by accretion phenomena are still not well explained. Size of the accretion disc, power of the jets can be powered by magnetic fields generated by the ionized particles of the accretion flow. We show the exact dependency of the disc size upon the magnetic field present along with the quantity of the central gravitating mass.

  19. GR-AMRVAC code applications: accretion onto compact objects, boson stars versus black holes

    NASA Astrophysics Data System (ADS)

    Meliani, Z.; Grandclément, P.; Casse, F.; Vincent, F. H.; Straub, O.; Dauvergne, F.

    2016-08-01

    In the close vicinity of a compact object strong gravity imprints its signature onto matter. Systems that contain at least one compact object are observed to exhibit extreme physical properties and typically emit highly energetic radiation. The nature of the compact objects that produce the strongest gravitational fields is to date not settled. General relativistic numerical simulations of fluid dynamics around black holes, neutron stars, and other compact objects such as boson stars (BSs) may give invaluable insights into this fundamental question. In order to study the behavior of fluid in the strong gravity regime of an arbitrary compact object we develop a new general relativistic hydrodynamics code. To this end we extend the existing versatile adaptive mesh refinement code MPI-AMRVAC into a general relativistic hydrodynamics framework and adapt it for the use of numerically given spacetime metrics. In the present article we study accretion flows in the vicinity of various types of BSs whose numerical metrics are calculated by the KADATH spectral solver library. We design specific tests to check the reliability of any code intending to study BSs and compare the solutions with those obtained in the context of Schwarzschild black holes. We perform the first ever general relativistic hydrodynamical simulations of gas accretion by a BS. The behavior of matter at small distances from the center of a BS differs notably from the black hole case. In particular we demonstrate that in the context of Bondi spherical accretion the mass accretion rate onto non-rotating BSs remains constant whereas it increases for Schwarzschild black holes. We also address the scenario of non-spherical accretion onto BSs and show that this may trigger mass ejection from the interior of the BS. This striking feature opens the door to forthcoming investigations regarding accretion-ejection flows around such types of compact objects.

  20. Modeling the optical-X-ray accretion lag in LMC X-3: Insights into black-hole accretion physics

    SciTech Connect

    Steiner, James F.; McClintock, Jeffrey E.; Orosz, Jerome A.; Buxton, Michelle M.; Bailyn, Charles D.; Remillard, Ronald A.; Kara, Erin

    2014-03-10

    The X-ray persistence and characteristically soft spectrum of the black hole X-ray binary LMC X-3 make this source a touchstone for penetrating studies of accretion physics. We analyze a rich, ten-year collection of optical/infrared (OIR) time-series data in conjunction with all available contemporaneous X-ray data collected by the All-Sky Monitor and Proportional Counter Array detectors aboard the Rossi X-ray Timing Explorer. A cross-correlation analysis reveals an X-ray lag of ≈2 weeks. Motivated by this result, we develop a model that reproduces the complex OIR light curves of LMC X-3. The model is comprised of three components of emission: stellar light, accretion luminosity from the outer disk inferred from the time-lagged X-ray emission, and light from the X-ray-heated star and outer disk. Using the model, we filter a strong noise component out of the ellipsoidal light curves and derive an improved orbital period for the system. Concerning accretion physics, we find that the local viscous timescale in the disk increases with the local mass accretion rate; this in turn implies that the viscosity parameter α decreases with increasing luminosity. Finally, we find that X-ray heating is a strong function of X-ray luminosity below ≈50% of the Eddington limit, while above this limit X-ray heating is heavily suppressed. We ascribe this behavior to the strong dependence of the flaring in the disk upon X-ray luminosity, concluding that for luminosities above ≈50% of Eddington, the star lies fully in the shadow of the disk.

  1. Probing the active massive black hole candidate in the center of NGC 404 with VLBI

    SciTech Connect

    Paragi, Z.; Frey, S.; Kaaret, P.; Cseh, D.; Kharb, P.

    2014-08-10

    Recently, Nyland et al. argued that the radio emission observed in the center of the dwarf galaxy NGC 404 originates in a low-luminosity active galactic nucleus powered by a massive black hole (MBH, M ≲ 10{sup 6} M{sub ☉}). High-resolution radio detections of MBHs are rare. Here we present sensitive, contemporaneous Chandra X-ray, and very long baseline interferometry (VLBI) radio observations with the European VLBI Network. The source is detected in the X-rays, and shows no long-term variability. If the hard X-ray source is powered by accretion, the apparent low accretion efficiency would be consistent with a black hole (BH) in the hard state. Hard state BHs are known to show radio emission compact on the milliarcsecond scales. However, the central region of NGC 404 is resolved out on 10 mas (0.15-1.5 pc) scales. Our VLBI non-detection of a compact, partially self-absorbed radio core in NGC 404 implies that either the BH mass is smaller than 3{sub −2}{sup +5}×10{sup 5} M{sub ☉}, or the source does not follow the fundamental plane of BH activity relation. An alternative explanation is that the central BH is not in the hard state. The radio emission observed on arcsecond (tens of parsecs) scales may originate in nuclear star formation or extended emission due to AGN activity, although the latter would not be typical considering the structural properties of low-ionization nuclear emission-line region galaxies with confirmed nuclear activity.

  2. Upper Limit of the Viscosity Parameter in Accretion Flows around a Black Hole with Shock Waves

    NASA Astrophysics Data System (ADS)

    Nagarkoti, Shreeram; Chakrabarti, Sandip K.

    2016-01-01

    Black hole accretion is necessarily transonic; thus, flows must become supersonic and, therefore, sub-Keplerian before they enter into the black hole. The viscous timescale is much longer than the infall timescale close to a black hole. Hence, the angular momentum remains almost constant and the centrifugal force ˜ {l}2/{r}3 becomes increasingly dominant over the gravitational force ˜ 1/{r}2. The slowed down matter piles creating an accretion shock. The flow between shock and inner sonic point is puffed up and behaves like a boundary layer. This so-called Comptonizing cloud/corona produces hard X-rays and jets/outflows and, therefore, is an important component of black hole astrophysics. In this paper, we study steady state viscous, axisymmetric, transonic accretion flows around a Schwarzschild black hole. We adopt a viscosity parameter α and compute the highest possible value of α (namely, {α }{cr}) for each pair of two inner boundary parameters (namely, specific angular momentum carried to horizon, lin and specific energy at inner sonic point, E({x}{in})) which is still capable of producing a standing or oscillating shock. We find that while such possibilities exist for α as high as {α }{cr}=0.3 in very small regions of the flow parameter space, typical {α }{cr} appears to be about ˜0.05-0.1. Coincidentally, this also happens to be the typical viscosity parameter achieved by simulations of magnetorotational instabilities in accretion flows. We therefore believe that all realistic accretion flows are likely to have centrifugal pressure supported shocks unless the viscosity parameter everywhere is higher than {α }{cr}.

  3. Regulation of black-hole accretion by a disk wind during a violent outburst of V404 Cygni

    NASA Astrophysics Data System (ADS)

    Muñoz-Darias, T.; Casares, J.; Mata Sánchez, D.; Fender, R. P.; Armas Padilla, M.; Linares, M.; Ponti, G.; Charles, P. A.; Mooley, K. P.; Rodriguez, J.

    2016-06-01

    Accretion of matter onto black holes is universally associated with strong radiative feedback and powerful outflows. In particular, black-hole transients have outflows whose properties are strongly coupled to those of the accretion flow. This includes X-ray winds of ionized material, expelled from the accretion disk encircling the black hole, and collimated radio jets. Very recently, a distinct optical variability pattern has been reported in the transient stellar-mass black hole V404 Cygni, and interpreted as disrupted mass flow into the inner regions of its large accretion disk. Here we report observations of a sustained outer accretion disk wind in V404 Cyg, which is unlike any seen hitherto. We find that the outflowing wind is neutral, has a large covering factor, expands at one per cent of the speed of light and triggers a nebular phase once accretion drops sharply and the ejecta become optically thin. The large expelled mass (>10‑8 solar masses) indicates that the outburst was prematurely ended when a sizeable fraction of the outer disk was depleted by the wind, detaching the inner regions from the rest of the disk. The luminous, but brief, accretion phases shown by transients with large accretion disks imply that this outflow is probably a fundamental ingredient in regulating mass accretion onto black holes.

  4. Regulation of black-hole accretion by a disk wind during a violent outburst of V404 Cygni.

    PubMed

    Muñoz-Darias, T; Casares, J; Mata Sánchez, D; Fender, R P; Armas Padilla, M; Linares, M; Ponti, G; Charles, P A; Mooley, K P; Rodriguez, J

    2016-06-01

    Accretion of matter onto black holes is universally associated with strong radiative feedback and powerful outflows. In particular, black-hole transients have outflows whose properties are strongly coupled to those of the accretion flow. This includes X-ray winds of ionized material, expelled from the accretion disk encircling the black hole, and collimated radio jets. Very recently, a distinct optical variability pattern has been reported in the transient stellar-mass black hole V404 Cygni, and interpreted as disrupted mass flow into the inner regions of its large accretion disk. Here we report observations of a sustained outer accretion disk wind in V404 Cyg, which is unlike any seen hitherto. We find that the outflowing wind is neutral, has a large covering factor, expands at one per cent of the speed of light and triggers a nebular phase once accretion drops sharply and the ejecta become optically thin. The large expelled mass (>10(-8) solar masses) indicates that the outburst was prematurely ended when a sizeable fraction of the outer disk was depleted by the wind, detaching the inner regions from the rest of the disk. The luminous, but brief, accretion phases shown by transients with large accretion disks imply that this outflow is probably a fundamental ingredient in regulating mass accretion onto black holes. PMID:27251277

  5. The MassiveBlack-II simulation: The evolution of haloes and galaxies to z ~ 0

    SciTech Connect

    Khandai, Nishikanta; Di Matteo, Tiziana; Croft, Rupert; Wilkins, Stephen; Feng, Yu; Tucker, Evan; DeGraf, Colin; Liu, Mao -Sheng

    2015-04-24

    We investigate the properties and clustering of halos, galaxies and blackholes to z = 0 in the high resolution hydrodynamical simulation MassiveBlack-II (MBII). MBII evolves a ΛCDM cosmology in a cubical comoving volume Vbox = (100Mpc/h)³. It is the highest resolution simulation of this size which includes a self-consistent model for star formation, black hole accretion and associated feedback. We provide a simulation browser web application which enables interactive search and tagging of the halos, subhalos and their properties and publicly release our galaxy catalogs to the scientific community. Our analysis of the halo mass function in MBII reveals that baryons have strong effects with changes in the halo abundance of 20–35% below the knee of the mass function (Mhalo 1013.2 M h at z = 0) when compared to dark-matter-only simulations. We provide a fitting function for the halo MF out to redshift z = 11 and discuss its limitations.

  6. The MassiveBlack-II simulation: The evolution of haloes and galaxies to z ~ 0

    DOE PAGESBeta

    Khandai, Nishikanta; Di Matteo, Tiziana; Croft, Rupert; Wilkins, Stephen; Feng, Yu; Tucker, Evan; DeGraf, Colin; Liu, Mao -Sheng

    2015-04-24

    We investigate the properties and clustering of halos, galaxies and blackholes to z = 0 in the high resolution hydrodynamical simulation MassiveBlack-II (MBII). MBII evolves a ΛCDM cosmology in a cubical comoving volume Vbox = (100Mpc/h)³. It is the highest resolution simulation of this size which includes a self-consistent model for star formation, black hole accretion and associated feedback. We provide a simulation browser web application which enables interactive search and tagging of the halos, subhalos and their properties and publicly release our galaxy catalogs to the scientific community. Our analysis of the halo mass function in MBII reveals thatmore » baryons have strong effects with changes in the halo abundance of 20–35% below the knee of the mass function (Mhalo 1013.2 M⊙ h at z = 0) when compared to dark-matter-only simulations. We provide a fitting function for the halo MF out to redshift z = 11 and discuss its limitations.« less

  7. Massive black-hole binary inspirals: results from the LISA parameter estimation taskforce

    NASA Astrophysics Data System (ADS)

    Arun, K. G.; Babak, Stas; Berti, Emanuele; Cornish, Neil; Cutler, Curt; Gair, Jonathan; Hughes, Scott A.; Iyer, Bala R.; Lang, Ryan N.; Mandel, Ilya; Porter, Edward K.; Sathyaprakash, Bangalore S.; Sinha, Siddhartha; Sintes, Alicia M.; Trias, Miquel; Van Den Broeck, Chris; Volonteri, Marta

    2009-05-01

    The LISA Parameter Estimation Taskforce was formed in September 2007 to provide the LISA Project with vetted codes, source distribution models and results related to parameter estimation. The Taskforce's goal is to be able to quickly calculate the impact of any mission design changes on LISA's science capabilities, based on reasonable estimates of the distribution of astrophysical sources in the universe. This paper describes our Taskforce's work on massive black-hole binaries (MBHBs). Given present uncertainties in the formation history of MBHBs, we adopt four different population models, based on (i) whether the initial black-hole seeds are small or large and (ii) whether accretion is efficient or inefficient at spinning up the holes. We compare four largely independent codes for calculating LISA's parameter-estimation capabilities. All codes are based on the Fisher-matrix approximation, but in the past they used somewhat different signal models, source parametrizations and noise curves. We show that once these differences are removed, the four codes give results in extremely close agreement with each other. Using a code that includes both spin precession and higher harmonics in the gravitational-wave signal, we carry out Monte Carlo simulations and determine the number of events that can be detected and accurately localized in our four population models.

  8. Growing black holes and galaxies: black hole accretion versus star formation rate

    NASA Astrophysics Data System (ADS)

    Volonteri, Marta; Capelo, Pedro R.; Netzer, Hagai; Bellovary, Jillian; Dotti, Massimo; Governato, Fabio

    2015-05-01

    We present a new suite of hydrodynamical simulations and use it to study, in detail, black hole and galaxy properties. The high time, spatial and mass resolution, and realistic orbits and mass ratios, down to 1:6 and 1:10, enable us to meaningfully compare star formation rate (SFR) and BH accretion rate (BHAR) time-scales, temporal behaviour, and relative magnitude. We find that (i) BHAR and galaxy-wide SFR are typically temporally uncorrelated, and have different variability time-scales, except during the merger proper, lasting ˜0.2-0.3 Gyr. BHAR and nuclear (<100 pc) SFR are better correlated, and their variability are similar. Averaging over time, the merger phase leads typically to an increase by a factor of a few in the BHAR/SFR ratio. (ii) BHAR and nuclear SFR are intrinsically proportional, but the correlation lessens if the long-term SFR is measured. (iii) Galaxies in the remnant phase are the ones most likely to be selected as systems dominated by an active galactic nucleus, because of the long time spent in this phase. (iv) The time-scale over which a given diagnostic probes the SFR has a profound impact on the recovered correlations with BHAR, and on the interpretation of observational data.

  9. Observing Massive Black-hole Binaries With A Redesigned Lisa

    NASA Astrophysics Data System (ADS)

    McWilliams, Sean T.

    2012-01-01

    In response to recent events in NASA and ESA, which necessitate the redesign of the Laser Interferometer Space Antenna (LISA) to lower its cost, we present results of a design study that evaluates the impact of various redesigns on the study of massive black-hole binaries (MBHB). As a result of the shift in sensitivity towards higher frequencies in all of the redesigns, the final merger signal will be even more critical for characterizing the coalescence of MBHBs. We assess the achievable parameter accuracy of MBHB measurements with various redesign options, and how well we expect the final design choices to perform. We include spinning mergers with higher harmonics in our calculation, which was never previously included in LISA calculations, and highlights the need to include all of the available physics in order to recover any performance lost in the redesign.

  10. Tidal capture of stars by a massive black hole

    NASA Technical Reports Server (NTRS)

    Novikov, I. D.; Pethick, C. J.; Polnarev, A. G.

    1992-01-01

    The processes leading to tidal capture of stars by a massive black hole and the consequences of these processes in a dense stellar cluster are discussed in detail. When the amplitude of a tide and the subsequent oscillations are sufficiently large, the energy deposited in a star after periastron passage and formation of a bound orbit cannot be estimated directly using the linear theory of oscillations of a spherical star, but rather numerical estimates must be used. The evolution of a star after tidal capture is discussed. The maximum ratio R of the cross-section for tidal capture to that for tidal disruption is about 3 for real systems. For the case of a stellar system with an empty capture loss cone, even in the case when the impact parameter for tidal capture only slightly exceeds the impact parameter for direct tidal disruption, tidal capture would be much more important than tidal disruption.

  11. Modelling aperiodic X-ray variability in black hole binaries as propagating mass accretion rate fluctuations: A short review

    NASA Astrophysics Data System (ADS)

    Ingram, A. R.

    2016-05-01

    Black hole binary systems can emit very bright and rapidly varying X-ray signals when material from the companion accretes onto the black hole, liberating huge amounts of gravitational potential energy. Central to this process of accretion is turbulence. In the propagating mass accretion rate fluctuations model, turbulence is generated throughout the inner accretion flow, causing fluctuations in the accretion rate. Fluctuations from the outer regions propagate towards the black hole, modulating the fluctuations generated in the inner regions. Here, I present the theoretical motivation behind this picture before reviewing the array of statistical variability properties observed in the light curves of black hole binaries that are naturally explained by the model. I also discuss the remaining challenges for the model, both in terms of comparison to data and in terms of including more sophisticated theoretical considerations.

  12. CONSTRAINTS ON THE VISCOSITY AND MAGNETIC FIELD IN HOT ACCRETION FLOWS AROUND BLACK HOLES

    SciTech Connect

    Liu, B. F.; Taam, Ronald E. E-mail: r-taam@northwestern.edu

    2013-07-15

    The magnitude of the viscosity and magnetic field parameters in hot accretion flows is investigated in low luminosity active galactic nuclei (LLAGNs). Theoretical studies show that a geometrically thin, optically thick disk is truncated at mass accretion rates less than a critical value by mass evaporated vertically from the disk to the corona, with the truncated region replaced by an advection dominated accretion flow (ADAF). The critical accretion rate for such a truncation is a function of the viscosity and magnetic field. Observations of X-ray photon indices and spectral fits of a number of LLAGNs published in the literature provide an estimate of the critical rate of mass accretion and the truncation radius, respectively. By comparing the observational results with theoretical predictions, the viscosity and magnetic field parameters in the hot accretion flow region are estimated. Specifically, the mass accretion rates inferred in different sources constrain the viscosity parameter, whereas the truncation radii of the disk, as inferred from spectral fits, further constrain the magnetic field parameter. It is found that the value of the viscosity parameter in the corona/ADAF ranges from 0.17 to 0.5, with values clustered about 0.2-0.3. Magnetic pressure is required by the relatively small truncation radii for some LLAGNs and is found to be as high as its equipartition value with the gas pressure. The inferred values of the viscosity parameter are in agreement with those obtained from the observations of non-stationary accretion in stellar mass black hole X-ray transients. This consistency provides support for the paradigm that a geometrically thin disk is truncated by means of a mass evaporation process from the disk to the corona at low mass accretion rates.

  13. A Massive Black Hole in NGC 3377: 3 Integral Models

    NASA Astrophysics Data System (ADS)

    Richstone, D.; Gebhardt, K.; Kormendy, J.; Bender, R.; Magorrian, J.; Tremaine, S.; Faber, S.; Lauer, T.

    1996-12-01

    We use a Hubble Space Telescope image combined with nuclear and flanking spectra of the galaxy NGC 3377 (E5, M_V = -19.7), together with somewhat lower resolution ground--based data from Hawaii, to determine the stellar kinematics of the central region of the galaxy. Because the galaxy is apparently very flat it must be highly inclined. We model the galaxy using an axisymmetric, fully general (3-integral) orbit-based maximum entropy program, which permits a complete exploration of all possible configurations in phase space consistent with a specified mass and light distribution. We considered intrinsic E5 models at 90 deg inclination and E6 models at 71 deg . All equilibrium models with satisfactory fits to the observations contain a massive central dark point mass in the range 0.5 - 2. x 10(8) M_sun. Models without a massive black hole cannot reproduce the rapid observed rotation seen at 0. arcsec 3 from the center in the HST data. Models matching the data have approximately isotropic distribution functions. The Nuker team was supported by HST data analysis funds through grant GO-02600.01-87A and by NSERC.

  14. Supermassive black hole formation by cold accretion shocks in the first galaxies

    NASA Astrophysics Data System (ADS)

    Inayoshi, Kohei; Omukai, Kazuyuki

    2012-05-01

    We propose a new scenario for supermassive star (SMS: >rsim 105 M⊙) formation in shocked regions of colliding cold accretion flows near the centres of the first galaxies. Recent numerical simulations indicate that assembly of a typical first galaxy with virial temperature Tvir≳104 K proceeds via cold and dense flows penetrating deep to the centre, where supersonic streams collide with each other to develop a hot (˜104 K) and dense (˜103 cm-3) shocked gas. The post-shock layer first cools by efficient Lyα emission and contracts isobarically until ≃8000 K. Whether the layer continues its isobaric contraction depends on the density at this moment: if the density is high enough to excite H2 rovibrational levels collisionally (>rsim 104 cm-3), enhanced H2 collisional dissociation suppresses the gas from cooling further. In this case, the layer fragments into massive (>rsim 105 M⊙) clouds, which collapse isothermally (˜8000 K) by Lyα cooling without subsequent fragmentation. As an outcome, SMSs are expected to form and eventually evolve into the seeds of supermassive black holes (SMBHs). By calculating the thermal evolution of the post-shock gas, we delimit the range of post-shock conditions for SMS formation, which can be expressed as T≳6000 K (nH/104 cm-3)-1 for ? and T>rsim 5000 -6000 K for nH≳104 cm-3, depending somewhat on the initial ionization degree. We found that metal enrichment does not affect the above condition for metallicity below ≃10-3 Z⊙ if metals are in the gas phase, while condensation of several per cent of metals into dust decreases this critical value of metallicity by an order of magnitude. Unlike the previously proposed scenario for SMS formation, which postulates extremely strong ultraviolet radiation to quench H2 cooling, our scenario here naturally explains SMBH seed formation in the assembly process of the first galaxies, even without such strong radiation.

  15. Formation Rates of Black Hole Accretion Disk Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Fryer, Chris L.; Woosley, S. E.; Hartmann, Dieter H.

    1999-11-01

    The cosmological origin of at least an appreciable fraction of classical gamma-ray bursts (GRBs) is now supported by redshift measurements for a half-dozen faint host galaxies. Still, the nature of the central engine (or engines) that provide the burst energy remains unclear. While many models have been proposed, those currently favored are all based upon the formation of and/or rapid accretion into stellar-mass black holes. Here we discuss a variety of such scenarios and estimate the probability of each. Population synthesis calculations are carried out using a Monte Carlo approach in which the many uncertain parameters intrinsic to such calculations are varied. We estimate the event rate for each class of model as well as the propagation distances for those having significant delay between formation and burst production, i.e., double neutron star (DNS) mergers and black hole-neutron star (BH/NS) mergers. One conclusion is a 1-2 order of magnitude decrease in the rate of DNS and BH/NS mergers compared to that previously calculated using invalid assumptions about common envelope evolution. Other major uncertainties in the event rates and propagation distances include the history of star formation in the universe, the masses of the galaxies in which merging compact objects are born, and the radii of the hydrogen-stripped cores of massive stars. For reasonable assumptions regarding each, we calculate a daily event rate in the universe for (1) merging neutron stars: ~100 day-1 (2) neutron star-black hole mergers: ~450 day-1 (3) collapsars: ~104 day-1 (4) helium star black hole mergers: ~1000 day-1 and (5) white dwarf-black hole mergers: ~20 day-1. The range of uncertainty in these numbers, however, is very large, typically 2-3 orders of magnitude. These rates must additionally be multiplied by any relevant beaming factor (fΩ<1) and sampling fraction (if the entire universal set of models is not being observed). Depending upon the mass of the host galaxy, one-half of

  16. HUBBLE UNCOVERS DUST DISK AROUND A MASSIVE BLACK HOLE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Resembling a gigantic hubcap in space, a 3,700 light-year-diameter dust disk encircles a 300 million solar-mass black hole in the center of the elliptical galaxy NGC 7052. The disk, possibly a remnant of an ancient galaxy collision, will be swallowed up by the black hole in several billion years. Because the front end of the disk eclipses more stars than the back, it appears darker. Also, because dust absorbs blue light more effectively than red light, the disk is redder than the rest of the galaxy (this same phenomenon causes the Sun to appear red when it sets in a smoggy afternoon). This NASA Hubble Space Telescope image was taken with the Wide Field and Planetary Camera 2, in visible light. Details as small as 50 light-years across can be seen. Hubble's Faint Object Spectrograph (replaced by the STIS spectrograph in 1997) was used to observe hydrogen and nitrogen emission lines from gas in the disk. Hubble measurements show that the disk rotates like an enormous carousel, 341,000 miles per hour (155 kilometers per second) at 186 light-years from the center. The rotation velocity provides a direct measure of the gravitational force acting on the gas by the black hole. Though 300 million times the mass of our Sun, the black hole is still only 0.05 per cent of the total mass of the NGC 7052 galaxy. Despite its size, the disk is 100 times less massive than the black hole. Still, it contains enough raw material to make three million sun-like stars. The bright spot in the center of the disk is the combined light of stars that have crowded around the black hole due to its strong gravitational pull. This stellar concentration matches theoretical models linking stellar density to a central black hole's mass. NGC 7052 is a strong source of radio emission and has two oppositely directed `jets' emanating from the nucleus. (The jets are streams of energetic electrons moving in a strong magnetic field and unleashing radio energy). Because the jets in NGC 7052 are not

  17. Stellar dynamics around a massive black hole - II. Resonant relaxation

    NASA Astrophysics Data System (ADS)

    Sridhar, S.; Touma, Jihad R.

    2016-06-01

    We present a first-principles theory of resonant relaxation (RR) of a low-mass stellar system orbiting a more massive black hole (MBH). We first extend the kinetic theory of Gilbert to include the Keplerian field of a black hole of mass M•. Specializing to a Keplerian stellar system of mass M ≪ M•, we use the orbit-averaging method of Sridhar & Touma to derive a kinetic equation for RR. This describes the collisional evolution of a system of N ≫ 1 Gaussian rings in a reduced 5-dim space, under the combined actions of self-gravity, 1 post-Newtonian (PN) and 1.5 PN relativistic effects of the MBH and an arbitrary external potential. In general geometries, RR is driven by both apsidal and nodal resonances, so the distinction between scalar RR and vector RR disappears. The system passes through a sequence of quasi-steady secular collisionless equilibria, driven by irreversible two-ring correlations that accrue through gravitational interactions, both direct and collective. This correlation function is related to a `wake function', which is the linear response of the system to the perturbation of a chosen ring. The wake function is easier to appreciate, and satisfies a simpler equation, than the correlation function. We discuss general implications for the interplay of secular dynamics and non-equilibrium statistical mechanics in the evolution of Keplerian stellar systems towards secular thermodynamic equilibria, and set the stage for applications to the RR of axisymmetric discs in Paper III.

  18. Observing Merging Massive Black Hole Binaries with LISA

    NASA Technical Reports Server (NTRS)

    Thorpe, J.; McWillimas, S.; Baker, J.; Arnaud, K.

    2009-01-01

    The Laser Interferometer Space Antenna (LISA) is expected to detect gravitational radiation from the inspiral and merger of massive black hole binaries at high redshifts with large signal-to-noise ratios (SNRs). These high-SNR observations will make it possible to extract physical parameters such as hole masses and spins, luminosity distance, and sky position from the observed waveforms. LISA'S effectiveness as a tool for astrophysics will be influenced by the precision with which these parameters can be measured. In addition, the practicality of coordinated observations with other instruments will be affected by the temporal evolution of parameter errors such as sky position. We present estimates of parameter errors for the special case of non-spinning black holes. Our focus is on the contribution of the late inspiral and merger portions of the waveform, a regime which typically dominates the SNR but has not been extensively studied due to the historic lack of a precise description of the waveform. Advances in numerical relativity have recently made such studies possible. Initial results suggest that the portion of the waveform beyond the Schwarzchild inner-most stable circular orbit can reduce parameter uncertainties by up to a factor of two.

  19. Non-axisymmetric relativistic wind accretion with velocity gradients on to a rotating black hole

    NASA Astrophysics Data System (ADS)

    Cruz-Osorio, A.; Lora-Clavijo, F. D.

    2016-08-01

    We model, for the first time, the Bondi-Hoyle accretion of a fluid with velocity gradients on to a Kerr black hole, by numerically solving the fully relativistic hydrodynamics equations. Specifically, we consider a supersonic ideal gas, which has velocity gradients perpendicular to the relative motion. We measure the mass and specific angular accretion rates to illustrate whether the fluid presents unstable patterns or not. The initial parameters, we consider in this work, are the velocity gradient ɛv, the black hole spin a, the asymptotic Mach number M_{∞} and adiabatic index Γ. We show that the flow accretion reaches a fairly stationary regime, unlike in the Newtonian case, where significant fluctuations of the mass and angular momentum accretion rates are found. On the other hand, we consider a special case where both density and velocity gradients of the fluid are taken into account. The spin of the black hole and the asymptotic Newtonian Mach number, for this case, are a = 0.98 and M_{∞}=1, respectively. A kind of flip-flop behaviour is found at the early times; nevertheless, the system also reaches a steady state.

  20. Non-axisymmetric relativistic wind accretion with velocity gradients on to a rotating black hole

    NASA Astrophysics Data System (ADS)

    Cruz-Osorio, A.; Lora-Clavijo, F. D.

    2016-08-01

    We model, for the first time, the Bondi-Hoyle accretion of a fluid with velocity gradients onto a Kerr black hole, by numerically solving the fully relativistic hydrodynamics equations. Specifically, we consider a supersonic ideal gas, which has velocity gradients perpendicular to the relative motion. We measure the mass and specific angular accretion rates to illustrate whether the fluid presents unstable patterns or not. The initial parameters, we consider in this work, are the velocity gradient $\\epsilon_{v}$, the black hole spin $a$, the asymptotic Mach number ${\\cal M}_{\\infty}$ and adiabatic index $\\Gamma$. We show that the flow accretion reaches a fairly stationary regime, unlike in the Newtonian case, where significant fluctuations of the mass and angular momentum accretion rates are found. On the other hand, we consider a special case where both density and velocity gradients of the fluid are taken into account. The spin of the black hole and the asymptotic Newtonian Mach number, for this case, are $a=0.98$ and ${\\cal M}_{\\infty}=1$, respectively. A kind of flip-flop behavior is found at the early times; nevertheless, the system also reaches a steady state.

  1. Inhomogeneous accretion discs and the soft states of black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Dexter, Jason; Quataert, Eliot

    2012-10-01

    Observations of black hole binaries (BHBs) have established a rich phenomenology of X-ray states. The soft states range from the low variability, accretion disc dominated thermal (TD) state to the higher variability, non-thermal steep power law (SPL) state. The disc component in all states is typically modelled with standard thin disc accretion theory. However, this theory is inconsistent with optical/UV spectral, variability and gravitational microlensing observations of active galactic nuclei (AGNs), the supermassive analogues of BHBs. An inhomogeneous disc (ID) model with large (≃0.4 dex) temperature fluctuations in each radial annulus can qualitatively explain all of these AGN observations. The inhomogeneity may be a consequence of instabilities in radiation-dominated discs, and therefore may be present in BHBs as well. We show that ID models can explain many features of the TD and SPL states of BHBs. The observed relationships between spectral hardness, disc fraction and rms variability amplitude in BHBs are reproduced with temperature fluctuations similar to those inferred in AGNs, suggesting a unified picture of luminous accretion discs across orders of magnitude in black hole mass. This picture can be tested with spectral fitting of ID models, X-ray polarization observations and radiation magnetohydrodynamic simulations. If BHB accretion discs are indeed inhomogeneous, only the most disc-dominated states (disc fraction ≳0.95) can be used to robustly infer black hole spin using current continuum fitting methods.

  2. A SWIFT SURVEY OF ACCRETION ONTO STELLAR-MASS BLACK HOLES

    SciTech Connect

    Reynolds, Mark T.; Miller, Jon M.

    2013-05-20

    We present a systemic analysis of all of the stellar-mass black hole binaries (confirmed and candidate) observed by the Swift observatory up to 2010 June. The broad Swift bandpass enables a trace of disk evolution over an unprecedented range in flux and temperature. The final data sample consists of 476 X-ray spectra containing greater than 100 counts, in the 0.6-10 keV band. This is the largest sample of high-quality CCD spectra of accreting black holes published to date. In addition, strictly simultaneous data at optical/UV wavelengths are available for 255 (54%) of these observations. The data are modeled with a combination of an accretion disk and a hard spectral component. For the hard component we consider both a simple power-law model and a thermal Comptonization model. An accretion disk is detected at greater than the 5{sigma} confidence level in 61% of the observations. Light curves and color-color diagrams are constructed for each system. Hardness-luminosity and disk fraction-luminosity diagrams are constructed and are observed to be consistent with those typically observed by RXTE, noting the sensitivity below 2 keV provided by Swift. The observed spectra have an average luminosity of {approx}1% Eddington, though we are sensitive to accretion disks down to a luminosity of 10{sup -3} L{sub Edd}. Thus, this is also the largest sample of such cool accretion disks studied to date. The accretion disk temperature distribution displays two peaks consistent with the classical hard and soft spectral states, with a smaller number of disks distributed between these. The distribution of inner disk radii is observed to be continuous regardless of which model is used to fit the hard continua. There is no evidence for large-scale truncation of the accretion disk in the hard state (at least for L{sub x} {approx}> 10{sup -3} L{sub Edd}), with all of the accretion disks having radii {approx}< 40 R{sub g} . Plots of the accretion disk inner radius versus hardness ratio

  3. Truncation of the Inner Accretion Disk Around a Black Hole at Low Luminosity

    NASA Technical Reports Server (NTRS)

    Tomsick, John A.; Yamoka, Kazutaka; Corbel, Stephane; Kaaret, Philip; Kalemci, Emrah; Migliari, Simone

    2011-01-01

    Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate. An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion disk recedes at low accretion rate. Measurements of the location of the inner edge (R(sub in)) can be made using iron emission lines that arise due to fluorescence of iron in the disk, and these indicate that R(sub in) is very close to the black hole at high and moderate luminosities (greater than or equal to 1% of the Eddington luminosity, L(sub Edd). Here, we report on X-ray observations of the black hole GX 339-4 in the hard state by Suzaku and the Rossi X-ray Timing Explorer that extend iron line studies to 0.14% L(sub Edd) and show that R(sub in) increases by a factor of greater than 27 over the value found when GX 339-4 was bright. The exact value of R(sub in) depends on the inclination of the inner disk (i), and we derive 90% confidence limits of R(sub in) greater than 35 R(sub g) at i = 0 degrees and R(sub in) greater than 175 R(sub g) at i = 30 degrees. This provides direct evidence that the inner portion of the disk is not present at low luminosity, allowing for the possibility that the inner disk is replaced by advection- or magnetically dominated accretion flows.

  4. Truncation of the Inner Accretion Disk Around a Black Hole at Low Luminosity

    NASA Technical Reports Server (NTRS)

    Tomsick, John A.; Yamaoka, Kazutaka; Corbel, Stephane; Kaaret, Philip; Kalemci, Emrah; Migliari, Simone

    2009-01-01

    Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate. An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion disk recedes at low accretion rate. Measurements of the location of the inner edge (R(sub in)) can be made using iron emission lines that arise due to fluorescence of iron in the disk, and these indicate that R(sub in) is very close to the black hole at high and moderate luminosities (greater than approximately equal to 1% of the Eddington luminosity, L(sub Edd). Here, we report on X-ray observation of the black hole GX 339-4 in the hard state by Suzaku and the Rossi X-ray Timing Explorer (RXTE) that extend iron line studies to 0.14% L(sub Edd) and show that R(sub in) increases by a factor of greater than 27 over the value found when GX 339-4 was bright. The exact value of R(sub in) depends on the inclination of the inner disk (i), and we derive 90% confidence limits of R(sub in) greater than 35R(sub g) at i = 0 degrees and R(sub in) greater than 175R(sub g) at i = 30 degrees. This provides direct evidence that the inner portion of the disk is not present at low luminosity, allowing for the possibility that the inner disk is replaced by advection- or magnetically-dominated accretion flows.

  5. Inner Accretion Disk Regions of Black Hole X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg

    2015-01-01

    The innermost regions of accretion disks in black hole X-ray binaries dominate the observed X-ray emission, which is the main diagnostic that one uses to gain insights into the physics of black holes and accretion. The standard spectrum predicted from a geometrically thin, optically thick disk experiences non-trivial modification due to conspiring physical effects operating within the vertical disk structure such as Comptonization, free-free emission/absorption, bound-free opacities, and energy dissipation by magnetic processes. The complicated interplay of these effects cause the seed accretion disk spectrum to become hardened and it is this hardened emergent spectrum that we observe. To zeroth order, this hardening can be described by a phenomenological parameter called the spectral hardening factor.In practice, the adopted degree of spectral hardening is confined to lie within a rather restrictive range. I will discuss the following consequences of relaxing this criterion, while still requiring the spectral hardening factor to take on physically plausible values. Examining multiple state transitions of the black hole X-ray binary GX 339-4 with archival data from the Rossi X-ray Timing Explorer, I will show that appealing to a spectral hardening factor that varies during state transitions provides a viable alternative to a truncated disk model for the evolution of the inner accretion disk. Having demonstrated that moderate degrees of accretion disk spectral hardening cannot be ruled out by observations, I will explore this possibility from a theoretical standpoint. Extending previous work on radiative transfer modeling coupled to the vertical disk structure, I present the impacts on the emergent accretion disk spectrum caused by disk inclination and by allowing accretion power to be dissipated in the corona. Using magnetohydrodynamic simulations of a localized patch of the accretion disk (i.e., shearing box) performed with the Athena code, I will present the

  6. Binary black hole accretion from a circumbinary disk: Gas dynamics inside the central cavity

    SciTech Connect

    Farris, Brian D.; Duffell, Paul; MacFadyen, Andrew I.; Haiman, Zoltan

    2014-03-10

    We present the results of two-dimensional (2D) hydrodynamical simulations of circumbinary disk accretion using the finite-volume code DISCO. This code solves the 2D viscous Navier-Stokes equations on a high-resolution moving mesh which shears with the fluid flow, greatly reducing advection errors in comparison with a fixed grid. We perform a series of simulations for binary mass ratios in the range 0.026 ≤ q ≤ 1.0, each lasting longer than a viscous time so that we reach a quasi-steady accretion state. In each case, we find that gas is efficiently stripped from the inner edge of the circumbinary disk and enters the cavity along accretion streams, which feed persistent 'mini disks' surrounding each black hole. We find that for q ≳ 0.1, the binary excites eccentricity in the inner region of the circumbinary disk, creating an overdense lump which gives rise to enhanced periodicity in the accretion rate. The dependence of the periodicity on mass ratio may provide a method for observationally inferring mass ratios from measurements of the accretion rate. We also find that for all mass ratios studied, the magnitude of the accretion onto the secondary is sufficient to drive the binary toward larger mass ratio. This suggests a mechanism for biasing mass-ratio distributions toward equal mass.

  7. Binary Black Hole Accretion from a Circumbinary Disk: Gas Dynamics inside the Central Cavity

    NASA Astrophysics Data System (ADS)

    Farris, Brian D.; Duffell, Paul; MacFadyen, Andrew I.; Haiman, Zoltan

    2014-03-01

    We present the results of two-dimensional (2D) hydrodynamical simulations of circumbinary disk accretion using the finite-volume code DISCO. This code solves the 2D viscous Navier-Stokes equations on a high-resolution moving mesh which shears with the fluid flow, greatly reducing advection errors in comparison with a fixed grid. We perform a series of simulations for binary mass ratios in the range 0.026 <= q <= 1.0, each lasting longer than a viscous time so that we reach a quasi-steady accretion state. In each case, we find that gas is efficiently stripped from the inner edge of the circumbinary disk and enters the cavity along accretion streams, which feed persistent "mini disks" surrounding each black hole. We find that for q >~ 0.1, the binary excites eccentricity in the inner region of the circumbinary disk, creating an overdense lump which gives rise to enhanced periodicity in the accretion rate. The dependence of the periodicity on mass ratio may provide a method for observationally inferring mass ratios from measurements of the accretion rate. We also find that for all mass ratios studied, the magnitude of the accretion onto the secondary is sufficient to drive the binary toward larger mass ratio. This suggests a mechanism for biasing mass-ratio distributions toward equal mass.

  8. Evidence for a Black Hole and Accretion Disk in the LINER NGC 4203.

    PubMed

    Shields; Rix; McIntosh; Ho; Rudnick; Filippenko; Sargent; Sarzi

    2000-05-01

    We present spectroscopic observations from the Hubble Space Telescope that reveal for the first time the presence of a broad pedestal of Balmer line emission in the LINER galaxy NGC 4203. The emission-line profile is suggestive of a relativistic accretion disk and is reminiscent of double-peaked transient Balmer emission observed in a handful of other LINERs. The very broad line emission thus constitutes clear qualitative evidence for a black hole, and spatially resolved narrow-line emission in NGC 4203 can be used to constrain its mass, MBHblack hole mass to bulge mass of less, similar7x10-4 in NGC 4203, which is less by a factor of approximately 3-9 than the mean ratio obtained for other galaxies. The availability of an independent constraint on central black hole mass makes NGC 4203 an important testbed for probing the physics of weak active galactic nuclei. Assuming MBH near the detection limit, the ratio of the observed luminosity to the Eddington luminosity is approximately 10-4. This value is consistent with advection-dominated accretion and hence with scenarios in which an ion torus irradiates an outer accretion disk that produces the observed double-peaked line emission. Follow-up observations will make it possible to improve the black hole mass estimate and study variability in the nuclear emission. PMID:10790063

  9. Binary Black Holes, Accretion Disks and Relativistic Jets: Photocenters of Nearby AGN and Quasars

    NASA Technical Reports Server (NTRS)

    Wehrle, Ann E.; Jones, Dayton L.; Meier, David L.; Piner, B. Glenn; Unwin, Stephen C.

    2004-01-01

    One of the most challenging questions in astronomy today is to understand the origin, structure, and evolution of the central engines in the nuclei of quasars and active galaxies (AGNs). The favoured theory involves the activation of relativistic jets from the fueling of a supermassive black hole through an accretion disk. In some AGN an outer optically thick, dusty torus is seen orbiting the black hole system. This torus is probably related to an inner accretion disk - black hole system that forms the actual powerhouse of the AGN. In radio-loud AGN two oppositely-directed radio jets are ejected perpendicular to the torus/disk system. Although there is a wealth of observational data on AGN, some very basic questions have not been definitively answered. The Space Interferometry Mission (SIM) will address the following three key questions about AGN. 1) Does the most compact optical emission from an AGN come from an accretion disk or from a relativistic jet? 2) Does the separation of the radio core and optical photocenter of the quasars used for the reference frame tie, change on the timescales of their photometric variability, or is the separation stable at the level of a few microarcseconds? 3) Do the cores of galaxies harbor binary supermassive black holes remaining from galaxy mergers? It is not known whether such mergers are common, and whether binaries would persist for a significant time.

  10. Radio Telescope Reveals Secrets of Massive Black Hole

    NASA Astrophysics Data System (ADS)

    2008-04-01

    At the cores of many galaxies, supermassive black holes expel powerful jets of particles at nearly the speed of light. Just how they perform this feat has long been one of the mysteries of astrophysics. The leading theory says the particles are accelerated by tightly-twisted magnetic fields close to the black hole, but confirming that idea required an elusive close-up view of the jet's inner throat. Now, using the unrivaled resolution of the National Radio Astronomy Observatory's Very Long Baseline Array (VLBA), astronomers have watched material winding a corkscrew outward path and behaving exactly as predicted by the theory. Galactic core and jet Artist's conception of region near supermassive black hole where twisted magnetic fields propel and shape jet of particles (Credit: Marscher et al., Wolfgang Steffen, Cosmovision, NRAO/AUI/NSF). Click on image for high-resolution file. Watch Video of Black-Hole-Powered Jet (Credit: Cosmovision, Wolfgang Steffen) Download: NTSC Format (90MB) | PAL Format (90MB) "We have gotten the clearest look yet at the innermost portion of the jet, where the particles actually are accelerated, and everything we see supports the idea that twisted, coiled magnetic fields are propelling the material outward," said Alan Marscher, of Boston University, leader of an international research team. "This is a major advance in our understanding of a remarkable process that occurs throughout the Universe," he added. Marscher's team studied a galaxy called BL Lacertae (BL Lac), some 950 million light-years from Earth. BL Lac is a blazar, the most energetic type of black-hole-powered galactic core. A black hole is a concentration of mass so dense that not even light can escape its gravitational pull. Supermassive black holes in galaxies' cores power jets of particles and intense radiation in similar objects including quasars and Seyfert galaxies. Material pulled inward toward the black hole forms a flattened, rotating disk, called an accretion disk

  11. The MassiveBlack-II simulation: the evolution of haloes and galaxies to z ˜ 0

    NASA Astrophysics Data System (ADS)

    Khandai, Nishikanta; Di Matteo, Tiziana; Croft, Rupert; Wilkins, Stephen; Feng, Yu; Tucker, Evan; DeGraf, Colin; Liu, Mao-Sheng

    2015-06-01

    We investigate the properties of haloes, galaxies and black holes to z = 0 in the high-resolution hydrodynamical simulation MassiveBlack-II (MBII) which evolves a Λ cold dark matter cosmology in a comoving volume Vbox = (100 Mpc h-1)3. MBII is the highest resolution simulation of this size which includes a self-consistent model for star formation, black hole accretion and associated feedback. We provide a simulation browser web application which enables interactive search and tagging of the MBII data set and publicly release our galaxy catalogues. We find that baryons affect strongly the halo mass function (MF), with 20-33 per cent change in the halo abundance below the knee of the MF (Mhalo < 1013.2 M⊙ h-1 at z = 0) when compared to dark-matter-only simulations. We provide a fitting function for the halo MF out to redshift z = 11 and discuss its limitations. We study the halo occupation distribution and clustering of galaxies, in particular the evolution and scale dependence of stochasticity and bias finding reasonable agreement with observational data. The shape of the cosmic spectral energy distribution of galaxies in MBII is consistent with observations, but lower in amplitude. The Galaxy stellar mass function (GSMF) function is broadly consistent with observations at z ≥ 2. At z < 2, the population of passive low-mass (M* < 109 M⊙) galaxies in MBII makes the GSMF too steep compared to observations whereas at the high-mass end (M* > 1011 M⊙) galaxies hosting bright AGNs make significant contributions to the GSMF. The quasar bolometric luminosity function is also largely consistent with observations. We note however that more efficient AGN feedback is necessary for the largest, rarest objects/clusters at low redshifts.

  12. Tangled Magnetic Fields in Black Hole Accretion Disks: Implications for Viscosity and Particle Acceleration

    NASA Astrophysics Data System (ADS)

    Subramanian, Prasad

    1997-12-01

    There is a substantial amount of observational evidence for the presence of relativistic outflows from blazars and also from some galactic black hole candidates, hut there has been little, if any, work done to explain the origin of these jets from the underlying accretion disks. In particular, proton-initiated radiation processes in jets have been invoked recently (e.g., Mannheim 1993; Mannheim et al. 1996; Dar & Laor 1997) in order to account for TeV emission from blazars like Mrk 421 and Mrk 521. The origin of the energetic protons in the jet in such models is somewhat unclear, and the work done in this thesis makes a significant contribution in that direction. Specifically, this work is concerned with the general scenario of hot, two temperature accretion disks around black holes. Such accretion disks are attractive candidates for explaining high energy emission from active galactic nuclei that are believed to contain black holes. The two principal issues addressed here are: (1) The structure of the disk as determined by the microphysical viscosity mechanism; (2) The connection between the jets (relativistic outflows) and the physics of the underlying disk. The first issue is important from the point of view of understanding the physical processes governing the disk structure. Matter fed into such disks invariably has angular momentum associated with it, and a viscosity mechanism is essential for the removal of angular momentum so that matter can accrete onto the central object. While there has been some work done in the past on identifying physical processes that give rise to viscosity in accretion disks, none of the previous models give satisfactory results for conditions prevalent in hot accretion disks. There is evidence from simulations of the magnetic shearing instability by the groups of Hawley et al. (1995), Brandenburg et al. (1995) and Matsumoto & Tajima (1995) for the existence of turbulent, tangled magnetic fields embedded in accretion disks. In hot

  13. Do Circumnuclear Dense Gas Disks Drive Mass Accretion onto Supermassive Black Holes?

    NASA Astrophysics Data System (ADS)

    Izumi, Takuma; Kawakatu, Nozomu; Kohno, Kotaro

    2016-08-01

    We present a positive correlation between the mass of dense molecular gas ({M}{{dense}}) of ∼100 pc scale circumnuclear disks (CNDs) and the black hole mass accretion rate ({\\dot{M}}{{BH}}) in a total of 10 Seyfert galaxies, based on data compiled from the literature and an archive (median aperture θ med = 220 pc). A typical {M}{{dense}} of CNDs is 107–8 {M}ȯ , estimated from the luminosity of the dense gas tracer, the HCN(1–0) emission line. Because dense molecular gas is the site of star formation, this correlation is virtually equivalent to the one between the nuclear star-formation rate and {\\dot{M}}{{BH}} revealed previously. Moreover, the {M}{{dense}}{--}{\\dot{M}}{{BH}} correlation was tighter for CND-scale gas than for the gas on kiloparsec or larger scales. This indicates that CNDs likely play an important role in fueling black holes, whereas greater than kiloparesec scale gas does not. To demonstrate a possible approach for studying the CND-scale accretion process with the Atacama Large Millimeter/submillimeter Array, we used a mass accretion model where angular momentum loss due to supernova explosions is vital. Based on the model prediction, we suggest that only the partial fraction of the mass accreted from the CND ({\\dot{M}}{{acc}}) is consumed as {\\dot{M}}{{BH}}. However, {\\dot{M}}{{acc}} agrees well with the total nuclear mass flow rate (i.e., {\\dot{M}}{{BH}} + outflow rate). Although these results are still tentative with large uncertainties, they support the view that star formation in CNDs can drive mass accretion onto supermassive black holes in Seyfert galaxies.

  14. Do Circumnuclear Dense Gas Disks Drive Mass Accretion onto Supermassive Black Holes?

    NASA Astrophysics Data System (ADS)

    Izumi, Takuma; Kawakatu, Nozomu; Kohno, Kotaro

    2016-08-01

    We present a positive correlation between the mass of dense molecular gas ({M}{{dense}}) of ˜100 pc scale circumnuclear disks (CNDs) and the black hole mass accretion rate ({\\dot{M}}{{BH}}) in a total of 10 Seyfert galaxies, based on data compiled from the literature and an archive (median aperture θ med = 220 pc). A typical {M}{{dense}} of CNDs is 107–8 {M}ȯ , estimated from the luminosity of the dense gas tracer, the HCN(1–0) emission line. Because dense molecular gas is the site of star formation, this correlation is virtually equivalent to the one between the nuclear star-formation rate and {\\dot{M}}{{BH}} revealed previously. Moreover, the {M}{{dense}}{--}{\\dot{M}}{{BH}} correlation was tighter for CND-scale gas than for the gas on kiloparsec or larger scales. This indicates that CNDs likely play an important role in fueling black holes, whereas greater than kiloparesec scale gas does not. To demonstrate a possible approach for studying the CND-scale accretion process with the Atacama Large Millimeter/submillimeter Array, we used a mass accretion model where angular momentum loss due to supernova explosions is vital. Based on the model prediction, we suggest that only the partial fraction of the mass accreted from the CND ({\\dot{M}}{{acc}}) is consumed as {\\dot{M}}{{BH}}. However, {\\dot{M}}{{acc}} agrees well with the total nuclear mass flow rate (i.e., {\\dot{M}}{{BH}} + outflow rate). Although these results are still tentative with large uncertainties, they support the view that star formation in CNDs can drive mass accretion onto supermassive black holes in Seyfert galaxies.

  15. A new route towards merging massive black holes

    NASA Astrophysics Data System (ADS)

    Marchant, Pablo; Langer, Norbert; Podsiadlowski, Philipp; Tauris, Thomas M.; Moriya, Takashi J.

    2016-04-01

    With recent advances in gravitational-wave astronomy, the direct detection of gravitational waves from the merger of two stellar-mass compact objects has become a realistic prospect. Evolutionary scenarios towards mergers of various double compact objects generally invoke so-called common-envelope evolution, which is poorly understood and leads to large uncertainties in the predicted merger rates. Here we explore, as an alternative, the scenario of massive overcontact binary (MOB) evolution, which involves two very massive stars in a very tight binary that remain fully mixed as a result of their tidally induced high spin. While many of these systems merge early on, we find many MOBs that swap mass several times, but survive as a close binary until the stars collapse. The simplicity of the MOB scenario allows us to use the efficient public stellar-evolution code MESA to explore it systematically by means of detailed numerical calculations. We find that, at low metallicity, MOBs produce double-black-hole (BH+BH) systems that will merge within a Hubble time with mass-ratios close to one, in two mass ranges, about 25...60 M⊙ and ≳130M⊙, with pair-instability supernovae (PISNe) being produced at intermediate masses. Our models are also able to reproduce counterparts of various stages in the MOB scenario in the local Universe, providing direct support for the scenario. We map the initial binary parameter space that produces BH+BH mergers, determine the expected chirp mass distribution, merger times, and expected Kerr parameters, and predict event rates. We find typically one BH+BH merger event for ~1000 core-collapse supernovae for Z ≲ Z⊙/ 10 . The advanced LIGO (aLIGO) detection rate is more uncertain and depends on the cosmic metallicity evolution. From deriving upper and lower limits from a local and a global approximation for the metallicity distribution of massive stars, we estimate aLIGO detection rates (at the aLIGO design limit) of ~19-550 yr-1 for BH

  16. Black hole accretion disks - Coronal stabilization of the Lightman-Eardley instability

    NASA Technical Reports Server (NTRS)

    Ionson, J. A.; Kuperus, M.

    1984-01-01

    Physical processes by which the presence of a corona around a black hole can raise the threshold of onset of the Lightman-Eardley (L-E, 1976) instability are explored analytically. The L-E model predicts that an optically thick disk becomes unstable when the disk radiation pressure exceeds the disk gas pressure. The model has important implications for the validity of either the coronal disk or two-temperature disk models for accretion zones around black holes. It is shown that a corona can dissipate accreting gravitational energy through radiative cooling. Specific ratios of hard/soft X-rays are quantified for stable and unstable conditions. X-ray spectra from Cyg X-1 are cited as residing below the instability threshold value and thus are supportive of the coronal disk model.

  17. Probing the Accretion Geometry of Black Holes with X-Ray Polarization

    NASA Technical Reports Server (NTRS)

    Schnitman, Jeremy D.

    2011-01-01

    In the coming years, new space missions will be able to measure X-ray polarization at levels of 1% or better in the approx.1-10 keV energy band. In particular, X-ray polarization is an ideal tool for determining the nature of black hole (BH) accretion disks surrounded by hot coronae. Using a Monte Carlo radiation transport code in full general relativity, we calculate the spectra and polarization features of these BH systems. At low energies, the signal is dominated by the thermal flux coming directly from the optically thick disk. At higher energies, the thermal seed photons have been inverse-Compton scattered by the corona, often reflecting back off the disk before reaching the observer, giving a distinctive polarization signature. By measuring the degree and angle of this X-ray polarization, we can infer the BH inclination, the emission geometry of the accretion flow, and also determine the spin of the black hole.

  18. Variabilities of Gamma-ray Bursts from Black Hole Hyper-accretion Disks

    NASA Astrophysics Data System (ADS)

    Lin, Da-Bin; Lu, Zu-Jia; Mu, Hui-Jun; Liu, Tong; Hou, Shu-Jin; Lü, Jing; Gu, Wei-Min; Liang, En-Wei

    2016-08-01

    The emission from black hole binaries (BHBs) and active galactic nuclei (AGNs) displays significant aperiodic variabilities. The most promising explanation for these variabilities is the propagating fluctuations in the accretion flow. It is natural to expect that the mechanism driving variabilities in BHBs and AGNs may operate in a black hole hyper-accretion disk, which is believed to power gamma-ray bursts (GRBs). We study the variabilities of jet power in GRBs based on the model of propagating fluctuations. It is found that the variabilities of jet power and the temporal profile of erratic spikes in this scenario are similar to those in observed light curves of prompt gamma-ray emission of GRBs. Our results show that the mechanism driving X-ray variabilities in BHBs and AGNs may operate in the central engine to drive the variabilities of GRBs.

  19. Estimation of mass outflow rates from viscous relativistic accretion discs around black holes

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Indranil; Kumar, Rajiv

    2016-07-01

    We investigated flow in Schwarzschild metric, around a non-rotating black hole and obtained self-consistent accretion-ejection solution in full general relativity. We covered the whole of parameter space in the advective regime to obtain shocked, as well as, shock-free accretion solution. We computed the jet streamline using von Zeipel surfaces and projected the jet equations of motion on to the streamline and solved them simultaneously with the accretion disc equations of motion. We found that steady shock cannot exist beyond α ≳ 0.06 in the general relativistic prescription, but is lower if mass-loss is considered too. We showed that for fixed outer boundary, the shock moves closer to the horizon with increasing viscosity parameter. The mass outflow rate increases as the shock moves closer to the black hole, but eventually decreases, maximizing at some intermediate value of shock location. The jet terminal speed increases with stronger shocks; quantitatively speaking, the terminal speed of jets vj∞ > 0.1 if rsh < 20rg. The maximum of the outflow rate obtained in the general relativistic regime is less than 6 per cent of the mass accretion rate.

  20. Estimation of mass outflow rates from viscous relativistic accretion discs around black holes

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Indranil; Kumar, Rajiv

    2016-04-01

    We investigated flow in Schwarzschild metric, around a non-rotating black hole and obtained self-consistent accretion-ejection solution in full general relativity. We covered the whole of parameter space in the advective regime to obtain shocked, as well as, shock-free accretion solution. We computed the jet streamline using von-Zeipel surfaces and projected the jet equations of motion onto the streamline and solved them simultaneously with the accretion disc equations of motion. We found that steady shock cannot exist beyond α ≲ 0.06 in the general relativistic prescription, but is lower if massloss is considered too. We showed that for fixed outer boundary, the shock moves closer to the horizon with increasing viscosity parameter. The mass outflow rate increases as the shock moves closer to the black hole, but eventually decreases, maximizing at some intermediate value of shock. The jet terminal speed increases with stronger shocks, quantitatively speaking, the terminal speed of jets vj∞ > 0.1 if rsh < 20rg. The maximum of the outflow rate obtained in the general relativistic regime is less than 6% of the mass accretion rate.

  1. Hydrodynamical Numerical Simulation of Wind Production from Black Hole Hot Accretion Flows at Very Large Radii

    NASA Astrophysics Data System (ADS)

    Bu, De-Fu; Yuan, Feng; Gan, Zhao-Ming; Yang, Xiao-Hong

    2016-02-01

    Previous works show that strong winds exist in hot accretion flows around black holes. Those works focus only on the region close to the black hole, so it is unknown whether or where the wind production stops at large radii. In this paper, we investigate this problem with hydrodynamical simulations. We take into account the gravities of both the black hole and the nuclear star clusters. For the latter, we assume that the velocity dispersion of stars is a constant and its gravitational potential \\propto {σ }2{ln}(r), where σ is the velocity dispersion of stars, and r is the distance from the center of the galaxy. We focus on the region where the gravitational potential is dominated by the star cluster. We find that, just as for the accretion flow at small radii, the mass inflow rate decreases inward, and the flow is convectively unstable. However, a trajectory analysis shows that there is very little wind launched from the flow. Our result, combined with the results of Yuan et al.’s study from 2015, indicates that the mass flux of wind launched from hot accretion flow {\\dot{M}}{{wind}}={\\dot{M}}{{BH}}(r/20{r}s), with r≲ {R}A\\equiv {{GM}}{{BH}}/{σ }2. Here, {\\dot{M}}{{BH}} is the accretion rate at the black hole horizon, and RA is similar to the Bondi radius. We argue that the inward decrease of inflow rate is not due to mass loss via wind, but to convective motion. The disappearance of wind outside RA must be due to the change of the gravitational potential, but the exact reason remains to be probed.

  2. Theory of magnetohydrodynamic accretion of matter with an ultrahard equation of state onto a black hole

    SciTech Connect

    Chernov, S. V.

    2015-06-15

    We consider the magnetohydrodynamic theory of spherically symmetric accretion of a perfect fluid onto a Schwarzschild black hole with an ultrahard equation of state, p = μ ∼ ρ{sup 2}, where p is the pressure, μ is the total energy density, and ρ is the fluid density. An approximate analytical solution is written out. We show that one critical sonic surface that coincides with the black hole event horizon is formed instead of two critical surfaces (fast and slow magnetosonic surfaces) for a degenerate ultrahard equation of state of matter.

  3. Nonlinear calculations of the time evolution of black hole accretion disks

    NASA Technical Reports Server (NTRS)

    Luo, C.

    1994-01-01

    Based on previous works on black hole accretion disks, I continue to explore the disk dynamics using the finite difference method to solve the highly nonlinear problem of time-dependent alpha disk equations. Here a radially zoned model is used to develop a computational scheme in order to accommodate functional dependence of the viscosity parameter alpha on the disk scale height and/or surface density. This work is based on the author's previous work on the steady disk structure and the linear analysis of disk dynamics to try to apply to x-ray emissions from black candidates (i.e., multiple-state spectra, instabilities, QPO's, etc.).

  4. Galactic Black Holes in the Hard State: A Multi-Wavelength View of Accretion and Ejection

    NASA Technical Reports Server (NTRS)

    Kalemci; Tomsick, John A.; Migliari; Corbel; Markoff

    2010-01-01

    The canonical hard state is associated with emission from all three fundamental accretion components: the accretion disk, the hot accretion disk corona and the jet. On top of these, the hard state also hosts very rich temporal variability properties (low frequency QPOs in the PDS, time lags, long time scale evolution). Our group has been working on the major questions of the hard state both observationally (with mult i-wavelength campaigns using RXTE, Swift, Suzaku, Spitzer, VLA, ATCA, SMARTS) and theoretically (through jet models that can fit entire SEDs). Through spectral and temporal analysis we seek to determine the geometry of accretion components, and relate the geometry to the formation and emission from a jet. In this presentation I will review the recent contributions of our group to the field, including the Swift results on the disk geometry at low accretion rates, the jet model fits to the hard state SEDs (including Spitzer data) of GRO J1655-40, and the final results on the evolution of spectral (including X-ray, radio and infrared) and temporal properties of elected black holes in the hard states. I will also talk about impact of ASTROSAT to the science objective of our group.

  5. Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre.

    PubMed

    Genzel, R; Schödel, R; Ott, T; Eckart, A; Alexander, T; Lacombe, F; Rouan, D; Aschenbach, B

    2003-10-30

    Recent measurements of stellar orbits provide compelling evidence that the compact radio source Sagittarius A* (refs 4, 5) at the Galactic Centre is a 3.6-million-solar-mass black hole. Sgr A* is remarkably faint in all wavebands other than the radio region, however, which challenges current theories of matter accretion and radiation surrounding black holes. The black hole's rotation rate is not known, and therefore neither is the structure of space-time around it. Here we report high-resolution infrared observations of Sgr A* that reveal 'quiescent' emission and several flares. The infrared emission originates from within a few milliarcseconds of the black hole, and traces very energetic electrons or moderately hot gas within the innermost accretion region. Two flares exhibit a 17-minute quasi-periodic variability. If the periodicity arises from relativistic modulation of orbiting gas, the emission must come from just outside the event horizon, and the black hole must be rotating at about half of the maximum possible rate. PMID:14586462

  6. X-Ray Spectra from MHD Simulations of Accreting Black Holes

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy D.; Krolik, Julian H.; Noble, Scott C.

    2012-01-01

    We present the results of a new global radiation transport code coupled to a general relativistic magneto-hydrodynamic simulation of an accreting, nonrotating black hole. For the first time, we are able to explain from first principles in a self-consistent way the X-ray spectra observed from stellar-mass black holes, including a thermal peak, Compton reflection hump, power-law tail, and broad iron line. Varying only the mass accretion rate, we are able to reproduce the low/hard, steep power-law, and thermal-dominant states seen in most galactic black hole sources. The temperature in the corona is T(sub e) 10 keV in a boundary layer near the disk and rises smoothly to T(sub e) greater than or approximately 100 keV in low-density regions far above the disk. Even as the disk's reflection edge varies from the horizon out to approximately equal to 6M as the accretion rate decreases, we find that the shape of the Fe Ka line is remarkably constant. This is because photons emitted from the plunging region are strongly beamed into the horizon and never reach the observer. We have also carried out a basic timing analysis of the spectra and find that the fractional variability increases with photon energy and viewer inclination angle, consistent with the coronal hot spot model for X-ray fluctuations.

  7. Accretion Disks Around Binary Black Holes of Unequal Mass: GRMHD Simulations Near Decoupling

    NASA Technical Reports Server (NTRS)

    Gold, Roman; Paschalidis, Vasileios; Etienne, Zachariah B.; Shapiro, Stuart L.; Pfeiffer, Harald, P.

    2013-01-01

    We report on simulations in general relativity of magnetized disks onto black hole binaries. We vary the binary mass ratio from 1:1 to 1:10 and evolve the systems when they orbit near the binary disk decoupling radius. We compare (surface) density profiles, accretion rates (relative to a single, non-spinning black hole), variability, effective alpha-stress levels and luminosities as functions of the mass ratio. We treat the disks in two limiting regimes: rapid radiative cooling and no radiative cooling. The magnetic field lines clearly reveal jets emerging from both black hole horizons and merging into one common jet at large distances. The magnetic fields give rise to much stronger shock heating than the pure hydrodynamic flows, completely alter the disk structure, and boost accretion rates and luminosities. Accretion streams near the horizons are among the densest structures; in fact, the 1:10 no-cooling evolution results in a refilling of the cavity. The typical effective temperature in the bulk of the disk is approx. 10(exp5) (M / 10(exp 8)M solar mass (exp -1/4(L/L(sub edd) (exp 1/4K) yielding characteristic thermal frequencies approx. 10 (exp 15) (M /10(exp 8)M solar mass) (exp -1/4(L/L (sub edd) (1+z) (exp -1)Hz. These systems are thus promising targets for many extragalactic optical surveys, such as LSST, WFIRST, and PanSTARRS.

  8. SECULAR STELLAR DYNAMICS NEAR A MASSIVE BLACK HOLE

    SciTech Connect

    Madigan, Ann-Marie; Hopman, Clovis; Levin, Yuri

    2011-09-01

    The angular momentum evolution of stars close to massive black holes (MBHs) is driven by secular torques. In contrast to two-body relaxation, where interactions between stars are incoherent, the resulting resonant relaxation (RR) process is characterized by coherence times of hundreds of orbital periods. In this paper, we show that all the statistical properties of RR can be reproduced in an autoregressive moving average (ARMA) model. We use the ARMA model, calibrated with extensive N-body simulations, to analyze the long-term evolution of stellar systems around MBHs with Monte Carlo simulations. We show that for a single-mass system in steady state, a depression is carved out near an MBH as a result of tidal disruptions. Using Galactic center parameters, the extent of the depression is about 0.1 pc, of similar order to but less than the size of the observed 'hole' in the distribution of bright late-type stars. We also find that the velocity vectors of stars around an MBH are locally not isotropic. In a second application, we evolve the highly eccentric orbits that result from the tidal disruption of binary stars, which are considered to be plausible precursors of the 'S-stars' in the Galactic center. We find that RR predicts more highly eccentric (e > 0.9) S-star orbits than have been observed to date.

  9. Stars and (furry) black holes in Lorentz breaking massive gravity

    SciTech Connect

    Comelli, D.; Nesti, F.; Pilo, L.

    2011-04-15

    We study the exact spherically symmetric solutions in a class of Lorentz-breaking massive gravity theories, using the effective-theory approach where the graviton mass is generated by the interaction with a suitable set of Stueckelberg fields. We find explicitly the exact black-hole solutions which generalizes the familiar Schwarzschild one, which shows a nonanalytic hair in the form of a powerlike term r{sup {gamma}}. For realistic self-gravitating bodies, we find interesting features, linked to the effective violation of the Gauss law: (i) the total gravitational mass appearing in the standard 1/r term gets a multiplicative renormalization proportional to the area of the body itself; (ii) the magnitude of the powerlike hairy correction is also linked to size of the body. The novel features can be ascribed to the presence of the Goldstones fluid turned on by matter inside the body; its equation of state approaching that of dark energy near the center. The Goldstones fluid also changes the matter equilibrium pressure, leading to an upper limit for the graviton mass, m < or approx. 10{sup -28/29} eV, derived from the largest stable gravitational bound states in the Universe.

  10. Secular Stellar Dynamics near a Massive Black Hole

    NASA Astrophysics Data System (ADS)

    Madigan, Ann-Marie; Hopman, Clovis; Levin, Yuri

    2011-09-01

    The angular momentum evolution of stars close to massive black holes (MBHs) is driven by secular torques. In contrast to two-body relaxation, where interactions between stars are incoherent, the resulting resonant relaxation (RR) process is characterized by coherence times of hundreds of orbital periods. In this paper, we show that all the statistical properties of RR can be reproduced in an autoregressive moving average (ARMA) model. We use the ARMA model, calibrated with extensive N-body simulations, to analyze the long-term evolution of stellar systems around MBHs with Monte Carlo simulations. We show that for a single-mass system in steady state, a depression is carved out near an MBH as a result of tidal disruptions. Using Galactic center parameters, the extent of the depression is about 0.1 pc, of similar order to but less than the size of the observed "hole" in the distribution of bright late-type stars. We also find that the velocity vectors of stars around an MBH are locally not isotropic. In a second application, we evolve the highly eccentric orbits that result from the tidal disruption of binary stars, which are considered to be plausible precursors of the "S-stars" in the Galactic center. We find that RR predicts more highly eccentric (e > 0.9) S-star orbits than have been observed to date.

  11. Constraining the initial conditions and final outcomes of accretion processes around young stars and supermassive black holes

    NASA Astrophysics Data System (ADS)

    Stone, Jordan M.

    In this thesis I discuss probes of small spatial scales around young stars and protostars and around the supermassive black hole at the galactic center. I begin by describing adaptive optics-fed infrared spectroscopic studies of nascent and newborn binary systems. Binary star formation is a significant mode of star formation that could be responsible for the production of a majority of the galactic stellar population. Better characterization of the binary formation mechanism is important for better understanding many facets of astronomy, from proper estimates of the content of unresolved populations, to stellar evolution and feedback, to planet formation. My work revealed episodic accretion onto the more massive component of the pre-main sequence binary system UY Aur. I also showed changes in the accretion onto the less massive component, revealing contradictory indications of the change in accretion rate when considering disk-based and shock-based tracers. I suggested two scenarios to explain the inconsistency. First, increased accretion should alter the disk structure, puffing it up. This change could obscure the accretion shock onto the central star if the disk is highly inclined. Second, if accretion through the disk is impeded before it makes it all the way onto the central star, then increased disk tracers of accretion would not be accompanied by increased shock tracers. In this case mass must be piling up at some radius in the disk, possibly supplying the material for planet formation or a future burst of accretion. My next project focused on characterizing the atmospheres of very low-mass companions to nearby young stars. Whether these objects form in an extension of the binary-star formation mechanism to very low masses or they form via a different process is an open question. Different accretion histories should result in different atmospheric composition, which can be constrained with spectroscopy. I showed that 3--4mum spectra of a sample of these

  12. Detecting tidal disruption events of massive black holes in normal galaxies with the Einstein Probe

    NASA Astrophysics Data System (ADS)

    Yuan, W.; Komossa, S.; Zhang, C.; Feng, H.; Ling, Z.-X.; Zhao, D. H.; Zhang, S.-N.; Osborne, J. P.; O'Brien, P.; Willingale, R.; Lapington, J.; Lapington

    2016-02-01

    Stars are tidally disrupted and accreted when they approach massive black holes (MBHs) closely, producing a flare of electromagnetic radiation. The majority of the (approximately two dozen) tidal disruption events (TDEs) identified so far have been discovered by their luminous, transient X-ray emission. Once TDEs are detected in much larger numbers, in future dedicated transient surveys, a wealth of new applications will become possible. Here, we present the proposed Einstein Probe mission, which is a dedicated time-domain soft X-ray all-sky monitor aiming at detecting X-ray transients including TDEs in large numbers. The mission consists of a wide-field micro-pore Lobster-eye imager (60° × 60°), and is designed to carry out an all-sky transient survey at energies of 0.5-4 keV. It will also carry a more sensitive telescope for X-ray follow-ups, and will be capable of issuing public transient alerts rapidly. Einstein Probe is expected to revolutionise the field of TDE research by detecting several tens to hundreds of events per year from the early phase of flares, many with long-term, well sampled lightcurves.

  13. Hawking radiation of massive vector particles from the linear dilaton black holes

    NASA Astrophysics Data System (ADS)

    Li, Ran; Zhao, Junkun

    2016-07-01

    By using the tunneling formalism, we calculated the massive vector particles' Hawking radiation from the non-rotating and rotating linear dilaton black holes. By applying the WKB approximation to the Proca field equation that govern the dynamics of massive vector bosons, we derive the tunneling probabilities and radiation spectrums of the emitted vector particles from the linear dilaton black holes. The Hawking temperatures of the linear dilaton black holes have been recovered, which are consistent with the previous results in the literature. This means that the vector particles' tunneling method can also be used in studying the Hawking radiation of asymptotically non-flat and non-AdS black holes.

  14. Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Meléndez, M.; Veilleux, S.; Reeves, J. N.; González-Alfonso, E.; Reynolds, C. S.

    2015-03-01

    Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies. Recent observations of large-scale molecular outflows in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies and a few higher-redshift quasars. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity of 1.5 × 1046 ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism that is the basis of the quasar feedback in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows).

  15. Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy.

    PubMed

    Tombesi, F; Meléndez, M; Veilleux, S; Reeves, J N; González-Alfonso, E; Reynolds, C S

    2015-03-26

    Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies. Recent observations of large-scale molecular outflows in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies and a few higher-redshift quasars. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity of 1.5 × 10(46) ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism that is the basis of the quasar feedback in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows). PMID:25810204

  16. HEROIC: 3D general relativistic radiative post-processor with comptonization for black hole accretion discs

    NASA Astrophysics Data System (ADS)

    Narayan, Ramesh; Zhu, Yucong; Psaltis, Dimitrios; Saḑowski, Aleksander

    2016-03-01

    We describe Hybrid Evaluator for Radiative Objects Including Comptonization (HEROIC), an upgraded version of the relativistic radiative post-processor code HERO described in a previous paper, but which now Includes Comptonization. HEROIC models Comptonization via the Kompaneets equation, using a quadratic approximation for the source function in a short characteristics radiation solver. It employs a simple form of accelerated lambda iteration to handle regions of high scattering opacity. In addition to solving for the radiation field, HEROIC also solves for the gas temperature by applying the condition of radiative equilibrium. We present benchmarks and tests of the Comptonization module in HEROIC with simple 1D and 3D scattering problems. We also test the ability of the code to handle various relativistic effects using model atmospheres and accretion flows in a black hole space-time. We present two applications of HEROIC to general relativistic magnetohydrodynamics simulations of accretion discs. One application is to a thin accretion disc around a black hole. We find that the gas below the photosphere in the multidimensional HEROIC solution is nearly isothermal, quite different from previous solutions based on 1D plane parallel atmospheres. The second application is to a geometrically thick radiation-dominated accretion disc accreting at 11 times the Eddington rate. Here, the multidimensional HEROIC solution shows that, for observers who are on axis and look down the polar funnel, the isotropic equivalent luminosity could be more than 10 times the Eddington limit, even though the spectrum might still look thermal and show no signs of relativistic beaming.

  17. Star formation and black hole accretion activity in rich local clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Bianconi, Matteo; Marleau, Francine R.; Fadda, Dario

    2016-04-01

    Context. We present a study of star formation and central black hole accretion activity of galaxies that are hosted in the two nearby (z ~ 0.2) rich galaxy clusters Abell 983 and 1731. Aims: We aim to quantify both the obscured and unobscured star formation rates, as well as the presence of active galactic nuclei (AGN) as a function of the environment in which the galaxy is located. Methods: We targeted the clusters with unprecedented deep infrared Spitzer observations (0.2 mJy at 24 micron), near-IR Palomar imaging and optical WIYN spectroscopy. The extent of our observations (~3 virial radii) covers the vast range of possible environments, from the very dense cluster centre to the very rarefied cluster outskirts and accretion regions. Results: The star-forming members of the two clusters present star formation rates that are comparable with those measured in coeval field galaxies. Analysis of the spatial arrangement of the spectroscopically confirmed members reveals an elongated distribution for A1731 with respect to the more uniform distribution of A983. The emerging picture is compatible with A983 being a fully evolved cluster, in contrast with the still actively accreting A1731. Conclusions: Analysis of the specific star formation rate reveals evidence of ongoing galaxy pre-processing along A1731's filament-like structure. Furthermore, the decrease in the number of star-forming galaxies and AGN towards the cluster cores suggests that the cluster environment is accelerating the ageing process of the galaxies and blocking further accretion of the cold gas that fuels both star formation and black hole accretion activity. The catalogue and the reduced images (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A105

  18. Numerical simulation of the disk dynamics around the black hole: Bondi-Hoyle accretion

    NASA Astrophysics Data System (ADS)

    Koyuncu, Fahrettin; Dönmez, Orhan

    2014-06-01

    We have solved the General Relativistic Hydrodynamic (GRH) equations using the high resolution shock capturing scheme (HRSCS) to find out the dependency of the disk dynamics to the Mach number, adiabatic index, the black hole rotation parameter and the outer boundary of the computational domain around the non-rotating and rotating black holes. We inject the gas to computational domain at upstream and downstream regions at the same time with different initial conditions. It is found that variety of the mass accretion rates and shock cone structures strongly depend on Mach number and adiabatic index of the gas. The shock cones on the accretion disk are important physical mechanisms to trap existing oscillation modes, thereupon these trapped modes may generate strong X-rays observed by different X-ray satellites. Besides, our numerical approach also show that the shock cones produces the flip-flop oscillation around the black holes. The flip-flop instabilities which are monitored in our simulations may explain the erratic spin behavior of the compact objects (the black holes and neutron stars) seen from observed data.

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

    PubMed

    Miller, Jon M; Kaastra, Jelle S; Miller, M Coleman; Reynolds, Mark T; Brown, Gregory; Cenko, S Bradley; Drake, Jeremy J; Gezari, Suvi; Guillochon, James; Gultekin, Kayhan; Irwin, Jimmy; Levan, Andrew; Maitra, Dipankar; Maksym, W Peter; Mushotzky, Richard; O'Brien, Paul; Paerels, Frits; de Plaa, Jelle; Ramirez-Ruiz, Enrico; Strohmayer, Tod; Tanvir, Nial

    2015-10-22

    Tidal forces close to massive black holes can violently disrupt stars that make a close approach. These extreme events are discovered via bright X-ray and optical/ultraviolet flares in galactic centres. Prior studies based on modelling decaying flux trends have been able to estimate broad properties, such as the mass accretion rate. Here we report the detection of flows of hot, ionized gas in high-resolution X-ray spectra of a nearby tidal disruption event, ASASSN-14li in the galaxy PGC 043234. Variability within the absorption-dominated spectra indicates that the gas is relatively close to the black hole. Narrow linewidths indicate that the gas does not stretch over a large range of radii, giving a low volume filling factor. Modest outflow speeds of a few hundred kilometres per second are observed; these are below the escape speed from the radius set by variability. The gas flow is consistent with a rotating wind from the inner, super-Eddington region of a nascent accretion disk, or with a filament of disrupted stellar gas near to the apocentre of an elliptical orbit. Flows of this sort are predicted by fundamental analytical theory and more recent numerical simulations. PMID:26490619

  20. Accretion and Nuclear Activity of Quiescent Supermassive Black Holes. I. X-Ray Study

    NASA Astrophysics Data System (ADS)

    Soria, R.; Fabbiano, G.; Graham, Alister W.; Baldi, A.; Elvis, M.; Jerjen, H.; Pellegrini, S.; Siemiginowska, A.

    2006-03-01

    We have studied the nuclear activity in a sample of six quiescent early-type galaxies, with new Chandra data and archival HST optical images. Their nuclear sources have X-ray luminosities ~1038-1039 ergs s-1 (LX/LEdd~10-8 to 10-7) and colors or spectra consistent with accreting supermassive black holes (SMBHs), except for the nucleus of NGC 4486B, which is softer than typical AGN spectra. In a few cases, the X-ray morphology of the nuclear sources shows hints of marginally extended structures, in addition to the surrounding diffuse thermal emission from hot gas, which is detectable on scales >~1 kpc. In one case (NGC 5845), a dusty disk may partially obstruct our direct view of the SMBH. We have estimated the temperature and density of the hot interstellar medium, which is one major source of fuel for the accreting SMBH; typical central densities are ne~(0.02+/-0.01) cm-3. Assuming that the hot gas is captured by the SMBH at the Bondi rate, we show that the observed X-ray luminosities are too faint to be consistent with standard disk accretion, but brighter than predicted by radiatively inefficient solutions (e.g., advection-dominated accretion flows [ADAFs]). In total, there are ~20 galaxies for which SMBH mass, hot gas density, and nuclear X-ray luminosity are simultaneously known. In some cases, the nuclear sources are brighter than predicted by the ADAF model; in other cases, they are consistent or fainter. We discuss the apparent lack of correlations between Bondi rate and X-ray luminosity and suggest that, in order to understand the observed distribution, we need to know two additional parameters: the amount of gas supplied by the stellar population inside the accretion radius, and the fraction (possibly <<1) of the total gas available that is accreted by the SMBH. We leave a detailed study of these issues to a subsequent paper.

  1. The role of Compton heating in radiation-regulated accretion on to black holes

    NASA Astrophysics Data System (ADS)

    Park, KwangHo; Ricotti, Massimo; Di Matteo, Tiziana; Reynolds, Christopher S.

    2014-12-01

    We investigate the role of Compton heating in radiation-regulated accretion on to black holes (BHs) from a neutral dense medium using 1D radiation-hydrodynamic simulations. We focus on the relative effects of Compton-heating and photoheating as a function of the spectral slope α, assuming a power-law spectrum in the energy range of 13.6 eV-100 keV. While Compton heating is dominant only close to the BH, it can reduce the accretion rate to 0.1 (l ∝ dot{m}^2 model)-0.01 per cent (l ∝ dot{m} model) of the Bondi accretion rate when the BH radiation is hard (α ˜ 1), where l and dot{m} are the luminosity and accretion rate normalized by Eddington rates, respectively. The oscillatory behaviour otherwise typically seen in simulations with α > 1, become suppressed when α ˜ 1 only for the l ∝ dot{m} model. The relative importance of the Compton heating over photoheating decreases and the oscillatory behaviour becomes stronger as the spectrum softens. When the spectrum is soft (α > 1.5), photoheating prevails regardless of models making the effect of Compton heating negligible. On the scale of the ionization front, where the gas supply into the Strömgren sphere from large scale is regulated, photoheating dominates. Our simulations show consistent results with the advection-dominated accretion flow (l ∝ dot{m}^2) where the accretion is inefficient and the spectrum is hard (α ˜ 1).

  2. Accretion and Orbital Inspiral in Gas-assisted Supermassive Black Hole Binary Mergers

    NASA Astrophysics Data System (ADS)

    Rafikov, Roman R.

    2016-08-01

    Many galaxies are expected to harbor binary supermassive black holes (SMBHs) in their centers. Their interaction with the surrounding gas results in the accretion and exchange of angular momentum via tidal torques, facilitating binary inspiral. Here, we explore the non-trivial coupling between these two processes and analyze how the global properties of externally supplied circumbinary disks depend on the binary accretion rate. By formulating our results in terms of the angular momentum flux driven by internal stresses, we come up with a very simple classification of the possible global disk structures, which differ from the standard constant \\dot{M} accretion disk solution. The suppression of accretion by the binary tides, leading to a significant mass accumulation in the inner disk, accelerates binary inspiral. We show that once the disk region strongly perturbed by the viscously transmitted tidal torque exceeds the binary semimajor axis, the binary can merge in less than its mass-doubling time due to accretion. Thus, unlike the inspirals driven by stellar scattering, the gas-assisted merger can occur even if the binary is embedded in a relatively low-mass disk (lower than its own mass). This is important for resolving the “last parsec” problem for SMBH binaries and understanding powerful gravitational wave sources in the universe. We argue that the enhancement of accretion by the binary found in some recent simulations cannot persist for a long time and should not affect the long-term orbital inspiral. We also review existing simulations of SMBH binary–disk coupling and propose a numerical setup which is particularly well suited to verifying our theoretical predictions.

  3. Massive vector particles tunneling from Kerr and Kerr-Newman black holes

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Qian; Chen, Ge-Rui

    2015-12-01

    In this paper, we investigate the Hawking radiation of massive spin-1 particles from 4-dimensional Kerr and Kerr-Newman black holes. By applying the Hamilton-Jacobi ansatz and the WKB approximation to the field equations of the massive bosons in Kerr and Kerr-Newman space-time, the quantum tunneling method is successfully implemented. As a result, we obtain the tunneling rate of the emitted vector particles and recover the standard Hawking temperature of both the two black holes.

  4. Black Holes

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Koekemoer, Anton M.

    2011-02-01

    Participants; Preface Mario Livio and Anton Koekemoer; 1. Black holes, entropy, and information G. T. Horowitz; 2. Gravitational waves from black-hole mergers J. G. Baker, W. D. Boggs, J. M. Centrella, B. J. Kelley, S. T. McWilliams and J. R. van Meter; 3. Out-of-this-world physics: black holes at future colliders G. Landsberg; 4. Black holes in globular clusters S. L. W. McMillan; 5. Evolution of massive black holes M. Volonteri; 6. Supermassive black holes in deep multiwavelength surveys C. M. Urry and E. Treister; 7. Black-hole masses from reverberation mapping B. M. Peterson and M. C. Bentz; 8. Black-hole masses from gas dynamics F. D. Macchetto; 9. Evolution of supermassive black holes A. Müller and G. Hasinger; 10. Black-hole masses of distant quasars M. Vestergaard; 11. The accretion history of supermassive black holes K. Brand and the NDWFS Boötes Survey Teams; 12. Strong field gravity and spin of black holes from broad iron lines A. C. Fabian; 13. Birth of massive black-hole binaries M. Colpi, M. Dotti, L. Mayer and S. Kazantzidis; 14. Dynamics around supermassive black holes A. Gualandris and D. Merritt; 15. Black-hole formation and growth: simulations in general relativity S. L. Shapiro; 16. Estimating the spins of stellar-mass black holes J. E. McClintock, R. Narayan and R. Shafee; 17. Stellar relaxation processes near the Galactic massive black hole T. Alexander; 18. Tidal disruptions of stars by supermassive black holes S. Gezari; 19. Where to look for radiatively inefficient accretion flows in low-luminosity AGN M. Chiaberge; 20. Making black holes visible: accretion, radiation, and jets J. H. Krolik.

  5. Geometry of X-ray sources in accreting black-hole binaries

    NASA Astrophysics Data System (ADS)

    Zdziarski, Andrzej

    2016-07-01

    The structure of the X-ray sources in the hard spectral state of accreting black-hole binaries has been a subject of intense debate. The paradigm dominant for many years postulated that the accretion disc in the hard state is truncated at some radius >> the innermost stable orbit (ISCO) whereas the disc reaches the ISCO in the soft state. This paradigm explains a large body of observed phenomena, including the spectral and variability differences between the states and outbursts of transient sources, proceeding from quiescence (where no disc is present) through the hard state to the peak flux in the soft state. On the other hand, there have been numerous claims in recent years that the disc extends to the ISCO in the hard state. Also, the primary X-ray source has been postulated to consist of a compact source on-axis of the rotating black hole (a lamppost). Those claims are based on observations of broad Fe K lines and of soft X-ray components interpreted as blackbody-emitting accretion discs. I will discuss arguments for and against the disc truncation and the lamppost geometry based on current spectral and timing results.

  6. Accretion of dark energy onto higher dimensional charged BTZ black hole

    NASA Astrophysics Data System (ADS)

    Debnath, Ujjal

    2015-09-01

    In this work, we have studied the accretion of the (n+2)-dimensional charged BTZ black hole (BH). The critical point and square speed of sound have been obtained. The mass of the BTZ BH has been calculated and we have observed that the mass of the BTZ BH is related with the square root of the energy density of the dark energy which accretes onto the BH in our accelerating FRW universe. We have assumed modified Chaplygin gas (MCG) as a candidate of dark energy which accretes onto the BH and we have found the expression of BTZ BH mass. Since in our solution of MCG, this model generates only quintessence dark energy (not phantom) and so BTZ BH mass increases during the whole evolution of the accelerating universe. Next we have assumed five kinds of parametrizations of well-known dark-energy models. These models generate both quintessence and phantom scenarios i.e., phantom crossing models. So if these dark energies accrete onto the BTZ BH, then in the quintessence stage, the BH mass increases up to a certain value (finite value) and then decreases to a certain finite value for the phantom stage during the whole evolution of the universe. We have shown these results graphically.

  7. Numerical simulations of optically thick accretion onto a black hole. II. Rotating flow

    SciTech Connect

    Fragile, P. Chris; Olejar, Ally; Anninos, Peter

    2014-11-20

    In this paper, we report on recent upgrades to our general relativistic radiation magnetohydrodynamics code, Cosmos++, including the development of a new primitive inversion scheme and a hybrid implicit-explicit solver with a more general M {sub 1} closure relation for the radiation equations. The new hybrid solver helps stabilize the treatment of the radiation source terms, while the new closure allows for a much broader range of optical depths to be considered. These changes allow us to expand by orders of magnitude the range of temperatures, opacities, and mass accretion rates, and move a step closer toward our goal of performing global simulations of radiation-pressure-dominated black hole accretion disks. In this work, we test and validate the new method against an array of problems. We also demonstrate its ability to handle super-Eddington, quasi-spherical accretion. Even with just a single proof-of-principle simulation, we already see tantalizing hints of the interesting phenomenology associated with the coupling of radiation and gas in super-Eddington accretion flows.

  8. Effects of High-energy Particles on Accretion Flows onto a Supermassive Black Hole

    NASA Astrophysics Data System (ADS)

    Kimura, Shigeo S.; Toma, Kenji; Takahara, Fumio

    2014-08-01

    We study the effects of high-energy particles (HEPs) on the accretion flows onto a supermassive black hole and luminosities of escaping particles such as protons, neutrons, gamma rays, and neutrinos. We formulate a one-dimensional model of the two-component accretion flow consisting of thermal particles and HEPs, supposing that some fraction of the released energy is converted to the acceleration of HEPs. The thermal component is governed by fluid dynamics while the HEPs obey the moment equations of the diffusion-convection equation. By solving the time evolution of these equations, we obtain advection-dominated flows as the steady state solutions. The effects of the HEPs on the flow structures turn out to be small even if the pressure of the HEPs dominates over the thermal pressure. For a model in which the escaping protons take away almost all the energy released, the HEPs have a large enough influence to make the flow have a Keplerian angular velocity at the inner region. We calculate the luminosities of the escaping particles for these steady solutions. The escaping particles can extract the energy from about 10^{-4}\\dot{M} c^2 to 10^{-2}\\dot{M} c^2, where \\dot{M} is the mass accretion rate. The luminosities of the escaping particles depend on parameters such as the injection Lorentz factors, the mass accretion rates, and the diffusion coefficients. We also discuss some implications on the relativistic jet production by the escaping particles.

  9. MASSIVE BLACK HOLE PAIRS IN CLUMPY, SELF-GRAVITATING CIRCUMNUCLEAR DISKS: STOCHASTIC ORBITAL DECAY

    SciTech Connect

    Fiacconi, Davide; Mayer, Lucio; Roškar, Rok; Colpi, Monica

    2013-11-01

    We study the dynamics of massive black hole pairs in clumpy gaseous circumnuclear disks. We track the orbital decay of the light, secondary black hole M {sub .2} orbiting around the more massive primary at the center of the disk, using N-body/smoothed particle hydrodynamic simulations. We find that the gravitational interaction of M {sub .2} with massive clumps M {sub cl} erratically perturbs the otherwise smooth orbital decay. In close encounters with massive clumps, gravitational slingshots can kick the secondary black hole out of the disk plane. The black hole moving on an inclined orbit then experiences the weaker dynamical friction of the stellar background, resulting in a longer orbital decay timescale. Interactions between clumps can also favor orbital decay when the black hole is captured by a massive clump that is segregating toward the center of the disk. The stochastic behavior of the black hole orbit emerges mainly when the ratio M {sub .2}/M {sub cl} falls below unity, with decay timescales ranging from ∼1 to ∼50 Myr. This suggests that describing the cold clumpy phase of the interstellar medium in self-consistent simulations of galaxy mergers, albeit so far neglected, is important to predict the black hole dynamics in galaxy merger remnants.

  10. The formation and gravitational-wave detection of massive stellar black hole binaries

    SciTech Connect

    Belczynski, Krzysztof; Walczak, Marek; Buonanno, Alessandra; Cantiello, Matteo; Fryer, Chris L.; Holz, Daniel E.; Mandel, Ilya; Miller, M. Coleman

    2014-07-10

    If binaries consisting of two ∼100 M{sub ☉} black holes exist, they would serve as extraordinarily powerful gravitational-wave sources, detectable to redshifts of z ∼ 2 with the advanced LIGO/Virgo ground-based detectors. Large uncertainties about the evolution of massive stars preclude definitive rate predictions for mergers of these massive black holes. We show that rates as high as hundreds of detections per year, or as low as no detections whatsoever, are both possible. It was thought that the only way to produce these massive binaries was via dynamical interactions in dense stellar systems. This view has been challenged by the recent discovery of several ≳ 150 M{sub ☉} stars in the R136 region of the Large Magellanic Cloud. Current models predict that when stars of this mass leave the main sequence, their expansion is insufficient to allow common envelope evolution to efficiently reduce the orbital separation. The resulting black hole-black hole binary remains too wide to be able to coalesce within a Hubble time. If this assessment is correct, isolated very massive binaries do not evolve to be gravitational-wave sources. However, other formation channels exist. For example, the high multiplicity of massive stars, and their common formation in relatively dense stellar associations, opens up dynamical channels for massive black hole mergers (e.g., via Kozai cycles or repeated binary-single interactions). We identify key physical factors that shape the population of very massive black hole-black hole binaries. Advanced gravitational-wave detectors will provide important constraints on the formation and evolution of very massive stars.

  11. General-relativistic magnetohydrodynamics simulations of black hole accretion disks: Dynamics and radiative properties

    NASA Astrophysics Data System (ADS)

    Shiokawa, Hotaka

    The goal of the series of studies in this thesis is to understand the black hole accretion process and predict its observational properties. The highly non-linear process involves a turbulent magnetized plasma in a general relativistic regime, thus making it hard to study analytically. We use numerical simulations, specifically general relativistic magnetohydrodynamics (GRMHD), to construct a realistic dynamical and radiation model of accretion disks. Our simulations are for black holes in low luminous regimes that probably possesses a hot and thick accretion disk. Flows in this regime are called radiatively inefficient accretion flows (RIAF). The most plausible mechanism for transporting angular momentum is turbulence induced by magnetorotational instability (MRI). The RIAF model has been used to model the supermassive black hole at the center of our Milky Way galaxy, Sagittarius A* (Sgr A*). Owing to its proximity, rich observational data of Sgr A* is available to compare with the simulation results. We focus mainly on four topics. First, we analyse numerical convergence of 3D GRMHD global disk simulations. Convergence is one of the essential factors in deciding quantitative outcomes of the simulations. We analyzed dimensionless shell-averaged quantities such as plasma beta, the azimuthal correlation length (angle) of fluid variables, and spectra of the source for four different resolutions. We found that all the variables converged with the highest resolution (384x384x256 in radial, poloidal, and azimuthal directions) except the magnetic field correlation length. It probably requires another factor of 2 in resolution to achieve convergence. Second, we studied the effect of equation of state on dynamics of GRMHD simulation and radiative transfer. Temperature of RIAF gas is high, and all the electrons are relativistic, but not the ions. In addition, the dynamical time scale of the accretion disk is shorter than the collisional time scale of electrons and ions

  12. Rapid variability as a probe of warped space-time around accreting black holes

    NASA Astrophysics Data System (ADS)

    Axelsson, Magnus

    2016-07-01

    The geometry of the inner accretion flow of X-ray binaries is complex, with multiple regions contributing to the observed emission. Frequency-resolved spectroscopy is a powerful tool in breaking this spectral degeneracy. We have extracted the spectra of the strong low-frequency quasi-periodic oscillation (QPO) and its harmonic in GX339-4 and XTE J1550-564, and compare these to the time-averaged spectrum and the spectrum of the rapid (<0.1 s) variability. Our results support the picture where the QPO arises from vertical (Lense-Thirring) precession of an inhomogeneous hot flow, softer at larger radii closer to the truncated disc and harder in the innermost parts where the rapid variability is produced. This coupling between variability and spectra allows us to constrain the soft Comptonization component, breaking the degeneracy plaguing the time-averaged spectrum and revealing the geometry of the accretion flow close to the black hole.

  13. Simulations of flux variability of oscillating accretion fluid tori around Kerr black holes

    NASA Astrophysics Data System (ADS)

    Bakala, Pavel; Goluchová, Kateřina; Šrámková, Eva; Kotrlová, Andrea; Török, Gabriel; Vincent, Frederic H.; Abramowicz, Marek A.

    2015-03-01

    High frequency quasi-periodic oscillations (HF QPOs) are observed in the X-ray power-density spectra (PDS) of several microquasars and low mass X-ray binaries. Many proposed QPO models are based on oscillations of accretion toroidal fluid structures orbiting in the vicinity of a compact object. We study oscillating accretion tori orbiting in the vicinity of a Kerr black hole. We demonstrate that significant variation of the observed flux can be caused by the combination of radial and vertical oscillation modes of a slender, polytropic, perfect fluid, non-self-graviting torus with constant specific angular momentum. We investigate two combinations of the oscillating modes corresponding to the direct resonance QPO model and the modified relativistic precession QPO model.

  14. X-Ray Spectra from MHD Simulations of Accreting Black Holes

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy D.; Noble, Scott C.; Krolik, Julian H.

    2011-01-01

    We present new global calculations of X-ray spectra from fully relativistic magneto-hydrodynamic (MHO) simulations of black hole (BH) accretion disks. With a self consistent radiative transfer code including Compton scattering and returning radiation, we can reproduce the predominant spectral features seen in decades of X-ray observations of stellar-mass BHs: a broad thermal peak around 1 keV, power-law continuum up to >100 keV, and a relativistically broadened iron fluorescent line. By varying the mass accretion rate, different spectral states naturally emerge: thermal-dominant, steep power-law, and low/hard. In addition to the spectral features, we briefly discuss applications to X-ray timing and polarization.

  15. Numerical Simulations of Accretion Flows, Jets, and Winds Around Black Holes

    NASA Astrophysics Data System (ADS)

    Narayan, Ramesh

    Accretion flows around black holes in X-ray binaries, active galactic nuclei and gamma- ray bursts are highly relativistic. This is especially true of the inner regions of these flows where the accreting gas comes close to the black hole and from where relativistic jets are launched. Understanding the properties of black holes and the effects of their associated relativistic ejections on their environment is a central goal of NASA's Astrophysics Theory program. We propose to carry out three-dimensional time-dependent numerical simulations, as well as analytical studies, focusing on two main problems: quantitatively studying the feedback effects of winds and jets ejected from AGN accretion flows on their environment, and pinning down the validity of the standard model of thin black-hole accretion disks by Novikov & Thorne (1973, NT). The PI and his team possess general relativistic magnetohydrodynamics (GRMHD) codes which are uniquely suited for simulating fully relativistic highly magnetized flows. These codes will be used to perform the following tasks: (1) To study the validity of the NT model in the region inside the innermost stable circular orbit (ISCO). On the one hand, simulations for a range of black hole spin values will be performed, in order to find the errors in spin estimates, obtained using the NT model, of black holes in X-ray binaries. On the other hand, we will look for an improved disk model using our simulation results. (2) Large-dynamic-range simulations of advection-dominated accretion flows (ADAFs) for a range of black hole spin values, to understand (i) the mass, energy and momentum output of winds and jets, which is important for understanding feedback effects on galaxy formation, and cooling flows; (ii) the relative importance of feedback through a relativistic jet versus a non-relativistic wind; and (iii) the effect of ADAF disk winds on jet collimation. The proposed research will be done by postdoctoral fellow Dr. Akshay Kulkarni and

  16. Microlensing of sub-parsec massive binary black holes in lensed QSOs: Light curves and size-wavelength relation

    SciTech Connect

    Yan, Chang-Shuo; Lu, Youjun; Mao, Shude; Yu, Qingjuan; Wambsganss, Joachim E-mail: luyj@nao.cas.cn

    2014-04-01

    Sub-parsec binary massive black holes (BBHs) have long been thought to exist in many QSOs but remain observationally elusive. In this paper, we propose a novel method to probe sub-parsec BBHs through microlensing of lensed QSOs. If a QSO hosts a sub-parsec BBH in its center, it is expected that the BBH is surrounded by a circumbinary disk, each component of the BBH is surrounded by a small accretion disk, and a gap is opened by the secondary component in between the circumbinary disk and the two small disks. Assuming such a BBH structure, we generate mock microlensing light curves for some QSO systems that host BBHs with typical physical parameters. We show that microlensing light curves of a BBH QSO system at the infrared-optical-UV bands can be significantly different from those of corresponding QSO system with a single massive black hole (MBH), mainly because of the existence of the gap and the rotation of the BBH (and its associated small disks) around the center of mass. We estimate the half-light radii of the emission region at different wavelengths from mock light curves and find that the obtained half-light radius versus wavelength relations of BBH QSO systems can be much flatter than those of single MBH QSO systems at a wavelength range determined by the BBH parameters, such as the total mass, mass ratio, separation, accretion rates, etc. The difference is primarily due to the existence of the gap. Such unique features on the light curves and half-light radius-wavelength relations of BBH QSO systems can be used to select and probe sub-parsec BBHs in a large number of lensed QSOs to be discovered by current and future surveys, including the Panoramic Survey Telescope and Rapid Response System, the Large Synoptic Survey telescope, and Euclid.

  17. X-ray Spectra from GRMHD Simulations of Accreting Black Holes

    NASA Astrophysics Data System (ADS)

    Schnittman, Jeremy; Noble, Scott; Krolik, Julian H.; Kinch, Brooks

    2016-04-01

    We present the results of a global radiation transport code coupled to general relativistic magnetohydrodynamic (GRMHD) simulations of accreting black holes. For the first time, we are able to explain from first principles in a self-consistent way all the components seen in the X-ray spectra of stellar-mass black holes, including a thermal peak and all the features associated with strong hard X-ray emission: a power law extending to high energies, a Compton reflection hump, and a broad iron line. Varying only the mass accretion rate, we are able to reproduce a wide range of X-ray states seen in most galactic black hole sources. The temperature in the corona is Te ~ 10 keV in a boundary layer near the disk and rises smoothly to Te >~ 100 keV in low-density regions far above the disk. We self-consistently solve for the ionization state of gas in each vertical column of the disk, in turn giving iron fluorescent emissivity profile.

  18. ON THE ROLE OF FAST MAGNETIC RECONNECTION IN ACCRETING BLACK HOLE SOURCES

    SciTech Connect

    Singh, C. B.; De Gouveia Dal Pino, E. M.; Kadowaki, L. H. S. E-mail: dalpino@iag.usp.br

    2015-01-30

    We attempt to explain the observed radio and gamma-ray emission produced in the surroundings of black holes by employing a magnetically dominated accretion flow model and fast magnetic reconnection triggered by turbulence. In earlier work, a standard disk model was used and we refine the model by focusing on the sub-Eddington regime to address the fundamental plane of black hole activity. The results do not change substantially with regard to previous work, ensuring that the details of accretion physics are not relevant in the magnetic reconnection process occurring in the corona. Rather, our work puts fast magnetic reconnection events as a powerful mechanism operating in the core region near the jet base of black hole sources on more solid ground. For microquasars and low-luminosity active galactic nuclei, the observed correlation between radio emission and the mass of the sources can be explained by this process. The corresponding gamma-ray emission also seems to be produced in the same core region. On the other hand, emission from blazars and gamma-ray bursts cannot be correlated to core emission based on fast reconnection.

  19. Physical properties of the inner shocks in hot, tilted black hole accretion flows

    SciTech Connect

    Generozov, Aleksey; Blaes, Omer; Fragile, P. Chris; Henisey, Ken B.

    2014-01-01

    Simulations of hot, pressure-supported, tilted black hole accretion flows, in which the angular momentum of the flow is misaligned with the black hole spin axis, can exhibit two nonaxisymmetric shock structures in the inner regions of the flow. We analyze the strength and significance of these shock structures in simulations with tilt angles of 10° and 15°. By integrating fluid trajectories in the simulations through the shocks and tracking the variations of fluid quantities along these trajectories, we show that these shocks are strong, with substantial compression ratios, in contrast to earlier claims. However, they are only moderately relativistic. We also show that the two density enhancements resembling flow streams in their shape are in fact merely post-shock compressions, as fluid trajectories cut across, rather than flow along, them. The dissipation associated with the shocks is a substantial fraction (≅ 3%-12%) of the rest mass energy advected into the hole, and therefore comparable to the dissipation expected from turbulence. The shocks should therefore make order unity changes in the observed properties of black hole accretion flows that are tilted.

  20. Massive vector particles tunneling from noncommutative charged black holes and their GUP-corrected thermodynamics

    NASA Astrophysics Data System (ADS)

    Övgün, Ali; Jusufi, Kimet

    2016-05-01

    In this paper, we investigate the tunneling process of charged massive bosons W^{±} (spin-1 particles) from noncommutative charged black holes such as charged RN black holes and charged BTZ black holes. By applying the WKB approximation and by using the Hamilton-Jacobi equation we derive the tunneling rate and the corresponding Hawking temperature for those black holes configuration. Furthermore, we show the quantum gravity effects using the GUP on the Hawking temperature for the noncommutative RN black holes. The tunneling rate shows that the radiation deviates from pure thermality and is consistent with an underlying unitary theory.

  1. A connection between accretion state and Fe K absorption in an accreting neutron star: black hole-like soft-state winds?

    NASA Astrophysics Data System (ADS)

    Ponti, Gabriele; Muñoz-Darias, Teodoro; Fender, Robert P.

    2014-10-01

    High-resolution X-ray spectra of accreting stellar-mass black holes reveal the presence of accretion disc winds, traced by high-ionization Fe K lines. These winds appear to have an equatorial geometry and to be observed only during disc-dominated states in which the radio jet is absent. Accreting neutron star systems also show equatorial high-ionization absorbers. However, the presence of any correlation with the accretion state has not been previously tested. We have studied EXO 0748-676, a transient neutron star system, for which we can reliably determine the accretion state, in order to investigate the Fe K absorption/accretion state/jet connection. Not one of 20 X-ray spectra obtained in the hard state revealed any significant Fe K absorption line. However, intense Fe XXV and Fe XXVI (as well as a rarely observed Fe XXIII line plus S XVI; a blend of S XVI and Ar XVII; Ca XX and Ca XIX, possibly produced by the same high-ionization material) absorption lines (EW_{Fe {XXIII-XXV}}=31± 3, EW_{Fe {XXVI}}=8± 3 eV) are clearly detected during the only soft-state observation. This suggests that the connection between Fe K absorption and states (and anticorrelation between the presence of Fe K absorption and jets) is also valid for EXO 0748-676 and therefore it is not a unique property of black hole systems but a more general characteristic of accreting sources.

  2. Evidence for a solar system-size accretion disk around the massive protostar G192.16-3.82.

    PubMed

    Shepherd, D S; Claussen, M J; Kurtz, S E

    2001-05-25

    Seven-millimeter continuum observations of a massive bipolar outflow source, G192.16-3.82, were made at a milli-arc-second resolution with a capability that links the National Radio Astronomy Observatory's Very Large Array radio interferometer with the Very Long Baseline Array antenna, located in Pie Town, New Mexico. The observations provide evidence for a true accretion disk that is about the size of our solar system and located around a massive star. A model of the radio emission suggests the presence of a binary protostellar system. The primary protostar, G192 S1, at the center of the outflow, with a protostar mass of about 8 to 10 times the solar mass, is surrounded by an accretion disk with a diameter of 130 astronomical units (AU). The mass of the disk is on the order of the protostar mass. The outflow is poorly collimated with a full opening angle of about 40 degrees; there is no indication of a more highly collimated jetlike component. The companion source, G192 S2, is located 80 AU north of the primary source. PMID:11375484

  3. X-RAY SPECTRA FROM MAGNETOHYDRODYNAMIC SIMULATIONS OF ACCRETING BLACK HOLES

    SciTech Connect

    Schnittman, Jeremy D.; Krolik, Julian H.; Noble, Scott C. E-mail: jhk@pha.jhu.edu

    2013-06-01

    We present the results of a new global radiation transport code coupled to a general relativistic magnetohydrodynamic simulation of an accreting, non-rotating black hole. For the first time, we are able to explain from first principles in a self-consistent way all the components seen in the X-ray spectra of stellar-mass black holes, including a thermal peak and all the features associated with strong hard X-ray emission: a power law extending to high energies, a Compton reflection hump, and a broad iron line. Varying only the mass accretion rate, we are able to reproduce a wide range of X-ray states seen in most galactic black hole sources. The temperature in the corona is T{sub e} {approx} 10 keV in a boundary layer near the disk and rises smoothly to T{sub e} {approx}> 100 keV in low-density regions far above the disk. Even as the disk's reflection edge varies from the horizon out to Almost-Equal-To 6M as the accretion rate decreases, we find that the shape of the Fe K{alpha} line is remarkably constant. This is because photons emitted from the plunging region are strongly beamed into the horizon and never reach the observer. We have also carried out a basic timing analysis of the spectra and find that the fractional variability increases with photon energy and viewer inclination angle, consistent with the coronal hot spot model for X-ray fluctuations.

  4. ON THE ROLE OF THE ACCRETION DISK IN BLACK HOLE DISK-JET CONNECTIONS

    SciTech Connect

    Miller, J. M.; Reis, R. C.; Pooley, G. G.; Fabian, A. C.; Cackett, E. M.; Nowak, M. A.; Pottschmidt, K.; Wilms, J.

    2012-09-20

    Models of jet production in black hole systems suggest that the properties of the accretion disk-such as its mass accretion rate, inner radius, and emergent magnetic field-should drive and modulate the production of relativistic jets. Stellar-mass black holes in the 'low/hard' state are an excellent laboratory in which to study disk-jet connections, but few coordinated observations are made using spectrometers that can incisively probe the inner disk. We report on a series of 20 Suzaku observations of Cygnus X-1 made in the jet-producing low/hard state. Contemporaneous radio monitoring was done using the Arcminute MicroKelvin Array radio telescope. Two important and simple results are obtained: (1) the jet (as traced by radio flux) does not appear to be modulated by changes in the inner radius of the accretion disk and (2) the jet is sensitive to disk properties, including its flux, temperature, and ionization. Some more complex results may reveal aspects of a coupled disk-corona-jet system. A positive correlation between the reflected X-ray flux and radio flux may represent specific support for a plasma ejection model of the corona, wherein the base of a jet produces hard X-ray emission. Within the framework of the plasma ejection model, the spectra suggest a jet base with v/c {approx_equal} 0.3 or the escape velocity for a vertical height of z {approx_equal} 20 GM/c {sup 2} above the black hole. The detailed results of X-ray disk continuum and reflection modeling also suggest a height of z {approx_equal} 20 GM/c {sup 2} for hard X-ray production above a black hole, with a spin in the range 0.6 {<=} a {<=} 0.99. This height agrees with X-ray time lags recently found in Cygnus X-1. The overall picture that emerges from this study is broadly consistent with some jet-focused models for black hole spectral energy distributions in which a relativistic plasma is accelerated at z = 10-100 GM/c {sup 2}. We discuss these results in the context of disk-jet connections

  5. Formation of the black-hole binary M33 X-7 through mass exchange in a tight massive system.

    PubMed

    Valsecchi, Francesca; Glebbeek, Evert; Farr, Will M; Fragos, Tassos; Willems, Bart; Orosz, Jerome A; Liu, Jifeng; Kalogera, Vassiliki

    2010-11-01

    The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65M(⊙) black hole orbiting an underluminous, 70M(⊙) main-sequence companion in a slightly eccentric 3.45-day orbit (M(⊙), solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85M(⊙)-99M(⊙) and a secondary body of 28M(⊙)-32M(⊙), in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ∼16M(⊙) helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, 'kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal. PMID:20962778

  6. Formation of the black-hole binary M33 X-7 through mass exchange in a tight massive system

    NASA Astrophysics Data System (ADS)

    Valsecchi, Francesca; Glebbeek, Evert; Farr, Will M.; Fragos, Tassos; Willems, Bart; Orosz, Jerome A.; Liu, Jifeng; Kalogera, Vassiliki

    2010-11-01

    The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65Msolar black hole orbiting an underluminous, 70Msolar main-sequence companion in a slightly eccentric 3.45-day orbit (Msolar, solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85Msolar-99Msolar and a secondary body of 28Msolar-32Msolar, in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ~16Msolar helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, `kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal.

  7. General Relativistic Magnetohydrodynamic Simulations of Jets from Black Hole Accretions Disks: Two-Component Jets Driven by Nonsteady Accretion of Magnetized Disks

    NASA Astrophysics Data System (ADS)

    Koide, Shinji; Shibata, Kazunari; Kudoh, Takahiro

    1998-03-01

    The radio observations have revealed the compelling evidence of the existence of relativistic jets not only from active galactic nuclei but also from ``microquasars'' in our Galaxy. In the cores of these objects, it is believed that a black hole exists and that violent phenomena occur in the black hole magnetosphere, forming the relativistic jets. To simulate the jet formation in the magnetosphere, we have newly developed the general relativistic magnetohydrodynamic code. Using the code, we present a model of these relativistic jets, in which magnetic fields penetrating the accretion disk around a black hole play a fundamental role of inducing nonsteady accretion and ejection of plasmas. According to our simulations, a jet is ejected from a close vicinity to a black hole (inside 3rS, where rS is the Schwarzschild radius) at a maximum speed of ~90% of the light velocity (i.e., a Lorentz factor of ~2). The jet has a two-layered shell structure consisting of a fast gas pressure-driven jet in the inner part and a slow magnetically driven jet in the outer part, both of which are collimated by the global poloidal magnetic field penetrating the disk. The former jet is a result of a strong pressure increase due to shock formation in the disk through fast accretion flow (``advection-dominated disk'') inside 3rS, which has never been seen in the nonrelativistic calculations.

  8. Event Rate for LISA Gravitational Wave Signals from Black Hole-Massive Black Hole Coalescences

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.; Salamon, Michael H. (Technical Monitor)

    2002-01-01

    Earlier work under a previous grant had been mainly on investigating the event rate for coalescences of white dwarfs or neutron stars with massive black holes (MBHs) in galactic nuclei. Under the new grant, two studies were undertaken. One was an approximate extension of the earlier study to stellar mass black holes as the lighter object, with masses in the range of roughly 3 to 20 M_sun, rather than about 1 M_sun. The other was an improved estimate of the confusion noise due to galactic binaries against which the signals from BH-MDH coalescences would have to be detected. In the earlier work, the mass of the white dwarfs (WDs) and neutron stars (NSs) was assumed to be about the same as that of the unevolved stars in the density cusp around the galactic center MBH. However, with the BH mass being substantially larger, the sinking down of BHs toward the center (mass segregation) became important and was included in the model. A single representative mass of 7 M_sun was used.

  9. MEASURING MASS ACCRETION RATE ONTO THE SUPERMASSIVE BLACK HOLE IN M87 USING FARADAY ROTATION MEASURE WITH THE SUBMILLIMETER ARRAY

    SciTech Connect

    Kuo, C. Y.; Asada, K.; Rao, R.; Nakamura, M.; Algaba, J. C.; Liu, H. B.; Inoue, M.; Koch, P. M.; Ho, P. T. P.; Matsushita, S.; Pu, H.-Y.; Nishioka, H.; Pradel, N.; Akiyama, K.

    2014-03-10

    We present the first constraint on the Faraday rotation measure (RM) at submillimeter wavelengths for the nucleus of M87. By fitting the polarization position angles (χ) observed with the Submillimeter Array at four independent frequencies around ∼230 GHz and interpreting the change in χ as a result of external Faraday rotation associated with accretion flow, we determine the RM of the M87 core to be between –7.5 × 10{sup 5} and 3.4 × 10{sup 5} rad m{sup –2}. Assuming a density profile of the accretion flow that follows a power-law distribution and a magnetic field that is ordered, radial, and has equipartition strength, the limit on the RM constrains the mass accretion rate M-dot to be below 9.2 × 10{sup –4} M {sub ☉} yr{sup –1} at a distance of 21 Schwarzschild radii from the central black hole. This value is at least two orders of magnitude smaller than the Bondi accretion rate, suggesting significant suppression of the accretion rate in the inner region of the accretion flow. Consequently, our result disfavors the classical advection-dominated accretion flow and prefers the adiabatic inflow-outflow solution or convection-dominated accretion flow for the hot accretion flow in M87.

  10. Mergers of Magnetized Neutron Stars with Spinning Black Holes: Disruption, Accretion, and Fallback

    NASA Astrophysics Data System (ADS)

    Chawla, Sarvnipun; Anderson, Matthew; Besselman, Michael; Lehner, Luis; Liebling, Steven L.; Motl, Patrick M.; Neilsen, David

    2010-09-01

    We investigate the merger of a neutron star in orbit about a spinning black hole in full general relativity with a mass ratio of 5∶1, allowing the star to have an initial magnetization of 1012G. We present the resulting gravitational waveform and analyze the fallback accretion as the star is disrupted. We see no significant dynamical effects in the simulations or changes in the gravitational waveform resulting from the initial magnetization. We find that only a negligible amount of matter becomes unbound; 99% of the neutron star material has a fallback time of 10 seconds or shorter to reach the region of the central engine and that 99.99% of the star will interact with the central disk and black hole within 3 hours.

  11. Testing propagating mass accretion rate fluctuations model PROPFLUC on black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Rapisarda, S.; Ingram, A.; van der Klis, M.

    2016-05-01

    Over the past 20 years, a consistent phenomenology has been established to describe the variability properties of black hole X-ray binaries. However, the physics behind the observational data is still poorly understood. The recently proposed model PROPFLUC assumes a truncated disc/hot inner flow geometry, with mass accretion rate fluctuations propagating through a precessing inner flow. These two processes give rise respectively to broad band variability and a quasi-periodic oscillation (QPO) on the precession frequency. We recently applied systematically for the first time PROPFLUC on a black hole candidate (MAXI J1543-564) in order to compare the results of phenomenological and physical modeling of the source power spectrum and to give a physical interpretation of the rising phase of the source outburst. Here we resume the results of our study on MAXI J1543-564 and we discuss future PROPFLUC implementations.

  12. Mergers of magnetized neutron stars with spinning black holes: disruption, accretion, and fallback.

    PubMed

    Chawla, Sarvnipun; Anderson, Matthew; Besselman, Michael; Lehner, Luis; Liebling, Steven L; Motl, Patrick M; Neilsen, David

    2010-09-10

    We investigate the merger of a neutron star in orbit about a spinning black hole in full general relativity with a mass ratio of 5:1, allowing the star to have an initial magnetization of 10(12)  G. We present the resulting gravitational waveform and analyze the fallback accretion as the star is disrupted. We see no significant dynamical effects in the simulations or changes in the gravitational waveform resulting from the initial magnetization. We find that only a negligible amount of matter becomes unbound; 99% of the neutron star material has a fallback time of 10 seconds or shorter to reach the region of the central engine and that 99.99% of the star will interact with the central disk and black hole within 3 hours. PMID:20867561

  13. Relativistic Outflows from Advection-dominated Accretion Disks around Black Holes

    NASA Astrophysics Data System (ADS)

    Subramanian, P.; Becker, P. A.

    1999-05-01

    Advection dominated accretion flows have been recently proposed as attractive models for explaining low luminosity black hole systems. However, the so-called ADAF models suffer from a serious drawback; namely, the accretion flow has a postive Bernoulli parameter, and is therefore gravitationally unbound. Blandford & Begelman (1999, MNRAS) recently proposed advection-dominated flows that incorporate an outflow that carries away an appreciable amount of mass, energy and angular momentum (ADIOS), thereby alleviating this problem. However, their solutions merely assume the existence of such outflows, and do not elaborate on the mechanisms that could drive them. Subramanian, Becker & Kazanas (1999, ApJ, astro-ph/9805044) have described a mechanism whereby particles are accelerated via collisions with magnetic scattering centers (kinks in the tangled magnetic field) embedded in the accreting plasma and form relativistic outflows. We examine the role of this mechanism in the context of Blandford & Begelman's ADIOS solutions with a view to elucidating the physical processes that drive the outflows, which in turn are a crucial component of the overall solution.

  14. Revealing the inner accretion flow around black holes using rapid variability

    NASA Astrophysics Data System (ADS)

    Axelsson, Magnus

    2015-08-01

    The geometry of the inner accretion flow of X-ray binaries is complex, with multiple regions contributing to the observed emission. Frequency-resolved spectroscopy is a powerful tool in breaking this spectral degeneracy. We have extracted the spectra of the strong low-frequency quasi-periodic oscillation (QPO) and its harmonic in GX339-4 and XTE J1550-564. We compare these to the time-averaged spectrum and the spectrum of the rapid (< 0.1s) variability. Our results support the picture where the QPO arises from vertical (Lense-Thirring) precession of an inhomogeneous hot flow, so that it is softer at larger radii closer to the truncated disc, and harder in the innermost parts of the flow where the rapid variability is produced. This coupling between variability and spectra allows us to constrain the soft Comptonization component, breaking the degeneracy plaguing the time-averaged spectrum and revealing the geometry of the accretion flow close to the black hole. We further show how the upcoming launch of ASTRO-H will allow even more specific regions in the accretion flow to be probed.

  15. Outflows from accretion discs formed in neutron star mergers: effect of black hole spin

    NASA Astrophysics Data System (ADS)

    Fernández, Rodrigo; Kasen, Daniel; Metzger, Brian D.; Quataert, Eliot

    2015-01-01

    The accretion disc that forms after a neutron star merger is a source of neutron-rich ejecta. The ejected material contributes to a radioactively powered electromagnetic transient, with properties that depend sensitively on the composition of the outflow. Here, we investigate how the spin of the black hole (BH) remnant influences mass ejection on the thermal and viscous time-scales. We carry out two-dimensional, time-dependent hydrodynamic simulations of merger remnant accretion discs including viscous angular momentum transport and approximate neutrino self-irradiation. The gravity of the spinning BH is included via a pseudo-Newtonian potential. We find that a disc around a spinning BH ejects more mass, up to a factor of several, relative to the non-spinning case. The enhanced mass-loss is due to energy release by accretion occurring deeper in the gravitational potential, raising the disc temperature and hence the rate of viscous heating in regions where neutrino cooling is ineffective. The mean electron fraction of the outflow increases moderately with BH spin due to a highly irradiated (though not neutrino-driven) wind component. While the bulk of the ejecta is still very neutron-rich, thus generating heavy r-process elements, the leading edge of the wind contains a small amount of Lanthanide-free material. This component can give rise to an ≲1 d blue optical `bump' in a kilonova light curve, even in the case of prompt BH formation, which may facilitate its detection.

  16. The Properties of Low-Luminosity AGN: Variability, Accretion Rate, Black Hole Mass and Color

    NASA Astrophysics Data System (ADS)

    Oleas, Juan; Podjed, Stephanie; Sarajedini, Vicki

    2016-01-01

    We present the results from a study of ~5000 Broad-Line selected AGN from the Sloan Digital Sky Survey DR7. Galaxy and AGN templates have been fit to the SDSS spectra to isolate the AGN component. The sources have absolute magnitudes in the range -23 < Mi < -18 and lie at redshifts less than z ~ 0.8. A variability analysis reveals that the anti-correlation between luminosity and variability amplitude continues to the faintest AGN in our sample (Gallastegui-Aizpun & Sarajedini 2014), though the underlying cause of the relation is still poorly understood. To address this, we further explore the connection between AGN luminosity and variability through measurement of the Hβ line width to determine black hole mass and accretion rate. We find that AGN with the highest variability amplitudes at a given luminosity appear to have lower accretion rates compared to low amplitude variables. We also investigate correlations with AGN color and accretion rate among these low-luminosity AGN.

  17. Anomalies and Hawking fluxes from the black holes of topologically massive gravity

    NASA Astrophysics Data System (ADS)

    Porfyriadis, Achilleas P.

    2009-05-01

    The anomaly cancelation method proposed by Wilczek et al. is applied to the black holes of topologically massive gravity (TMG) and topologically massive gravito-electrodynamics (TMGE). Thus the Hawking temperature and fluxes of the ACL and ACGL black holes are found. The Hawking temperatures obtained agree with the surface gravity formula. Both black holes are rotating and this gives rise to appropriate terms in the effective U (1) gauge field of the reduced (1 + 1)-dimensional theory. It is found that the terms in this U (1) gauge field correspond exactly to the correct angular velocities on the horizon of both black holes as well as the correct electrostatic potential of the ACGL black hole. So the results for the Hawking fluxes derived here from the anomaly cancelation method, are in complete agreement with the ones obtained from integrating the Planck distribution.

  18. Steady-state Relativistic Stellar Dynamics Around a Massive Black hole

    NASA Astrophysics Data System (ADS)

    Bar-Or, Ben; Alexander, Tal

    2016-04-01

    A massive black hole (MBH) consumes stars whose orbits evolve into the small phase-space volume of unstable orbits, the “loss cone,” which take them into the MBH, or close enough to interact strongly with it. The resulting phenomena, e.g., tidal heating and disruption, binary capture and hyper-velocity star ejection, gravitational wave (GW) emission by inspiraling compact remnants, or hydrodynamical interactions with an accretion disk, can produce observable signatures and thereby reveal the MBH, affect its mass and spin evolution, test strong gravity, and probe stars and gas near the MBH. These continuous stellar loss and resupply processes shape the central stellar distribution. We investigate relativistic stellar dynamics near the loss cone of a non-spinning MBH in steady state, analytically and by Monte Carlo simulations of the diffusion of the orbital parameters. These take into account Newtonian mass precession due to enclosed stellar mass, in-plane precession due to general relativity, dissipation by GW, uncorrelated two-body relaxation, correlated resonant relaxation (RR), and adiabatic invariance due to secular precession, using a rigorously derived description of correlated post-Newtonian dynamics in the diffusion limit. We argue that general maximal entropy considerations strongly constrain the orbital diffusion in steady state, irrespective of the relaxation mechanism. We identify the exact phase-space separatrix between plunges and inspirals, and predict their steady-state rates. We derive the dependence of the rates on the mass of the MBH, show that the contribution of RR in steady state is small, and discuss special cases where unquenched RR in restricted volumes of phase-space may affect the steady state substantially.

  19. The statistical mechanics of relativistic orbits around a massive black hole

    NASA Astrophysics Data System (ADS)

    Bar-Or, Ben; Alexander, Tal

    2014-12-01

    Stars around a massive black hole (MBH) move on nearly fixed Keplerian orbits, in a centrally-dominated potential. The random fluctuations of the discrete stellar background cause small potential perturbations, which accelerate the evolution of orbital angular momentum by resonant relaxation. This drives many phenomena near MBHs, such as extreme mass-ratio gravitational wave inspirals, the warping of accretion disks, and the formation of exotic stellar populations. We present here a formal statistical mechanics framework to analyze such systems, where the background potential is described as a correlated Gaussian noise. We derive the leading order, phase-averaged 3D stochastic Hamiltonian equations of motion, for evolving the orbital elements of a test star, and obtain the effective Fokker-Planck equation for a general correlated Gaussian noise, for evolving the stellar distribution function. We show that the evolution of angular momentum depends critically on the temporal smoothness of the background potential fluctuations. Smooth noise has a maximal variability frequency {{ν }max }. We show that in the presence of such noise, the evolution of the normalized angular momentum j=\\sqrt{1-{{e}2}} of a relativistic test star, undergoing Schwarzschild (in-plane) general relativistic precession with frequency {{ν }GR}/{{j}2}, is exponentially suppressed for j\\lt {{j}b}, where {{ν }GR}/jb2˜ {{ν }max }, due to the adiabatic invariance of the precession against the slowly varying random background torques. This results in an effective Schwarzschild precession-induced barrier in angular momentum. When jb is large enough, this barrier can have significant dynamical implications for processes near the MBH.

  20. Testing theories for longterm accretion variability in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Cambier, Hal J.

    Many X-ray sources are now understood to be "black hole X-ray binaries'' in which a stellar remnant black hole either tidally "squeezes'' gas off a companion star, or pulls in some fraction the companion's wind. This gas can drain inward through a dense, thin disk characterized by thermalized radiation, or a sparse and radiatively-inefficient flow, or some combination of the two. Observations at other energies often provide crucial information, but our primary tools to study accretion, especially closest to the black hole, are X-ray spectra and their time evolution. This evolution includes numerous behaviors spanning orders of magnitude in timescale and luminosity, and also hints at spatial structure since draining is generally faster at smaller radii. This includes variability at time-scales of weeks to months which remains difficult to explain despite an abundance of possible variability mechanisms since direct simulations covering the full spatial and temporal range remain impractical. After reviewing general aspects of accretion, I present both more and less familiar forms of longterm variability. Based on these, I argue the problem involves finding a physical process (or combination) that can generate repeatable yet adjustable cycles in luminosity and evolution of low and high energy spectral components, while letting the ionization instability dominate conventional outbursts. Specific models examined include: disks embedded in, and interacting with, hot, sparse flows, and another instability that quenches viscous-draining of the disk at more fundamental level. Testing these theories, alone and in combination, motivates building a very general and simplified numerical model presented here. I find that two-phase flow models still predict excessive recondensation in LMC X-3 among other problems, while the viscosity-quenching instability may account for rapid drops and slow recoveries in disk accretion rate but also likely requires diffusivity orders of magnitude

  1. Application of the Cubed-Sphere Grid to Tilted Black-Hole Accretion Disks

    SciTech Connect

    Fragile, P C; Lindner, C C; Anninos, P; Salmonson, J D

    2008-09-24

    In recent work we presented the first results of global general relativistic magnetohydrodynamic (GRMHD) simulations of tilted (or misaligned) accretion disks around rotating black holes. The simulated tilted disks showed dramatic differences from comparable untilted disks, such as asymmetrical accretion onto the hole through opposing 'plunging streams' and global precession of the disk powered by a torque provided by the black hole. However, those simulations used a traditional spherical-polar grid that was purposefully underresolved along the pole, which prevented us from assessing the behavior of any jets that may have been associated with the tilted disks. To address this shortcoming we have added a block-structured 'cubed-sphere' grid option to the Cosmos++ GRMHD code, which will allow us to simultaneously resolve the disk and polar regions. Here we present our implementation of this grid and the results of a small suite of validation tests intended to demonstrate that the new grid performs as expected. The most important test in this work is a comparison of identical tilted disks, one evolved using our spherical-polar grid and the other with the cubed-sphere grid. We also demonstrate an interesting dependence of the early-time evolution of our disks on their orientation with respect to the grid alignment. This dependence arises from the differing treatment of current sheets within the disks, especially whether they are aligned with symmetry planes of the grid or not.

  2. THERMAL EQUILIBRIA OF OPTICALLY THIN, MAGNETICALLY SUPPORTED, TWO-TEMPERATURE, BLACK HOLE ACCRETION DISKS

    SciTech Connect

    Oda, H.; Machida, M.; Nakamura, K. E.; Matsumoto, R.

    2010-03-20

    We obtained thermal equilibrium solutions for optically thin, two-temperature black hole accretion disks incorporating magnetic fields. The main objective of this study is to explain the bright/hard state observed during the bright/slow transition of galactic black hole candidates. We assume that the energy transfer from ions to electrons occurs via Coulomb collisions. Bremsstrahlung, synchrotron, and inverse Compton scattering are considered as the radiative cooling processes. In order to complete the set of basic equations, we specify the magnetic flux advection rate instead of beta = p{sub gas}/p{sub mag}. We find magnetically supported (low-beta), thermally stable solutions. In these solutions, the total amount of the heating via the dissipation of turbulent magnetic fields goes into electrons and balances the radiative cooling. The low-beta solutions extend to high mass accretion rates ({approx}>alpha{sup 2}M-dot{sub Edd}) and the electron temperature is moderately cool (T{sub e} {approx} 10{sup 8}-10{sup 9.5} K). High luminosities ({approx}>0.1L{sub Edd}) and moderately high energy cutoffs in the X-ray spectrum ({approx}50-200 keV) observed in the bright/hard state can be explained by the low-beta solutions.

  3. The Accretion Disk Wind in the Black Hole GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Miller, J. M.; Raymond, J.; Fabian, A. C.; Gallo, E.; Kaastra, J.; Kallman, T.; King, A. L.; Proga, D.; Reynolds, C. S.; Zoghbi, A.

    2016-04-01

    We report on a 120 ks Chandra/HETG spectrum of the black hole GRS 1915+105. The observation was made during an extended and bright soft state in 2015 June. An extremely rich disk wind absorption spectrum is detected, similar to that observed at lower sensitivity in 2007. The very high resolution of the third-order spectrum reveals four components to the disk wind in the Fe K band alone; the fastest has a blueshift of v=0.03c. Broadened re-emission from the wind is also detected in the first-order spectrum, giving rise to clear accretion disk P Cygni profiles. Dynamical modeling of the re-emission spectrum gives wind launching radii of r≃ {10}2-4 {GM}/{{{c}}}2. Wind density values of n≃ {10}13-16 {{{cm}}}-3 are then required by the ionization parameter formalism. The small launching radii, high density values, and inferred high mass outflow rates signal a role for magnetic driving. With simple, reasonable assumptions, the wind properties constrain the magnitude of the emergent magnetic field to be B≃ {10}3-4 G if the wind is driven via magnetohydrodynamic (MHD) pressure from within the disk and B≃ {10}4-5 G if the wind is driven by magnetocentrifugal acceleration. The MHD estimates are below upper limits predicted by the canonical α-disk model. We discuss these results in terms of fundamental disk physics and black hole accretion modes.

  4. Hot versus Cold: the Dichotomy in Spherical Accretion of Cooling Flows onto Supermassive Black Holes in Elliptical Galaxies, Galaxy Groups, and Clusters

    NASA Astrophysics Data System (ADS)

    Guo, Fulai; Mathews, William G.

    2014-01-01

    Feedback heating from active galactic nuclei (AGNs) has been commonly invoked to suppress cooling flows predicted in hot gas in elliptical galaxies, galaxy groups, and clusters. Previous studies have focused on if and how AGN feedback heats the gas but have little paid attention to its triggering mechanism. Using spherically symmetric simulations, we investigate how large-scale cooling flows are accreted by central supermassive black holes (SMBHs) in eight well-observed systems and find an interesting dichotomy. In massive clusters, the gas develops a central cooling catastrophe within about the cooling time (typically ~100-300 Myr), resulting in cold-mode accretion onto SMBHs. However, in our four simulated systems on group and galaxy scales at a low metallicity Z = 0.3 Z ⊙, the gas quickly settles into a long-term state that has a cuspy central temperature profile extending to several tens to about 100 pc. At the more realistic solar metallicity, two groups (with R e ~ 4 kpc) still host the long-term, hot-mode accretion. Both accretion modes naturally appear in our idealized calculations where only cooling, gas inflow, and compressional heating are considered. The long-term, hot-mode accretion is maintained by the quickly established closeness between the timescales of these processes, preferably in systems with low gas densities, low gas metallicities, and importantly, compact central galaxies, which result in strong gravitational acceleration and compressional heating at the intermediate radii. Our calculations predict that central cuspy temperature profiles appear more often in smaller systems than galaxy clusters, which instead often host significant cold gas and star formation.

  5. Hot versus cold: The dichotomy in spherical accretion of cooling flows onto supermassive black holes in elliptical galaxies, galaxy groups, and clusters

    SciTech Connect

    Guo, Fulai; Mathews, William G.

    2014-01-10

    Feedback heating from active galactic nuclei (AGNs) has been commonly invoked to suppress cooling flows predicted in hot gas in elliptical galaxies, galaxy groups, and clusters. Previous studies have focused on if and how AGN feedback heats the gas but have little paid attention to its triggering mechanism. Using spherically symmetric simulations, we investigate how large-scale cooling flows are accreted by central supermassive black holes (SMBHs) in eight well-observed systems and find an interesting dichotomy. In massive clusters, the gas develops a central cooling catastrophe within about the cooling time (typically ∼100-300 Myr), resulting in cold-mode accretion onto SMBHs. However, in our four simulated systems on group and galaxy scales at a low metallicity Z = 0.3 Z {sub ☉}, the gas quickly settles into a long-term state that has a cuspy central temperature profile extending to several tens to about 100 pc. At the more realistic solar metallicity, two groups (with R {sub e} ∼ 4 kpc) still host the long-term, hot-mode accretion. Both accretion modes naturally appear in our idealized calculations where only cooling, gas inflow, and compressional heating are considered. The long-term, hot-mode accretion is maintained by the quickly established closeness between the timescales of these processes, preferably in systems with low gas densities, low gas metallicities, and importantly, compact central galaxies, which result in strong gravitational acceleration and compressional heating at the intermediate radii. Our calculations predict that central cuspy temperature profiles appear more often in smaller systems than galaxy clusters, which instead often host significant cold gas and star formation.

  6. RELICS OF GALAXY MERGING: OBSERVATIONAL PREDICTIONS FOR A WANDERING MASSIVE BLACK HOLE AND ACCOMPANYING STAR CLUSTER IN THE HALO OF M31

    SciTech Connect

    Kawaguchi, Toshihiro; Saito, Yuriko; Miki, Yohei; Mori, Masao

    2014-07-01

    Galaxies and massive black holes (BHs) presumably grow via galactic merging events and subsequent BH coalescence. As a case study, we investigate the merging event between the Andromeda galaxy (M31) and a satellite galaxy. We compute the expected observational appearance of the massive BH that was at the center of the satellite galaxy prior to the merger and is currently wandering in the M31 halo. We demonstrate that a radiatively inefficient accretion flow with a bolometric luminosity of a few tens of solar luminosities develops when Hoyle-Lyttleton accretion onto the BH is assumed. We compute the associated broadband spectrum and show that the radio band (observable with EVLA, ALMA, and the Square Kilometre Array) is the best frequency range in which to detect the emission. We also evaluate the mass and the luminosity of the stars bound by the wandering BH and find that such a star cluster is sufficiently luminous that it could correspond to one of the star clusters found by the PAndAS survey. The discovery of a relic massive BH wandering in a galactic halo will provide a direct means of investigating in detail the coevolution of galaxies and BHs. It also means a new population of BHs (off-center massive BHs) and offers targets for clean BH imaging that avoid strong interstellar scattering in the centers of galaxies.

  7. Relics of Galaxy Merging: Observational Predictions for a Wandering Massive Black Hole and Accompanying Star Cluster in the Halo of M31

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Toshihiro; Saito, Yuriko; Miki, Yohei; Mori, Masao

    2014-07-01

    Galaxies and massive black holes (BHs) presumably grow via galactic merging events and subsequent BH coalescence. As a case study, we investigate the merging event between the Andromeda galaxy (M31) and a satellite galaxy. We compute the expected observational appearance of the massive BH that was at the center of the satellite galaxy prior to the merger and is currently wandering in the M31 halo. We demonstrate that a radiatively inefficient accretion flow with a bolometric luminosity of a few tens of solar luminosities develops when Hoyle-Lyttleton accretion onto the BH is assumed. We compute the associated broadband spectrum and show that the radio band (observable with EVLA, ALMA, and the Square Kilometre Array) is the best frequency range in which to detect the emission. We also evaluate the mass and the luminosity of the stars bound by the wandering BH and find that such a star cluster is sufficiently luminous that it could correspond to one of the star clusters found by the PAndAS survey. The discovery of a relic massive BH wandering in a galactic halo will provide a direct means of investigating in detail the coevolution of galaxies and BHs. It also means a new population of BHs (off-center massive BHs) and offers targets for clean BH imaging that avoid strong interstellar scattering in the centers of galaxies.

  8. Variability of accretion disks surrounding black holes: The role of inertial-acoustic mode instabilities

    NASA Technical Reports Server (NTRS)

    Chen, Xingming; Taam, Ronald E.

    1995-01-01

    The global nonlinear time-dependent evolution of the inertial-acoustic mode instability in accretion disks surrounding black holes has been investigated. The viscous stress is assumed to be proportional to the gas pressure only, i.e., tau = alphap(sub g). It is found that an oscillatory nonsteady behavior exists in the inner regions of disks (r is less than 10r(sub g) where r(sub g) is the Schwarzschild radius) for sufficiently large alpha(greater than or approximately equal to 0.2) and for mass accretion rates less than about 0.3 times the Eddington value. The variations of the integrated bolometric luminosity from the disk, Delta L/L, are less than 3%. A power spectrum analysis of these variations reveals a power spectrum which can be fitted to a power-law function of the frequency Pis proportional to f(exp -gamma), with index gamma = 1.4-2.3 and a low-frequency feature at about 4 Hz in one case. In addition, a narrow peak centered at a frequency corresponding to the maximum epicyclic frequency of the disk at approximately 100-130 Hz and its first harmonic is also seen. The low-frequency modulations are remarkably similar to those observed in black hole candidate systems. The possible existence of a scattering corona in the inner region of the disk and/or other processes contributing to the power at high frequencies in the inner region of the accretion disk may make the detection of the high-frequency component difficult.

  9. Powerful radiative jets in supercritical accretion discs around non-spinning black holes

    NASA Astrophysics Data System (ADS)

    Sądowski, Aleksander; Narayan, Ramesh

    2015-11-01

    We describe a set of simulations of supercritical accretion on to a non-rotating supermassive black hole (BH). The accretion flow takes the form of a geometrically thick disc with twin low-density funnels around the rotation axis. For accretion rates {gtrsim } 10 dot{M}_Edd, there is sufficient gas in the funnel to make this region optically thick. Radiation from the disc first flows into the funnel, after which it accelerates the optically thick funnel gas along the axis. The resulting jet is baryon loaded and has a terminal density-weighted velocity ≈0.3c. Much of the radiative luminosity is converted into kinetic energy by the time the escaping gas becomes optically thin. These jets are not powered by BHrotation or magnetic driving, but purely by radiation. Their characteristic beaming angle is ˜0.2 rad. For an observer viewing down the axis, the isotropic equivalent luminosity of total energy is as much as 1048 erg s- 1 for a 107 M⊙ BH accreting at 103 Eddington. Therefore, energetically, the simulated jets are consistent with observations of the most powerful tidal disruption events, e.g. Swift J1644. The jet velocity is, however, too low to match the Lorentz factor γ > 2 inferred in J1644. There is no such conflict in the case of other tidal disruption events. Since favourably oriented observers see isotropic equivalent luminosities that are highly super-Eddington, the simulated models can explain observations of ultraluminous X-ray sources, at least in terms of luminosity and energetics, without requiring intermediate-mass BHs.

  10. Massive antigravity field and incomplete black hole evaporation

    NASA Astrophysics Data System (ADS)

    Massa, Corrado

    2008-04-01

    If gravity is a mixture of the ordinary attractive force carried by the massless graviton, and of a repulsive force carried by a particle with nonzero mass, an evaporating black hole might leave a stable remnant.

  11. Properties of galaxies around AGNs with the most massive supermassive black holes revealed by clustering analysis

    NASA Astrophysics Data System (ADS)

    Shirasaki, Yuji; Komiya, Yutaka; Ohishi, Masatoshi; Mizumoto, Yoshihiko

    2016-04-01

    We present results of the clustering analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1.0, which was performed to investigate the properties of galaxies associated with the AGNs and reveal the nature of the fueling mechanism of supermassive black holes (SMBHs). We used 8059 AGNs/quasi-stellar objects (QSOs) for which virial masses of individual SMBHs were measured, and divided them into four mass groups.Cross-correlation analysis was performed to reconfirm our previous result that cross-correlation length increases with SMBH mass MBH; we obtained consistent results. A linear bias of AGN for each mass group was measured as 1.47 for MBH = 107.5-108.2 M⊙ and 3.08 for MBH = 109-1010 M⊙. The averaged color and luminosity distributions of galaxies around the AGNs/QSOs were also derived for each mass group. The galaxy color Dopt-IR was estimated from a spectral energy distribution (SED) constructed from a catalog derived by merging the Sloan Digital Sky Survey (SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS) catalogs. The distributions of color and luminosity were derived by a subtraction method, which does not require redshift information of galaxies. The main results of this work are as follows. (1) A linear bias increases by a factor of two from the lower-mass group to the highest-mass group. (2) The environment around AGNs with the most massive SMBHs (MBH > 109 M⊙) is dominated by red sequence galaxies. (3) Marginal indication of decline in luminosity function at dimmer side of MIR > -19.5 is found for galaxies around AGNs with MBH = 108.2-109 M⊙ and nearest redshift group (z = 0.1-0.3). These results indicate that AGNs with the most massive SMBHs reside in haloes where a large fraction of galaxies have been transited to the red sequence. The accretion of hot halo gas as well as recycled gas from evolving stars can be one of the plausible mechanisms to fuel the SMBHs above ˜ 109 M⊙.

  12. Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. VI. Velocity-resolved Reverberation Mapping of the Hβ Line

    NASA Astrophysics Data System (ADS)

    Du, Pu; Lu, Kai-Xing; Hu, Chen; Qiu, Jie; Li, Yan-Rong; Huang, Ying-Ke; Wang, Fang; Bai, Jin-Ming; Bian, Wei-Hao; Yuan, Ye-Fei; Ho, Luis C.; Wang, Jian-Min; SEAMBH Collaboration

    2016-03-01

    In the sixth of a series of papers reporting on a large reverberation mapping (RM) campaign of active galactic nuclei (AGNs) with high accretion rates, we present velocity-resolved time lags of Hβ emission lines for nine objects observed in the campaign during 2012-2013. In order to correct the line broadening caused by seeing and instruments before analyzing the velocity-resolved RM, we adopt the Richardson-Lucy deconvolution to reconstruct their Hβ profiles. The validity and effectiveness of the deconvolution are checked using Monte Carlo simulation. Five among the nine objects show clear dependence of the time delay on velocity. Mrk 335 and Mrk 486 show signatures of gas inflow whereas the clouds in the broad-line regions (BLRs) of Mrk 142 and MCG +06-26-012 tend to be radial outflowing. Mrk 1044 is consistent with having virialized motions. The lags of the remaining four are not velocity-resolvable. The velocity-resolved RM of super-Eddington accreting massive black holes (SEAMBHs) shows that they have diverse kinematics in their BLRs. Comparing with the AGNs with sub-Eddington accretion rates, we do not find significant differences in the BLR kinematics of SEAMBHs.

  13. Massive Particle Tunnels from the Taub-NUT Black Hole

    NASA Astrophysics Data System (ADS)

    Chen, D.; Zu, X.; Yang, S.

    2008-06-01

    In this paper, we investigate the Hawking radiation of the Taub-NUT black hole by Hamilton-Jacobi method. When the unfixed background space-time and self-gravitational interaction are considered, the tunnelling rate is related to the change of Bekenstein-Hawking entropy and the radiation spectrum deviates from the purely thermal one. This result is in accordance with Parikh and Wilczek's opinion and gives a correction to the Hawking radiation of the black hole.

  14. Event Rate for LISA Gravitational Wave Signals from Black Hole-Massive Black Hole Coalescences

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.

    2002-01-01

    Earlier work under a previous grant had been mainly on investigating the event rate for coalescences of white dwarfs or neutron stars with massive black holes (MBHs) in galactic nuclei. Under the new grant, two studies were undertaken. One was an approximate extension of the earlier study to stellar mass black holes as the lighter object, with masses in the range of roughly 3 to 20 solar mass rather than about 1 solar mass. The other was an improved estimate of the confusion noise due to galactic binaries against which the signals from BH-MBH coalescences would have to be detected. In the earlier work, the mass of the white dwarfs (WDs) and neutron stars (NSs) was assumed to be about the same as that of the evolved stars in the density cusp around the galactic center MBH. However, with the BH mass being substantially larger, the sinking down of pHs toward the center (mass segregation) became important, and was included in the model. A single representative mass of 7 solar mass was used. The other main difference involved what happened after the compact object got scattered in close enough to the MBH to start losing appreciable energy and angular momentum by gravitational radiation. For WDs or NSs, it had been found in most cases that the object would be perturbed considerably by other stars in the cusp before much energy had been lost. Thus the angular momentum would either increase enough so that gravitational radiation would be cut off, or would decrease enough so that the WD or NS would plunge into the MBH in just a few revolutions. The latter event would mean that the signal-to noise ratio would not have time to build up, and the event would not be detectable. The ratio of gradual energy loss events to plunges was found to be roughly one to a few percent, and thus substantially decreased the expected rate of detectable events.

  15. Accretions of dark matter and dark energy onto (n+2)-dimensional Schwarzschild black hole and Morris-Thorne wormhole

    NASA Astrophysics Data System (ADS)

    Debnath, Ujjal

    2015-12-01

    In this work, we have studied accretion of the dark matter and dark energy onto of (n+2)-dimensional Schwarzschild black hole and Morris-Thorne wormhole. The mass and the rate of change of mass for (n+2)-dimensional Schwarzschild black hole and Morris-Thorne wormhole have been found. We have assumed some candidates of dark energy like holographic dark energy, new agegraphic dark energy, quintessence, tachyon, DBI-essence, etc. The black hole mass and the wormhole mass have been calculated in term of redshift when dark matter and above types of dark energies accrete onto them separately. We have shown that the black hole mass increases and wormhole mass decreases for holographic dark energy, new agegraphic dark energy, quintessence, tachyon accretion and the slope of increasing/decreasing of mass sensitively depends on the dimension. But for DBI-essence accretion, the black hole mass first increases and then decreases and the wormhole mass first decreases and then increases and the slope of increasing/decreasing of mass not sensitively depends on the dimension.

  16. Decay of Dirac massive hair in the background of a spherical black hole

    SciTech Connect

    Moderski, Rafal; Rogatko, Marek

    2008-06-15

    The intermediate and late-time behavior of massive Dirac hair in the static spherically general black hole spacetime is studied. It is revealed that the intermediate asymptotic pattern of decay of massive Dirac spinor hair is dependent on the mass of the field under consideration as well as the multiple number of the wave mode. The long-lived oscillatory tail observed at timelike infinity in the considered background decays slowly as t{sup -5/6}.

  17. Decay of massive Dirac hair on a brane-world black hole

    SciTech Connect

    Gibbons, Gary W.; Rogatko, Marek; Szyplowska, Agnieszka

    2008-03-15

    We investigate the intermediate and late-time behavior of the massive Dirac spinor field in the background of static spherically symmetric brane-world black hole solutions. The intermediate asymptotic behavior of the massive spinor field exhibits a dependence on the field's parameter mass as well as the multiple number of the wave mode. On the other hand, the late-time behavior power-law decay has a rate which is independent of those factors.

  18. Massive black holes and light-element nucleosynthesis in a baryonic universe

    NASA Technical Reports Server (NTRS)

    Gnedin, Nickolay Y.; Ostriker, Jeremiah P.; Rees, Martin J.

    1995-01-01

    We reexamine the model proposed by Gnedin & Ostriker (1992) in which Jeans mass black holes (M(sub BH) approximately = 10(exp 6) solar mass) form shortly after decoupling. There is no nonbaryonic dark matter in this model, but we examine the possibility that Omega(sub b) is considerably larger than given by normal nucleosynthesis. Here we allow for the fact that much of the high baryon-to-photon ratio material will collapse leaving the universe of remaining material with light-element abundances more in accord with the residual baryonic density (approximately = 10(exp -2)) than with Omega(sub 0) and the initial baryonic density (approximately = 10(exp -1)). We find that no reasonable model can be made with random-phase density fluctuations, if the power on scales smaller than 10(exp 6) solar mass is as large as expected. However, phase-correlated models of the type that might occur in connection with topological singularities can be made with Omega(sub b) h(exp 2) = 0.013 +/- 0.001, 0.15 approximately less than Omega(sub 0) approximately less than 0.4, which are either flat (Omega(sub lambda) = 1 - Omega(sub 0)) or open (Omega(sub lambda) = 0) and which satisfy all the observational constraints which we apply, including the large baryon-to-total mass ratio found in the X-ray clusters. The remnant baryon density is thus close to that obtained in the standard picture (Omega(sub b) h(exp 2) = 0.0125 +/- 0.0025; Walker et al. 1991). The spectral index implied for fluctuations in the baryonic isocurvature scenario, -1 less than m less than 0, is in the range expected by other arguments based on large-scale structure and microwave fluctuation constraints. The dark matter in this picture is in the form of massive black holes. Accretion onto them at early epochs releases high-energy photons which significantly heat and reionize the universe. But photodissociation does not materially change light-element abundances. A typical model gives bar-y approximately = 1 x 10(exp -5

  19. Tunneling of massive and charged particles from noncommutative Reissner-Nordström black hole

    NASA Astrophysics Data System (ADS)

    Nozari, Kourosh; Islamzadeh, Sara

    2013-10-01

    Massive charged and uncharged particles tunneling from commutative Reissner-Nordström black hole horizon has been studied with details in literature. Here, by adopting the coherent state picture of spacetime noncommutativity, we study tunneling of massive and charged particles from a noncommutative inspired Reissner-Nordström black hole horizon. We show that Hawking radiation in this case is not purely thermal and there are correlations between emitted modes. These correlations may provide a solution to the information loss problem. We also study thermodynamics of noncommutative horizon in this setup.

  20. Tunnelling of relativistic particles from new type black hole in new massive gravity

    NASA Astrophysics Data System (ADS)

    Gecim, Ganim; Sucu, Yusuf

    2013-02-01

    In the framework of the three dimensional New Massive Gravity theory introduced by Bergshoeff, Hohm and Townsend, we analyze the behavior of relativistic spin-1/2 and spin-0 particles in the New-type Black Hole backgroud, solution of the New Massive Gravity.We solve Dirac equation for spin-1/2 and Klein-Gordon equation for spin-0. Using Hamilton-Jacobi method, we discuss tunnelling probability and Hawking temperature of the spin-1/2 and spin-0 particles for the black hole. We observe that the tunnelling probability and Hawking temperature are same for the spin-1/2 and spin-0.

  1. A high-frequency Doppler feature in the power spectra of simulated GRMHD black hole accretion disks

    SciTech Connect

    Wellons, Sarah; Zhu, Yucong; Narayan, Ramesh; McClintock, Jeffrey E.; Psaltis, Dimitrios

    2014-04-20

    Black hole binaries exhibit a wide range of variability phenomena, from large-scale state changes to broadband noise and quasi-periodic oscillations, but the physical nature of much of this variability is poorly understood. We examine the variability properties of three GRMHD simulations of thin accretion disks around black holes of varying spin, producing light curves and power spectra as would be seen by observers. We find that the simulated power spectra show a broad feature at high frequency, which increases in amplitude with the inclination of the observer. We show that this high-frequency feature is a product of the Doppler effect and that its location is a function of the mass and spin of the black hole. This Doppler feature demonstrates that power spectral properties of the accretion disk can be tied to, and potentially used to determine, physical properties of the black hole.

  2. Towards a Comprehensive Fueling-Controlled Theory on the Growth of Massive Black Holes And Host Spheroids

    SciTech Connect

    Escala, Andres; /KIPAC, Menlo Park

    2007-06-11

    We study the relation between nuclear massive black holes and their host spheroid gravitational potential. Using AMR numerical simulations, we analyze how gas is transported in the nuclear (central kpc) regions of galaxies. We study the gas fueling onto the inner accretion disk (sub-pc scale) and the star formation in a massive nuclear disk like those generally found in proto-spheroids (ULIRGs, SCUBA Galaxies). These sub-pc resolution simulation of gas fueling that is mainly depleted by star formation naturally satisfy the 'M{sub BH} - M{sub virial}' relation, with a scatter considerably less than the observed one. We found a generalized version of Kennicutt-Schmidt Law for starbursts is satisfied, in which the total gas depletion rate ({dot M}{sub gas} = {dot M}{sub BH} + {dot M}{sub SF}) is the one that scales as M{sub gas}/t{sub orbital}. We also found that the 'M{sub BH} - {sigma}' relation is a byproduct of the 'M{sub BH} - M{sub virial}' relation.

  3. Ion Viscosity Mediated by Tangled Magnetic Fields: An Application to Black Hole Accretion Disks

    NASA Technical Reports Server (NTRS)

    Subramanian, Prasad; Becker, Peter A.; Kafatos, Menas

    1996-01-01

    We examine the viscosity associated with the shear stress exerted by ions in the presence of a tangled magnetic field. As an application, we consider the effect of this mechanism on the structure of black hole accretion disks. We do not attempt to include a self-consistent description of the magnetic field. Instead, we assume the existence of a tangled field with coherence length lambda(sub coh), which is the average distance between the magnetic 'kinks' that scatter the particles. For simplicity, we assume that the field is self-similar, and take lambda(sub coh) to be a fixed fraction zeta of the local disk height H. Ion viscosity in the presence of magnetic fields is generally taken to be the cross-field viscosity, wherein the effective mean free path is the ion Larmor radius lambda(sub L), which is much less than the ion-ion Coulomb mean free path A(sub ii) in hot accretion disks. However, we arrive at a formulation for a 'hybrid' viscosity in which the tangled magnetic field acts as an intermediary in the transfer of momentum between different layers in the shear flow. The hybrid viscosity greatly exceeds the standard cross-field viscosity when (lambda/lambda(sub L)) much greater than (lambda(sub L)/lambda(sub ii)), where lambda = ((lambda(sub ii)(sup -1) + lambda(sub (coh)(sup -1))(sup -1) is the effective mean free path for the ions. This inequality is well satisfied in hot accretion disks, which suggests that the ions may play a much larger role in the momentum transfer process in the presence of magnetic fields than was previously thought. The effect of the hybrid viscosity on the structure of a steady-state, two-temperature, quasi-Keplerian accretion disk is analyzed. The hybrid viscosity is influenced by the degree to which the magnetic field is tangled (represented by zeta = lambda(sub coh)), and also by the relative accretion rate M/M(sub E), where M(sub E) = L(sub E)/c(sup 2) and L(sub E) is the Eddington luminosity. We find that ion viscosity in the

  4. General Relativistic Magnetohydrodynamic Simulations of Magnetically Choked Accretion Flows around Black Holes

    SciTech Connect

    McKinney, Jonathan C.; Tchekhovskoy, Alexander; Blandford, Roger D.

    2012-04-26

    Black hole (BH) accretion flows and jets are qualitatively affected by the presence of ordered magnetic fields. We study fully three-dimensional global general relativistic magnetohydrodynamic (MHD) simulations of radially extended and thick (height H to cylindrical radius R ratio of |H/R| {approx} 0.2-1) accretion flows around BHs with various dimensionless spins (a/M, with BH mass M) and with initially toroidally-dominated ({phi}-directed) and poloidally-dominated (R-z directed) magnetic fields. Firstly, for toroidal field models and BHs with high enough |a/M|, coherent large-scale (i.e. >> H) dipolar poloidal magnetic flux patches emerge, thread the BH, and generate transient relativistic jets. Secondly, for poloidal field models, poloidal magnetic flux readily accretes through the disk from large radii and builds-up to a natural saturation point near the BH. While models with |H/R| {approx} 1 and |a/M| {le} 0.5 do not launch jets due to quenching by mass infall, for sufficiently high |a/M| or low |H/R| the polar magnetic field compresses the inflow into a geometrically thin highly non-axisymmetric 'magnetically choked accretion flow' (MCAF) within which the standard linear magneto-rotational instability is suppressed. The condition of a highly-magnetized state over most of the horizon is optimal for the Blandford-Znajek mechanism that generates persistent relativistic jets with and 100% efficiency for |a/M| {approx}> 0.9. A magnetic Rayleigh-Taylor and Kelvin-Helmholtz unstable magnetospheric interface forms between the compressed inflow and bulging jet magnetosphere, which drives a new jet-disk oscillation (JDO) type of quasi-periodic oscillation (QPO) mechanism. The high-frequency QPO has spherical harmonic |m| = 1 mode period of {tau} {approx} 70GM/c{sup 3} for a/M {approx} 0.9 with coherence quality factors Q {approx}> 10. Overall, our models are qualitatively distinct from most prior MHD simulations (typically, |H/R| << 1 and poloidal flux is limited by

  5. A Stochastic Model for the Luminosity Fluctuations of Accreting Black Holes

    NASA Astrophysics Data System (ADS)

    Kelly, Brandon C.; Sobolewska, Małgorzata; Siemiginowska, Aneta

    2011-03-01

    In this work, we have developed a new stochastic model for the fluctuations in light curves of accreting black holes. The model is based on a linear combination of stochastic processes and is also the solution to the linear diffusion equation perturbed by a spatially correlated noise field. This allows flexible modeling of the power spectral density (PSD), and we derive the likelihood function for the process, enabling one to estimate the parameters of the process, including break frequencies in the PSD. Our statistical technique is computationally efficient, unbiased by aliasing and red noise leak, and fully accounts for irregular sampling and measurement errors. We show that our stochastic model provides a good approximation to the X-ray light curves of galactic black holes, and the optical and X-ray light curves of active galactic nuclei (AGNs). We use the estimated timescales of our stochastic model to recover the correlation between characteristic timescale of the high-frequency X-ray fluctuations and black hole mass for AGNs, including two new "detections" of the timescale for Fairall 9 and NGC 5548. We find a tight anti-correlation between the black hole mass and the amplitude of the driving noise field, which is proportional to the amplitude of the high-frequency X-ray PSD, and we estimate that this parameter gives black hole mass estimates to within ~0.2 dex precision, potentially the most accurate method for AGNs yet. We also find evidence that ≈13% of AGN optical PSDs fall off flatter than 1/f 2 and, similar to previous work, find that the optical fluctuations are more suppressed on short timescales compared to the X-rays, but are larger on long timescales, suggesting that the optical fluctuations are not solely due to reprocessing of X-rays.

  6. Dirac and scalar particles tunnelling from topological massive warped-AdS3 black hole

    NASA Astrophysics Data System (ADS)

    Gecim, G.; Sucu, Y.

    2015-06-01

    We investigate the Dirac and scalar particles tunnelling as a radiation of Warped AdS3 black holes in Topological Massive Gravity. Using Hamilton-Jacobi method, we discuss tunnelling probability and Hawking temperature of the spin-1/2 and spin-0 particles for the black hole. We observe the tunnelling probability and Hawking temperature to be same for the spin-1/2 and spin-0. We show that the tunnelling process may occur, for both Dirac and scalar particles.

  7. Formation of discs around super-massive black hole binaries

    NASA Astrophysics Data System (ADS)

    Goicovic, Felipe G.; Cuadra, Jorge; Sesana, Alberto

    2016-02-01

    We model numerically the evolution of 104 M ⊙ turbulent molecular clouds in near-radial infall onto 106 M ⊙, equal-mass supermassive black hole binaries, using a modified version of the SPH code gadget-3. We investigate the different gas structures formed depending on the relative inclination between the binary and the cloud orbits. Our first results indicate that an aligned orbit produces mini-discs around each black hole, almost aligned with the binary; a perpendicular orbit produces misaligned mini-discs; and a counter-aligned orbit produces a circumbinary, counter-rotating ring.

  8. The Milky Way's nuclear star cluster and massive black hole

    NASA Astrophysics Data System (ADS)

    Schödel, Rainer

    2016-02-01

    Because of its nearness to Earth, the centre of the Milky Way is the only galaxy nucleus in which we can study the characteristics, distribution, kinematics, and dynamics of the stars on milli-parsec scales. We have accurate and precise measurements of the Galactic centre's central black hole, Sagittarius A*, and can study its interaction with the surrounding nuclear star cluster in detail. This contribution aims at providing a concise overview of our current knowledge about the Milky Way's central black hole and nuclear star cluster, at highlighting the observational challenges and limitations, and at discussing some of the current key areas of investigation.

  9. Transient jet formation and state transitions from large-scale magnetic reconnection in black hole accretion discs

    NASA Astrophysics Data System (ADS)

    Dexter, Jason; McKinney, Jonathan C.; Markoff, Sera; Tchekhovskoy, Alexander

    2014-05-01

    Magnetically arrested accretion discs (MADs), where the magnetic pressure in the inner disc is dynamically important, provide an alternative mechanism for regulating accretion to what is commonly assumed in black hole systems. We show that a global magnetic field inversion in the MAD state can destroy the jet, significantly increase the accretion rate, and move the effective inner disc edge in to the marginally stable orbit. Reconnection of the MAD field in the inner radii launches a new type of transient outflow containing hot plasma generated by magnetic dissipation. This transient outflow can be as powerful as the steady magnetically dominated Blandford-Znajek jet in the MAD state. The field inversion qualitatively describes many of the observational features associated with the high-luminosity hard-to-soft state transition in black hole X-ray binaries: the jet line, the transient ballistic jet, and the drop in rms variability. These results demonstrate that the magnetic field configuration can influence the accretion state directly, and hence the magnetic field structure is an important second parameter in explaining observations of accreting black holes across the mass and luminosity scales.

  10. Transient Probes of Accretion Physics, Jet Formation, and Black Hole Demographic

    NASA Astrophysics Data System (ADS)

    Gezari, Suvi

    2012-10-01

    Theorists first surmised that massive black holes (MBHs) will inevitably tidally disrupt and consume stars in their vicinity, and that the resulting flare of radiation could be used as a signpost for a dormant MBH lurking otherwise undetectable in the center of a galaxy. In the last decade, major progress has been made in the discovery of candidates using surveys across the electromagnetic spectrum, from the X-rays to the optical. We propose for TOO XMM-Newton X-ray imaging of TDE candidates from the Pan- STARRS1 Medium Deep Survey in order to characterize the prompt X-ray properties of optically-selected candidates for the first time.

  11. COSMIC TRAIN WRECK BY MASSIVE BLACK HOLES: DISCOVERY OF A KILOPARSEC-SCALE TRIPLE ACTIVE GALACTIC NUCLEUS

    SciTech Connect

    Liu Xin; Shen Yue; Strauss, Michael A.

    2011-07-20

    Hierarchical galaxy mergers will lead to the formation of binary and, in the case of a subsequent merger before a binary coalesces, triple supermassive black holes (SMBHs), given that most massive galaxies harbor SMBHs. A triple of SMBHs becomes visible as a triple active galactic nucleus (AGN) when the BHs accrete large amounts of gas at the same time. Here, we report the discovery of a kiloparsec-scale triple AGN, SDSS J1027+1749 at z = 0.066, from our systematic search for hierarchical mergers of AGNs. The galaxy contains three emission-line nuclei, two of which are offset by 450 and 110 km s{sup -1} in velocity and by 2.4 and 3.0 kpc in projected separation from the central nucleus. All three nuclei are classified as obscured AGNs based on optical diagnostic emission line ratios, with black hole mass estimates M{sub .} {approx}> 10{sup 8} M{sub sun} from stellar velocity dispersions measured in the associated stellar components. Based on dynamical friction timescale estimates, the three stellar components in SDSS J1027+1749 will merge in {approx}40 Myr, and their associated SMBHs may evolve into a gravitationally interacting triple system in {approx}< 200 Myr. Our result sets a lower limit of {approx}5 x 10{sup -5} for the fraction of kiloparsec-scale triples in optically selected AGNs at z {approx} 0.1.

  12. Testing the no-hair property of black holes with x-ray observations of accretion disks

    NASA Astrophysics Data System (ADS)

    Moore, Christopher J.; Gair, Jonathan R.

    2015-07-01

    Accretion disks around black holes radiate a significant fraction of the rest mass of the accreting material in the form of thermal radiation from within a few gravitational radii of the black hole (r ≲20 G M /c2). In addition, the accreting matter may also be illuminated by hard x rays from the surrounding plasma which adds fluorescent transition lines to the emission. This radiation is emitted by matter moving along geodesics in the metric; therefore the strong Doppler and gravitational redshifts observed in the emission encode information about the strong gravitational field around the black hole. In this paper the possibility of using the x-ray emission as a strong field test of general relativity is explored by calculating the spectra for both the transition line and thermal emission from a thin accretion disk in a series of parametrically deformed Kerr metrics. In addition the possibility of constraining a number of known black hole spacetimes in alternative theories of gravity is also considered.

  13. Evaporation of Accretion Disks around Black Holes: The Disk-Corona Transition and the Connection to the Advection-dominated Accretion Flow.

    PubMed

    Liu; Yuan; Meyer; Meyer-Hofmeister; Xie

    1999-12-10

    We apply the disk-corona evaporation model (Meyer & Meyer-Hofmeister) originally derived for dwarf novae to black hole systems. This model describes the transition of a thin cool outer disk to a hot coronal flow. The mass accretion rate determines the location of this transition. For a number of well-studied black hole binaries, we take the mass flow rates derived from a fit of the advection-dominated accretion flow (ADAF) model to the observed spectra (for a review, see Narayan, Mahadevan, & Quataert) and determine where the transition of accretion via a cool disk to a coronal flow/ADAF would be located for these rates. We compare this with the observed location of the inner disk edge, as estimated from the maximum velocity of the Halpha emission line. We find that the transition caused by evaporation agrees with this determination in stellar disks. We also show that the ADAF and the "thin outer disk + corona" are compatible in terms of the physics in the transition region. PMID:10566989

  14. Beltrami state in black-hole accretion disk: A magnetofluid approach.

    PubMed

    Bhattacharjee, Chinmoy; Das, Rupam; Stark, David J; Mahajan, S M

    2015-12-01

    Using the magnetofluid unification framework, we show that the accretion disk plasma (embedded in the background geometry of a black hole) can relax to a class of states known as the Beltrami-Bernoulli (BB) equilibria. Modeling the disk plasma as a Hall magnetohydrodynamics (MHD) system, we find that the space-time curvature can significantly alter the magnetic (velocity) decay rates as we move away from the compact object; the velocity profiles in BB states, for example, deviate substantially from the predicted corresponding geodesic velocity profiles. These departures imply a rich interplay of plasma dynamics and general relativity revealed by examining the corresponding Bernoulli condition representing "homogeneity" of total energy. The relaxed states have their origin in the constraints provided by the two helicity invariants of Hall MHD. These helicities conspire to introduce an oscillatory length scale into the system that is strongly influenced by relativistic and thermal effects. PMID:26764835

  15. Beltrami state in black-hole accretion disk: A Magnetofluid approach

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Chinmoy; Das, Rupam; Stark, David J.; Mahajan, S. M.

    2015-11-01

    We examine electron-ion Beltrami states in a black hole accretion disk (both Schwarzchild and Kerr) using magnetofluid unification in order to delineate the types of plasma behavior accessible in these geometries. Following the same assumptions as Hall MHD, we find both that the curvature in the spacetime radically alters the magnetic/velocity decay rate and that the predicted geodesic velocity profiles for particles solely constrained by gravity also deviate substantially from our solutions. These departures suggest that these systems are governed by the rich interplay of plasma dynamics and general relativity. Furthermore, the relationship between the helicities of each species introduces a new oscillatory length scale into the system that is strongly influenced by relativistic and thermal effects. C. B and S. M. M's research was supported by the U.S. Department of Energy Grant No. DE-FG02- 04ER-54742.

  16. Reprocessing of Soft X-ray Emission Lines in Black Hole Accretion Disks

    SciTech Connect

    Mauche, C W; Liedahl, D A; Mathiesen, B F; Jimenez-Garate, M A; Raymond, J C

    2003-10-17

    By means of a Monte Carlo code that accounts for Compton scattering and photoabsorption followed by recombination, we have investigated the radiation transfer of Ly{alpha}, He{alpha}, and recombination continua photons of H- and He-like C, N, O, and Ne produced in the photoionized atmosphere of a relativistic black hole accretion disk. We find that photoelectric opacity causes significant attenuation of photons with energies above the O VIII K-edge; that the conversion efficiencies of these photons into lower-energy lines and recombination continua are high; and that accounting for this reprocessing significantly (by factors of 21% to 105%) increases the flux of the Ly{alpha} and He{alpha} emission lines of H- and He-like C and O escaping the disk atmosphere.

  17. Beltrami state in black-hole accretion disk: A magnetofluid approach

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Chinmoy; Das, Rupam; Stark, David J.; Mahajan, S. M.

    2015-12-01

    Using the magnetofluid unification framework, we show that the accretion disk plasma (embedded in the background geometry of a black hole) can relax to a class of states known as the Beltrami-Bernoulli (BB) equilibria. Modeling the disk plasma as a Hall magnetohydrodynamics (MHD) system, we find that the space-time curvature can significantly alter the magnetic (velocity) decay rates as we move away from the compact object; the velocity profiles in BB states, for example, deviate substantially from the predicted corresponding geodesic velocity profiles. These departures imply a rich interplay of plasma dynamics and general relativity revealed by examining the corresponding Bernoulli condition representing "homogeneity" of total energy. The relaxed states have their origin in the constraints provided by the two helicity invariants of Hall MHD. These helicities conspire to introduce an oscillatory length scale into the system that is strongly influenced by relativistic and thermal effects.

  18. Jet-induced star formation by accreting black holes: impact on stellar, galaxy, and cosmic evolution

    NASA Astrophysics Data System (ADS)

    Mirabel, Igor Felix

    2016-07-01

    Evidence that relativistic jets trigger star formation along their axis has been found associated to low redshift and high redshift accreting supermassive black holes. However, the physical processes by which jet-cloud interaction may trigger star formation has so far not been elucidated. To gain insight into this potentially important star formation mechanism during reionization, when microquasars were form prolifically before AGN, our international team is carrying out a muliwavelength study of a microquasar jet-induced star formation region in the Milky Way using data from space missions (Chandra, Integral, ISO, Herschel) and from the ground (at cm and mm wavelengths with the VLA and IRAM, and IR with Gemini and VLT). I will show that this relative nearby star forming region is an ideal laboratory to test models of jet-induced star formation elsewhere in the universe.

  19. Dichotomy Between Black Hole and Neutron Star Accretion: Effect of Hard Surface

    NASA Astrophysics Data System (ADS)

    Dhang, Prasun; Mukhopadhyay, Banibrata; Sharma, Prateek

    2016-07-01

    Estimates of accretion rate on to compact objects have been explored based on the well-known, spherically symmetric, inviscid, steady-state solution given by Bondi. This solution assumes that there is a sink of mass at the center -- which in case of a black hole (BH) corresponds to the advection of matter across the event horizon. Other stars, such as a neutron star (NS), have surfaces and hence the infalling matter has to come to rest at the surface. We study the initial value problem in which the matter distribution is uniform and at rest at time t=0 with different inner radial boundary conditions for BHs and NSs: inflow boundary condition valid for BHs; and reflective or settling boundary condition for NSs. We obtain a similarity solution for the flow with inner inflow and reflective boundary conditions (assuming a cold ambient medium) and compare with numerical simulations of the Euler equations. One-dimensional simulations show the formation of an outward propagating and a standing shock in NS system for reflective and settling boundary conditions respectively. Two-dimensional simulations show that both these flows are unstable (locally to convection and globally to a standing shock instability). Numerical simulations show that in steady state, spherical accretion rate on to a NS for reflective boundary condition is suppressed by orders of magnitude compared to that on to a BH.

  20. XMM-Newton reveals matter accreting onto the central supermassive black hole of NGC 2617

    NASA Astrophysics Data System (ADS)

    Giustini, M.

    2016-06-01

    NGC 2617 (z=0.042) underwent a strong broad-band outburst during 2013/14, concurrently switching from being a Seyfert 1.8 to be a Seyfert 1.0 sometimes during the previous 10 years. Thanks to the combination of the large effective area and the good spectral resolution of the EPIC-pn onboard XMM-Newton, striking insights about the very inner accretion flow of this AGN have been revealed. In particular, persistent Fe K absorption redshifted by ˜ 35,000 km/s was solidly detected in two observations spaced by one month: a highly ionised flow of mass toward the central supermassive black hole of NGC 2617 has started to be traced. So far NGC 2617 is a quasi-unique observational example: what are the perspectives of enlarging these studies in the future? Thanks to current large and prolonged optical surveys like the SDSS/BOSS, many "optically changing-look AGN" like NGC 2617 are being discovered month after month: XMM-Newton has the ideal instruments to perform a proper X-ray study of such objects in the near future. I will assess the impact of XMM-Newton on studying the dynamics of the inner accretion flow in AGN in a systematic way and in synergy with near- and mid-future X-ray instruments such as (ASTRO-H)Hitomi and ATHENA.

  1. Black holes in the lab: A review of accretion experiments using plasmas and liquid metals

    NASA Astrophysics Data System (ADS)

    Forest, Cary

    2016-04-01

    In this talk, we will survey recent liquid metal and plasma experiments attempting to study the magnetorotational instability, and ultimately, turbulent transport of angular momentum in laboratory plasmas that can mimic the Keplerian velocity profiles of accretion disks. We will describe the basic requirements of such experiments, the techniques used to create such laboratory experiments, and then review the results obtained thus far. The experiments fall into two camps, the first of which use resisitve liquid metal in couette flow geometry, and the second of which uses confined plasma that is stirred by induction on the plasma boundary. The regimes covered by liquid metals are compimentary: liquid metals are very resistive but nearly inviscid and may be appropriate for modeling protostellar disks, while hot plasmas are more viscous than resisitve and may be appropriate for hot accretion disks around black holes. Both approaches have overcome major experimental hurdles and now have dimensionless parameters that are in a regime where the MRI should be observed.

  2. Time-dependent X-ray emission from unstable accretion disks around black holes

    NASA Technical Reports Server (NTRS)

    Mineshige, Shin; Kim, Soon-Wook; Wheeler, J. Craig

    1990-01-01

    The spectral evolution of accretion disks in X-ray binaries containing black holes is studied, based on the disk instability model. The thermal transition of the outer portions of the disk controls the mass flow rate into the inner portions of the disk, thus modulating the soft X-ray flux which is thought to arise from the inner disk. Calculated soft X-ray spectra are consistent with the observations of the X-ray transient A0620 - 00 and especially ASM 2000 + 25, the soft X-ray spectra of which are well fitted by blackbody radiation with a fixed inner edge of the disk, Rin, and with monotonically decreasing temperature at Rin with time. Since the gas pressure is always dominant over the radiation pressure during the decay in these models, a two-temperature region is difficult to create. Instead, it is suggested that hard X-rays are generated in a hot (kT greater than 10 keV) accretion disk corona above the cool (kT less than 1 keV) disk.

  3. Measuring the Direction and Angular Velocity of a Black Hole Accretion Disk via Lagged Interferometric Covariance

    NASA Astrophysics Data System (ADS)

    Johnson, Michael D.; Loeb, Abraham; Shiokawa, Hotaka; Chael, Andrew A.; Doeleman, Sheperd S.

    2015-11-01

    We show that interferometry can be applied to study irregular, rapidly rotating structures, as are expected in the turbulent accretion flow near a black hole. Specifically, we analyze the lagged covariance between interferometric baselines of similar lengths but slightly different orientations. For a flow viewed close to face-on, we demonstrate that the peak in the lagged covariance indicates the direction and angular velocity of the emission pattern from the flow. Even for moderately inclined flows, the covariance robustly estimates the flow direction, although the estimated angular velocity can be significantly biased. Importantly, measuring the direction of the flow as clockwise or counterclockwise on the sky breaks a degeneracy in accretion disk inclinations when analyzing time-averaged images alone. We explore the potential efficacy of our technique using three-dimensional, general relativistic magnetohydrodynamic simulations, and we highlight several baseline pairs for the Event Horizon Telescope (EHT) that are well-suited to this application. These results indicate that the EHT may be capable of estimating the direction and angular velocity of the emitting material near Sgr A*, and they suggest that a rotating flow may even be utilized to improve imaging capabilities.

  4. ACCRETION ONTO BLACK HOLES FROM LARGE SCALES REGULATED BY RADIATIVE FEEDBACK. II. GROWTH RATE AND DUTY CYCLE

    SciTech Connect

    Park, Kwang Ho; Ricotti, Massimo E-mail: ricotti@astro.umd.edu

    2012-03-01

    This paper, the second in a series on radiation-regulated accretion onto black holes (BHs) from galactic scales, focuses on the effects of radiation pressure and angular momentum of the accreting gas. We simulate accretion onto intermediate-mass black holes, but we derive general scaling relationships that are solutions of the Bondi problem with radiation feedback valid for any mass of the BH M{sub bh}. Thermal pressure of the ionized sphere around the BH regulates the accretion rate, producing periodic and short-lived luminosity bursts. We find that for ambient gas densities exceeding n{sup cr}{sub H,{infinity}}{proportional_to}M{sup -1}{sub bh}, the period of the oscillations decreases rapidly and the duty cycle increases from 6%, in agreement with observations of the fraction of active galactic nuclei at z {approx} 3, to 50%. The mean accretion rate becomes Eddington limited for n{sub H,{infinity}} > n{sup Edd}{sub H,{infinity}} {approx_equal} n{sup cr}{sub H,{infinity}} T{sub {infinity},4}{sup -1} where T{sub {infinity},4} is the gas temperature in units of 10{sup 4} K. In the sub-Eddington regime, the mean accretion rate onto BHs is about 1%T{sup 2.5}{sub {infinity},4} of the Bondi rate, and thus is proportional to the thermal pressure of the ambient medium. The period of the oscillations coincides with the depletion timescale of the gas inside the ionized bubble surrounding the BH. Gas depletion is dominated by a pressure gradient pushing the gas outward if n{sub H,{infinity}} < n{sup cr}{sub H,{infinity}} and by accretion onto the BH otherwise. Generally, for n{sub H,{infinity}} < n{sup cr}{sub H,{infinity}} angular momentum does not significantly affect the accretion rate and period of the oscillations.

  5. Massive Black Hole Mergers: Can We "See" what LISA will "Hear"?

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2010-01-01

    The final merger of massive black holes produces strong gravitational radiation that can be detected by the space-borne LISA. If the black hole merger takes place in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts of the final merger requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We will review current efforts to simulate these systems, and discuss possibilities for observing the electromagnetic signals they produce.

  6. Evolution of accretion discs around a kerr black hole using extended magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Foucart, Francois; Chandra, Mani; Gammie, Charles F.; Quataert, Eliot

    2016-02-01

    Black holes accreting well below the Eddington rate are believed to have geometrically thick, optically thin, rotationally supported accretion discs in which the Coulomb mean free path is large compared to GM/c2. In such an environment, the disc evolution may differ significantly from ideal magnetohydrodynamic (MHD) predictions. We present non-ideal global axisymmetric simulations of geometrically thick discs around a rotating black hole. The simulations are carried out using a new code GRIM, which evolves a covariant extended magnetohydrodynamics model derived by treating non-ideal effects as a perturbation of ideal MHD. Non-ideal effects are modelled through heat conduction along magnetic field lines, and a difference between the pressure parallel and perpendicular to the field lines. The model relies on an effective collisionality in the disc from wave-particle scattering and velocity-space (mirror and firehose) instabilities. We find that the pressure anisotropy grows to match the magnetic pressure, at which point it saturates due to the mirror instability. The pressure anisotropy produces outward angular momentum transport with a magnitude comparable to that of MHD turbulence in the disc, and a significant increase in the temperature in the wall of the jet. We also find that, at least in our axisymmetric simulations, conduction has a small effect on the disc evolution because (1) the heat flux is constrained to be parallel to the field and the field is close to perpendicular to temperature gradients, and (2) the heat flux is choked by an increase in effective collisionality associated with the mirror instability.

  7. The low-metallicity QSO HE 2158 - 0107: a massive galaxy growing by accretion of nearly pristine gas from its environment?

    NASA Astrophysics Data System (ADS)

    Husemann, B.; Wisotzki, L.; Jahnke, K.; Sánchez, S. F.

    2011-11-01

    The metallicities of active galactic nuclei (AGN) are usually well above solar in their narrow-line regions, often reaching up to several times solar in their broad-line regions independent of redshift. Low-metallicity AGN are rare objects that have so far always been associated with low-mass galaxies hosting low-mass black holes (MBH106M⊙). We present integral field spectroscopy data of the low-redshift (z = 0.212) quasi-stellar object (QSO) HE 2158 - 0107 for which we find strong evidence of sub-solar NLR metallicities associated with a massive black hole (MBH ~ 3 × 108M⊙). The QSO is surrounded by a large extended emission-line region reaching out to 30 kpc from the QSO in a tail-like geometry. We present optical and near-infrared images and investigate the properties of the host galaxy. The host of HE 2158 - 0107 is most likely a very compact bulge-dominated galaxy with a size of re ~ 1.4 kpc. The multi-colour spectral energy distribution (SED) of the host is quite blue, indicative of a significant young age stellar population formed within the last 1 Gyr. A 3σ upper limit of Lbulge,H < 4.5 × 1010L ⊙ ,H for the H-band luminosity and a corresponding stellar mass upper limit of Mbulge < 3.4 × 1010M⊙ show that the host is offset from the local black hole-bulge relations. This is independently supported by the kinematics of the gas. Although the stellar mass of the host galaxy is lower than expected, it cannot explain the exceptionally low metallicity of the gas. We suggest that the extended emission-line region and the galaxy growth are caused by the infall of nearly pristine gas from the environment of the QSO host. Minor mergers of low-metallicity dwarf galaxies or the theoretically predicted smooth accretion of cold (~ 104 K) gas are both potential drivers behind that process. Because the metallicity of the gas in the QSO narrow-line region is much lower than expected, we suspect that the external gas has already reached the galaxy centre and may

  8. Puzzling accretion onto a black hole in the ultraluminous X-ray source M 101 ULX-1.

    PubMed

    Liu, Ji-Feng; Bregman, Joel N; Bai, Yu; Justham, Stephen; Crowther, Paul

    2013-11-28

    There are two proposed explanations for ultraluminous X-ray sources (ULXs) with luminosities in excess of 10(39) erg s(-1). They could be intermediate-mass black holes (more than 100-1,000 solar masses, M sun symbol) radiating at sub-maximal (sub-Eddington) rates, as in Galactic black-hole X-ray binaries but with larger, cooler accretion disks. Alternatively, they could be stellar-mass black holes radiating at Eddington or super-Eddington rates. On its discovery, M 101 ULX-1 had a luminosity of 3 × 10(39) erg s(-1) and a supersoft thermal disk spectrum with an exceptionally low temperature--uncomplicated by photons energized by a corona of hot electrons--more consistent with the expected appearance of an accreting intermediate-mass black hole. Here we report optical spectroscopic monitoring of M 101 ULX-1. We confirm the previous suggestion that the system contains a Wolf-Rayet star, and reveal that the orbital period is 8.2 days. The black hole has a minimum mass of 5 M sun symbol, and more probably a mass of 20 M sun symbol-30 M sun symbol, but we argue that it is very unlikely to be an intermediate-mass black hole. Therefore, its exceptionally soft spectra at high Eddington ratios violate the expectations for accretion onto stellar-mass black holes. Accretion must occur from captured stellar wind, which has hitherto been thought to be so inefficient that it could not power an ultraluminous source. PMID:24284727

  9. Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size–Luminosity Scaling Relation for the Broad-line Region

    NASA Astrophysics Data System (ADS)

    Du, Pu; Lu, Kai-Xing; Zhang, Zhi-Xiang; Huang, Ying-Ke; Wang, Kai; Hu, Chen; Qiu, Jie; Li, Yan-Rong; Fan, Xu-Liang; Fang, Xiang-Er; Bai, Jin-Ming; Bian, Wei-Hao; Yuan, Ye-Fei; Ho, Luis C.; Wang, Jian-Min; SEAMBH collaboration

    2016-07-01

    This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014 and 2015. Ten new targets were selected from the quasar sample of the Sloan Digital Sky Survey (SDSS), which have generally been more luminous than the SEAMBH candidates in the last two years. Hβ lags ({τ }{{H}β }) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known R H β–L 5100 relation. The five quasars have dimensionless accretion rates of \\dot{{M}\\quad }=10–103. Combining these with measurements of the previous SEAMBHs, we find that the reduction of Hβ lags depends tightly on accretion rates, {τ }{{H}β }/{τ }R-L\\propto {\\dot{{M}}}-0.42, where {τ }R-L is the Hβ lag from the normal R H β–L 5100 relation. Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line region: {R}{{H}β }={α }1{{\\ell }}44{β 1} {min} [1,{(\\dot{{M}}/{\\dot{{M}}}c)}-{γ 1}], where {{\\ell }}44={L}5100/{10}44 {erg} {{{s}}}-1 is the 5100 Å continuum luminosity, and the coefficients are {α }1={29.6}-2.8+2.7 lt-day, {β }1={0.56}-0.03+0.03, {γ }1={0.52}-0.16+0.33, and {\\dot{{M}}}c={11.19}-6.22+2.29. This relation is applicable to AGNs over a wide range of accretion rates, from 10‑3 to 103. Implications of this new relation are briefly discussed.

  10. Simulating Gravitational Wave Emission from Massive Black Hole Binaries

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2008-01-01

    The final merger of two black holes releases a tremendous amount of energy and is one of the brightest sources in the gravitational wave sky. Observing these sources with gravitational wave detectors requires that we know the radiation waveforms they emit. Since these mergers take place in regions of very strong gravitational fields, we need to solve Einstein's equations of general relativity on a computer in order to calculate these waveforms. For more than 30 years, scientists have tried to compute these waveforms using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. In the past few years, this situation has changed dramatically, with a series of amazing breakthroughs. This talk will focus on the recent advances that are revealing these waveforms. highlighting their astrophysical consequences and the dramatic new potential for discovery that arises when merging black holes will be observed using gravitational waves.

  11. Black hole accretion disks - Electrodynamic coupling of accretion-disk coronae and the partitioning of soft and hard X-ray emission

    NASA Technical Reports Server (NTRS)

    Kuperus, M.; Ionson, J. A.

    1985-01-01

    It is demonstrated that the observed large ratio of hard to soft X-ray emission and the bimodel behavior of black hole accreting X-ray sources such as Cygnus X-1 can be described in terms of a magnetically structured accretion disk corona which is electrodynamically coupled to the disk turbulent motions while the disk is thermodynamically coupled to the corona as described by a feedback parameter delta. The observed ratio of hard to soft X-ray emission is independent of the disk thickness, and weakly dependent of the disk parameter alpha relating the disk viscous stresses to the total pressure. Observed values of the luminosity ratio point towards strong differences of the feedback of the low state compared to the high state, in the sense that low state means small feedback (delta less than 0.2) and high state means strong feedback delta of about 0.5.

  12. Floating and sinking: the imprint of massive scalars around rotating black holes.

    PubMed

    Cardoso, Vitor; Chakrabarti, Sayan; Pani, Paolo; Berti, Emanuele; Gualtieri, Leonardo

    2011-12-01

    We study the coupling of massive scalar fields to matter in orbit around rotating black holes. It is generally expected that orbiting bodies will lose energy in gravitational waves, slowly inspiraling into the black hole. Instead, we show that the coupling of the field to matter leads to a surprising effect: because of superradiance, matter can hover into "floating orbits" for which the net gravitational energy loss at infinity is entirely provided by the black hole's rotational energy. Orbiting bodies remain floating until they extract sufficient angular momentum from the black hole, or until perturbations or nonlinear effects disrupt the orbit. For slowly rotating and nonrotating black holes floating orbits are unlikely to exist, but resonances at orbital frequencies corresponding to quasibound states of the scalar field can speed up the inspiral, so that the orbiting body sinks. These effects could be a smoking gun of deviations from general relativity. PMID:22242985

  13. Computations of Photon Orbits Emitted by Flares at the ISCO of Accretion Disks Around Rotating Black Holes

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes; Fukumura, K.

    2009-01-01

    We present detailed computations of photon orbits emitted by flares at the ISCO of accretion disks around rotating black holes. We show that for sufficiently large spin parameter, i.e. $a > 0.94 M$, following a flare at ISCO, a sufficient number of photons arrive at an observer after multiple orbits around the black hole, to produce an "photon echo" of constant lag, i.e. independent of the relative phase between the black hole and the observer, of $\\Delta T \\simeq 14 M$. This constant time delay, then, leads to the presence of a QPO in the source power spectrum at a frequency $\

  14. Radiation hydrodynamics simulations of wide-angle outflows from super-critical accretion disks around black holes

    NASA Astrophysics Data System (ADS)

    Hashizume, Katsuya; Ohsuga, Ken; Kawashima, Tomohisa; Tanaka, Masaomi

    2015-08-01

    By performing two-dimensional radiation hydrodynamics simulations with a large computational domain of 5000 times the Schwarzschild radius, we revealed that wide-angle outflow is launched via the radiation force from the super-critical accretion flows around black holes. The angular size of the outflow, where the radial velocity (vr) exceeds the escape velocity (vesc), increases with an increase of the distance from the black hole. As a result, the mass is blown away with speed of vr > vesc in all directions except for in the vicinity of the equatorial plane, θ = 0°-85°, where θ is the polar angle. The mass ejected from the outer boundary per unit time by the outflow is larger than the mass accretion rate onto the black hole, ˜ 150 LEdd/c2, where LEdd and c are the Eddington luminosity and the speed of light. The kinetic power of such wide-angle high-velocity outflow is comparable to the photon luminosity and is a few times larger than the Eddington luminosity. This corresponds to ˜ 1039-1040 erg s-1 for the stellar mass black holes. Our model is consistent with the observations of shock excited bubbles observed in some ultra-luminous X-ray sources (ULXs), supporting a hypothesis that ULXs are powered by the super-critical accretion onto stellar mass black holes.

  15. Stability of warped AdS3 black holes in topologically massive gravity under scalar perturbations

    NASA Astrophysics Data System (ADS)

    Ferreira, Hugo R. C.

    2013-06-01

    We demonstrate that the warped AdS3 black hole solutions of topologically massive gravity are classically stable against massive scalar field perturbations by analyzing the quasinormal and bound state modes of the scalar field. In particular, it is found that although classical superradiance is present it does not give rise to superradiant instabilities. The stability is shown to persist even when the black hole is enclosed by a stationary mirror with Dirichlet boundary conditions. This is a surprising result in view of the similarity between the causal structure of the warped AdS3 black hole and the Kerr spacetime in 3+1 dimensions. This work provides the foundations for the study of quantum field theory in this spacetime.

  16. Dusty Feedback from Massive Black Holes in Two Elliptical Galaxies

    NASA Technical Reports Server (NTRS)

    Temi, P.; Brighenti, F.; Mathews, W. G.; Amblard, A.; Riguccini, L.

    2013-01-01

    Far-infrared dust emission from elliptical galaxies informs us about galaxy mergers, feedback energy outbursts from supermassive black holes and the age of galactic stars. We report on the role of AGN feedback observationally by looking for its signatures in elliptical galaxies at recent epochs in the nearby universe. We present Herschel observations of two elliptical galaxies with strong and spatially extended FIR emission from colder grains 5-10 kpc distant from the galaxy cores. Extended excess cold dust emission is interpreted as evidence of recent feedback-generated AGN energy outbursts in these galaxies, visible only in the FIR, from buoyant gaseous outflows from the galaxy cores.

  17. Self-regulated black hole accretion, the M-σ relation and the growth of bulges in galaxies

    NASA Astrophysics Data System (ADS)

    Begelman, Mitchell C.; Nath, Biman B.

    2005-08-01

    We argue that the velocity dispersions and masses of galactic bulges and spheroids are byproducts of the feedback that regulates rapid black hole growth in protogalaxies. We suggest that the feedback energy liberated by accretion must pass through the accreting material, in an energy-conserving flux near the black hole and a momentum-conserving flux farther away from the black hole. If the inflowing gas dominates the gravitational potential outside the Bondi radius, feedback from Eddington-limited accretion drives the density profile of the gas to that of a singular isothermal sphere. We find that the velocity dispersion associated with the isothermal potential, σ, increases with time as the black hole mass M grows, in such a way that M~σ4. The coefficient of this proportionality depends on the radius at which the flow switches from energy conserving to momentum conserving, and gives the observed M-σ relation if the transition occurs at ~100 Schwarzschild radii. We associate this transition with radiative cooling and show that bremsstrahlung, strongly boosted by inverse Compton scattering in a two-temperature (Tp>>Te) plasma, leads to a transition at the desired radius. According to this picture, bulge masses Mb are insensitive to the virial masses of their dark matter haloes, but correlate linearly with black hole mass. Our analytic model also explains the Mb-σ (Faber-Jackson) relation as a relic of black hole accretion. The model naturally explains why the M-σ relation has less scatter than either the M-Mb (Magorrian) or the Faber-Jackson relation. It suggests that the M-σ relation could extend down to very low velocity dispersions, and predicts that the relation should not evolve with redshift.

  18. Accretion of Supersonic Winds onto Black Holes in 3D: Stability of the Shock Cone

    NASA Astrophysics Data System (ADS)

    Gracia-Linares, M.; Guzmán, F. S.

    2015-10-01

    Using numerical simulations we present the accretion of supersonic winds onto a rotating black hole in three dimensions. We study five representative directions of the wind with respect to the axis of rotation of the black hole and focus on the evolution and stability of the high-density shock cone that is formed during the process. We explore both the regime in which the shock cone is expected to be stable in order to confirm previous results obtained with two-dimensional simulations, and the regime in which the shock cone is expected to show a flip-flop (FF) type of instability. The methods used to attempt a triggering of the instability were (i) the accumulation of numerical errors and (ii) the explicit application of a perturbation on the velocity field after the shock cone was formed. The result is negative, that is, we did not find the FF instability within the parameter space we explored, including cases that are expected to be unstable.

  19. High-Frequency QPOs and Overstable Oscillations of Black-Hole Accretion Disks

    NASA Astrophysics Data System (ADS)

    Lai, Dong; Fu, Wen; Tsang, David; Horak, Jiri; Yu, Cong

    2013-02-01

    The physical origin of high-frequency QPOs (HFQPOs) in black-hole X-ray binaries remains an enigma despite many years of detailed observational studies. Although there exists a number of models for HFQPOs, many of these are simply ``notions'' or ``concepts'' without actual calculation derived from fluid or disk physics. Future progress requires a combination of numerical simulations and semi-analytic studies to extract physical insights. We review recent works on global oscillation modes in black-hole accretion disks, and explain how, with the help of general relativistic effects, the energy stored in the disk differential rotation can be pumped into global spiral density modes in the disk, making these modes grow to large amplitudes under certain conditions (``corotational instability''). These modes are robust in the presence of disk magnetic fields and turbulence. The computed oscillation mode frequencies are largely consistent with the observed values for HFQPOs in BH X-ray binaries. The approximate 2:3 frequency ratio is also expected from this model. The connection of HFQPOs with other disk properties (such as production of episodic jets) is also discussed.

  20. Active galactic nuclei at z ˜ 1.5 - III. Accretion discs and black hole spin

    NASA Astrophysics Data System (ADS)

    Capellupo, D. M.; Netzer, H.; Lira, P.; Trakhtenbrot, B.; Mejía-Restrepo, J.

    2016-07-01

    This is the third paper in a series describing the spectroscopic properties of a sample of 39 AGN at z ˜ 1.5, selected to cover a large range in black hole mass (MBH) and Eddington ratio (L/LEdd). In this paper, we continue the analysis of the VLT/X-shooter observations of our sample with the addition of nine new sources. We use an improved Bayesian procedure, which takes into account intrinsic reddening, and improved MBH estimates, to fit thin accretion disc (AD) models to the observed spectra and constrain the spin parameter (a*) of the central black holes. We can fit 37 out of 39 AGN with the thin AD model, and for those with satisfactory fits, we obtain constraints on the spin parameter of the BHs, with the constraints becoming generally less well defined with decreasing BH mass. Our spin parameter estimates range from ˜-0.6 to maximum spin for our sample, and our results are consistent with the `spin-up' scenario of BH spin evolution. We also discuss how the results of our analysis vary with the inclusion of non-simultaneous GALEX photometry in our thin AD fitting. Simultaneous spectra covering the rest-frame optical through far-UV are necessary to definitively test the thin AD theory and obtain the best constraints on the spin parameter.

  1. Active galactic nuclei at z ˜ 1.5: III. Accretion discs and Black Hole Spin

    NASA Astrophysics Data System (ADS)

    Capellupo, D. M.; Netzer, H.; Lira, P.; Trakhtenbrot, B.; Mejía-Restrepo, J.

    2016-04-01

    This is the third paper in a series describing the spectroscopic properties of a sample of 39 AGN at z ˜ 1.5, selected to cover a large range in black hole mass (MBH) and Eddington ratio (L/LEdd). In this paper, we continue the analysis of the VLT/X-shooter observations of our sample with the addition of 9 new sources. We use an improved Bayesian procedure, which takes into account intrinsic reddening, and improved MBH estimates, to fit thin accretion disc (AD) models to the observed spectra and constrain the spin parameter (a★) of the central black holes. We can fit 37 out of 39 AGN with the thin AD model, and for those with satisfactory fits, we obtain constraints on the spin parameter of the BHs, with the constraints becoming generally less well defined with decreasing BH mass. Our spin parameter estimates range from ˜-0.6 to maximum spin for our sample, and our results are consistent with the "spin-up" scenario of BH spin evolution. We also discuss how the results of our analysis vary with the inclusion of non-simultaneous GALEX photometry in our thin AD fitting. Simultaneous spectra covering the rest-frame optical through far-UV are necessary to definitively test the thin AD theory and obtain the best constraints on the spin parameter.

  2. Low-Frequency Gravitational Radiation from Coalescing Massive Black Hole Binaries in Hierarchical Cosmologies

    NASA Astrophysics Data System (ADS)

    Sesana, Alberto; Haardt, Francesco; Madau, Piero; Volonteri, Marta

    2004-08-01

    We compute the expected low-frequency gravitational wave signal from coalescing massive black hole (MBH) binaries at the center of galaxies in a hierarchical structure formation scenario in which seed holes of intermediate mass form far up in the dark halo ``merger tree.'' The merger history of dark matter halos and associated MBHs is followed via cosmological Monte Carlo realizations of the merger hierarchy from redshift z=20 to the present in a ΛCDM cosmology. MBHs get incorporated through halo mergers into larger and larger structures, sink to the center because of dynamical friction against the dark matter background, accrete cold material in the merger remnant, and form MBH binary systems. Stellar dynamical (three-body) interactions cause the hardening of the binary at large separations, while gravitational wave emission takes over at small radii and leads to the final coalescence of the pair. A simple scheme is applied in which the ``loss cone'' is constantly refilled and a constant stellar density core forms because of the ejection of stars by the shrinking binary. The integrated emission from inspiraling MBH binaries at all redshifts is computed in the quadrupole approximation and results in a gravitational wave background (GWB) with a well-defined shape that reflects the different mechanisms driving the late orbital evolution. The characteristic strain spectrum has the standard hc(f)~f-2/3 behavior only in the range f=10-9to10-6 Hz. At lower frequencies the orbital decay of MBH binaries is driven by the ejection of background stars (``gravitational slingshot''), and the strain amplitude increases with frequency, hc(f)~f. In this range the GWB is dominated by 109-1010 Msolar MBH pairs coalescing at 0<~z<~2. At higher frequencies, f>10-6Hz, the strain amplitude, as steep as hc(f)~f-1.3, is shaped by the convolution of last stable circular orbit emission by lighter binaries (102-107 Msolar) populating galaxy halos at all redshifts. We discuss the

  3. An Accretion Model for the Growth of the Central Black Holes Associated with Ionization Instability in Quasars

    NASA Technical Reports Server (NTRS)

    Lu, Y.; Cheng, K. S.; Zhang, S. N.

    2003-01-01

    A possible accretion model associated with the ionization instability of quasar disks is proposed to address the growth of the central black hole (BH) harbored in the host galaxy. The evolution of quasars in cosmic time is assumed to change from a highly active state to a quiescent state triggered by the S-shaped ionization instability of the quasar accretion disk. For a given external mass transfer rate supplied by the quasar host galaxy, ionization instability can modify the accretion rate in the disk and separate the accretion flows of the disk into three different phases, like an S-shape. We suggest that the bright quasars observed today are those quasars with disks in the upper branch of the S-shaped instability, and the faint or 'dormant' quasars are simply these systems in the lower branch. The middle branch is the transition state, which is unstable. We assume the quasar disk evolves according to the advection-dominated inflow-outflow solution (ADIOS) configuration in the stable lower branch of the S-shaped instability, and the Eddington accretion rate is used to constrain the accretion rate in the highly active phase. The mass ratio between a BH and its host galactic bulge is a natural consequence of an ADIOS. Our model also demonstrates that a seed BH approx. 2 x 10(exp 6) solar masses similar to those found in spiral galaxies today is needed to produce a BH with a final mass of approx. 2 x 10(exp 8) solar masses.

  4. As Above, So Below: Exploiting Mass Scaling in Black Hole Accretion to Break Degeneracies in Spectral Interpretation

    NASA Astrophysics Data System (ADS)

    Markoff, Sera; Nowak, Michael A.; Gallo, Elena; Hynes, Robert; Wilms, Jörn; Plotkin, Richard M.; Maitra, Dipankar; Silva, Catia V.; Drappeau, Samia

    2015-10-01

    Over the past decade, evidence has mounted that several aspects of black hole (BH) accretion physics proceed in a mass-invariant way. One of the best examples of this scaling is the empirical “fundamental plane of BH accretion” relation linking mass, radio, and X-ray luminosity over eight orders of magnitude in BH mass. The currently favored theoretical interpretation of this relation is that the physics governing power output in weakly accreting BHs depends more on relative accretion rate than on mass. In order to test this theory, we explore whether a mass-invariant approach can simultaneously explain the broadband spectral energy distributions from two BHs at opposite ends of the mass scale but that are at similar Eddington accretion fractions. We find that the same model, with the same value of several fitted physical parameters expressed in mass-scaling units to enforce self-similarity, can provide a good description of two data sets from V404 Cyg and M81*, a stellar and supermassive BH, respectively. Furthermore, only one of several potential emission scenarios for the X-ray band is successful, suggesting it is the dominant process driving the fundamental plane relation at this accretion rate. This approach thus holds promise for breaking current degeneracies in the interpretation of BH high-energy spectra and for constructing better prescriptions of BH accretion for use in various local and cosmological feedback applications.

  5. An over-massive black hole in the compact lenticular galaxy NGC 1277.

    PubMed

    van den Bosch, Remco C E; Gebhardt, Karl; Gültekin, Kayhan; van de Ven, Glenn; van der Wel, Arjen; Walsh, Jonelle L

    2012-11-29

    Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC 4486B. Here we report observations of the stellar kinematics of NGC 1277, which is a compact, lenticular galaxy with a mass of 1.2 × 10(11) solar masses. From the data, we determine that the mass of the central black hole is 1.7 × 10(10) solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC 1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations. PMID:23192149

  6. The Final Merger of Massive Black Holes: Recoils, Gravitational Waves, and Electromagnetic Signatures

    NASA Technical Reports Server (NTRS)

    Centrella, Joan M.

    2010-01-01

    The final merger of two massive black holes produces a powerful burst of gravitational radiation, emitting more energy than all the stars in the observable universe combined. The resulting gravitational waveforms will be easily detectable by the space-based LISA out to redshifts z greater than 10, revealing the masses and spins of the black holes to high precision. If the merging black holes have unequal masses, or asymmetric spins, the final black hole that forms can recoil with a velocity exceeding 1000 km/s. And, when the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new results that are revealing the dynamics and waveforms of binary black hole mergers, recoil velocities, and the possibility of accompanying electromagnetic outbursts.

  7. Accretion shock signatures in the spectrum of two-temperature advective flows around black holes

    NASA Astrophysics Data System (ADS)

    Mandal, S.; Chakrabarti, S. K.

    2005-05-01

    The centrifugal barrier supported boundary layer (CENBOL) of a black hole affects the spectrum exactly in the same way the boundary layer of a neutron star does. The CENBOL is caused by standing or oscillating shock waves that accelerate electrons very efficiently and produce a power-law distribution. The accelerated particles in turn emit synchrotron radiation in the presence of the magnetic field. We study the spectral properties of an accretion disk as a function of shock strength, compression ratio, flow accretion rate and flow geometry. In the absence of a satisfactory description of magnetic fields inside the advective disk, we only consider the stochastic fields and use the ratio of field energy density to gravitational energy density as a parameter. Not surprisingly, stronger fields produce larger humps due to synchrotron radiation. We not only include “conventional” synchrotron emission and Comptonization due to Maxwell-Boltzmann electrons in the gas, but also compute the effects of power-law electrons. For strong shocks, a bump is produced just above the synchrotron self-absorption frequency at ν_bump ˜ ν_inj [1+4/3 {R-1}/{R} {1}/{x_s1/2}]x_s^{1/2}, where, ν_inj is the frequency of the dominant photons from the pre-shock flow, and R the compression ratio of the shock located at x_s. For strong shocks, a bump at a higher frequency appears predominantly due to the power-law electrons formed at the shock front.

  8. Improved reflection models of black hole accretion disks: Treating the angular distribution of X-rays

    SciTech Connect

    García, J.; Steiner, J. F.; McClintock, J. E.; Brenneman, L. E-mail: jsteiner@head.cfa.harvard.edu E-mail: lbrenneman@cfa.harvard.edu; and others

    2014-02-20

    X-ray reflection models are used to constrain the properties of the accretion disk, such as the degree of ionization of the gas and the elemental abundances. In combination with general relativistic ray tracing codes, additional parameters like the spin of the black hole and the inclination to the system can be determined. However, current reflection models used for such studies only provide angle-averaged solutions for the flux reflected at the surface of the disk. Moreover, the emission angle of the photons changes over the disk due to relativistic light bending. To overcome this simplification, we have constructed an angle-dependent reflection model with the XILLVER code and self-consistently connected it with the relativistic blurring code RELLINE. The new model, relxill, calculates the proper emission angle of the radiation at each point on the accretion disk and then takes the corresponding reflection spectrum into account. We show that the reflected spectra from illuminated disks follow a limb-brightening law highly dependent on the ionization of disk and yet different from the commonly assumed form I∝ln (1 + 1/μ). A detailed comparison with the angle-averaged model is carried out in order to determine the bias in the parameters obtained by fitting a typical relativistic reflection spectrum. These simulations reveal that although the spin and inclination are mildly affected, the Fe abundance can be overestimated by up to a factor of two when derived from angle-averaged models. The fit of the new model to the Suzaku observation of the Seyfert galaxy Ark 120 clearly shows a significant improvement in the constraint of the physical parameters, in particular by enhancing the accuracy in the inclination angle and the spin determinations.

  9. Relativistic boost as the cause of periodicity in a massive black-hole binary candidate.

    PubMed

    D'Orazio, Daniel J; Haiman, Zoltán; Schiminovich, David

    2015-09-17

    Because most large galaxies contain a central black hole, and galaxies often merge, black-hole binaries are expected to be common in galactic nuclei. Although they cannot be imaged, periodicities in the light curves of quasars have been interpreted as evidence for binaries, most recently in PG 1302-102, which has a short rest-frame optical period of four years (ref. 6). If the orbital period of the black-hole binary matches this value, then for the range of estimated black-hole masses, the components would be separated by 0.007-0.017 parsecs, implying relativistic orbital speeds. There has been much debate over whether black-hole orbits could be smaller than one parsec (ref. 7). Here we report that the amplitude and the sinusoid-like shape of the variability of the light curve of PG 1302-102 can be fitted by relativistic Doppler boosting of emission from a compact, steadily accreting, unequal-mass binary. We predict that brightness variations in the ultraviolet light curve track those in the optical, but with a two to three times larger amplitude. This prediction is relatively insensitive to the details of the emission process, and is consistent with archival ultraviolet data. Follow-up ultraviolet and optical observations in the next few years can further test this prediction and confirm the existence of a binary black hole in the relativistic regime. PMID:26381982

  10. Black hole radiation of massive spin-2 particles in (3+1) dimensions

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Övgün, A.

    2016-06-01

    This paper is devoted to the study of radiation of a massive spin-2 boson (graviton with a nonzero mass) through the event horizon of a generic static and spherically symmetric black hole in (3+1) dimensions. To this end, we consider the problem in the framework of the quantum tunneling phenomenon. We evaluate the tunneling rate of the massive gravitons by applying the semiclassical WKB approximation to the Fierz-Pauli equation. The temperature of the radiation is obtained with the aid of the Boltzmann expression. Our findings are in good agreement with the existing Hawking radiation studies in the current literature.

  11. Supersymmetric backgrounds and black holes in {N}=(1,1) cosmological new massive supergravity

    NASA Astrophysics Data System (ADS)

    Alkaç, Gökhan; Basanisi, Luca; Bergshoeff, Eric A.; Devecioğlu, Deniz Olgu; Ozkan, Mehmet

    2015-10-01

    Using an off-shell Killing spinor analysis we perform a systematic investigation of the supersymmetric background and black hole solutions of the N=(1,1) Cosmological New Massive Gravity model. The solutions with a null Killing vector are the same pp-wave solutions that one finds in the N=1 model but we find new solutions with a time-like Killing vector that are absent in the N=1 case. An example of such a solution is a Lifshitz spacetime. We also consider the supersymmetry properties of the so-called rotating hairy BTZ black holes and logarithmic black holes in an AdS 3 background. Furthermore, we show that under certain assumptions there is no supersymmetric Lifshitz black hole solution.

  12. Massive Black Hole Mergers: Can we see what LISA will hear?

    NASA Technical Reports Server (NTRS)

    Centrella, Joan

    2009-01-01

    Coalescing massive black hole binaries are formed when galaxies merge. The final stages of this coalescence produce strong gravitational wave signals that can be detected by the space-borne LISA. When the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We have taken a first step towards this problem by mapping the flow of pressureless matter in the dynamic, 3-D general relativistic spacetime around the merging black holes. We report on the results of these initial simulations and discuss their likely importance for future hydrodynamical simulations.

  13. Waveforms in massive gravity and neutralization of giant black hole ringings

    NASA Astrophysics Data System (ADS)

    Décanini, Yves; Folacci, Antoine; Ould El Hadj, Mohamed

    2016-06-01

    A distorted black hole radiates gravitational waves in order to settle down in a smoother geometry. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from both the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. In the framework of massive gravity, the excitation factors of the Schwarzschild black hole have an unexpected strong resonant behavior which, theoretically, could lead to giant and slowly decaying ringings. If massive gravity is relevant to physics, one can hope to observe these extraordinary ringings by using the next generations of gravitational wave detectors. Indeed, they could be generated by supermassive black holes if the graviton mass is not too small. In fact, by focusing on the odd-parity ℓ=1 mode of the Fierz-Pauli field, we shall show here that such ringings are neutralized in waveforms due to (i) the excitation of the quasibound states of the black hole and (ii) the evanescent nature of the particular partial modes which could excite the concerned quasinormal modes. Despite this, with observational consequences in mind, it is interesting to note that the waveform amplitude is nevertheless rather pronounced and slowly decaying (this effect is now due to the long-lived quasibound states). It is worth noting also that, for very low values of the graviton mass (corresponding to the weak instability regime for the black hole), the waveform is now very clean and dominated by an ordinary ringing which could be used as a signature of massive gravity.

  14. Tilted black hole accretion disc models of Sagittarius A*: time-variable millimetre to near-infrared emission

    NASA Astrophysics Data System (ADS)

    Dexter, Jason; Fragile, P. Chris

    2013-07-01

    High-resolution, multiwavelength and time-domain observations of the Galactic Centre black hole candidate, Sgr A*, allow for a direct test of contemporary accretion theory. Most models assume alignment between the accretion disc and black hole angular momentum axes, but this is not necessarily the case for geometrically thick accretion flows like that on to Sgr A*. Instead, we calculate images and spectra from a set of numerical simulations of accretion flows misaligned (`tilted') by 15° from the black hole spin axis and compare them with millimetre (mm) to near-infrared (NIR) observations. Non-axisymmetric standing shocks from eccentric fluid orbits dominate the emission, leading to a wide range of possible image morphologies. The strong effects of disc tilt lead to poorly constrained model parameters. These results suggest that previous parameter estimates from fitting aligned models, including estimates of the dimensionless black hole spin, likely only apply for small values of spin or tilt (upper limits of a < 0.3 or β < 15°). At 1.3 mm, the black hole images have crescent morphologies as in the aligned case, and the black hole shadow may still be accessible to future very long baseline interferometry (mm-VLBI) observations. Shock heating leads to multiple populations of electrons, some at high energies (Te > 1012 K). These electrons can naturally produce the observed NIR flux, spectral index and rapid variability (`flaring'). This NIR emission is uncorrelated with that in the mm, which also agrees with observations. These are the first numerical models to explain the time-variable mm to NIR emission of Sgr A*. Predictions of the model include significant structural changes observable with mm-VLBI on both the dynamical (hour) and Lense-Thirring precession (day-year) time-scales, and ≃ 30-50 μas changes in centroid position from extreme gravitational lensing events during NIR flares, detectable with the future VLT instrument GRAVITY. We further predict

  15. Astrophysical constraints on massive black hole binary evolution from pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Middleton, Hannah; Del Pozzo, Walter; Farr, Will M.; Sesana, Alberto; Vecchio, Alberto

    2016-01-01

    We consider the information that can be derived about massive black hole binary (MBHB) populations and their formation history solely from current and possible future pulsar timing array (PTA) results. We use models of the stochastic gravitational-wave background from circular MBHBs with chirp mass in the range 106-1011 M⊙ evolving solely due to radiation reaction. Our parametrized models for the black hole merger history make only weak assumptions about the properties of the black holes merging over cosmic time. We show that current PTA results place an upper limit on the black hole merger density which does not depend on the choice of a particular merger history model; however, they provide no information about the redshift or mass distribution. We show that even in the case of a detection resulting from a factor of 10 increase in amplitude sensitivity, PTAs will only put weak constraints on the source merger density as a function of mass, and will not provide any additional information on the redshift distribution. Without additional assumptions or information from other observations, a detection cannot meaningfully bound the massive black hole merger rate above zero for any particular mass.

  16. Galaxy Formation with Self-Consistently Modeled Stars and Massive Black Holes. I: Feedback-Regulated Star Formation and Black Hole Growth

    SciTech Connect

    Kim, Ji-hoon; Wise, John H.; Alvarez, Marcelo A.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys. Dept.

    2011-11-04

    There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto an MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full three-dimensional adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2 x 10{sup 11} M {circle_dot} galactic halo and its 10{sup 5} {circle_dot} M embedded MBH at redshift 3 in a cosmological CDM simulation. The MBH feedback heats the surrounding interstellar medium (ISM) up to 10{sup 6} K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. The feedback considerably changes the stellar distribution there. This new channel of feedback from a slowly growing MBH is particularly interesting because it is only locally dominant and does not require the heating of gas globally on the disk. The MBH also self-regulates its growth by keeping the surrounding ISM hot for an extended period of time.

  17. General Relativistic Radiative Transfer and GeneralRelativistic MHD Simulations of Accretion and Outflows of Black Holes

    SciTech Connect

    Fuerst, Steven V.; Mizuno, Yosuke; Nishikawa, Ken-Ichi; Wu, Kinwah; /Mullard Space Sci. Lab.

    2007-01-05

    We calculate the emission from relativistic flows in black hole systems using a fully general relativistic radiative transfer formulation, with flow structures obtained by general relativistic magneto-hydrodynamic simulations. We consider thermal free-free emission and thermal synchrotron emission. Bright filament-like features protrude (visually) from the accretion disk surface, which are enhancements of synchrotron emission where the magnetic field roughly aligns with the line-of-sight in the co-moving frame. The features move back and forth as the accretion flow evolves, but their visibility and morphology are robust. We propose that variations and drifts of the features produce certain X-ray quasi-periodic oscillations (QPOs) observed in black-hole X-ray binaries.

  18. Dark-matter distributions around massive black holes: A general relativistic analysis

    NASA Astrophysics Data System (ADS)

    Sadeghian, Laleh; Ferrer, Francesc; Will, Clifford M.

    2013-09-01

    The cold dark matter at the center of a galaxy will be redistributed by the presence of a massive black hole. The redistribution may be determined using an approach pioneered by Gondolo and Silk: begin with a model distribution function for the dark matter, and “grow” the black hole adiabatically, holding the adiabatic invariants of the motion constant. Unlike the approach of Gondolo and Silk, which adopted Newtonian theory together with ad hoc correction factors to mimic general relativistic effects, we carry out the calculation fully relativistically, using the exact Schwarzschild geometry of the black hole. We find that the density of dark matter generically vanishes at r=2RS, not 4RS as found by Gondolo and Silk, where RS is the Schwarzschild radius, and that the spike very close to the black hole reaches significantly higher densities. We apply the relativistic adiabatic growth framework to obtain the final dark-matter density for both cored and cusped initial distributions. Besides the implications of these results for indirect detection estimates, we show that the gravitational effects of such a dark-matter spike are significantly smaller than the relativistic effects of the black hole, including frame dragging and quadrupolar effects, for stars orbiting close to the black hole that might be candidates for testing the black-hole no-hair theorems.

  19. Modelling galaxy and AGN evolution in the infrared: black hole accretion versus star formation activity

    NASA Astrophysics Data System (ADS)

    Gruppioni, C.; Pozzi, F.; Zamorani, G.; Vignali, C.

    2011-09-01

    We present a new backward evolution model for galaxies and active galactic nuclei (AGNs) in the infrared (IR). What is new in this model is the separate study of the evolutionary properties of different IR populations (i.e. spiral galaxies, starburst galaxies, low-luminosity AGNs, 'unobscured' type 1 AGNs and 'obscured' type 2 AGNs) defined through a detailed analysis of the spectral energy distributions (SEDs) of large samples of IR-selected sources. The evolutionary parameters have been constrained by means of all the available observables from surveys in the mid- and far-IR (source counts, redshift and luminosity distributions, luminosity functions). By decomposing the SEDs representative of the three AGN classes into three distinct components (a stellar component emitting most of its power in the optical/near-IR, an AGN component due to the hot dust heated by the central black hole peaking in the mid-IR, and a starburst component dominating the far-IR spectrum), we have disentangled the AGN contribution to the monochromatic and total IR luminosity emitted by different populations considered in our model from that due to star formation activity. We have then obtained an estimate of the total IR luminosity density [and star formation density (SFD) produced by IR galaxies] and the first ever estimate of the black hole mass accretion density (BHAR) from the IR. The derived evolution of the BHAR is in agreement with estimates from X-rays, though the BHAR values we derive from the IR are slightly higher than the X-ray ones. Finally, we have simulated source counts, redshift distributions, and SFD and BHAR that we expect to obtain with the future cosmological surveys in the mid-/far-IR that will be performed with the JWST-MIRI and SPICA-SAFARI. Outputs of the model are available online.1

  20. LOW-FREQUENCY OSCILLATIONS IN GLOBAL SIMULATIONS OF BLACK HOLE ACCRETION

    SciTech Connect

    O'Neill, Sean M.; Reynolds, Christopher S.; Coleman Miller, M.; Sorathia, Kareem A.

    2011-08-01

    We have identified the presence of large-scale, low-frequency dynamo cycles in a long-duration, global, magnetohydrodynamic (MHD) simulation of black hole accretion. Such cycles have previously been seen in local shearing box simulations, but we discuss their evolution over 1500 inner disk orbits of a global {pi}/4 disk wedge spanning two orders of magnitude in radius and seven scale heights in elevation above/below the disk midplane. The observed cycles manifest themselves as oscillations in azimuthal magnetic field occupying a region that extends into a low-density corona several scale heights above the disk. The cycle frequencies are 10-20 times lower than the local orbital frequency, making them potentially interesting sources of low-frequency variability when scaled to real astrophysical systems. Furthermore, power spectra derived from the full time series reveal that the cycles manifest themselves at discrete, narrowband frequencies that often share power across broad radial ranges. We explore possible connections between these simulated cycles and observed low-frequency quasi-periodic oscillations (LFQPOs) in galactic black hole binary systems, finding that dynamo cycles have the appropriate frequencies and are located in a spatial region associated with X-ray emission in real systems. Derived observational proxies, however, fail to feature peaks with rms amplitudes comparable to LFQPO observations, suggesting that further theoretical work and more sophisticated simulations will be required to form a complete theory of dynamo-driven LFQPOs. Nonetheless, this work clearly illustrates that global MHD dynamos exhibit quasi-periodic behavior on timescales much longer than those derived from test particle considerations.

  1. Nuclear star formation activity and black hole accretion in nearby Seyfert galaxies

    SciTech Connect

    Esquej, P.; Alonso-Herrero, A.; Hernán-Caballero, A.; González-Martín, O.; Ramos Almeida, C.; Rodríguez Espinosa, J. M.; Roche, P.; Mason, R. E.; Díaz-Santos, T.; Levenson, N. A.; Aretxaga, I.; Packham, C.

    2014-01-01

    Recent theoretical and observational works indicate the presence of a correlation between the star-formation rate (SFR) and active galactic nucleus (AGN) luminosity (and, therefore, the black hole accretion rate, M-dot {sub BH}) of Seyfert galaxies. This suggests a physical connection between the gas-forming stars on kpc scales and the gas on sub-pc scales that is feeding the black hole. We compiled the largest sample of Seyfert galaxies to date with high angular resolution (∼0.''4-0.''8) mid-infrared (8-13 μm) spectroscopy. The sample includes 29 Seyfert galaxies drawn from the AGN Revised Shapley-Ames catalog. At a median distance of 33 Mpc, our data allow us to probe nuclear regions on scales of ∼65 pc (median value). We found no general evidence of suppression of the 11.3 μm polycyclic aromatic hydrocarbon (PAH) emission in the vicinity of these AGN, and we used this feature as a proxy for the SFR. We detected the 11.3 μm PAH feature in the nuclear spectra of 45% of our sample. The derived nuclear SFRs are, on average, five times lower than those measured in circumnuclear regions of 600 pc in size (median value). However, the projected nuclear SFR densities (median value of 22 M {sub ☉} yr{sup –1} kpc{sup –2}) are a factor of 20 higher than those measured on circumnuclear scales. This indicates that the SF activity per unit area in the central ∼65 pc region of Seyfert galaxies is much higher than at larger distances from their nuclei. We studied the connection between the nuclear SFR and M-dot {sub BH} and showed that numerical simulations reproduce our observed relation fairly well.

  2. Nuclear Star Formation Activity and Black Hole Accretion in Nearby Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Esquej, P.; Alonso-Herrero, A.; González-Martín, O.; Hönig, S. F.; Hernán-Caballero, A.; Roche, P.; Ramos Almeida, C.; Mason, R. E.; Díaz-Santos, T.; Levenson, N. A.; Aretxaga, I.; Rodríguez Espinosa, J. M.; Packham, C.

    2014-01-01

    Recent theoretical and observational works indicate the presence of a correlation between the star-formation rate (SFR) and active galactic nucleus (AGN) luminosity (and, therefore, the black hole accretion rate, \\dot{M}_BH) of Seyfert galaxies. This suggests a physical connection between the gas-forming stars on kpc scales and the gas on sub-pc scales that is feeding the black hole. We compiled the largest sample of Seyfert galaxies to date with high angular resolution (~0.''4-0.''8) mid-infrared (8-13 μm) spectroscopy. The sample includes 29 Seyfert galaxies drawn from the AGN Revised Shapley-Ames catalog. At a median distance of 33 Mpc, our data allow us to probe nuclear regions on scales of ~65 pc (median value). We found no general evidence of suppression of the 11.3 μm polycyclic aromatic hydrocarbon (PAH) emission in the vicinity of these AGN, and we used this feature as a proxy for the SFR. We detected the 11.3 μm PAH feature in the nuclear spectra of 45% of our sample. The derived nuclear SFRs are, on average, five times lower than those measured in circumnuclear regions of 600 pc in size (median value). However, the projected nuclear SFR densities (median value of 22 M ⊙ yr-1 kpc-2) are a factor of 20 higher than those measured on circumnuclear scales. This indicates that the SF activity per unit area in the central ~65 pc region of Seyfert galaxies is much higher than at larger distances from their nuclei. We studied the connection between the nuclear SFR and \\dot{M}_BH and showed that numerical simulations reproduce our observed relation fairly well.

  3. Vacuum polarization of massive spinor fields in static black-string backgrounds

    SciTech Connect

    Fernandez Piedra, Owen Pavel; Cabo Montes de Oca, Alejandro

    2008-01-15

    The renormalized mean value of the quantum Lagrangian and the corresponding components of the energy-momentum tensor for massive spinor fields coupled to an arbitrary gravitational field configuration having cylindrical symmetry are analytically evaluated using the Schwinger-DeWitt approximation, up to second order in the inverse mass value. The general results are employed to explicitly derive compact analytical expressions for the quantum mean Lagrangian and Energy-Momentum tensor in the particular background of the black-string spacetime.

  4. New modes for massive Dirac field in higher-dimensional black holes

    NASA Astrophysics Data System (ADS)

    Sporea, Ciprian A.

    2015-08-01

    In this paper, we derive new modes for massive Dirac field in the background of a higher-dimensional Schwarzschild black hole. We use in our approach the Cartesian gauge defined in local frames. We work in the context of Arkani-Hamed, Dimopoulos and Dvali (ADD)-like theories, assuming that the Standard Model fields (fermions and bosons) live only on a (3+1)-dimensional brane and the extra dimensions of space can be large in size.

  5. CONSTRAINTS ON COMPTON-THICK WINDS FROM BLACK HOLE ACCRETION DISKS: CAN WE SEE THE INNER DISK?

    SciTech Connect

    Reynolds, Christopher S.

    2012-11-01

    Strong evidence is emerging that winds can be driven from the central regions of accretion disks in both active galactic nuclei and Galactic black hole binaries. Direct evidence for highly ionized, Compton-thin inner-disk winds comes from observations of blueshifted (v {approx} 0.05-0.1c) iron-K X-ray absorption lines. However, it has been suggested that the inner regions of black hole accretion disks can also drive Compton-thick winds-such winds would enshroud the inner disk, preventing us from seeing direct signatures of the accretion disk (i.e., the photospheric thermal emission, or the Doppler/gravitationally broadened iron K{alpha} line). Here, we show that, provided the source is sub-Eddington, the well-established wind-driving mechanisms fail to launch a Compton-thick wind from the inner disk. For the accelerated region of the wind to be Compton-thick, the momentum carried in the wind must exceed the available photon momentum by a factor of at least 2/{lambda}, where {lambda} is the Eddington ratio of the source, ruling out radiative acceleration unless the source is very close to the Eddington limit. Compton-thick winds also carry large mass fluxes, and a consideration of the connections between the wind and the disk shows this to be incompatible with magneto-centrifugal driving. Finally, thermal driving of the wind is ruled out on the basis of the large Compton radii that typify black hole systems. In the absence of some new acceleration mechanisms, we conclude that the inner regions of sub-Eddington accretion disks around black holes are indeed naked.

  6. MHD accretion of a perfect fluid with an ultrahard equation of state onto a moving Schwarzschild black hole

    NASA Astrophysics Data System (ADS)

    Chernov, S. V.

    2016-06-01

    The full version of the magnetohydrodynamical (MHD) theory of accretion of a perfect fluid with an ultrahard equation of state, p = μ ~ ρ 2 (where p is the pressure, μ the total energy density, and ρ the fluid density), onto a moving Schwarzschild black hole is considered. Exact and approximate analytical solutions have been found. It is shown that smooth continuous solutions exist only in the case when a single critical sound surface is formed.

  7. A CORRELATION BETWEEN STAR FORMATION RATE AND AVERAGE BLACK HOLE ACCRETION IN STAR-FORMING GALAXIES

    SciTech Connect

    Chen, Chien-Ting J.; Hickox, Ryan C.; Alberts, Stacey; Pope, Alexandra; Brodwin, Mark; Jones, Christine; Forman, William R.; Goulding, Andrew D.; Murray, Stephen S.; Alexander, David M.; Mullaney, James R.; Assef, Roberto J.; Gorjian, Varoujan; Brown, Michael J. I.; Dey, Arjun; Jannuzi, Buell T.; Le Floc'h, Emeric

    2013-08-10

    We present a measurement of the average supermassive black hole accretion rate (BHAR) as a function of the star formation rate (SFR) for galaxies in the redshift range 0.25 < z < 0.8. We study a sample of 1767 far-IR-selected star-forming galaxies in the 9 deg{sup 2} Booetes multi-wavelength survey field. The SFR is estimated using 250 {mu}m observations from the Herschel Space Observatory, for which the contribution from the active galactic nucleus (AGN) is minimal. In this sample, 121 AGNs are directly identified using X-ray or mid-IR selection criteria. We combined these detected AGNs and an X-ray stacking analysis for undetected sources to study the average BHAR for all of the star-forming galaxies in our sample. We find an almost linear relation between the average BHAR (in M{sub Sun} yr{sup -1}) and the SFR (in M{sub Sun} yr{sup -1}) for galaxies across a wide SFR range 0.85 < log SFR < 2.56: log BHAR = (- 3.72 {+-} 0.52) + (1.05 {+-} 0.33)log SFR. This global correlation between SFR and average BHAR is consistent with a simple picture in which SFR and AGN activity are tightly linked over galaxy evolution timescales.

  8. Geometry of X-ray sources in accreting black-hole binaries

    NASA Astrophysics Data System (ADS)

    Zdziarski, Andrzej

    2016-07-01

    According to the long-dominant paradigm, the accretion disc in the hard state is truncated at a radius >> ISCO whereas it reaches the ISCO in the soft state. This explains many observed phenomena, e.g., spectral and variability differences between the states and transition from quiescence in transients. On the other hand, there have been many claims that the disc extends to the ISCO in the hard state, and the X-ray source has been postulated to be a lamppost very close to the horizon. I will discuss the current evidence for and against the disc truncation and the lamppost geometry, and their implications. If the lamppost model were correct, most of the produced photons would be trapped by the black hole, and the source luminosity as measured at infinity would then be much larger than that observed. Also, the luminosity measured in the local frame would be >> that observed, due to the photon trapping, time dilation and redshift, and T_e would be significantly higher than that observed. I will also present results of a study of off of the X-ray spectra of the hard state of GX 339-4 observed by XMM-Newton. These results show the truncation radius to be ISCO for all the data sets. These radii also agree with the independent determination of De Marco et al. (2015) based on soft X-ray lags.

  9. Photon-conserving Comptonization in simulations of accretion discs around black holes

    NASA Astrophysics Data System (ADS)

    Sądowski, Aleksander; Narayan, Ramesh

    2015-12-01

    We introduce a new method for treating Comptonization in computational fluid dynamics. By construction, this method conserves the number of photons. Whereas the traditional `blackbody Comptonization' approach assumes that the radiation is locally a perfect blackbody and therefore uses a single parameter, the radiation temperature, to describe the radiation, the new `photon-conserving Comptonization' approach treats the photon gas as a Bose-Einstein fluid and keeps track of both the radiation temperature and the photon number density. We have implemented photon-conserving Comptonization in the general relativistic radiation magnetohydrodynamical code KORAL and we describe its impact on simulations of mildly supercritical black hole accretion discs. We find that blackbody Comptonization underestimates the gas and radiation temperature by up to a factor of 2 compared to photon-conserving Comptonization. This discrepancy could be serious when computing spectra. The photon-conserving simulation indicates that the spectral colour correction factor of the escaping radiation in the funnel region of the disc could be as large as 5.

  10. Truncated disks - advective tori; new solutions of accretion flows around black holes

    NASA Astrophysics Data System (ADS)

    Hujeirat, A.; Camenzind, M.

    2000-09-01

    Our quasi-steady 2D numerical radiative hydrodynamical investigations of two-temperature accretion flows around black holes indicate that standard disks are thermally and hydrodynamically stable against transition to optically thin disks at large radii. Optically thin disks cool sufficiently rapid at large radii inducing a vertical collapse and forming thereby a standard disk which truncates close to the last stable orbit. In the absence of soft photons from the adjusting standard disk, we confirm the runaway cooling of the inner optically thin disk. This runaway however terminates if the radial flux of soft photons from the outer standard disk is taken into account. Instead, a cooling-driven front starts to propagates from outside-to-inside continuously extending the thick disk down to the very inner region where it terminates via an oppositely-oriented heating front that forms a hot advective and sub-keplerian torus. The transition between the two configuration occurs where the ratio of the cooling to the heating time attains a minimum value. The transition is found to be rather sharp and gives rise to outwards-oriented motions of very hot plasma that enlarges the combined Compton-Synchrotron cooling regions considerably. While the disk-torus configuration obtained depends weakly on whether the flow is a one or two-temperature plasma, one-temperature tori are hotter and fill larger volumes than their two-temperature counterparts.

  11. HERO - A 3D general relativistic radiative post-processor for accretion discs around black holes

    NASA Astrophysics Data System (ADS)

    Zhu, Yucong; Narayan, Ramesh; Sadowski, Aleksander; Psaltis, Dimitrios

    2015-08-01

    HERO (Hybrid Evaluator for Radiative Objects) is a 3D general relativistic radiative transfer code which has been tailored to the problem of analysing radiation from simulations of relativistic accretion discs around black holes. HERO is designed to be used as a post-processor. Given some fixed fluid structure for the disc (i.e. density and velocity as a function of position from a hydrodynamic or magnetohydrodynamic simulation), the code obtains a self-consistent solution for the radiation field and for the gas temperatures using the condition of radiative equilibrium. The novel aspect of HERO is that it combines two techniques: (1) a short-characteristics (SC) solver that quickly converges to a self-consistent disc temperature and radiation field, with (2) a long-characteristics (LC) solver that provides a more accurate solution for the radiation near the photosphere and in the optically thin regions. By combining these two techniques, we gain both the computational speed of SC and the high accuracy of LC. We present tests of HERO on a range of 1D, 2D, and 3D problems in flat space and show that the results agree well with both analytical and benchmark solutions. We also test the ability of the code to handle relativistic problems in curved space. Finally, we discuss the important topic of ray defects, a major limitation of the SC method, and describe our strategy for minimizing the induced error.

  12. Late time tails of the massive vector field in a black hole background

    SciTech Connect

    Konoplya, R. A.; Zhidenko, A.; Molina, C.

    2007-04-15

    We investigate the late-time behavior of the massive vector field in the background of the Schwarzschild and Schwarzschild-de Sitter black holes. For Schwarzschild black hole, at intermediately late times the massive vector field is represented by three functions with different decay law {psi}{sub 0}{approx}t{sup -(l+3/2)}sinmt, {psi}{sub 1}{approx}t{sup -(l+5/2)}sinmt, {psi}{sub 2}{approx}t{sup -(l+1/2)}sinmt, while at asymptotically late times the decay law {psi}{approx}t{sup -5/6}sin(mt) is universal and does not depend on the multipole number l. Together with a previous study of massive scalar and Dirac fields where the same asymptotically late-time decay law was found, it means that the asymptotically late-time decay law {approx}t{sup -5/6}sin(mt) does not depend also on the spin of the field under consideration. For Schwarzschild-de Sitter black holes it is observed in two different regimes in the late-time decay of perturbations: nonoscillatory exponential damping for small values of m and oscillatory quasinormal mode decay for high enough m. Numerical and analytical results are found for these quasinormal frequencies.

  13. Massive charged BTZ black holes in asymptotically (a)dS spacetimes

    NASA Astrophysics Data System (ADS)

    Hendi, S. H.; Panah, B. Eslam; Panahiyan, S.

    2016-05-01

    Motivated by recent developments of BTZ black holes and interesting results of massive gravity, we investigate massive BTZ black holes in the presence of Maxwell and Born-Infeld (BI) electrodynamics. We study geometrical properties such as type of singularity and asymptotical behavior as well as thermodynamic structure of the solutions through canonical ensemble. We show that despite the existence of massive term, obtained solutions are asymptotically (a)dS and have a curvature singularity at the origin. Then, we regard varying cosmological constant and examine the Van der Waals like behavior of the solutions in extended phase space. In addition, we employ geometrical thermodynamic approaches and show that using Weinhold, Ruppeiner and Quevedo metrics leads to existence of ensemble dependency while HPEM metric yields consistent picture. For neutral solutions, it will be shown that generalization to massive gravity leads to the presence of non-zero temperature and heat capacity for vanishing horizon radius. Such behavior is not observed for linearly charged solutions while generalization to nonlinearly one recovers this property.

  14. Millimeter Flares and VLBI Visibilities from Relativistic Simulations of Magnetized Accretion Onto the Galactic Center Black Hole

    NASA Astrophysics Data System (ADS)

    Dexter, Jason; Agol, Eric; Fragile, P. Chris

    2009-10-01

    The recent very long baseline interferometry (VLBI) observation of the Galactic center black hole candidate Sgr A* at 1.3 mm shows source structure on event-horizon scales. This detection enables a direct comparison of the emission region with models of the accretion flow onto the black hole. We present the first results from time-dependent radiative transfer of general relativistic MHD simulation data, and compare simulated synchrotron images at black hole spin a = 0.9 with the VLBI measurements. After tuning the accretion rate to match the millimeter flux, we find excellent agreement between predicted and observed visibilities, even when viewed face-on (i lsim 30°). VLBI measurements on 2000-3000 km baselines should constrain the inclination. The data constrain the accretion rate to be (1.0-2.3)×10-9 M sun yr-1 with 99% confidence, consistent with but independent of prior estimates derived from spectroscopic and polarimetric measurements. Finally, we compute light curves, which show that magnetic turbulence can directly produce flaring events with 0.5 hr rise times, 2-3.5 hr durations, and 40%-50% flux modulation, in agreement with observations of Sgr A* at millimeter wavelengths.

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

    SciTech Connect

    Reynolds, Christopher S.; Lohfink, Anne M.; Babul, Arif; Fabian, Andrew C.; Russell, Helen R.; Walker, Stephen A.; Hlavacek-Larrondo, Julie

    2014-09-10

    We present a deep Suzaku observation of H1821+643, an extremely rare example of a powerful quasar hosted by the central massive galaxy of a rich cooling-core cluster of galaxies. Informed by previous Chandra studies of the cluster, we achieve a spectral separation of emission from the active galactic nucleus (AGN) and the intracluster medium (ICM). With a high degree of confidence, we identify the signatures of X-ray reflection/reprocessing by cold and slowly moving material in the AGN's immediate environment. The iron abundance of this matter is found to be significantly sub-solar (Z ≈ 0.4 Z {sub ☉}), an unusual finding for powerful AGN but in line with the idea that this quasar is feeding from the ICM via a Compton-induced cooling flow. We also find a subtle soft excess that can be described phenomenologically (with an additional blackbody component) or as ionized X-ray reflection from the inner regions of a high inclination (i ≈ 57°) accretion disk around a spinning (a > 0.4) black hole. We describe how the ionization state of the accretion disk can be used to constrain the Eddington fraction of the source. Applying these arguments to our spectrum implies an Eddington fraction of 0.25-0.5, with an associated black hole mass of 3--6×10{sup 9} M{sub ⊙}.

  16. Formation of massive black holes through runaway collisions in dense young star clusters.

    PubMed

    Zwart, Simon F Portegies; Baumgardt, Holger; Hut, Piet; Makino, Junichiro; McMillan, Stephen L W

    2004-04-15

    A luminous X-ray source is associated with MGG 11--a cluster of young stars approximately 200 pc from the centre of the starburst galaxy M 82 (refs 1, 2). The properties of this source are best explained by invoking a black hole with a mass of at least 350 solar masses (350 M(o)), which is intermediate between stellar-mass and supermassive black holes. A nearby but somewhat more massive cluster (MGG 9) shows no evidence of such an intermediate-mass black hole, raising the issue of just what physical characteristics of the clusters can account for this difference. Here we report numerical simulations of the evolution and motion of stars within the clusters, where stars are allowed to merge with each other. We find that for MGG 11 dynamical friction leads to the massive stars sinking rapidly to the centre of the cluster, where they participate in a runaway collision. This produces a star of 800-3,000 M(o) which ultimately collapses to a black hole of intermediate mass. No such runaway occurs in the cluster MGG 9, because the larger cluster radius leads to a mass segregation timescale a factor of five longer than for MGG 11. PMID:15085124

  17. Resonant excitation of black holes by massive bosonic fields and giant ringings

    NASA Astrophysics Data System (ADS)

    Décanini, Yves; Folacci, Antoine; Ould El Hadj, Mohamed

    2014-04-01

    We consider the massive scalar field, the Proca field, and the Fierz-Pauli field in the Schwarzschild spacetime and we focus more particularly on their long-lived quasinormal modes. We show numerically that the associated excitation factors have a strong resonant behavior and we confirm this result analytically from semiclassical considerations based on the properties of the unstable circular geodesics on which a massive particle can orbit the black hole. The conspiracy of (i) the long-lived behavior of the quasinormal modes and (ii) the resonant behavior of their excitation factors induces intrinsic giant ringings, i.e., ringings of a huge amplitude. Such ringings, which are moreover slowly decaying, are directly constructed from the retarded Green function. If we describe the source of the black hole perturbation by an initial value problem with Gaussian initial data, i.e., if we consider the excitation of the black hole from an extrinsic point of view, we can show that these extraordinary ringings are still present. This suggests that physically realistic sources of perturbations should generate giant and slowly decaying ringings and that their existence could be used to constrain ultralight bosonic field theory interacting with black holes.

  18. Magnetohydrodynamic Numerical Simulation of Wind Production from Hot Accretion Flows around Black Holes at Very Large Radii

    NASA Astrophysics Data System (ADS)

    Bu, De-Fu; Yuan, Feng; Gan, Zhao-Ming; Yang, Xiao-Hong

    2016-06-01

    Numerical simulations of hot accretion flows around black holes have shown the existence of strong wind. Those works focused only on the region close to the black hole and thus it is unknown whether or where the wind production stops at large radii. To address this question, we have recently performed hydrodynamic (HD) simulations by taking into account the gravitational potential of both the black hole and the nuclear star cluster. The latter is assumed to be proportional to {σ }2{ln}(r), with σ being the velocity dispersion of stars and r the distance from the center of the galaxy. It was found that when the gravity is dominated by nuclear stars, i.e., outside a radius {R}A\\equiv {{GM}}{{BH}}/{σ }2, winds can no longer be produced. That work, however, neglects the magnetic field, which is believed to play a crucial dynamical role in the accretion and thus must be taken into account. In this paper, we revisit this problem by performing magnetohydrodynamic (MHD) simulations. We confirm the result of our previous paper, namely that wind cannot be produced in the region R\\gt {R}A. Our result, combined with recent results of Yuan et al., indicates that the formula describing the mass flux of wind, {\\dot{M}}{{wind}}={\\dot{M}}{{BH}}(r/20{r}s), can only be applied to the region where the black hole potential is dominant. Here {\\dot{M}}{{BH}} is the mass accretion rate at the black hole horizon and the value of R A is similar to the Bondi radius.

  19. The Black Hole Safari: Big Game Hunting in 30+ Massive Galaxies

    NASA Astrophysics Data System (ADS)

    McConnell, Nicholas J.; Ma, Chung-Pei; Janish, Ryan; Gebhardt, Karl; Lauer, Tod R.; Graham, James R.

    2015-01-01

    The current census of the most massive black holes in the local universe turns up an odd variety of galaxy hosts: central galaxies in rich clusters, second- or lower-ranked cluster members, and compact relics from the early universe. More extensive campaigns are required to explore the number density and environmental distribution of these monsters. Over the past three years we have collected a large set of stellar kinematic data with sufficient resolution to detect the gravitational signatures of supermassive black holes with MBH > 109 MSun. This Black Hole Safari targets enormous galaxies at the centers of nearby galaxy clusters, as well as their similarly luminous counterparts in weaker galaxy groups. To date we have observed more than 30 early-type galaxies with integral-field spectrographs on the Keck, Gemini North, and Gemini South telescopes. Here I present preliminary stellar kinematics from 10 objects.

  20. Gravitational waves from the collision of tidally disrupted stars with massive black holes

    SciTech Connect

    East, William E.

    2014-11-10

    We use simulations of hydrodynamics coupled with full general relativity to investigate the gravitational waves produced by a star colliding with a massive black hole when the star's tidal disruption radius lies far outside of the black hole horizon. We consider both main-sequence and white-dwarf compaction stars, and nonspinning black holes, as well as those with near-extremal spin. We study the regime in between where the star can be accurately modeled by a point particle, and where tidal effects completely suppress the gravitational wave signal. We find that nonnegligible gravitational waves can be produced even when the star is strongly affected by tidal forces, as well as when it collides with large angular momentum. We discuss the implications that these results have for the potential observation of gravitational waves from these sources with future detectors.

  1. Three-dimensional black holes, gravitational solitons, kinks and wormholes for BHT massive gravity

    NASA Astrophysics Data System (ADS)

    Oliva, Julio; Tempo, David; Troncoso, Ricardo

    2009-07-01

    The theory of massive gravity in three dimensions recently proposed by Bergshoeff, Hohm and Townsend (BHT) is considered. At the special case when the theory admits a unique maximally symmetric solution, a conformally flat solution that contains black holes and gravitational solitons for any value of the cosmological constant is found. For negative cosmological constant, the black hole is characterized in terms of the mass and the ``gravitational hair'' parameter, providing a lower bound for the mass. For negative mass parameter, the black hole acquires an inner horizon, and the entropy vanishes at the extremal case. Gravitational solitons and kinks, being regular everywhere, can be obtained from a double Wick rotation of the black hole. A wormhole solution in vacuum that interpolates between two static universes of negative spatial curvature is obtained as a limiting case of the gravitational soliton with a suitable identification. The black hole and the gravitational soliton fit within a set of relaxed asymptotically AdS conditions as compared with the one of Brown and Henneaux. In the case of positive cosmological constant the black hole possesses an event and a cosmological horizon, whose mass is bounded from above. Remarkably, the temperatures of the event and the cosmological horizons coincide, and at the extremal case one obtains the analogue of the Nariai solution, dS2 × S1. A gravitational soliton is also obtained through a double Wick rotation of the black hole. The Euclidean continuation of these solutions describes instantons with vanishing Euclidean action. For vanishing cosmological constant the black hole and the gravitational soliton are asymptotically locally flat spacetimes. The rotating solutions can be obtained by boosting the previous ones in the t-phi plane.

  2. GALAXY EVOLUTION. An over-massive black hole in a typical star-forming galaxy, 2 billion years after the Big Bang.

    PubMed

    Trakhtenbrot, Benny; Urry, C Megan; Civano, Francesca; Rosario, David J; Elvis, Martin; Schawinski, Kevin; Suh, Hyewon; Bongiorno, Angela; Simmons, Brooke D

    2015-07-10

    Supermassive black holes (SMBHs) and their host galaxies are generally thought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of the host galaxy mass in the present day. The radiation emitted from the growing SMBH is expected to affect star formation throughout the host galaxy. The relevance of this scenario at early cosmic epochs is not yet established. We present spectroscopic observations of a galaxy at redshift z = 3.328, which hosts an actively accreting, extremely massive BH, in its final stages of growth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy, suggesting that it has grown much more efficiently than the host, contrary to models of synchronized coevolution. The host galaxy is forming stars at an intense rate, despite the presence of a SMBH-driven gas outflow. PMID:26160942

  3. Effects of Accretion Disks on Spins and Eccentricities of Binaries, and Implications for Gravitational Waves

    NASA Technical Reports Server (NTRS)

    Baker, John

    2012-01-01

    Effects of accretion disks on spins and eccentricities of binaries, and implications for gravitational waves. John Baker Space-based gravitational wave observations will allow exquisitely precise measurements of massive black hole binary properties. Through several recently suggested processes, these properties may depend on interactions with accretion disks through the merger process. I will discuss ways that accretion may influence those binary properties which may be probed by gravitational-wave observations.

  4. Enhanced Accretion Rates of Stars on Supermassive Black Holes by Star-Disk Interactions in Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Just, Andreas; Yurin, Denis; Makukov, Maxim; Berczik, Peter; Omarov, Chingis; Spurzem, Rainer; Vilkoviskij, Emmanuil Y.

    2012-10-01

    We investigate the dynamical interaction of a central star cluster surrounding a supermassive black hole (SMBH) and a central accretion disk (AD). The dissipative force acting on stars in the disk leads to an enhanced mass flow toward the SMBH and to an asymmetry in the phase space distribution due to the rotating AD. The AD is considered as a stationary Keplerian rotating disk, which is vertically extended in order to employ a fully self-consistent treatment of stellar dynamics including the dissipative force originating from star-gas ram pressure effects. The stellar system is treated with a direct high-accuracy N-body integration code. A star-by-star representation, desirable in N-body simulations, cannot be extended to real particle numbers yet. Hence, we carefully discuss the scaling behavior of our model with regard to particle number and tidal accretion radius. The main idea is to find a family of models for which the ratio of two-body relaxation time and dissipation time (for kinetic energy of stellar orbits) is constant, which then allows us to extrapolate our results to real parameters of galactic nuclei. Our model is derived from basic physical principles and as such it provides insight into the role of physical processes in galactic nuclei, but it should be regarded as a first step toward more realistic and more comprehensive simulations. Nevertheless, the following conclusions appear to be robust: the star accretion rate onto the AD and subsequently onto the SMBH is enhanced by a significant factor compared to purely stellar dynamical systems neglecting the disk. This process leads to enhanced fueling of central disks in active galactic nuclei (AGNs) and to an enhanced rate of tidal stellar disruptions. Such disruptions may produce electromagnetic counterparts in the form of observable X-ray flares. Our models improve predictions for their rates in quiescent galactic nuclei. We do not yet model direct stellar collisions in the gravitational potential

  5. ENHANCED ACCRETION RATES OF STARS ON SUPERMASSIVE BLACK HOLES BY STAR-DISK INTERACTIONS IN GALACTIC NUCLEI

    SciTech Connect

    Just, Andreas; Yurin, Denis; Makukov, Maxim; Berczik, Peter; Omarov, Chingis; Spurzem, Rainer; Vilkoviskij, Emmanuil Y.

    2012-10-10

    We investigate the dynamical interaction of a central star cluster surrounding a supermassive black hole (SMBH) and a central accretion disk (AD). The dissipative force acting on stars in the disk leads to an enhanced mass flow toward the SMBH and to an asymmetry in the phase space distribution due to the rotating AD. The AD is considered as a stationary Keplerian rotating disk, which is vertically extended in order to employ a fully self-consistent treatment of stellar dynamics including the dissipative force originating from star-gas ram pressure effects. The stellar system is treated with a direct high-accuracy N-body integration code. A star-by-star representation, desirable in N-body simulations, cannot be extended to real particle numbers yet. Hence, we carefully discuss the scaling behavior of our model with regard to particle number and tidal accretion radius. The main idea is to find a family of models for which the ratio of two-body relaxation time and dissipation time (for kinetic energy of stellar orbits) is constant, which then allows us to extrapolate our results to real parameters of galactic nuclei. Our model is derived from basic physical principles and as such it provides insight into the role of physical processes in galactic nuclei, but it should be regarded as a first step toward more realistic and more comprehensive simulations. Nevertheless, the following conclusions appear to be robust: the star accretion rate onto the AD and subsequently onto the SMBH is enhanced by a significant factor compared to purely stellar dynamical systems neglecting the disk. This process leads to enhanced fueling of central disks in active galactic nuclei (AGNs) and to an enhanced rate of tidal stellar disruptions. Such disruptions may produce electromagnetic counterparts in the form of observable X-ray flares. Our models improve predictions for their rates in quiescent galactic nuclei. We do not yet model direct stellar collisions in the gravitational potential

  6. Looking into the inner black hole accretion disc with relativistic models of iron line

    NASA Astrophysics Data System (ADS)

    Svoboda, Jiri

    2010-07-01

    We discuss black hole spin measurements employing the relativistic iron line profiles in the X-ray domain. We investigate the iron line band for two representative sources -- MCG -6-30-15 (active galaxy) and GX 339-4 (X-ray binary). We compare two models of the broad iron line, LAOR and KYRLINE. We realise that the spin is currently determined entirely from the position of the marginally stable orbit while the effect of the spin on the overall line shape would be resolvable with higher resolution X-ray missions. We show that the precision of the spin measurements depends on an unknown angular distribution of the disc emission. We study how sensitive the spin determination is to the assumptions about the intrinsic angular distribution of the emitted photons. We find that the uncertainty of the directional emission distribution translates to 20% uncertainty in the determination of the radius of marginally stable orbit. We perform radiation transfer computations of an X-ray irradiated disc atmosphere (NOAR code) to determine the directionality of outgoing X-rays in the 2-10 keV energy band. Based on these computations, we find that from the simple formulae for the directionality, the isotropic case reproduces the simulated data with the best accuracy. The most frequently used limb-darkening law favours higher values of spin and, in addition, a steeper radial emissivity profile. Furthermore, we present a spectral analysis of an XMM-Newton observation of a Seyfert 1.5 galaxy IRAS 05078+1626 being the first X-ray spectroscopic study of this source. The lack of the significant relativistic blurring of the reflection model component suggests the accretion disc to be truncated at a farther radius.

  7. UNLEASHING POSITIVE FEEDBACK: LINKING THE RATES OF STAR FORMATION, SUPERMASSIVE BLACK HOLE ACCRETION, AND OUTFLOWS IN DISTANT GALAXIES

    SciTech Connect

    Silk, Joseph

    2013-08-01

    Pressure-regulated star formation is a simple variant on the usual supernova-regulated star formation efficiency that controls the global star formation rate as a function of cold gas content in star-forming galaxies, and accounts for the Schmidt-Kennicutt law in both nearby and distant galaxies. Inclusion of active galactic nucleus (AGN) induced pressure, by jets and/or winds that flow back onto a gas-rich disk, can lead, under some circumstances, to significantly enhanced star formation rates, especially at high redshift and most likely followed by the more widely accepted phase of star formation quenching. Simple expressions are derived that relate supermassive black hole growth, star formation, and outflow rates. The ratios of black hole to spheroid mass and of both black hole accretion and outflow rates to star formation rate are predicted as a function of time. I suggest various tests of the AGN-triggered star formation hypothesis.

  8. ACCRETION ONTO BLACK HOLES FROM LARGE SCALES REGULATED BY RADIATIVE FEEDBACK. III. ENHANCED LUMINOSITY OF INTERMEDIATE-MASS BLACK HOLES MOVING AT SUPERSONIC SPEEDS

    SciTech Connect

    Park, KwangHo; Ricotti, Massimo E-mail: ricotti@astro.umd.edu

    2013-04-20

    In this third paper of a series, we study the growth and luminosity of black holes (BHs) in motion with respect to their surrounding medium. We run a large set of two-dimensional axis-symmetric simulations to explore a large parameter space of initial conditions and formulate an analytical model for the accretion. Contrary to the case without radiation feedback, the accretion rate increases with increasing BH velocity v{sub bh} reaching a maximum value at v{sub bh} = 2c{sub s,in} {approx} 50 km s{sup -1}, where c{sub s,in} is the sound speed inside the ''cometary-shaped'' H II region around the BH, before decreasing as v{sub bh}{sup -3} when the ionization front (I-front) becomes R-type (rarefied) and the accretion rate approaches the classical Bondi-Hoyle-Lyttleton solution. The increase of the accretion rate with v{sub bh} is produced by the formation of a D-type (dense) I-front preceded by a standing bow shock that reduces the downstream gas velocity to transonic values. There is a range of densities and velocities where the dense shell is unstable producing periodic accretion rate peaks which can significantly increase the detectability of intermediate-mass BHs. We find that the mean accretion rate for a moving BH is larger than that of a stationary BH of the same mass if the medium temperature is T{sub {infinity}} < 10{sup 4} K. This result could be important for the growth of seed BHs in the multi-phase medium of the first galaxies and for building an early X-ray background that may affect the formation of the first galaxies and the reionization process.

  9. Tidal Disruption and Ignition of White Dwarfs by Moderately Massive Black Holes

    SciTech Connect

    Rosswog, S.; Ramirez-Ruiz, E.; Hix, William Raphael

    2009-01-01

    We present a numerical investigation of the tidal disruption of white dwarfs by moderately massive black holes, with particular reference to the centers of dwarf galaxies and globular clusters. Special attention is given to the fate of white dwarfs of all masses that approach the black hole close enough to be disrupted and severely compressed to such an extent that explosive nuclear burning can be triggered. Consistent modeling of the gas dynamics together with the nuclear reactions allows for a realistic determination of the explosive energy release. In the most favorable cases, the nuclear energy release may be comparable to that of typical Type Ia supernovae. Although the explosion will increase the mass fraction escaping on hyperbolic orbits, a good fraction of the debris remains to be swallowed by the hole, causing a bright soft X-ray flare lasting for about a year. Such transient signatures, if detected, would be a compelling testimony for the presence of a moderately massive black hole (below 10{sup 5} M {sub {circle_dot}}).

  10. Einstein-Born-Infeld-massive gravity: adS-black hole solutions and their thermodynamical properties

    NASA Astrophysics Data System (ADS)

    Hendi, S. H.; Panah, B. Eslam; Panahiyan, S.

    2015-11-01

    In this paper, we study massive gravity in the presence of Born-Infeld nonlinear electrodynamics. First, we obtain metric function related to this gravity and investigate the geometry of the solutions and find that there is an essential singularity at the origin ( r = 0). It will be shown that due to contribution of the massive part, the number, type and place of horizons may be changed. Next, we calculate the conserved and thermodynamic quantities and check the validation of the first law of thermodynamics. We also investigate thermal stability of these black holes in context of canonical ensemble. It will be shown that number, type and place of phase transition points are functions of different parameters which lead to dependency of stability conditions to these parameters. Also, it will be shown how the behavior of temperature is modified due to extension of massive gravity and strong nonlinearity parameter. Next, critical behavior of the system in extended phase space by considering cosmological constant as pressure is investigated. A study regarding neutral Einstein-massive gravity in context of extended phase space is done. Geometrical approach is employed to study the thermodynamical behavior of the system in context of heat capacity and extended phase space. It will be shown that GTs, heat capacity and extended phase space have consistent results. Finally, critical behavior of the system is investigated through use of another method. It will be pointed out that the results of this method is in agreement with other methods and follow the concepts of ordinary thermodynamics.

  11. Acceleration of relativistic electrons by magnetohydrodynamic turbulence: Implications for non-thermal emission from black hole accretion disks

    SciTech Connect

    Lynn, Jacob W.; Quataert, Eliot; Chandran, Benjamin D. G.; Parrish, Ian J.

    2014-08-10

    We use analytic estimates and numerical simulations of test particles interacting with magnetohydrodynamic (MHD) turbulence to show that subsonic MHD turbulence produces efficient second-order Fermi acceleration of relativistic particles. This acceleration is not well described by standard quasi-linear theory but is a consequence of resonance broadening of wave-particle interactions in MHD turbulence. We provide momentum diffusion coefficients that can be used for astrophysical and heliospheric applications and discuss the implications of our results for accretion flows onto black holes. In particular, we show that particle acceleration by subsonic turbulence in radiatively inefficient accretion flows can produce a non-thermal tail in the electron distribution function that is likely important for modeling and interpreting the emission from low-luminosity systems such as Sgr A* and M87.

  12. EVIDENCE FOR THREE ACCRETING BLACK HOLES IN A GALAXY AT z {approx} 1.35: A SNAPSHOT OF RECENTLY FORMED BLACK HOLE SEEDS?

    SciTech Connect

    Schawinski, Kevin; Urry, Meg; Treister, Ezequiel; Simmons, Brooke; Natarajan, Priyamvada; Glikman, Eilat

    2011-12-20

    One of the key open questions in cosmology today pertains to understanding when, where, and how supermassive black holes form. While it is clear that mergers likely play a significant role in the growth cycles of black holes, the issue of how supermassive black holes form, and how galaxies grow around them, still needs to be addressed. Here, we present Hubble Space Telescope Wide Field Camera 3/IR grism observations of a clumpy galaxy at z = 1.35, with evidence for 10{sup 6}-10{sup 7} M{sub Sun} rapidly growing black holes in separate sub-components of the host galaxy. These black holes could have been brought into close proximity as a consequence of a rare multiple galaxy merger or they could have formed in situ. Such holes would eventually merge into a central black hole as the stellar clumps/components presumably coalesce to form a galaxy bulge. If we are witnessing the in situ formation of multiple black holes, their properties can inform seed formation models and raise the possibility that massive black holes can continue to emerge in star-forming galaxies as late as z = 1.35 (4.8 Gyr after the big bang).

  13. Impact of LISA's Low Frequency Sensitivity on Observations of Massive Black Hole Mergers

    NASA Technical Reports Server (NTRS)

    Baker, J.; Centrella, J.

    2005-01-01

    LISA will be able to detect gravitational waves from inspiralling massive black hole (MBH) binaries out to redshifts z > 10. If the binary masses and luminosity distances can be extracted from the Laser Interferometer Space Antenna (LISA) data stream, this information can be used to reveal the merger history of MBH binaries and their host galaxies in the evolving universe. Since this parameter extraction generally requires that LISA observe the inspiral for a significant fraction of its yearly orbit, carrying out this program requires adequate sensitivity at low frequencies, f < 10(exp -4) Hz. Using several candidate low frequency sensitivities, we examine LISA's potential for characterizing MBH binary coalescences at redshifts z > 1.

  14. A test of the massive binary black hole hypothesis - Arp 102B

    NASA Technical Reports Server (NTRS)

    Helpern, J. P.; Filippenko, Alexei V.

    1988-01-01

    The emission-line spectra of several AGN have broad peaks which are significantly displaced in velocity with respect to the host galaxy. An interpretation of this effect in terms of orbital motion of a binary black hole predicts periods of a few centuries. It is pointed out here that recent measurements of the masses and sizes of many low-luminosity AGN imply orbital periods much shorter than this. In particular, it is found that the elliptical galaxy Arp 102B is the most likely candidate for observation of radial velocity variations; its period is expected to be about 3 yr. The H-alpha line profile of Arp 102B has been measured for 5 yr without detecting any change in velocity, and it is thus found that a rather restrictive observational test of the massive binary black hole hypothesis already exists, albeit for this one object.

  15. Relativistic tidal interaction of a white dwarf with a massive black hole

    NASA Technical Reports Server (NTRS)

    Frolov, V. P.; Khokhlov, A. M.; Novikov, I. D.; Pethick, C. J.

    1994-01-01

    We compute encounters of a realistic white dwarf model with a massive black hole in the regime where relativistic effects are important, using a three-dimensional, finite-difference, Eulerian, piecewise parabolic method (PPM) hydrodynamical code. Both disruptive and nondisruptive encounters are considered. We identify and discuss relativistic effects important for the problem: relativistic shift of the pericenter distance, time delay, relativistic precession, and the tensorial structure of the tidal forces. In the nondisruptive case, stripping of matter takes place. In the surface layers of the surviving core, complicated hydrodynamical phenomena are revealed. In both disruptive and nondispruptive encounters, material flows out in the form of two thin, S-shaped, supersonic jets. Our results provide realistic initial conditions for the subsequent investigation of the dynamics of the debris in the field of the black hole. We evaluate the critical conditions for complete disruption of the white dwarf, and compare our results with the corresponding results for nonrelativistic encounters.

  16. Ultra--Low-Frequency Gravitational Radiation from Massive Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Rajagopal, Mohan; Romani, Roger W.

    1995-06-01

    For massive black hole binaries produced in galactic mergers, we examine the possibility of inspiral induced by interaction with field stars. We model the evolution of such binaries for a range of galaxy core and binary parameters, using numerical results from the literature to compute the binary's energy and angular momentum loss rates due to stellar encounters and including the effect of back-action on the field stars. We find that only a small fraction of binary systems can merge within a Hubble time via unassisted stellar dynamics. External perturbations may, however, cause efficient inspiral. Averaging over a population of central black holes and galaxy mergers, we computed the expected background of gravitational radiation with periods Pw ˜ 1-10 yr. Comparison with sensitivities from millisecond pulsar timing suggests that the strongest sources may be detectable with modest improvements to present experiments.

  17. Can massive primordial black holes be produced in mild waterfall hybrid inflation?

    NASA Astrophysics Data System (ADS)

    Kawasaki, Masahiro; Tada, Yuichiro

    2016-08-01

    We studied the possibility whether the massive primordial black holes (PBHs) surviving today can be produced in hybrid inflation. Though it is of great interest since such PBHs can be the candidate for dark matter or seeds of the supermassive black holes in galaxies, there have not been quantitatively complete works yet because of the non-perturbative behavior around the critical point of hybrid inflation. Therefore, combining the stochastic and δN formalism, we numerically calculated the curvature perturbations in a non-perturbative way and found, without any specific assumption of the types of hybrid inflation, PBHs are rather overproduced when the waterfall phase of hybrid inflation continues so long that the PBH scale is well enlarged and the corresponding PBH mass becomes sizable enough.

  18. Accretion and Nuclear Activity of Quiescent Supermassive Black Holes. II. Optical Study and Interpretation

    NASA Astrophysics Data System (ADS)

    Soria, R.; Graham, Alister W.; Fabbiano, G.; Baldi, A.; Elvis, M.; Jerjen, H.; Pellegrini, S.; Siemiginowska, A.

    2006-03-01

    Our X-ray study of the nuclear activity in a new sample of six quiescent early-type galaxies, as well as in a larger sample from the literature, confirmed (Paper I) that the Bondi accretion rate of diffuse hot gas is not a good indicator of the SMBH X-ray luminosity. Here we suggest that a more reliable estimate of the accretion rate must include the gas released by the stellar population inside the sphere of influence of the SMBH, in addition to the Bondi inflow of hot gas across that surface. We use optical surface brightness profiles to estimate the mass-loss rate from stars in the nuclear region: we show that for our sample of galaxies it is an order of magnitude higher (~10-4 to 10-3 Msolar yr-1) than the Bondi inflow rate of hot gas, as estimated from Chandra (Paper I). Only by taking into account both sources of fuel can we constrain the true accretion rate, the accretion efficiency, and the power budget. Radiatively efficient accretion is ruled out, for quiescent SMBHs. For typical radiatively inefficient flows, the observed X-ray luminosities of the SMBHs imply accretion fractions ~1%-10% (i.e., ~90%-99% of the available gas does not reach the SMBH) for at least five of our six target galaxies and most of the other galaxies with known SMBH masses. We discuss the conditions for mass conservation inside the sphere of influence, so that the total gas injection is balanced by accretion plus outflows. We show that a fraction of the total accretion power (mechanical plus radiative) would be sufficient to sustain a self-regulating, slow outflow that removes from the nuclear region all the gas that does not sink into the BH (``BH feedback''). The rest of the accretion power may be carried out in a jet or advected. We also discuss scenarios that would lead to an intermittent nuclear activity.

  19. Warping of an accretion disc and launching of a jet by a spinning black hole in NGC 4258

    NASA Astrophysics Data System (ADS)

    Wu, Qingwen; Yan, Hao; Yi, Zhu

    2013-12-01

    We fit the most up-to-date broad-band spectral energy distribution from radio to X-rays for NGC 4258 with a coupled accretion-jet model that surrounds a Kerr black hole (BH). Here, both the jet and the warped H2O maser disc are assumed to be triggered by a spinning BH through the Blandford-Znajek mechanism and the Bardeen-Petterson effect, respectively. The accretion flow consists of an inner radiatively inefficient accretion flow and an outer truncated standard thin disc, where the transition radius Rtr ≃ 3 × 103Rg for NGC 4258, based on the width and variability of its narrow Fe Kα line. The hybrid jet formation model, as a variant of the Blandford-Znajek model, is used to model the jet power. Therefore, we can estimate the accretion rate and BH spin through the two observed quantities (i.e. X-ray emission and jet power), where the observed jet power is estimated from the low-frequency radio emission. Using this method, we find that the BH of NGC 4258 should be mildly spinning with dimensionless spin parameter a* ≃ 0.7 ± 0.2. The outer thin disc mainly radiates at the near-infrared waveband and the jet contributes predominantly at the radio waveband. Using the above-estimated BH spin and the inferred accretion rate at the region of the maser disc based on the physical existence of the H2O maser, we find that the warp radius is ˜8.6 × 104Rg if it is driven by the Bardeen-Petterson effect. This is very consistent with the observational result.

  20. Episodic jet power extracted from a spinning black hole surrounded by a neutrino-dominated accretion flow in gamma-ray bursts

    SciTech Connect

    Cao, Xinwu; Liang, En-Wei; Yuan, Ye-Fei E-mail: lew@gxu.edu.cn

    2014-07-10

    It was suggested that the relativistic jets in gamma-ray bursts (GRBs) are powered via the Blandford-Znajek (BZ) mechanism or the annihilation of neutrinos and anti-neutrinos from a neutrino cooling-dominated accretion flow (NDAF). The advection and diffusion of the large-scale magnetic field of an NDAF is calculated, and the external magnetic field is found to be dragged inward efficiently by the accretion flow for a typical magnetic Prandtl number P{sub m}=η/ν∼1. The maximal BZ jet power can be ∼10{sup 53}-10{sup 54} erg s{sup –1} for an extreme Kerr black hole, if an external magnetic field with 10{sup 14} Gauss is advected by the NDAF. This is roughly consistent with the field strength of the disk formed after a tidal disrupted magnetar. The accretion flow near the black hole horizon is arrested by the magnetic field if the accretion rate is below than a critical value for a given external field. The arrested accretion flow fails to drag the field inward and the field strength decays, and then the accretion re-starts, which leads to oscillating accretion. The typical timescale of such episodic accretion is of an order of one second. This can qualitatively explain the observed oscillation in the soft extended emission of short-type GRBs.

  1. Episodic Jet Power Extracted from a Spinning Black Hole Surrounded by a Neutrino-dominated Accretion Flow in Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Cao, Xinwu; Liang, En-Wei; Yuan, Ye-Fei

    2014-07-01

    It was suggested that the relativistic jets in gamma-ray bursts (GRBs) are powered via the Blandford-Znajek (BZ) mechanism or the annihilation of neutrinos and anti-neutrinos from a neutrino cooling-dominated accretion flow (NDAF). The advection and diffusion of the large-scale magnetic field of an NDAF is calculated, and the external magnetic field is found to be dragged inward efficiently by the accretion flow for a typical magnetic Prandtl number \\mathscr{P}_m=η /ν ˜ 1. The maximal BZ jet power can be ~1053-1054 erg s-1 for an extreme Kerr black hole, if an external magnetic field with 1014 Gauss is advected by the NDAF. This is roughly consistent with the field strength of the disk formed after a tidal disrupted magnetar. The accretion flow near the black hole horizon is arrested by the magnetic field if the accretion rate is below than a critical value for a given external field. The arrested accretion flow fails to drag the field inward and the field strength decays, and then the accretion re-starts, which leads to oscillating accretion. The typical timescale of such episodic accretion is of an order of one second. This can qualitatively explain the observed oscillation in the soft extended emission of short-type GRBs.

  2. Relationship between star formation rate and black hole accretion at z=3: the different contributions in quiescent, normal, and starburst galaxies

    SciTech Connect

    Rodighiero, G.; Franceschini, A.; Baronchelli, I.; Brusa, M.; Delvecchio, I.; Pozzi, F.; Cimatti, A.; Mullaney, J. R.; Lutz, D.; Gruppioni, C.; Silverman, J.

    2015-02-10

    We investigate the co-evolution of the black hole accretion rate (BHAR) and the star formation rate (SFR) in 1.5massive galaxies at z∼2. Furthermore, BHAR/SFR during the starburst is a factor of two lower than in MS galaxies, at odds with the predictions of hydrodynamical simulations of merger galaxies that foresee a sudden enhancement of L{sub X}/SFR during the merger. Finally, we estimate that the bulk of the accretion density of the universe at z∼2 is associated with normal star-forming systems, with only ∼6(±1)% and ∼11(±1)% associated with starburst and quiescent galaxies, respectively.

  3. Relationship between Star Formation Rate and Black Hole Accretion At Z = 2: the Different Contributions in Quiescent, Normal, and Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Rodighiero, G.; Brusa, M.; Daddi, E.; Negrello, M.; Mullaney, J. R.; Delvecchio, I.; Lutz, D.; Renzini, A.; Franceschini, A.; Baronchelli, I.; Pozzi, F.; Gruppioni, C.; Strazzullo, V.; Cimatti, A.; Silverman, J.

    2015-02-01

    We investigate the co-evolution of the black hole accretion rate (BHAR) and the star formation rate (SFR) in 1.5\\lt z\\lt 2.5 galaxies displaying a greater diversity of star-forming properties compared to previous studies. We combine X-ray stacking and far-IR photometry of stellar mass-limited samples of normal star-forming, starburst, and quiescent/quenched galaxies in the COSMOS field. We corroborate the existence of a strong correlation between BHAR (i.e., the X-ray luminosity, LX) and stellar mass (M*) for normal star-forming galaxies, though we find a steeper relation than previously reported. We find that starbursts show a factor of three enhancement in BHAR compared to normal SF galaxies (against a factor of six excess in SFR), while quiescents show a deficit of a factor times 5.5 at a given mass. One possible interpretation of this is that the starburst phase does not coincide with cosmologically relevant BH growth, or that starburst-inducing mergers are more efficient at boosting SFR than BHAR. Contrary to studies based on smaller samples, we find that the BHAR/SFR ratio of main-sequence (MS) galaxies is not mass invariant, but scales weakly as M*0.43+/- 0.09, implying faster BH growth in more massive galaxies at z∼ 2. Furthermore, BHAR/SFR during the starburst is a factor of two lower than in MS galaxies, at odds with the predictions of hydrodynamical simulations of merger galaxies that foresee a sudden enhancement of LX/SFR during the merger. Finally, we estimate that the bulk of the accretion density of the universe at z∼ 2 is associated with normal star-forming systems, with only ∼ 6(+/- 1)% and ∼ 11(+/- 1)% associated with starburst and quiescent galaxies, respectively.

  4. The Biases of Optical Line-Ratio Selection for Active Galactic Nuclei and the Intrinsic Relationship between Black Hole Accretion and Galaxy Star Formation

    NASA Astrophysics Data System (ADS)

    Trump, Jonathan R.; Sun, Mouyuan; Zeimann, Gregory R.; Luck, Cuyler; Bridge, Joanna S.; Grier, Catherine J.; Hagen, Alex; Juneau, Stephanie; Montero-Dorta, Antonio; Rosario, David J.; Brandt, W. Niel; Ciardullo, Robin; Schneider, Donald P.

    2015-09-01

    We use 317,000 emission-line galaxies from the Sloan Digital Sky Survey to investigate line-ratio selection of active galactic nuclei (AGNs). In particular, we demonstrate that “star formation (SF) dilution” by H ii regions causes a significant bias against AGN selection in low-mass, blue, star-forming, disk-dominated galaxies. This bias is responsible for the observed preference of AGNs among high-mass, green, moderately star-forming, bulge-dominated hosts. We account for the bias and simulate the intrinsic population of emission-line AGNs using a physically motivated Eddington ratio distribution, intrinsic AGN narrow line region line ratios, a luminosity-dependent {L}{bol}/L[{{O}} {{III}}] bolometric correction, and the observed {M}{BH}-σ relation. These simulations indicate that, in massive ({log}({M}*/{M}⊙ )≳ 10) galaxies, AGN accretion is correlated with specific star formation rate (SFR) but is otherwise uniform with stellar mass. There is some hint of lower black hole occupation in low-mass ({log}({M}*/{M}⊙ )≲ 10) hosts, although our modeling is limited by uncertainties in measuring and interpreting the velocity dispersions of low-mass galaxies. The presence of SF dilution means that AGNs contribute little to the observed strong optical emission lines (e.g., [{{O}} {{III}}] and {{H}}α ) in low-mass and star-forming hosts. However the AGN population recovered by our modeling indicates that feedback by typical (low- to moderate-accretion) low-redshift AGNs has nearly uniform efficiency at all stellar masses, SFRs, and morphologies. Taken together, our characterization of the observational bias and resultant AGN occupation function suggest that AGNs are unlikely to be the dominant source of SF quenching in galaxies, but instead are fueled by the same gas which drives SF activity.

  5. Is there a blackhole among the black-hole candidates?

    NASA Astrophysics Data System (ADS)

    Kundt, Wolfgang; Fischer, Daniel

    1989-03-01

    None of the tentative black-hole identifications has remained without serious difficulties. As a class, the black-hole candidates differ in no obvious property from neutron-star binaries other than in their estimated high mass. An interpretation of the black-hole candidates as binary neutron stars surrounded by a more or less massive accretion disk is favored.

  6. THERMAL AND DYNAMICAL PROPERTIES OF GAS ACCRETING ONTO A SUPERMASSIVE BLACK HOLE IN AN ACTIVE GALACTIC NUCLEUS

    SciTech Connect

    Moscibrodzka, M.; Proga, D.

    2013-04-20

    We study stability of gas accretion in active galactic nuclei (AGNs). Our grid-based simulations cover a radial range from 0.1 to 200 pc, which may enable linking the galactic/cosmological simulations with small-scale black hole (BH) accretion models within a few hundreds of Schwarzschild radii. Here, as in previous studies by our group, we include gas radiative cooling as well as heating by a sub-Eddington X-ray source near the central supermassive BH of 10{sup 8} M{sub Sun }. Our theoretical estimates and simulations show that for the X-ray luminosity, L{sub X} {approx} 0.008 L{sub Edd}, the gas is thermally and convectively unstable within the computational domain. In the simulations, we observe that very tiny fluctuations in an initially smooth, spherically symmetric, accretion flow, grow first linearly and then nonlinearly. Consequently, an initially one-phase flow relatively quickly transitions into a two-phase/cold-hot accretion flow. For L{sub X} = 0.015 L{sub Edd} or higher, the cold clouds continue to accrete but in some regions of the hot phase, the gas starts to move outward. For L{sub X} < 0.015 L{sub Edd}, the cold phase contribution to the total mass accretion rate only moderately dominates over the hot phase contribution. This result might have some consequences for cosmological simulations of the so-called AGN feedback problem. Our simulations confirm the previous results of Barai et al. who used smoothed particle hydrodynamic (SPH) simulations to tackle the same problem. Here, however, because we use a grid-based code to solve equations in one dimension and two dimensions, we are able to follow the gas dynamics at much higher spacial resolution and for longer time compared with the three-dimensional SPH simulations. One of the new features revealed by our simulations is that the cold condensations in the accretion flow initially form long filaments, but at the later times, those filaments may break into smaller clouds advected outward within the

  7. Bondi accretion in early-type galaxies

    NASA Astrophysics Data System (ADS)

    Korol, Valeriya; Ciotti, Luca; Pellegrini, Silvia

    2016-05-01

    Accretion on to central massive black holes in galaxies is often modelled with the Bondi solution. In this paper we study a generalization of the classical Bondi accretion theory, considering the additional effects of the gravitational potential of the host galaxy, and of electron scattering in the optically thin limit. We provide a general analysis of the bias in the estimates of the Bondi radius and mass accretion rate, when adopting as fiducial values for the density and temperature at infinity the values of these quantities measured at finite distance from the central black hole. We also give general formulae to compute the correction terms of the critical accretion parameter in relevant asymptotic regimes. A full analytical discussion is presented in the case of an Hernquist galaxy, when the problem reduces to the discussion of a cubic equation, therefore allowing for more than one critical point in the accretion structure. The results are useful for observational works (especially in the case of systems with a low Eddington ratio), as well as for numerical simulations, where accretion rates are usually defined in terms of the gas properties near the black hole.

  8. Bondi accretion in early-type galaxies

    NASA Astrophysics Data System (ADS)

    Korol, Valeriya; Ciotti, Luca; Pellegrini, Silvia

    2016-08-01

    Accretion on to central massive black holes in galaxies is often modelled with the Bondi solution. In this paper, we study a generalization of the classical Bondi accretion theory, considering the additional effects of the gravitational potential of the host galaxy, and of electron scattering in the optically thin limit. We provide a general analysis of the bias in the estimates of the Bondi radius and mass accretion rate, when adopting as fiducial values for the density and temperature at infinity the values of these quantities measured at finite distance from the central black hole. We also give general formulae to compute the correction terms of the critical accretion parameter in relevant asymptotic regimes. A full analytical discussion is presented in the case of a Hernquist galaxy, when the problem reduces to the discussion of a cubic equation, therefore, allowing for more than one critical point in the accretion structure. The results are useful for observational works (especially in the case of systems with a low Eddington ratio), as well as for numerical simulations, where accretion rates are usually defined in terms of the gas properties near the black hole.

  9. Massive black hole binaries from runaway collisions: the impact of metallicity

    NASA Astrophysics Data System (ADS)

    Mapelli, Michela

    2016-07-01

    The runaway collision scenario is one of the most promising mechanisms to explain the formation of intermediate-mass black holes (IMBHs) in young dense star clusters. On the other hand, the massive stars that participate in the runaway collisions lose mass by stellar winds. In this paper, we discuss new N-body simulations of massive (6.5 × 104 M⊙) star clusters, in which we added upgraded recipes for stellar winds and supernova explosion at different metallicity. We follow the evolution of the principal collision product (PCP), through dynamics and stellar evolution, till it forms a stellar remnant. At solar metallicity, the mass of the final merger product spans from few solar masses up to ˜30 M⊙. At low metallicity (0.01-0.1 Z⊙) the maximum remnant mass is ˜250 M⊙, in the range of IMBHs. A large fraction (˜0.6) of the PCPs are not ejected from the parent star cluster and acquire stellar or black hole (BH) companions. Most of the long-lived binaries hosting a PCP are BH-BH binaries. We discuss the importance of this result for gravitational wave detection.

  10. Massive black hole binaries from runaway collisions: the impact of metallicity

    NASA Astrophysics Data System (ADS)

    Mapelli, Michela

    2016-04-01

    The runaway collision scenario is one of the most promising mechanisms to explain the formation of intermediate-mass black holes (IMBHs) in young dense star clusters. On the other hand, the massive stars that participate in the runaway collisions lose mass by stellar winds. In this paper, we discuss new N-body simulations of massive (6.5 × 104 M⊙) star clusters, in which we added upgraded recipes for stellar winds and supernova explosion at different metallicity. We follow the evolution of the principal collision product (PCP), through dynamics and stellar evolution, till it forms a stellar remnant. At solar metallicity, the mass of the final merger product spans from few solar masses up to ˜30 M⊙. At low metallicity (0.01 - 0.1 Z⊙) the maximum remnant mass is ˜250 M⊙, in the range of IMBHs. A large fraction (˜0.6) of the PCPs are not ejected from the parent star cluster and acquire stellar or black hole (BH) companions. Most of the long-lived binaries hosting a PCP are BH-BH binaries. We discuss the importance of this result for gravitational wave detection.

  11. Galaxy shapes and Intrinsic Alignments in the MassiveBlack-II SImulation

    NASA Astrophysics Data System (ADS)

    Tenneti, Ananth; Mandelbaum, Rachel; DiMatteo, Tiziana; Feng, Yu; Khandai, Nishikanta

    2014-06-01

    The intrinsic alignment of galaxy shapes with the large-scale density field is a contaminant to weak lensing measurements, as well as being an interesting signature of galaxy formation and evolution (albeit one that is difficult to predict theoretically). Here we investigate the shapes and relative orientations of the stars and dark matter of halos and subhalos (central and satellite) extracted from the MassiveBlack-II simulation, a state-of-the-art high resolution hydrodynamical cosmological simulation which includes stellar and AGN feedback in a volume of (100h-1Mpc)3. We consider redshift evolution from z = 1 to 0.06 and mass evolution within the range of subhalo masses, 1010 - 6.0 × 1014.0h-1M⊙. The shapes of the dark matter distributions are generally more round than the shapes defined by stellar matter. We find that the shapes of stellar and dark matter are more round for less massive subhalos and at lower redshifts. By directly measuring the relative orientation of the stellar matter and dark matter of subgroups, we find that, on average, the misalignment between the two components is larger for less massive subhalos. The mean misalignment angle varies from ˜ 30°-10° for M ˜ 1010 - 1014 h-1M⊙ and shows a weak dependence on redshift. We also compare the misalignment angles in central and satellite subhalos at fixed subhalo mass, and find that centrals are more misaligned than satellites.

  12. A jet emission model to probe the dynamics of accretion and ejection coupling in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Malzac, Julien

    2016-07-01

    Compact jets are probably the most common form of jets in X-ray binaries and Active Galactic Nuclei. They seem to be present in all sources in the so-called hard X-ray spectral state. They are characterised by a nearly flat Spectral Energy Distribution (SED) extending from the radio to the infrared bands. This emission is usually interpreted as partially self absorbed synchrotron emission from relativistic leptons accelerated in the jet. The observed flat spectral shape requires energy dissipation and acceleration of particules over a wide range of distances along the jet. This distributed energy dissipation is likely to be powered by internal shocks caused by fluctuations of the outflow velocity. I will discuss such an internal shock model in the context of black hole binaries. I will show that internal shocks can produce the observed SEDs and also predict a strong, wavelength dependent, variability that resembles the observed one. The assumed velocity fluctuations of the jet must originate in the accretion flow. The model thus predicts a strong connection between the observable properties of the jet in the radio to IR bands, and the variability of the accretion flow as observed in X-rays. If the model is correct, this offers a unique possibility to probe the dynamics of the coupled accretion and ejection processes leading to the formation of compact jets.

  13. Interpreting the radio/X-ray correlation of black hole X-ray binaries based on the accretion-jet model

    NASA Astrophysics Data System (ADS)

    Xie, Fu-Guo; Yuan, Feng

    2016-03-01

    Two types of correlations between the radio and X-ray luminosities (LR and LX) have been found in black hole X-ray binaries. For some sources, they follow the `original' type of correlation which is described by a single power law. Later it was found that some other sources follow a different correlation consisting of three power-law branches, with each branch having different power-law indexes. In this work, we explain these two types of correlation under the coupled accretion-jet model. We attribute the difference between these two types of sources to the different value of viscosity parameter α. One possible reason for different α is the different configuration of magnetic field in the accretion material coming from the companion stars. For the `single power-law' sources, their α is high; so their accretion is always in the mode of advection-dominated accretion flow (ADAF) for the whole range of X-ray luminosity. For those `hybrid power-law' sources, the value of α is small so their accretion mode changes from an ADAF to a luminous hot accretion flow, and eventually to two-phase accretion as the accretion rate increases. Because the dependence of radiative efficiency on the mass accretion rate is different for these three accretion modes, different power-law indexes in the LR-LX correlation are expected. Constraints on the ratio of the mass-loss rate into the jet and the mass accretion rate in the accretion flow are obtained, which can be tested in future by radiative magnetohydrodynamic numerical simulations of jet formation.

  14. Chaotic and stochastic processes in the accretion flows of the black hole X-ray binaries revealed by recurrence analysis

    NASA Astrophysics Data System (ADS)

    Suková, Petra; Grzedzielski, Mikolaj; Janiuk, Agnieszka

    2016-02-01

    Aims: Both the well known microquasar GRS 1915+105, as well as its recently discovered analogue, IGR J17091-3624, exhibit variability that is characteristic of a deterministic chaotic system. Their specific kind of quasi-periodic flares that are observed in some states is intrinsically connected with the global structure of the accretion flow, which are governed by the nonlinear hydrodynamics. One plausible mechanism that is proposed to explain this kind of variability is the thermal-viscous instability that operates in the accretion disk. The purely stochastic variability that occurs because of turbulent conditions in the plasma, is quantified by the power density spectra and appears in practically all types of sources and their spectral states. Methods: We pose a question as to whether these two microquasars are one of a kind, or if the traces of deterministic chaos, and hence the accretion disk instability, may also be hidden in the observed variability of other sources. We focus on the black hole X-ray binaries that accrete at a high rate and are, therefore, theoretically prone to the development of radiation pressure-induced instability. To study the nonlinear behaviour of the X-ray sources and distinguish between the chaotic and stochastic nature of their emission, we propose a novel method, which is based on recurrence analysis. Widely known in other fields of physics, this powerful method is used here for the first time in an astrophysical context. We estimate the indications of deterministic chaos quantitatively, such as the Rényi's entropy for the observed time series, and we compare them with surrogate data. Results: Using the observational data collected by the RXTE satellite, we reveal the oscillations pattern and the observable properties of six black hole systems. For five of them, we confirm the signatures of deterministic chaos being the driver of their observed variability. Conclusions: We test the method and confirm the deterministic nature of

  15. The connection between the formation of galaxies and that of their central supermassive black holes.

    PubMed

    Haehnelt, Martin G

    2005-03-15

    Massive black holes appear to be an essential ingredient of massive galactic bulges but little is known yet to what extent massive black holes reside in dwarf galaxies and globular clusters. Massive black holes most likely grow by a mixture of merging and accretion of gas in their hierarchically merging host galaxies. While the hierarchical merging of dark matter structures extends to sub-galactic scales and very high redshift, it is uncertain if the same is true for the build-up of massive black holes. I discuss here some of the relevant problems and open questions. PMID:15681288

  16. Strong constraints on a super-Eddington accretion flow: XMM-Newton observations of an intermediate-mass black hole

    NASA Astrophysics Data System (ADS)

    Jin, Chichuan; Done, Chris; Ward, Martin

    2016-01-01

    RX J1140.1+0307 is a Narrow Line Seyfert 1 (NLS1) with one of the lowest black hole masses known in an AGN (M ≤ 106 M⊙). We show results from two new XMM-Newton observations, exhibiting soft 2-10 keV spectra, a strong excess at lower energies, and fast X-ray variability which is typical of this class of AGN. The soft excess can be equally well fit using either low-temperature Comptonization or highly smeared, ionized reflection models, but we additionally consider the fast X-ray variability to produce covariance, lag and coherence spectra to show that the low-temperature Comptonization model gives a better description of the break in variability properties between soft and hard X-rays. Both these models require an additional component at the softest energies, as expected from the accretion disc. However, standard disc models cannot connect this to the optical/UV emission from the outer disc unless the mass is underestimated by an order of magnitude. The variable optical and far UV emission instead suggests that L/LEdd ˜ 10 through the outer disc, in which case advection and/or wind losses are required to explain the observed broad-band spectral energy distribution. This implies that the accretion geometry close to the black hole is unlikely to be a flat disc as assumed in the recent X-ray reverberation mapping techniques.

  17. Revealing accretion on to black holes: X-ray reflection throughout three outbursts of GX 339-4

    NASA Astrophysics Data System (ADS)

    Plant, D. S.; Fender, R. P.; Ponti, G.; Muñoz-Darias, T.; Coriat, M.

    2014-08-01

    Understanding the dynamics behind black hole state transitions and the changes they reflect in outbursts has become long-standing problem. The X-ray reflection spectrum describes the interaction between the hard X-ray source (the power-law continuum) and the cool accretion disc it illuminates, and thus permits an indirect view of how the two evolve. We present a systematic analysis of the reflection spectrum throughout three outbursts (500+ observations) of the black hole binary GX 339-4, representing the largest study applying a self-consistent treatment of reflection to date. Particular attention is paid to the coincident evolution of the power law and reflection, which can be used to determine the accretion geometry. The hard state is found to be distinctly reflection weak; however, the ratio of reflection to power law gradually increases as the source luminosity rises. In contrast, the reflection is found to dominate the power law throughout most of the soft state, with increasing supremacy as the source decays. We discuss potential dynamics driving this, favouring inner disc truncation and decreasing coronal height for the hard and soft states, respectively. Evolution of the ionization parameter, power-law slope and high-energy cut-off also agree with this interpretation.

  18. Numerical parameter survey of non-radiative black hole accretion: flow structure and variability of the rotation measure

    NASA Astrophysics Data System (ADS)

    Pang, Bijia; Pen, Ue-Li; Matzner, Christopher D.; Green, Stephen R.; Liebendörfer, Matthias

    2011-08-01

    We conduct a survey of numerical simulations to probe the structure and appearance of non-radiative black hole accretion flows like the supermassive black hole at the Galactic Centre. We find a generic set of solutions, and make specific predictions for currently feasible rotation measure (RM) observations, which are accessible to current instruments including the Expanded Very Large Array (EVLA), Giant Metrewave Radio Telescope (GMRT) and Atacama Large Millimeter Array (ALMA). The slow time variability of the RM is a key quantitative signature of this accretion flow. The time variability of RM can be used to quantitatively measure the nature of the accretion flow, and to differentiate models. Sensitive measurements of RM can be achieved using RM synthesis or using pulsars. Our energy conserving ideal magnetohydrodynamical simulations, which achieve high dynamical range by means of a deformed-mesh algorithm, stretch from several Bondi radii to about one-thousandth of that radius, and continue for tens of Bondi times. Magnetized flows which lack outward convection possess density slopes around -1, almost independent of physical parameters, and are more consistent with observational constraints than are strongly convective flows. We observe no tendency for the flows to become rotationally supported in their centres, or to develop steady outflow. We support these conclusions with formulae which encapsulate our findings in terms of physical and numerical parameters. We discuss the relation of these solutions to other approaches. The main potential uncertainties are the validity of ideal magnetohydrodynamic and the absence of a fully relativistic inner boundary condition. The RM variability predictions are testable with current and future telescopes.

  19. Near horizon symmetries of the non-extremal black hole solutions of Generalized Minimal Massive Gravity

    NASA Astrophysics Data System (ADS)

    Setare, M. R.; Adami, H.

    2016-09-01

    We consider the Generalized Minimal Massive Gravity (GMMG) model in the first order formalism. We show that all the solutions of the Einstein gravity with negative cosmological constants solve the equations of motion of considered model. Then we find an expression for the off-shell conserved charges of this model. By considering the near horizon geometry of a three dimensional black hole in the Gaussian null coordinates, we find near horizon conserved charges and their algebra. The obtained algebra is centrally extended. By writing the algebra of conserved charges in terms of Fourier modes and considering the BTZ black hole solution as an example, one can see that the charge associated with rotations along Y0 coincides exactly with the angular momentum, and the charge associated with time translations T0 is the product of the black hole entropy and its temperature. As we expect, in the limit when the GMMG tends to the Einstein gravity, all the results we obtain in this paper reduce to the results of the paper [1].

  20. Model dependence of the multi-transonic behaviour, stability properties and the corresponding acoustic geometry for accretion onto rotating black holes

    NASA Astrophysics Data System (ADS)

    Saha, Sonali; Sen, Sharmistha; Nag, Sankhasubhra; Raychowdhury, Suparna; Das, Tapas K.

    2016-02-01

    Stationary, multi-transonic, integral solutions of hydrodynamic axisymmetric accretion onto a rotating black hole have been compared for different geometrical configurations of the associated accretion disc structures described using the polytropic as well as the isothermal equations of state. Such analysis is performed for accretion under the influence of generalised post Newtonian pseudo Kerr black hole potential. The variations of the stationary shock characteristics with black hole spin have been studied in details for all the disc models and are compared for the flow characterised by the two aforementioned equations of state. Using a novel linear perturbation technique it has been demonstrated that the aforementioned stationary solutions are stable, at least upto an astrophysically relevant time scale. It has been demonstrated that the emergence of the horizon related gravity like phenomena (the analogue gravity effects) is a natural consequence of such stability analysis, and the corresponding acoustic geometry embedded within the transonic accretion can be constructed for the propagation of the linear acoustic perturbation of the mass accretion rate. The analytical expression for the associated sonic surface gravity κ has been obtained self consistently. The variations of κ with the black hole spin parameter for all different geometric configurations of matter and for various thermodynamic equations of state have been demonstrated.

  1. THE NOT-SO-MASSIVE BLACK HOLE IN THE MICROQUASAR GRS1915+105

    SciTech Connect

    Steeghs, D.; Parsons, S. G.; McClintock, J. E.; Reid, M. J.; Littlefair, S.; Dhillon, V. S.

    2013-05-10

    We present a new dynamical study of the black hole X-ray transient GRS1915+105 making use of near-infrared spectroscopy obtained with X-shooter at the Very Large Telescope. We detect a large number of donor star absorption features across a wide range of wavelengths spanning the H and K bands. Our 24 epochs covering a baseline of over 1 yr permit us to determine a new binary ephemeris including a refined orbital period of P = 33.85 {+-} 0.16 days. The donor star radial velocity curves deliver a significantly improved determination of the donor semi-amplitude which is both accurate (K{sub 2} = 126 {+-} 1 km s{sup -1}) and robust against choice of donor star template and spectral features used. We furthermore constrain the donor star's rotational broadening to vsin i = 21 {+-} 4 km s{sup -1}, delivering a binary mass ratio of q = 0.042 {+-} 0.024. If we combine these new constraints with distance and inclination estimates derived from modeling the radio emission, a black hole mass of M{sub BH} = 10.1 {+-} 0.6 M{sub Sun} is inferred, paired with an evolved mass donor of M{sub 2} = 0.47 {+-} 0.27 M{sub Sun }. Our analysis suggests a more typical black hole mass for GRS1915+105 rather than the unusually high values derived in the pioneering dynamical study by Greiner et al. Our data demonstrate that high-resolution infrared spectroscopy of obscured accreting binaries can deliver dynamical mass determinations with a precision on par with optical studies.

  2. The Not-so-massive Black Hole in the Microquasar GRS1915+105

    NASA Astrophysics Data System (ADS)

    Steeghs, D.; McClintock, J. E.; Parsons, S. G.; Reid, M. J.; Littlefair, S.; Dhillon, V. S.

    2013-05-01

    We present a new dynamical study of the black hole X-ray transient GRS1915+105 making use of near-infrared spectroscopy obtained with X-shooter at the Very Large Telescope. We detect a large number of donor star absorption features across a wide range of wavelengths spanning the H and K bands. Our 24 epochs covering a baseline of over 1 yr permit us to determine a new binary ephemeris including a refined orbital period of P = 33.85 ± 0.16 days. The donor star radial velocity curves deliver a significantly improved determination of the donor semi-amplitude which is both accurate (K 2 = 126 ± 1 km s-1) and robust against choice of donor star template and spectral features used. We furthermore constrain the donor star's rotational broadening to vsin i = 21 ± 4 km s-1, delivering a binary mass ratio of q = 0.042 ± 0.024. If we combine these new constraints with distance and inclination estimates derived from modeling the radio emission, a black hole mass of M BH = 10.1 ± 0.6 M ⊙ is inferred, paired with an evolved mass donor of M 2 = 0.47 ± 0.27 M ⊙. Our analysis suggests a more typical black hole mass for GRS1915+105 rather than the unusually high values derived in the pioneering dynamical study by Greiner et al. Our data demonstrate that high-resolution infrared spectroscopy of obscured accreting binaries can deliver dynamical mass determinations with a precision on par with optical studies.

  3. Dynamics of massive black holes as a possible candidate of Galactic dark matter

    NASA Technical Reports Server (NTRS)

    Xu, Guohong; Ostriker, Jeremiah P.

    1994-01-01

    If the dark halo of the Galaxy is comprised of massive black holes (MBHs), then those within approximately 1 kpc will spiral to the center, where they will interact with one another, forming binaries which contract, owing to further dynamical friction, and then possibly merge to become more massive objects by emission of gravitational radiation. If successive mergers would invariably lead, as has been proposed by various authors, to the formation of a very massive nucleus of 10(exp 8) solar mass, then the idea of MBHs as a dark matter candidate could be excluded on observational grounds, since the observed limit (or value) for a Galactic central black hole is approximately 10(exp 6.5) solar mass. But, if successive mergers are delayed or prevented by other processes, such as the gravitational slingshot or rocket effect of gravitational radiation, then a large mass accumulation will not occur. In order to resolve this issue, we perform detailed N-body simulations using a modfied Aarseth code to explore the dynamical behavior of the MBHs, and we find that for a 'best estimate' model of the Galaxy a runaway does not occur. The code treates the MBHs as subject to the primary gravitational forces of one another and to the smooth stellar distribution, as well as the secondary perturbations in their orbits due to another and to the smooth stellar distribution, as well as the secondary perturbations in their orbits due to dynamical friction and gravitational radiation. Instead of a runaway, three-body interactions between hard binaries and single MBHs eject massive objects before accumulation of more than a few units, so that typically the center will contain zero, one, or two MBHs. We study how the situation depends in detail on the mass per MBH, the rotation of the halo, the mass distribution within the Galaxy, and other parameters. A runaway will most sensitively depend on the ratio of initial (spheroid/halo) central mass densities and secondarily on the typical values

  4. Effects of turbulence and rotation on protostar formation as a precursor of massive black holes

    NASA Astrophysics Data System (ADS)

    Van Borm, C.; Bovino, S.; Latif, M. A.; Schleicher, D. R. G.; Spaans, M.; Grassi, T.

    2014-12-01

    Context. The seeds of the first supermassive black holes may have resulted from the direct collapse of hot primordial gas in ≳104 K haloes, forming a supermassive or quasi-star as an intermediate stage. Aims: We explore the formation of a protostar resulting from the collapse of primordial gas in the presence of a strong Lyman-Werner radiation background. Particularly, we investigate the impact of turbulence and rotation on the fragmentation behaviour of the gas cloud. We accomplish this goal by varying the initial turbulent and rotational velocities. Methods: We performed 3D adaptive mesh refinement simulations with a resolution of 64 cells per Jeans length using the ENZO code, simulating the formation of a protostar up to unprecedentedly high central densities of 1021 cm-3 and spatial scales of a few solar radii. To achieve this goal, we employed the KROME package to improve modelling of the chemical and thermal processes. Results: We find that the physical properties of the simulated gas clouds become similar on small scales, irrespective of the initial amount of turbulence and rotation. After the highest level of refinement was reached, the simulations have been evolved for an additional ~5 freefall times. A single bound clump with a radius of 2 × 10-2 AU and a mass of ~7 × 10-2 M⊙ is formed at the end of each simulation, marking the onset of protostar formation. No strong fragmentation is observed by the end of the simulations, regardless of the initial amount of turbulence or rotation, and high accretion rates of a few solar masses per year are found. Conclusions: Given such high accretion rates, a quasi-star of 105 M⊙ is expected to form within 105 years. Appendix A is available in electronic form at http://www.aanda.org

  5. Effect of Accretion of Phantom Energy on Initial Mass of a Primordial Black Hole

    NASA Astrophysics Data System (ADS)

    Naz, Sumaira; Qadir, Asghar

    2012-03-01

    Hawking had shown that black holes radiate with a temperature inversely proportional to their mass, thereby losing energy and hence mass. For sufficiently small masses (less than 1015 g) the black hole would evaporate today and hence has a "life" equal to the present age of the universe. One explanation of the observed acceleration of the universe is by phantom energy. In 2010 Jamil and Qadir have showed that this energy enhances the rate of evaporation. Thus, to have a primordial black hole evaporating today, its initial mass should be larger than 1015 g or the primordial black holes of mass less than 1015 g should evaporate earlier. In fact, it was claimed that the black holes would be ten orders of magnitude larger! This effect is revisited and its dependence on the value of equation of state parameter is studied. It is found that the effect of phantom energy for the 1015 g black hole is negligible but for a 1022 g black hole would be significant. In that case, though, the black hole would not be now exploding. The mass at which the effect of phantom energy equals the effect of Hawking radiation has been called the transition mass. The transition mass has been discussed and the correction term in the lifetime for primordial black holes is computed.

  6. A Decade in the Life of the Massive Black-Hole Binary IC10 X-1

    NASA Astrophysics Data System (ADS)

    Laycock, Silas

    2014-11-01

    Chandra thanks to its angular resolution, sensitivity and endurance has been able to monitor individual X-ray binaries in the starburst galaxy IC 10. The WR+BH binary known as IC10 X-1 is regarded as one of the most massive stellar black holes; a class of objects representing the pinnacle of the stellar mass function. BH binaries occupy key roles in seeding SMBHs, producing long GRBs at birth, and gravitational waves at death. We report our use of Chandra to refine the orbital ephemeris of X1 and match-up the radial velocity curve of the optical spectral lines with the X-ray eclipse. The resulting phase offset has fascinating implications for our understanding of the interactions between the WR star, its wind, and the radiation field of the BH.

  7. Gravitational lensing by a massive black hole at the Galactic center

    NASA Technical Reports Server (NTRS)

    Wardle, Mark; Yusef-Zadeh, Farhad

    1992-01-01

    The manifestations of gravitational lensing by a massive black hole at the Galactic center, with particular attention given to lensing of stars in the stellar cluster that lie behind Sgr A*, and of Sgr A east, a nonthermal extended radio source which is known with certainty to lie behind the Galactic center. Lensing of the stellar cluster produces a deficit of stellar images within 10 mas of the center, and a surplus between 30 and 300 mas. The results suggest that the proper motion of the stars will produce brightness variations of stellar images on a time scale of a few years or less. Both images of such a source should be visible, and will rise and fall in luminosity together.

  8. Searching for massive black hole binaries in the first Mock LISA Data Challenge

    NASA Astrophysics Data System (ADS)

    Cornish, Neil J.; Porter, Edward K.

    2007-10-01

    The Mock LISA Data Challenge is a worldwide effort to solve the LISA data analysis problem. We present here our results for the massive black hole binary (BBH) section of round 1. Our results cover challenge 1.2.1, where the coalescence of the binary is seen, and challenge 1.2.2, where the coalescence occurs after the simulated observational period. The data stream is composed of Gaussian instrumental noise plus an unknown BBH waveform. Our search algorithm is based on a variant of the Markov chain Monte Carlo method that uses Metropolis Hastings sampling and thermostated frequency annealing. We present results from the training data sets where we know the parameter values a priori and the blind data sets where we were informed of the parameter values after the challenge had finished. We demonstrate that our algorithm is able to rapidly locate the sources, accurately recover the source parameters and provide error estimates for the recovered parameters.

  9. Effect of higher harmonic corrections on the detection of massive black hole binaries with LISA

    NASA Astrophysics Data System (ADS)

    Porter, Edward K.; Cornish, Neil J.

    2008-09-01

    Massive black hole binaries are key targets for the space based gravitational wave Laser Interferometer Space Antenna (LISA). Several studies have investigated how LISA observations could be used to constrain the parameters of these systems. Until recently, most of these studies have ignored the higher harmonic corrections to the waveforms. Here we analyze the effects of the higher harmonics in more detail by performing extensive Monte Carlo simulations. We pay particular attention to how the higher harmonics impact parameter correlations, and show that the additional harmonics help mitigate the impact of having two laser links fail, by allowing for an instantaneous measurement of the gravitational wave polarization with a single interferometer channel. By looking at parameter correlations we are able to explain why certain mass ratios provide dramatic improvements in certain parameter estimations, and illustrate how the improved polarization measurement improves the prospects for single interferometer operation.

  10. Measuring Parameters of Massive Black Hole Binaries with Partially-Aligned Spins

    NASA Technical Reports Server (NTRS)

    Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

    2010-01-01

    It is important to understand how well the gravitational-wave observatory LISA can measure parameters of massive black hole binaries. It has been shown that including spin precession in the waveform breaks degeneracies and produces smaller expected parameter errors than a simpler, precession-free analysis. However, recent work has shown that gas in binaries can partially align the spins with the orbital angular momentum, thus reducing the precession effect. We show how this degrades the earlier results, producing more pessimistic errors in gaseous mergers. However, we then add higher harmonics to the signal model; these also break degeneracies, but they are not affected by the presence of gas. The harmonics often restore the errors in partially-aligned binaries to the same as, or better than/ those that are obtained for fully precessing binaries with no harmonics. Finally, we investigate what LISA measurements of spin alignment can tell us about the nature of gas around a binary,

  11. Type III Dyson Sphere of Highly Advanced Civilisations around a Super Massive Black Hole

    NASA Astrophysics Data System (ADS)

    Inoue, M.; Yokoo, H.

    We describe a new system for a society of highly advanced civilizations around a super massive black hole (SMBH), as an advanced Type III “Dyson Sphere,” pointing out an efficient usage of energy for the advanced civilizations. SMBH also works as a sink for waste materials. Here we assume that Type III civilisations of Kardashev classification [1] form a galactic club [2] in a galaxy, and the energy from the SMBH will be delivered to the club members, forming an energy control system similar to power grids in our present society. The energy is probably transmitted by a sharp beam with coherent electro-magnetic waves, which provide a new concept for the search for extraterrestrial intelligence (SETI) via detection of such energy transmission signals. This expands the search window for other intelligences within the Universe.

  12. Supermassive black holes with high accretion rates in active galactic nuclei. I. First results from a new reverberation mapping campaign

    SciTech Connect

    Du, Pu; Hu, Chen; Qiu, Jie; Li, Yan-Rong; Wang, Jian-Min; Lu, Kai-Xing; Wang, Fang; Bai, Jin-Ming; Kaspi, Shai; Netzer, Hagai; Collaboration: SEAMBH collaboration

    2014-02-10

    We report first results from a large project to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). Such objects may be different from other AGNs in being powered by slim accretion disks and showing saturated accretion luminosities, but both are not yet fully understood. The results are part of a large reverberation mapping (RM) campaign using the 2.4 m Shangri-La telescope at the Yunnan Observatory in China. The goals are to investigate the gas distribution near the BH and the properties of the central accretion disks, to measure BH mass and Eddington ratios, and to test the feasibility of using such objects as a new type of cosmological candles. The paper presents results for three objects, Mrk 335, Mrk 142, and IRAS F12397+3333, with Hβ time lags relative to the 5100 Å continuum of 10.6{sub −2.9}{sup +1.7}, 6.4{sub −2.2}{sup +0.8} and 11.4{sub −1.9}{sup +2.9} days, respectively. The corresponding BH masses are (8.3{sub −3.2}{sup +2.6})×10{sup 6} M{sub ⊙}, (3.4{sub −1.2}{sup +0.5})×10{sup 6} M{sub ⊙}, and (7.5{sub −4.1}{sup +4.3})×10{sup 6} M{sub ⊙}, and the lower limits on the Eddington ratios are 0.6, 2.3, and 4.6 for the minimal radiative efficiency of 0.038. Mrk 142 and IRAS F12397+333 (extinction corrected) clearly deviate from the currently known relation between Hβ lag and continuum luminosity. The three Eddington ratios are beyond the values expected in thin accretion disks and two of them are the largest measured so far among objects with RM-based BH masses. We briefly discuss implications for slim disks, BH growth, and cosmology.

  13. NEW CONSTRAINTS ON THE BLACK HOLE LOW/HARD STATE INNER ACCRETION FLOW WITH NuSTAR

    SciTech Connect

    Miller, J. M.; King, A. L.; Tomsick, J. A.; Boggs, S. E.; Bachetti, M.; Wilkins, D.; Christensen, F. E.; Craig, W. W.; Fabian, A. C.; Kara, E.; Grefenstette, B. W.; Harrison, F. A.; Hailey, C. J.; Stern, D. K; Zhang, W. W.

    2015-01-20

    We report on an observation of the Galactic black hole candidate GRS 1739–278 during its 2014 outburst, obtained with NuSTAR. The source was captured at the peak of a rising ''low/hard'' state, at a flux of ∼0.3 Crab. A broad, skewed iron line and disk reflection spectrum are revealed. Fits to the sensitive NuSTAR spectra with a number of relativistically blurred disk reflection models yield strong geometrical constraints on the disk and hard X-ray ''corona''. Two models that explicitly assume a ''lamp post'' corona find its base to have a vertical height above the black hole of h=5{sub −2}{sup +7} GM/c{sup 2} and h = 18 ± 4 GM/c {sup 2} (90% confidence errors); models that do not assume a ''lamp post'' return emissivity profiles that are broadly consistent with coronae of this size. Given that X-ray microlensing studies of quasars and reverberation lags in Seyferts find similarly compact coronae, observations may now signal that compact coronae are fundamental across the black hole mass scale. All of the models fit to GRS 1739–278 find that the accretion disk extends very close to the black hole—the least stringent constraint is r{sub in}=5{sub −4}{sup +3} GM/c{sup 2}. Only two of the models deliver meaningful spin constraints, but a = 0.8 ± 0.2 is consistent with all of the fits. Overall, the data provide especially compelling evidence of an association between compact hard X-ray coronae and the base of relativistic radio jets in black holes.

  14. Galaxy shapes and intrinsic alignments in the MassiveBlack-II simulation

    NASA Astrophysics Data System (ADS)

    Tenneti, Ananth; Mandelbaum, Rachel; Di Matteo, Tiziana; Feng, Yu; Khandai, Nishikanta

    2014-06-01

    The intrinsic alignment of galaxy shapes with the large-scale density field is a contaminant to weak lensing measurements, as well as being an interesting signature of galaxy formation and evolution (albeit one that is difficult to predict theoretically). Here we investigate the shapes and relative orientations of the stars and dark matter of haloes and subhaloes (central and satellite) extracted from the MassiveBlack-II simulation, a state-of-the-art high-resolution hydrodynamical cosmological simulation which includes stellar and active galactic nucleus feedback in a volume of (100 h-1 Mpc)3. We consider redshift evolution from z = 1 to 0.06 and mass evolution within the range of subhalo masses, 1010-6.0 × 1014.0 h-1 M⊙. The shapes of the dark matter distributions are generally more round than the shapes defined by stellar matter. The projected root-mean-square ellipticity per component for stellar matter is measured to be erms = 0.28 at z = 0.3 for Msubhalo > 1012.0 h-1 M⊙, which compares favourably with observational measurements. We find that the shapes of stellar and dark matter are more round for less massive subhaloes and at lower redshifts. By directly measuring the relative orientation of the stellar matter and dark matter of subgroups, we find that, on average, the misalignment between the two components is larger for less massive subhaloes. The mean misalignment angle varies from ˜30° to 10° for M ˜ 1010-1014 h-1 M⊙ and shows a weak dependence on redshift. We also compare the misalignment angles in central and satellite subhaloes at fixed subhalo mass, and find that centrals are more misaligned than satellites. We present fitting formulae for the shapes of dark and stellar matter in subhaloes and also the probability distributions of misalignment angles.

  15. Towards the most complete solution of black hole accretion and outflows for the spectral and the timing studies

    NASA Astrophysics Data System (ADS)

    Chakrabarti, Sandip Kumar

    2012-07-01

    Last twenty five years a completely new paradigm has been evolved by our group which describes the most general solution of the accretion and wind flows around black holes. A major component in this paradigm is the centrifugal pressure supported shock wave which glues the pre-shock transonic flow, with the post-shock transonic flow. The post-shock transonic flow regime is called the Centrifugal pressure dominated boundary layer (CENBOL) and is the essence of black hole astrophysics. CENBOL and the outflows generated from it comprises the so-called 'Compton cloud' that is required to explain power-law components in the spectral properties of the black hole. The oscillation of the CENBOL which causes the modulation of X-rays is the cause of low/intermediate frequency QPOs. The existence of CENBOL (and therefore the outflows) depends on viscosity in the flow which desegregates the Keplerian component (equatorial plane) from the low-angular momentum flow (away from the equator). Thus a two component flow is produced where the Keplerian disk up to the CENBOL or the ISCO whichever is at the higher radius. The CENBOL is extremely stable, even under non-axisymmetric perturbations. The outburst sources have propagating and oscillating CENBOLs. Our results come entirely from theoretical considerations, with no scope for speculation. We show that many of cartoon models which claim to explain observations are offshoots of this paradigm.

  16. Irradiation of an Accretion Disc by a Jet: General Properties and Implications for Spin Measurements of Black Holes

    NASA Technical Reports Server (NTRS)

    T.Dauser; Garcia, J.; Wilms, J.; Boeck, M.; Brenneman, L. W.; Falanga, M.; Fukumura, Keigo; Reynolds, C. S.

    2013-01-01

    X-ray irradiation of the accretion disc leads to strong reflection features, which are then broadened and distorted by relativistic effects. We present a detailed, general relativistic approach to model this irradiation for different geometries of the primary X-ray source. These geometries include the standard point source on the rotational axis as well as more jet-like sources, which are radially elongated and accelerating. Incorporating this code in the RELLINE model for relativistic line emission, the line shape for any configuration can be predicted. We study how different irradiation geometries affect the determination of the spin of the black hole. Broad emission lines are produced only for compact irradiating sources situated close to the black hole. This is the only case where the black hole spin can be unambiguously determined. In all other cases the line shape is narrower, which could either be explained by a low spin or an elongated source. We conclude that for those cases and independent of the quality of the data, no unique solution for the spin exists and therefore only a lower limit of the spin value can be given

  17. Massive black hole and gas dynamics in mergers of galaxy nuclei - II. Black hole sinking in star-forming nuclear discs

    NASA Astrophysics Data System (ADS)

    Lupi, Alessandro; Haardt, Francesco; Dotti, Massimo; Colpi, Monica

    2015-11-01

    Mergers of gas-rich galaxies are key events in the hierarchical built-up of cosmic structures, and can lead to the formation of massive black hole binaries. By means of high-resolution hydrodynamical simulations we consider the late stages of a gas-rich major merger, detailing the dynamics of two circumnuclear discs, and of the hosted massive black holes during their pairing phase. During the merger gas clumps with masses of a fraction of the black hole mass form because of fragmentation. Such high-density gas is very effective in forming stars, and the most massive clumps can substantially perturb the black hole orbits. After ˜10 Myr from the start of the merger a gravitationally bound black hole binary forms at a separation of a few parsecs, and soon after, the separation falls below our resolution limit of 0.39 pc. At the time of binary formation the original discs are almost completely disrupted because of SNa feedback, while on pc scales the residual gas settles in a circumbinary disc with mass ˜ 105 M⊙. We also test that binary dynamics is robust against the details of the SNa feedback employed in the simulations, while gas dynamics is not. We finally highlight the importance of the SNa time-scale on our results.

  18. The light up and evolution of early Massive Black Holes: Athena observations

    NASA Astrophysics Data System (ADS)

    Comastri, Andrea

    2012-07-01

    The known AGN population at z > 6 is made by luminous optical QSO hosting Supermassive Black Holes (M > 10^9 solar masses), likely to represent the tip of the iceberg of the luminosity and mass function. According to theoretical models for structure formation, Massive Black Holes (MBH -- 10^4-10^7 solar masses) are predicted to be abundant in the early Universe (z > 6). The detection of such a population would provide unique constraints on the MBH formation mechanism and subsequent growth and is within the capabilities of deep and ultradeep ATHENA surveys. I will summarize the state of the art of present deep XMM and Chandra surveys, as far as the search for and spectral characterization of high redshift AGN is concerned. I will also present the observational strategy of future multi-cone ATHENA Wide Field Imager (WFI) surveys and the expected breakthroughs in the determination of the luminosity function and its evolution at high (> 4) and very high (> 6) redshifts. Perspectives for high spectral resolution observations with the XMS calorimeter onboard ATHENA will also be outlined.

  19. High-energy neutrino as observational signature of massive black hole formation

    NASA Astrophysics Data System (ADS)

    Berezinsky, V.; Dokuchaev, V.

    2006-08-01

    We describe the formation of a seed massive black hole (MBH) inside a supermassive star (SMS) in a distant galactic nucleus. The short-lived SMS is naturally formed due to collision destructions of normal stars in the evolving galactic nucleus. The neutron stars (NSs) and stellar-mass black holes form a compact self-gravitating subsystem deep inside a SMS. This subsystem is short-lived in comparison with a host SMS and collapses finally into the MBH. Just before gravitational collapse of compact subsystem the frequent NS collisions are accompanied by the generation of numerous ultra-relativistic fireballs. A combined ram pressure of multiple coexisting fireballs produces a quasi-stationary rarefied cavity in the central part of SMS. The protons are accelerated in the fireballs and by relativistic shocks in the cavity. All secondary particles, produced in collisions, except the high-energy neutrinos are absorbed in the SMS interiors. An estimated high-energy neutrino signal from this hidden source can be detected by the neutrino telescope with an effective area S˜1 km2 providing the evidence for MBH formation in a distant galactic nucleus. A corresponding lifetime of this high-energy hidden neutrino source is ~0.1-1 yr.

  20. Massive primordial black holes from hybrid inflation as dark matter and the seeds of galaxies

    NASA Astrophysics Data System (ADS)

    Clesse, Sébastien; García-Bellido, Juan

    2015-07-01

    In this paper we present a new scenario where massive primordial black holes (PBHs) are produced from the collapse of large curvature perturbations generated during a mild-waterfall phase of hybrid inflation. We determine the values of the inflaton potential parameters leading to a PBH mass spectrum peaking on planetarylike masses at matter-radiation equality and producing abundances comparable to those of dark matter today, while the matter power spectrum on scales probed by cosmic microwave background (CMB) anisotropies agrees with Planck data. These PBHs could have acquired large stellar masses today, via merging, and the model passes both the constraints from CMB distortions and microlensing. This scenario is supported by Chandra observations of numerous BH candidates in the central region of Andromeda. Moreover, the tail of the PBH mass distribution could be responsible for the seeds of supermassive black holes at the center of galaxies, as well as for ultraluminous x-ray sources. We find that our effective hybrid potential can originate e.g. from D-term inflation with a Fayet-Iliopoulos term of the order of the Planck scale but sub-Planckian values of the inflaton field. Finally, we discuss the implications of quantum diffusion at the instability point of the potential, able to generate a Swiss-cheese-like structure of the Universe, eventually leading to apparent accelerated cosmic expansion.

  1. EXTREME CORONAL LINE EMITTERS: TIDAL DISRUPTION OF STARS BY MASSIVE BLACK HOLES IN GALACTIC NUCLEI?

    SciTech Connect

    Wang Tinggui; Zhou Hongyan; Wang Huiyuan; Yang Chenwei; Komossa, S.

    2012-04-20

    Tidal disruption of stars by supermassive black holes at the centers of galaxies is expected to produce unique emission-line signatures, which have not yet been explored adequately. Here we report the discovery of extremely strong coronal lines from [Fe X] up to [Fe XIV] in a sample of seven galaxies (including two recently reported cases), which we interpret as such signatures. This is the first systematic search for objects of this kind, by making use of the immense database of the Sloan Digital Sky Survey. The galaxies, which are non-active as evidenced by the narrow line ratios, show broad emission lines of complex profiles in more than half of the sample. Both the high-ionization coronal lines and the broad lines are fading on timescales of years in objects observed with spectroscopic follow-ups, suggesting their transient nature. Variations of inferred non-stellar continua, which have absolute magnitudes of at least -16 to -18 mag in the g band, are also detected in more than half of the sample. The coronal line emitters reside in sub-L{sub *} disk galaxies (-21.3 < M{sub i} < -18.5) with small stellar velocity dispersions. The sample seems to form two distinct types based on the presence or absence of the [Fe VII] lines, with the latter having relatively low luminosities of [O III], [Fe XI], and the host galaxies. These characteristics can most naturally be understood in the context of transient accretion onto intermediate-mass black holes at galactic centers following tidal disruption of stars in a gas-rich environment. We estimate the incidence of such events to be around 10{sup -5} yr{sup -1} for a galaxy with -21.3 < M{sub i} < -18.5.

  2. Three-Layered Atmospheric Structure in Accretion Disks Around Stellar-Mass Black Holes

    NASA Technical Reports Server (NTRS)

    Zhang, S. N.; Cui, Wei; Chen, Wan; Yao, Yangsen; Zhang, Xiaoling; Sun, Xuejun; Wu, Xue-Bing; Xu, Haiguang

    2000-01-01

    Modeling of the x-ray spectra of the Galactic superluminal jet sources GRS 1915+105 and GRO J1655-40 reveals a three-layered atmospheric structure in the inner region of the inner accretion disks. Above the cold and optically thick disk with a temperature of 0.2 to 0.5 kiloelectron volts, there is a warm layer with a temperature of 1.0 to 1.5 kiloelectron volts and an optical depth around 10. Sometimes there is also a much hotter, optically thin corona above the warm layer, with a temperature of 100 kiloelectron volts or higher and an optical depth around unity. The structural similarity between the accretion disks and the solar atmosphere suggests that similar physical processes may be operating in these different systems.

  3. SIMULATIONS OF RECOILING MASSIVE BLACK HOLES IN THE VIA LACTEA HALO

    SciTech Connect

    Guedes, J.; Madau, P.; Diemand, J.; Kuhlen, M.; Zemp, M.

    2009-09-10

    The coalescence of a massive black hole (MBH) binary leads to the gravitational-wave recoil of the system and its ejection from the galaxy core. We have carried out N-body simulations of the motion of a M{sub BH} = 3.7 x 10{sup 6} M{sub sun} MBH remnant in the 'Via Lactea I' simulation, a Milky Way-sized dark matter halo. The black hole receives a recoil velocity of V{sub kick} = 80, 120, 200, 300, and 400 km s{sup -1} at redshift 1.5, and its orbit is followed for over 1 Gyr within a 'live' host halo, subject only to gravity and dynamical friction against the dark matter background. We show that, owing to asphericities in the dark matter potential, the orbit of the MBH is highly nonradial, resulting in a significantly increased decay timescale compared to a spherical halo. The simulations are used to construct a semi-analytic model of the motion of the MBH in a time-varying triaxial Navarro-Frenk-White dark matter halo plus a spherical stellar bulge, where the dynamical friction force is calculated directly from the velocity dispersion tensor. Such a model should offer a realistic picture of the dynamics of kicked MBHs in situations where gas drag, friction by disk stars, and the flattening of the central cusp by the returning black hole are all negligible effects. We find that MBHs ejected with initial recoil velocities V{sub kick} {approx}> 500 km s{sup -1} do not return to the host center within a Hubble time. In a Milky Way-sized galaxy, a recoiling hole carrying a gaseous disk of initial mass {approx}M{sub BH} may shine as a quasar for a substantial fraction of its 'wandering' phase. The long decay timescales of kicked MBHs predicted by this study may thus be favorable to the detection of off-nuclear quasar activity.

  4. Measuring Parameters of Massive Black Hole Binaries with Partially Aligned Spins

    NASA Technical Reports Server (NTRS)

    Lang, Ryan N.; Hughes, Scott A.; Cornish, Neil J.

    2011-01-01

    The future space-based gravitational wave detector LISA will be able to measure parameters of coalescing massive black hole binaries, often to extremely high accuracy. Previous work has demonstrated that the black hole spins can have a strong impact on the accuracy of parameter measurement. Relativistic spin-induced precession modulates the waveform in a manner which can break degeneracies between parameters, in principle significantly improving how well they are measured. Recent studies have indicated, however, that spin precession may be weak for an important subset of astrophysical binary black holes: those in which the spins are aligned due to interactions with gas. In this paper, we examine how well a binary's parameters can be measured when its spins are partially aligned and compare results using waveforms that include higher post-Newtonian harmonics to those that are truncated at leading quadrupole order. We find that the weakened precession can substantially degrade parameter estimation, particularly for the "extrinsic" parameters sky position and distance. Absent higher harmonics, LISA typically localizes the sky position of a nearly aligned binary about an order of magnitude less accurately than one for which the spin orientations are random. Our knowledge of a source's sky position will thus be worst for the gas-rich systems which are most likely to produce electromagnetic counterparts. Fortunately, higher harmonics of the waveform can make up for this degradation. By including harmonics beyond the quadrupole in our waveform model, we find that the accuracy with which most of the binary's parameters are measured can be substantially improved. In some cases, the improvement is such that they are measured almost as well as when the binary spins are randomly aligned.

  5. Evidence for a Super-massive Black Hole at the Center of the Milky Way

    NASA Astrophysics Data System (ADS)

    Reid, Mark

    2012-03-01

    While the concept of a black hole formed by the explosive collapse of a dying star is astounding, the possibility that matter from billions of stars can condense into a single super-massive black hole (SMBH) is even more fantastic. Yet astronomers are now confident that they exist at the centers of most galaxies and hold more than 0.01% of the baryonic mass of the Universe. Early evidence for SMBHs came from ``radio galaxies'' with two lobes symmetrically placed about the parent galaxy. These lobes are immense and minimum energy estimates require the total conversion of 10^7 stars to energy! The source of energy was traced to galaxy's center and observed to vary on time scales <1 year. Since nuclear reactions convert less than 1% of mass to energy, this would require channeling >10^9 stars through a region smaller than that between the Sun and the nearest star. A very compact radio source was discovered toward the center of the Milky Way and named Sgr A*, leading to speculation that it might be a SMBH. Infrared observations of stars on elliptical orbits give clear evidence of an unseen gravitational source of 4x10^6 solar masses. One star has been seen moving at 5000 km/s in its 16 year eccentric orbit. Sgr A* has been located at the position of the gravitational focus of the stellar orbits. However, in contrast to the rapidly moving stars, Sgr A* is motionless (<1 km/s), requiring the source to be extremely massive. For comparison, gravitational ``Brownian motion'' of a SMBH at the center of a dense stellar cluster would be comparable to the measured limits. Recent radio interferometric observations show that the radio emission from Sgr A* comes from a region comparable in size to the Schwarzschild radius (2GM/c^2) of 0.1 AU (1.5x10^7 km)! Placing any known concentration of 4x10^6 solar masses within this tiny volume would rapidly condense to a black hole.

  6. High Performance Simulations of Accretion Disk Dynamics and Jet Formations Around Kerr Black Holes

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi; Mizuno, Yosuke; Watson, Michael

    2007-01-01

    We investigate jet formation in black-hole systems using 3-D General Relativistic Particle-In-Cell (GRPIC) and 3-D GRMHD simulations. GRPIC simulations, which allow charge separations in a collisionless plasma, do not need to invoke the frozen condition as in GRMHD simulations. 3-D GRPIC simulations show that jets are launched from Kerr black holes as in 3-D GRMHD simulations, but jet formation in the two cases may not be identical. Comparative study of black hole systems with GRPIC and GRMHD simulations with the inclusion of radiate transfer will further clarify the mechanisms that drive the evolution of disk-jet systems.

  7. Impact of initial models and variable accretion rates on the pre-main-sequence evolution of massive and intermediate-mass stars and the early evolution of H II regions

    NASA Astrophysics Data System (ADS)

    Haemmerlé, Lionel; Peters, Thomas

    2016-05-01

    Massive star formation requires the accretion of gas at high rate while the star is already bright. Its actual luminosity depends sensitively on the stellar structure. We compute pre-main-sequence tracks for massive and intermediate-mass stars with variable accretion rates and study the evolution of stellar radius, effective temperature and ionizing luminosity, starting at 2 M⊙ with convective or radiative structures. The radiative case shows a much stronger swelling of the protostar for high accretion rates than the convective case. For radiative structures, the star is very sensitive to the accretion rate and reacts quickly to accretion bursts, leading to considerable chang