scholarly journals Variability in Ultra-luminous X-ray Sources

2014 ◽  
Vol 31 ◽  
Author(s):  
N. A. Webb ◽  
D. Cseh ◽  
F. Kirsten
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Resolution ◽  
Temporal Variability ◽  
Intermediate Mass ◽  
X Ray ◽  
Open Questions ◽  
The Subject ◽  
State Changes ◽  
New Facilities

AbstractMany upcoming surveys, particularly in the radio and optical domains, are designed to probe either the temporal and/or the spatial variability of a range of astronomical objects. In the light of these high resolution surveys, we review the subject of ultra-luminous X-ray (ULX) sources, which are thought to be accreting black holes for the most part. We also discuss the sub-class of ULXs known as the hyper-luminous X-ray sources, which may be accreting intermediate mass black holes. We focus on some of the open questions that will be addressed with the new facilities, such as the mass of the black hole in ULXs, their temporal variability and the nature of the state changes, their surrounding nebulae, and the nature of the region in which ULXs reside.

scholarly journals Intermediate-mass black holes in Galactic globular clusters

2009 ◽  
Vol 5 (S266) ◽  
pp. 491-494
Author(s):  
Carolina Pepe ◽  
Leonardo J. Pellizza
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Interstellar Medium ◽  
Globular Clusters ◽  
Velocity Profiles ◽  
Hydrodynamical Model ◽  
Interstellar Matter ◽  
Intermediate Mass ◽  
Central Black Hole ◽  
X Ray

AbstractOver the last few years, different observations have suggested the existence of intermediate-mass (~103 M⊙) black holes in the centers of globular clusters. However, the issue is still a matter of debate, as current observations have alternative explanations. We previously developed a hydrodynamical model for the interstellar medium in these systems to explain the luminosity of the central X-ray source found in NGC 6388, assuming a black hole accreting from the insterstellar medium. Here, we explore the predictions of our model regarding the flow of the interstellar matter in the inner cluster regions and find that the density and velocity profiles could help to determine the presence of a central black hole as well as its mass.

scholarly journals The Cosmic History of Black Hole Growth from Deep Multiwavelength Surveys

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Ezequiel Treister ◽  
C. Megan Urry
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Optical Emission ◽  
Supermassive Black Holes ◽  
X Ray ◽  
Open Questions ◽  
Black Hole Growth ◽  
History Of ◽  
Hole Growth ◽  
Cosmic History

Significant progress has been made in the last few years on understanding how supermassive black holes form and grow. In this paper, we begin by reviewing the spectral signatures of active galactic nuclei (AGN) ranging from radio to hard X-ray wavelengths. We then describe the most commonly used methods to find these sources, including optical/UV, radio, infrared, and X-ray emission, and optical emission lines. We then describe the main observational properties of the obscured and unobscured AGN population. Finally, we summarize the cosmic history of black hole accretion, that is, when in the history of the universe supermassive black holes were getting most of their mass. We finish with a summary of open questions and a description of planned and future observatories that are going to help answer them.

scholarly journals A fast and long-lived outflow from the supermassive black hole in NGC 5548

Science ◽  
2014 ◽  
Vol 345 (6192) ◽  
pp. 64-68 ◽  
Author(s):  
J. S. Kaastra ◽  
G. A. Kriss ◽  
M. Cappi ◽  
M. Mehdipour ◽  
P.-O. Petrucci ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Resolution ◽  
Accretion Disk ◽  
Active Galaxies ◽  
Ionized Gas ◽  
X Ray ◽  
Supermassive Black Hole ◽  
Space Observatories ◽  
Ngc 5548

Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution x-ray and ultraviolet (UV) observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six space observatories shows the nucleus to be obscured by a long-lasting, clumpy stream of ionized gas not seen before. It blocks 90% of the soft x-ray emission and causes simultaneous deep, broad UV absorption troughs. The outflow velocities of this gas are up to five times faster than those in the persistent outflow, and, at a distance of only a few light days from the nucleus, it may likely originate from the accretion disk.

scholarly journals Investigating ultraluminous X-ray sources through their multiwavelength variability and broadband spectra

2016 ◽  
Vol 12 (S324) ◽  
pp. 31-34
Author(s):  
Luca Zampieri ◽  
Elena Ambrosi ◽  
Amid Nayerhoda
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Compact Objects ◽  
Intermediate Mass ◽  
Local Universe ◽  
X Ray ◽  
Multiwavelength Variability ◽  
Black Hole Masses ◽  
Eddington Limit

AbstractThe population of ultraluminous X-ray sources encompasses accreting compact objects with significantly different masses, from black holes of intermediate mass, to black holes of stellar origin, to neutron stars. Investigating these sources will help us answering crucial questions on the distribution of black hole masses and on mass accretion above the Eddington limit in the local Universe, that have potential implications in other astrophysical areas. In order to perform a detailed investigation of ultraluminous X-ray sources, an accurate modeling of their evolution and multiwavelength emission properties is needed. We report some preliminary results of the activities that we are carrying out at present in this area.

scholarly journals ULX contribution to stellar feedback: an intermediate-mass black hole candidate and the population of ULXs in the low-metallicity starburst galaxy ESO 338-4

2019 ◽  
Vol 627 ◽  
pp. A63 ◽  
Author(s):  
L. M. Oskinova ◽  
A. Bik ◽  
J. M. Mas-Hesse ◽  
M. Hayes ◽  
A. Adamo ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Formation Rate ◽  
Compact Objects ◽  
Starburst Galaxy ◽  
Intermediate Mass ◽  
X Ray ◽  
Black Hole Candidate ◽  
Stellar Feedback

Context. X-ray radiation from accreting compact objects is an important part of stellar feedback. The metal-poor galaxy ESO 338-4 has experienced vigorous starburst during the last <40 Myr and contains some of the most massive super star clusters in the nearby Universe. Given its starburst age and its star-formation rate, ESO 338-4 is one of the most efficient nearby manufactures of neutron stars and black holes, hence providing an excellent laboratory for feedback studies. Aims. We aim to use X-ray observations with the largest modern X-ray telescopes XMM-Newton and Chandra to unveil the most luminous accreting neutron stars and black holes in ESO 338-4. Methods. We compared X-ray images and spectra with integral field spectroscopic observations in the optical to constrain the nature of strong X-ray emitters. Results. X-ray observations uncover three ultraluminous X-ray sources (ULXs) in ESO 338-4. The brightest among them, ESO 338 X-1, has X-ray luminosity in excess of 1040 erg s−1. We speculate that ESO 338-4 X-1 is powered by accretion on an intermediate-mass (≳300 M⊙) black hole. We show that X-ray radiation from ULXs and hot superbubbles strongly contributes to He II ionization and general stellar feedback in this template starburst galaxy.

scholarly journals Observational evidence for intermediate-mass black holes: ultra-luminous X-ray sources

2006 ◽  
Vol 2 (S238) ◽  
pp. 209-218 ◽  
Author(s):  
Kazuo Makishima
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Accretion Disks ◽  
Power Law ◽  
Observational Evidence ◽  
Early Data ◽  
Intermediate Mass ◽  
X Ray ◽  
Black Hole Binaries ◽  
Intermediate Mass Black Holes

AbstractIncorporating early data from the Suzaku satellite launched in July 2005, properties of Ultra-Luminous compact X-ray sources (ULXs) were studied in close comparison with those of Galactic and Magellanic black-hole binaries. Based on an analogy between these two types of X-ray sources, ULXs showing power-law type spectra are considered to host Comptonized accretion disks, while those with multicolor-disk type spectra are interpreted to harbor “slim” disks. The analogy also suggests that ULXs are radiating near their Eddington limits, and hence their central black holes are significantly more massive than the ordinary stellar-mass black holes contained in Galactic and Magellanic black-hole binaries. In this sense, ULXs can be regarded as intermediate-mass black holes.

scholarly journals The aperiodic variability of the Ultraluminous X-ray source in NGC 5408

2012 ◽  
Vol 8 (S290) ◽  
pp. 13-16
Author(s):  
M. D. Caballero-Garcia ◽  
S. E. Motta ◽  
T. M. Belloni ◽  
A. Wolter
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Strong Evidence ◽  
Broad Band ◽  
Theoretical Studies ◽  
Mean Square ◽  
Intermediate Mass ◽  
X Ray ◽  
Black Hole Binaries ◽  
Band Noise

AbstractUltra-Luminous X-ray sources are accreting black holes that might represent strong evidence of the Intermediate Mass Black Holes (IMBH), proposed to exist by theoretical studies but with no firm detection (as a class) so far. We analyze the best X-ray timing and spectral data from the ULX in NGC 5408 provided by XMM-Newton. The main goal is to study the broad-band noise variability of the source. We found an anti-correlation of the fractional root-mean square variability versus the intensity of the source, similar to black-hole binaries during hard states.

scholarly journals X-ray properties of reverberation-mapped AGNs with super-Eddington accreting massive black holes

2019 ◽  
Vol 15 (S356) ◽  
pp. 143-143
Author(s):  
Jaya Maithil ◽  
Michael S. Brotherton ◽  
Bin Luo ◽  
Ohad Shemmer ◽  
Sarah C. Gallagher ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Accretion Rate ◽  
Time Lags ◽  
Black Hole Mass ◽  
Host Galaxies ◽  
Massive Black Holes ◽  
X Ray ◽  
Photon Index ◽  
The Impact

AbstractActive Galactic Nuclei (AGN) exhibit multi-wavelength properties that are representative of the underlying physical processes taking place in the vicinity of the accreting supermassive black hole. The black hole mass and the accretion rate are fundamental for understanding the growth of black holes, their evolution, and the impact on the host galaxies. Recent results on reverberation-mapped AGNs show that the highest accretion rate objects have systematic shorter time-lags. These super-Eddington accreting massive black holes (SEAMBHs) show BLR size 3-8 times smaller than predicted by the Radius-Luminosity (R-L) relationship. Hence, the single-epoch virial black hole mass estimates of highly accreting AGNs have an overestimation of a factor of 3-8 times. SEAMBHs likely have a slim accretion disk rather than a thin disk that is diagnostic in X-ray. I will present the extreme X-ray properties of a sample of dozen of SEAMBHs. They indeed have a steep hard X-ray photon index, Γ, and demonstrate a steeper power-law slope, ασx.

scholarly journals Feeding and feedback from little monsters: AGN in dwarf galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 238-242
Author(s):  
Mar Mezcua
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Early Universe ◽  
Dwarf Galaxies ◽  
Scaling Relations ◽  
Strong Impact ◽  
Hole Formation ◽  
Intermediate Mass ◽  
Black Hole Formation ◽  
Low Mass

AbstractDetecting the seed black holes from which quasars formed is extremely challenging; however, those seeds that did not grow into supermassive should be found as intermediate-mass black holes (IMBHs) of 100 – 105 M⊙ in local dwarf galaxies. The use of deep multiwavelength surveys has revealed that a population of actively accreting IMBHs (low-mass AGN) exists in dwarf galaxies at least out to z ˜3. The black hole occupation fraction of these galaxies suggests that the early Universe seed black holes formed from direct collapse of gas, which is reinforced by the possible flattening of the black hole-galaxy scaling relations at the low-mass end. This scenario is however challenged by the finding that AGN feedback can have a strong impact on dwarf galaxies, which implies that low-mass AGN in dwarf galaxies might not be the untouched relics of the early seed black holes. This has important implications for seed black hole formation models.

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