scholarly journals Multiwavelength Temporal Behavior of GRS 1915+105

1998 ◽  
Vol 188 ◽  
pp. 396-397
Author(s):  
D. Hannikainen ◽  
Ph. Durouchoux
Keyword(s):  
Galactic Plane ◽  
Compact Object ◽  
Optical Counterpart ◽  
High Luminosity ◽  
Relativistic Jets ◽  
X Ray ◽  
Black Hole Candidate ◽  
Superluminal Motion ◽  
Extreme Variability ◽  
Sky Monitor

The transient X-ray source GRS 1915+105 was discovered in August 1992 with the GRANAT/WATCH all-sky monitor (Castro-Tirado et al. 1994). Subsequent VLA observations from March through April 1994 led to the discovery of apparent superluminal motion in a pair of radio condensations moving away from the compact radio core (Mirabel & Rodriguez 1994). These jet-like features are interpreted as a bipolar outflow with bulk velocity ~ 0.9c. Although no optical counterpart has been observed, due to the heavy extinction in the Galactic plane, and therefore not enabling measurements of the mass of the compact object, the hard X-ray spectrum and high luminosity (~ 1039 erg s−1), extreme variability in the X-ray light curve and the relativistic jets make GRS 1915+105 a strong black hole candidate.

scholarly journals Tracing Black Hole Signatures in Several Black Hole Candidates Based on Their X-Ray Spectral Evolution

2020 ◽  
Vol 240 ◽  
pp. 04001
Author(s):  
Fahmi Iman Alfarizki ◽  
Kiki Vierdayanti
Keyword(s):  
Black Hole ◽  
Compact Object ◽  
Spectral Evolution ◽  
Thermal Component ◽  
X Ray ◽  
Black Hole Candidate ◽  
Spectral Fitting ◽  
Transient Nature ◽  
Transient System ◽  
Black Hole Candidates

Investigation of spectral evolution of four black hole candidates was carried out by using color-color diagram as well as spectral fitting on Swift/XRT data. Newly found candidates, which are classified as low-mass X-ray binary system based on their transient nature, are the focus of our work. We compare their spectral evolutions to that of XTE J1752-223, a transient system and a more convincing black hole candidate whose mass has been determined from spectral-timing correlation scaling. In addition, comparison to Cygnus X-1, a well-known stellar-mass black hole, was done despite its persistent nature. The spectral fitting, by using a combination of thermal disk and non-thermal component model, results in the innermost temperature values in the range of the typical innermost temperature of black hole binary which is 0.7 – 1.5 keV. The spectral evolutions of the candidates bear a resemblance to both Cygnus X-1 and XTE J1752-223. We note that during Swift/XRT observations, the spectra of Cygnus X-1 and IGR J17451-3022 are mostly dominated by the non- thermal component. We conclude that the compact object of MAXI J1535- 571 and MAXI J1828-249 is highly likely to be a black hole. However, the lack of data rendered conclusive result impossible for IGR J17454-2919.

scholarly journals X-ray Spectroscopy of the Ultra-soft Transient 4U1543-47

1990 ◽  
Vol 115 ◽  
pp. 205-208
Author(s):  
H. van der Woerd ◽  
N.E. White ◽  
S.M. Kahn
Keyword(s):  
Emission Line ◽  
Compact Object ◽  
Relativistic Effects ◽  
Emission Feature ◽  
Continuum Emission ◽  
X Ray ◽  
Black Hole Candidate ◽  
Transmission Grating ◽  
Cool Plasma ◽  
The Continuum

AbstractThe X-ray transient 4U1543-47 was observed in 1983 by the EXOSAT observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). Two emission line features are resolved. A broad (FWHM ~2.7 keV) line at 5.9 keV is detected in the GSPC, which we interprete as a redshifted and broadened iron Kα line. The Une broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth (τ ≈ 5), or from Doppler and relativistic effects in the vicinity of a compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission line feature at 0.74 keV, which may be an iron L-transition complex. However, we find that such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral Oxygen. The continuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from a very cool plasma (kT = 0.84 keV) with large scattering depth (τ ≈ 27). The continuum spectrum is strikingly similar to that of black hole candidate LMC X-3.

scholarly journals Evolution of MAXI J1631–479 during the January 2019 outburst observed by INTEGRAL/IBIS

2020 ◽  
Vol 492 (3) ◽  
pp. 3657-3661 ◽  
Author(s):  
M Fiocchi ◽  
F Onori ◽  
A Bazzano ◽  
A J Bird ◽  
A Bodaghee ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Thermal Emission ◽  
Spectral Characteristics ◽  
Monitoring Program ◽  
High Energy ◽  
Thermal Electron ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Black Hole Candidate ◽  
Decay Times

ABSTRACT We report on a recent bright outburst from the new X-ray binary transient MAXI J1631–479, observed in January 2019. In particular, we present the 30–200 keV analysis of spectral transitions observed with INTEGRAL/IBIS during its Galactic plane monitoring program. In the MAXI and BAT monitoring period, we observed two different spectral transitions between the high/soft and low/hard states. The INTEGRAL spectrum from data taken soon before the second transition is best described by a Comptonized thermal component with a temperature of kTe ∼ 30 keV and a high-luminosity value of $L_{2-200\, \mathrm{keV}}\sim 3\times 10^{38}$ erg−1 (assuming a distance of 8 kpc). During the second transition, the source shows a hard, power-law spectrum. The lack of high energy cut-off indicates that the hard X-ray spectrum from MAXI J1631–479 is due to a non-thermal emission. Inverse Compton scattering of soft X-ray photons from a non-thermal or hybrid thermal/non-thermal electron distribution can explain the observed X-ray spectrum although a contribution to the hard X-ray emission from a jet cannot be determined at this stage. The outburst evolution in the hardness-intensity diagram, the spectral characteristics, and the rise and decay times of the outburst are suggesting that this system is a black hole candidate.

Galactic X- ray observations - Observations of compact X-ray sources

1979 ◽  
Vol 366 (1726) ◽  
pp. 281-293 ◽  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
White Dwarf ◽  
Compact Object ◽  
Bright Star ◽  
High Luminosity ◽  
Multiple Star ◽  
X Ray ◽  
Normal Star ◽  
Radio Outburst

The high luminosity galactic X-ray sources, apart from the supernovae remnants, probably all exist in multiple star systems in which matter from a normal star is being transferred to a compact object such as a white dwarf, neutron star or black hole. Recent results, obtained with the Ariel 5 and Copernicus satellites, are presented. A number of sources have been studied over extended periods in order to measure the regular periodicities in their X-ray emission. Observations also included are of the Cygnus X-1 source, which is probably the first black hole discovered in our galaxy. X-ray emission, coincident with a radio outburst, from a nearby bright star HR1099 is also reported.

scholarly journals X-Ray Bursts

1977 ◽  
Vol 4 (1) ◽  
pp. 101-110 ◽  
Author(s):  
George W. Clark
Keyword(s):  
Neutron Star ◽  
Compact Star ◽  
Compact Object ◽  
Gravitational Potential Energy ◽  
X Rays ◽  
High Luminosity ◽  
Emission Pattern ◽  
X Ray ◽  
Accretion Rates ◽  
Nuclear Burning

Most of the variable phenomena of high-luminosity (≳1036erg s−1) stellar X-ray sources can be explained, at least qualitatively, within the general framework of binary accretion models in which thermal X-rays are emitted in the vicinity of a neutron star or blackhole by plasma that has flowed downhill from the surface of a nuclear burning companion and been heated by conversion of its gravitational potential energy. The yield of X-ray energy in this process is so high, exceeding in some cases 0.1c2per unit mass, that X-ray luminosities in excess of 104L⊙can be generated with accretion rates of only ˜10−BM⊙per year. Since the transfer process depends strongly on many parameters that specify the relevant properties of two stars and their interaction, one finds a remarkable variety and range of X-ray phenomena. If the compact object is a magnetized neutron star, rotation will cause its X-ray emission pattern to sweep over a distant observer and thereby produce regular pulsations like those observed with periods in the range from 1 to 103seconds. Orbital motions can cause regular eclipses and absorption dips like those observed with periods in the range from hours to days. Changes in the rate of mass loss by the nuclear burning star or in the transfer efficiency can account for the variations in intrinsic X-ray luminosities that appear as flares, novae and on-off transitions. Irregularities in the flow of plasma near the compact star can also affect the intrinsic luminosity and appear as erratic fluctuations, spikes and shot-noise in the observed intensity.

scholarly journals Monitoring of the eclipsing Wolf-Rayet ULX in the Circinus galaxy

2018 ◽  
Vol 14 (S346) ◽  
pp. 228-234
Author(s):  
Yanli Qiu ◽  
Roberto Soria
Keyword(s):  
Gravitational Wave ◽  
Fast Moving ◽  
Compact Object ◽  
Roche Lobe ◽  
Bow Shock ◽  
High Luminosity ◽  
X Ray ◽  
Dense Shell

Abstract. We studied the eclipsing ultraluminous X-ray source CG X-1 in the Circinus galaxy, re-examining two decades of Chandra and XMM-Newton observations. The short binary period (7.21 hr) and high luminosity (LX ≈ 1040 erg s-1) suggest a Wolf-Rayet donor, close to filling its Roche lobe; this is the most luminous Wolf-Rayet X-ray binary known to-date, and a potential progenitor of a gravitational-wave merger. We phase-connect all observations, and show an intriguing dipping pattern in the X-ray lightcurve, variable from orbit to orbit. We interpret the dips as partial occultation of the X-ray emitting region by fast-moving clumps of Compton-thick gas. We suggest that the occulting clouds are fragments of the dense shell swept-up by a bow shock ahead of the compact object, as it orbits in the wind of the more massive donor.

scholarly journals The Unification of Radio-Loud AGN

1996 ◽  
Vol 175 ◽  
pp. 379-380
Author(s):  
C. M. Urry ◽  
Paolo Padovani
Keyword(s):  
Uv Light ◽  
Radio Galaxies ◽  
Current Status ◽  
High Luminosity ◽  
Relativistic Jets ◽  
Bl Lac Objects ◽  
X Ray ◽  
Relativistic Beaming ◽  
Bl Lac ◽  
Bl Lacs

In a recent review paper we summarized the current status of unification of radio-loud AGN (Urry & Padovani 1995 PASP 107, 803), connecting high-luminosity (FR II) radio galaxies with quasars, and low-luminosity (FR I) radio galaxies with BL Lac objects. Unified schemes are motivated by the knowledge that AGN appearance depends strongly on orientation (Fig. 1): optical/UV light from the centers of many AGN is obscured by circumnuclear matter, and in radio-loud AGN, bipolar relativistic jets beam light along the jet axes. Understanding these radiation anisotropics allows us to unify apparently distinct classes of AGN that differ primarily because of orientation.Our review described the classification and general properties of AGN and summarized the evidence for anisotropic emission caused by circumnuclear obscuration and relativistic beaming. We outlined the evidence, both observed isotropic properties and statistical arguments, for connecting FR IIs with quasars and FR Is with BL Lacs. The population statistics (with beaming) are in accordance with available data and suggest γ ≃ 5 for low-luminosity AGN and γ ≃ 10 for high-luminosity AGN. The distinctions between X-ray-selected and radio-selected BL Lac objects, and between BL Lacs and flat-spectrum variable quasars, still not understood, provide clues to the underlying physics of blazars. Our review discussed several possible problems and complications, and concluded with a list of the ten questions we believe are the most pressing in this field.

scholarly journals Searching for New Be/X-ray Binaries in the Galactic Plane: the Case of GS 0834 – 43, 1WGA J1958.2+3232 and AXJ1820.5–1434

2000 ◽  
Vol 175 ◽  
pp. 739-742
Author(s):  
G.L. Israel ◽  
S. Covino ◽  
V.F. Polcaro ◽  
S. Campana ◽  
S. Mereghetti ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Astronomical Observatory ◽  
Optical Counterpart ◽  
X Ray ◽  
Infra Red ◽  
X Ray Binaries

AbstractOver the last year we obtained X-ray (ROSAT, BeppoSAX and ASCA) and optical (at ESO and at the Astronomical Observatory of Loiano) to infra-red (AAO) observations of a sample of newly discovered X-ray pulsars. Among this sample we discovered the likely optical counterpart of three of them located in the Galactic plane: GS 0834–43, 1WGA J1958.2+3232 and AX J1820.5–1434.

scholarly journals An X-ray Pulsar, Metal-rich Ejecta, and Shocked Ambient Medium in the Supernova Remnant G292.0+1.8

2004 ◽  
Vol 218 ◽  
pp. 199-202
Author(s):  
John P. Hughes ◽  
Robert B. Friedman ◽  
Patrick Slane ◽  
Sangwook Park
Keyword(s):  
High Resolution ◽  
Supernova Remnant ◽  
Ambient Medium ◽  
Compact Object ◽  
Optical Counterpart ◽  
Reverse Shock ◽  
X Ray ◽  
Pulsar Wind ◽  
Circumstellar Medium

We report the discovery of pulsed X-ray emission from the compact object CXOU J112439.1-591620 within the Galactic supernova remnant G292.0+1.8 using the High Resolution Camera on the Chandra X-Ray Observatory. The X-ray period is consistent with the extrapolation of the radio period and spindown rate of PSR J1124−5916. The X-ray pulse is single peaked and broad. There is no optical counterpart to a limit of MV ∼ 26. The pressure in the pulsar wind nebula is considerably less than that in the reverse-shock-heated ejecta and circumstellar medium, indicating that the reverse shock has not yet begun to interact with the nebula.

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