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

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.

2019 ◽  
Vol 627 ◽  
pp. A63 ◽  
Author(s):  
L. M. Oskinova ◽  
A. Bik ◽  
J. M. Mas-Hesse ◽  
M. Hayes ◽  
A. Adamo ◽  
...  

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.


2018 ◽  
Vol 14 (S346) ◽  
pp. 1-13
Author(s):  
Edward P. J. van den Heuvel

AbstractA summary is given of the present state of our knowledge of High-Mass X-ray Binaries (HMXBs), their formation and expected future evolution. Among the HMXB-systems that contain neutron stars, only those that have orbital periods upwards of one year will survive the Common-Envelope (CE) evolution that follows the HMXB phase. These systems may produce close double neutron stars with eccentric orbits. The HMXBs that contain black holes do not necessarily evolve into a CE phase. Systems with relatively short orbital periods will evolve by stable Roche-lobe overflow to short-period Wolf-Rayet (WR) X-ray binaries containing a black hole. Two other ways for the formation of WR X-ray binaries with black holes are identified: CE-evolution of wide HMXBs and homogeneous evolution of very close systems. In all three cases, the final product of the WR X-ray binary will be a double black hole or a black hole neutron star binary.


2014 ◽  
Vol 10 (S312) ◽  
pp. 203-212
Author(s):  
Natalia Ivanova

AbstractDynamical interactions that take place between objects in dense stellar systems lead to frequent formation of exotic stellar objects, unusual binaries, and systems of higher multiplicity. They are most important for the formation of binaries with neutron stars and black holes, which are usually observationally revealed in mass-transferring binaries. Here we review the current understanding of compact object's retention, of the metallicity dependence on the formation of low-mass X-ray binaries with neutron stars, and how mass-transferring binaries with a black hole and a white dwarf can be formed. We discuss as well one old unsolved puzzle and two new puzzles posed by recent observations: what descendants do ultra-compact X-ray binaries produce, how are very compact triples formed, and how can black hole low-mass X-ray binaries acquire non-degenerate companions?


2019 ◽  
Vol 493 (1) ◽  
pp. 1500-1511 ◽  
Author(s):  
Francesco Shankar ◽  
David H Weinberg ◽  
Christopher Marsden ◽  
Philip J Grylls ◽  
Mariangela Bernardi ◽  
...  

ABSTRACT The masses of supermassive black holes at the centres of local galaxies appear to be tightly correlated with the mass and velocity dispersions of their galactic hosts. However, the local Mbh–Mstar relation inferred from dynamically measured inactive black holes is up to an order-of-magnitude higher than some estimates from active black holes, and recent work suggests that this discrepancy arises from selection bias on the sample of dynamical black hole mass measurements. In this work, we combine X-ray measurements of the mean black hole accretion luminosity as a function of stellar mass and redshift with empirical models of galaxy stellar mass growth, integrating over time to predict the evolving Mbh–Mstar relation. The implied relation is nearly independent of redshift, indicating that stellar and black hole masses grow, on average, at similar rates. Matching the de-biased local Mbh–Mstar relation requires a mean radiative efficiency ε ≳ 0.15, in line with theoretical expectations for accretion on to spinning black holes. However, matching the ‘raw’ observed relation for inactive black holes requires ε ∼ 0.02, far below theoretical expectations. This result provides independent evidence for selection bias in dynamically estimated black hole masses, a conclusion that is robust to uncertainties in bolometric corrections, obscured active black hole fractions, and kinetic accretion efficiency. For our fiducial assumptions, they favour moderate-to-rapid spins of typical supermassive black holes, to achieve ε ∼ 0.12–0.20. Our approach has similarities to the classic Soltan analysis, but by using galaxy-based data instead of integrated quantities we are able to focus on regimes where observational uncertainties are minimized.


1974 ◽  
Vol 64 ◽  
pp. 194-212
Author(s):  
M. J. Rees

The physics of spherically symmetrical accretion onto a compact object is briefly reviewed. Neither neutron stars nor stellar-mass black holes are likely to be readily detectable if they are isolated and accreting from the interstellar medium. Supermassive black holes in intergalactic space may however be detectable. The effects of accretion onto compact objects in binary systems are then discussed, with reference to the phenomena observed in variable X-ray sources.


2006 ◽  
Vol 2 (S238) ◽  
pp. 241-246
Author(s):  
Sachiko Tsuruta ◽  
Takuya Ohkubo ◽  
Hideyuki Umeda ◽  
Keiichi Maeda ◽  
Ken'ichi Nomoto ◽  
...  

AbstractWe calculate evolution, collapse, explosion, and nucleosynthesis of Population III very massive stars with 500 M⊙ and 1000 M⊙. It was found that both 500 M⊙ and 1000 M⊙ models enter the region of pair-instability but continue to undergo core collapse to black holes. For moderately aspherical explosions, the patterns of nucleosynthesis match the observational data of intergalactic and intercluster medium and hot gases in M82, better than models involving hypernovae and pair instability supernovae.Our results suggest that explosions of Population III core-collapse very massive stars contribute significantly to the chemical evolution of gases in clusters of galaxies. The final black hole masses are about 500 M⊙ for our most massive 1000 M⊙ models. This result may support the view that Population III very massive stars are responsible for the origin of intermediate mass black holes which were recently reported to be discovered.


2012 ◽  
Vol 8 (S290) ◽  
pp. 49-52
Author(s):  
Włodek Kluźniak

AbstractA sudden increase in stellar luminosity may lead to the ejection of a large part of any optically thin gas orbiting the star. Test particles in circular orbits will become unbound, and will escape to infinity (if radiation drag is neglected), when the luminosity changes from zero to at least one half the Eddington value, or more generally, from L to (LEdd+L)/2 or more. Conversely, a decrease in luminosity will lead to the tightening of orbits of optically thin fluid. Even a modest fluctuation of luminosity of accreting neutron stars or black holes is expected to lead to substantial coronal heating. Luminosity fluctuations may thus account for the high temperatures of the X-ray corona in accreting black hole and neutron star systems.


1995 ◽  
Vol 151 ◽  
pp. 321-329
Author(s):  
M. van der Klis

The X-ray spectrum and the rapid X-ray variability of accreting compact objects have a common origin, and their properties can therefore be expected to be coupled. Indeed, it turns out that the X-ray spectrum and the power spectrum show correlated variations, which occur as a function of variations in the mass fluxx Ṁ.Stellar mass black holes and neutron stars have similar mass and size, and therefore their accretion phenomena may be expected to show similarities. Indeed, similarities exist that indicate that a unified description may be possible. If a particular phenomenon is seen in both neutron star and black-hole candidate systems this shows immediately that it cannot be due to any property that is unique to either neutron stars or black holes, such as the presence or absence of a surface, or of a strong non-aligned magnetic field. The quest for characteristics that are unique to black holes continues - I shall mention a few candidates below.


2009 ◽  
Vol 5 (S266) ◽  
pp. 491-494
Author(s):  
Carolina Pepe ◽  
Leonardo J. Pellizza

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.


2020 ◽  
Vol 644 ◽  
pp. A175
Author(s):  
G. Vietri ◽  
V. Mainieri ◽  
D. Kakkad ◽  
H. Netzer ◽  
M. Perna ◽  
...  

Aims. The SINFONI survey for Unveiling the Physics and Effect of Radiative feedback (SUPER) was designed to conduct a blind search for AGN-driven outflows on X-ray-selected AGNs at redshift z ∼ 2 with high (∼2 kpc) spatial resolution, and to correlate them with the properties of their host galaxy and central black hole. The main aims of this paper are: (a) to derive reliable estimates for the masses of the black holes and accretion rates for the Type-1 AGNs in this survey; and (b) to characterise the properties of the AGN-driven winds in the broad line region (BLR). Methods. We analysed rest-frame optical and UV spectra of 21 Type-1 AGNs. We used Hα, Hβ, and MgII line profiles to estimate the masses of the black holes. We used the blueshift of the CIV line profile to trace the presence of winds in the BLR. Results. We find that the Hα and Hβ line widths are strongly correlated, as is the line continuum luminosity at 5100 Å with Hα line luminosity, resulting in a well-defined correlation between black hole masses estimated from Hα and Hβ. Using these lines, we estimate that the black hole masses for our objects are in the range Log (MBH/M⊙) = 8.4–10.8 and are accreting at λEdd = 0.04–1.3. Furthermore, we confirm the well-known finding that the CIV line width does not correlate with the Balmer lines and the peak of the line profile is blueshifted with respect to the [OIII]-based systemic redshift. These findings support the idea that the CIV line is tracing outflowing gas in the BLR for which we estimated velocities up to ∼4700 km s−1. We confirm the strong dependence of the BLR wind velocity on the UV-to-X-ray continuum slope, the bolometric luminosity, and Eddington ratio. We infer BLR mass outflow rates in the range 0.005–3 M⊙ yr−1, revealing a correlation with the bolometric luminosity consistent with that observed for ionised winds in the narrow line region (NLR), and X-ray winds detected in local AGNs, and kinetic power ∼10−7 − 10−4 × LBol. The coupling efficiencies predicted by AGN-feedback models are much higher than the values reported for the BLR winds in the SUPER sample; although it should be noted that only a fraction of the energy injected by the AGN into the surrounding medium is expected to become kinetic power in the outflow. Finally, we find an anti-correlation between the equivalent width of the [OIII] line and the CIV velocity shift, and a positive correlation between this latter parameter and [OIII] outflow velocity. These findings, for the first time in an unbiased sample of AGNs at z ∼ 2, support a scenario where BLR winds are connected to galaxy-scale detected outflows, and are therefore capable of affecting the gas in the NLR located at kiloparsec scale distances.


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