scholarly journals The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524

2018 ◽  
Vol 614 ◽  
pp. A121 ◽  
Author(s):  
R. Nanni ◽  
R. Gilli ◽  
C. Vignali ◽  
M. Mignoli ◽  
A. Comastri ◽  
...  
Keyword(s):  
Black Hole ◽  
Rest Frame ◽  
Signal To Noise Ratio ◽  
X Ray ◽  
Cluster Of Galaxies ◽  
Radio Lobe ◽  
Full Band ◽  
Photon Index ◽  
Gas Cloud ◽  
Extended Emission

We present the results from a ~ 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. This is the deepest X-ray observation to date of a z ~ 6 QSO. The QSO is detected with a total of 125 net counts in the full (0.500A0–7 keV) band and its spectrum can be modeled by a single power-law model with photon index of Γ = 1.81 ± 0.18 and full band flux of f = 3.95 × 10−15 erg s−1 cm−2. When compared with the data obtained by XMM-Newton in 2003, our Chandra observation in 2017 shows a harder (ΔΓ ≈ −0.6) spectrum and a 2.5 times fainter flux. Such a variation, in a timespan of ~ 2 yr rest-frame, is unexpected for such a luminous QSO powered by a > 109M⨀ black hole. The observed source hardening and weakening could be related to an intrinsic variation in the accretion rate. However, the limited photon statistics does not allow us to discriminate between an intrinsic luminosity and spectral change, and an absorption event produced by an intervening gas cloud along the line of sight. We also report the discovery of diffuse X-ray emission that extends for 30″ × 20″ southward of the QSO with a signal-to-noise ratio (S/N) of approximately six, hardness ratio of HR = 0.03+0.20−0.25, and soft band flux of f0.5– keV = 1.1+0.3−0.3 × 10−15 erg s−1 cm−2 , that is not associated to a group or cluster of galaxies. We discuss two possible explanations for the extended emission, which may be either associated with the radio lobe of a nearby, foreground radio galaxy (at z ≈ 1 – 2), or ascribed to the feedback from the QSO itself acting on its surrounding environment, as proposed by simulations of early black hole formation.

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 Discovery of a New X-ray Transient in Scorpius GRO J1655-40 ≡ X-ray Nova Scorpii 1994

1996 ◽  
Vol 165 ◽  
pp. 363-367
Author(s):  
W.S. Paciesas ◽  
S.N. Zhang ◽  
B.C. Rubin ◽  
B.A. Harmon ◽  
C.A. Wilson ◽  
...  
Keyword(s):  
Black Hole ◽  
High Resolution ◽  
Power Law ◽  
Radio Observations ◽  
X Ray ◽  
Black Hole Candidate ◽  
Radio Jets ◽  
Transient Source ◽  
Galactic Source ◽  
Photon Index

A bright transient X-ray source, GRO J1655-40 (X-ray Nova Scorpii 1994) was discovered with BATSE (the Burst and Transient Source Experiment) in late July 1994. More recently, the source also became a strong radio emitter, its rise in the radio being approximately anti-correlated with a decline in the hard X-ray intensity. High-resolution radio observations subsequent to this symposium showed evidence for superluminally expanding jets. Since the hard X-ray emission extends to at least 200 keV and we find no evidence of pulsations, we tentatively classify the source as a black-hole candidate. However, its hard X-ray spectrum is unusually steep (power-law photon index α ≃ −3) relative to most other black-hole candidates. In this regard, it resembles GRS 1915+105, the first galactic source to show superluminal radio jets.

scholarly journals Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation

2014 ◽  
Vol 447 (2) ◽  
pp. 1692-1704 ◽  
Author(s):  
Qi-Xiang Yang ◽  
Fu-Guo Xie ◽  
Feng Yuan ◽  
Andrzej A. Zdziarski ◽  
Marek Gierliński ◽  
...  
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
X Ray ◽  
Photon Index ◽  
X Ray Binaries

scholarly journals Black hole masses from X-rays

2012 ◽  
Vol 8 (S290) ◽  
pp. 371-372
Author(s):  
Xin-Lin Zhou ◽  
Roberto Soria
Keyword(s):  
Black Hole ◽  
X Rays ◽  
X Ray ◽  
Reverberation Mapping ◽  
Photon Index ◽  
Bolometric Correction ◽  
Black Hole Masses ◽  
Intrinsic Scatter

AbstractWe discuss two methods to estimate black hole (BH) masses using X-ray data only: from the X-ray variability amplitude and from the photon index Γ. The first method is based on the anti-correlation between BH mass and X-ray variability amplitude. Using a sample of AGN with BH masses from reverberation mapping, we show that this method shows small intrinsic scatter. The second method is based on the correlation between Γ and both the Eddington ratio Lbol/LEdd and the bolometric correction Lbol/L2−10keV.

scholarly journals The photon-index–time-lag correlation in black hole X-ray binaries

2017 ◽  
Vol 473 (4) ◽  
pp. 4644-4652 ◽  
Author(s):  
Pablo Reig ◽  
Nikolaos D. Kylafis ◽  
Iossif E. Papadakis ◽  
María Teresa Costado
Keyword(s):  
Black Hole ◽  
Time Lag ◽  
X Ray ◽  
Photon Index ◽  
X Ray Binaries ◽  
Time Lag Correlation

scholarly journals Quasars as standard candles II

2019 ◽  
Vol 631 ◽  
pp. A120 ◽  
Author(s):  
F. Salvestrini ◽  
G. Risaliti ◽  
S. Bisogni ◽  
E. Lusso ◽  
C. Vignali
Keyword(s):  
Active Galactic Nuclei ◽  
Rest Frame ◽  
Galactic Nuclei ◽  
Observational Cosmology ◽  
X Ray ◽  
Uv Emission ◽  
Wide Range ◽  
Photon Index ◽  
Lower Redshift

A tight non-linear relation between the X-ray and the optical-ultraviolet (UV) emission has been observed in active galactic nuclei (AGN) over a wide range of redshift and several orders of magnitude in luminosity, suggesting the existence of an ubiquitous physical mechanism regulating the energy transfer between the accretion disc and the X-ray emitting corona. Recently, our group developed a method to use this relation in observational cosmology, turning quasars into standardizable candles. This work mainly seeks to investigate the potential evolution of this correction at high redshifts. We thus studied the LX − LUV relation for a sample of quasars in the redshift range 4 <  z <  7, adopting the selection criteria proposed in our previous work regarding their spectral properties. The resulting sample consists of 53 type 1 (unobscured) quasars, observed either with Chandra or XMM-Newton, for which we performed a full spectral analysis, determining the rest-frame 2 keV flux density, as well as more general X-ray properties such as the estimate of photon index, and the soft (0.5–2 keV) and hard (2–10 keV) unabsorbed luminosities. We find that the relation shows no evidence for evolution with redshift. The intrinsic dispersion of the LX–LUV for a sample free of systematics/contaminants is of the order of 0.22 dex, which is consistent with previous estimates from our group on quasars at lower redshift.

scholarly journals Inclination effects on the X-ray emission of Galactic black-hole binaries

2019 ◽  
Vol 625 ◽  
pp. A90 ◽  
Author(s):  
Pablo Reig ◽  
Nikolaos D. Kylafis
Keyword(s):  
Black Hole ◽  
Linear Regression Analysis ◽  
Time Lag ◽  
Light Curves ◽  
Energy Spectra ◽  
Time Lags ◽  
X Ray ◽  
Galactic Black Hole ◽  
Photon Index ◽  
Inclination Angles

Context. Galactic black-hole X-ray binaries (BHBs) emit a compact, optically thick, mildly relativistic radio jet when they are in hard and hard-intermediate states. In these states, BHBs exhibit a correlation between the time lag of hard with respect to softer photons and the photon index of the power law component that characterizes the X-ray spectral continuum above ∼10 keV. The correlation, however, shows large scatter. In recent years, several works have brought to light the importance of taking into account the inclination of the systems to understand the X-ray and radio phenomenology of BHBs. Aims. Our objective is to investigate the role that the inclination plays on the correlation between the time lag and photon index. Methods. We obtained RXTE energy spectra and light curves of a sample of BHBs with different inclination angles. We computed the photon index and the time lag between hard and soft photons and performed a correlation and linear regression analysis of the two variables. We also computed energy spectra and light curves of BHBs using the Monte Carlo technique that reproduces the process of Comptonization in the jet. We account for the inclination effects by recording the photons that escape from the jet at different angles. From the simulated light curves and spectra we obtained model-dependent photon index and time lags, which we compared with those obtained from the real data. Results. We find that the correlation between the time lag and photon index is tight in low-inclination systems and becomes weaker in high-inclination systems. The amplitude of the lags is also larger at low- and intermediate-inclination angles than at high inclination. We also find that the photon index and time lag, obtained from the simulated spectra and light curves, also follow different relationships for different inclination angle ranges. Our jet model reproduces the observations remarkably well. The same set of models that reproduces the correlation for the low-inclination systems, also accounts for the correlation for intermediate- and high-inclination systems fairly well. Conclusions. The large dispersion observed in the time lag – photon index correlation in BHBs can naturally be explained as an inclination effect. Comptonization in the jet explains the steeper dependence of the lags on the photon index in low- and intermediate-inclination systems than in high-inclination systems.

scholarly journals Accretion and jets in a low-luminosity AGN: the nucleus of NGC 1052

2020 ◽  
Vol 638 ◽  
pp. A67
Author(s):  
S. Falocco ◽  
J. Larsson ◽  
S. Nandi
Keyword(s):  
Power Law ◽  
Hot Spots ◽  
Surrounding Medium ◽  
Central Area ◽  
Energy Bands ◽  
Very Large Array ◽  
X Ray ◽  
Hard Power ◽  
Photon Index ◽  
Extended Emission

Aims. We aim to determine the properties of the central region of NGC 1052 using X-ray and radio data. NGC 1052 (z = 0.005) has been investigated for decades in different energy bands and shows radio lobes and a low-luminosity active galactic nucleus. Methods. We used X-ray images from Chandra and radio images from Very Large Array to explore the morphology of the central area. We also studied the spectra of the nucleus and the surrounding region using observations from Chandra and XMM-Newton. Results. We find diffuse soft X-ray radiation and hot-spots along the radio lobes. The spectrum of the circum-nuclear region is well described by a thermal plasma (T ∼ 0.6 keV) and a power law with photon index Γ ∼ 2.3. The nucleus shows a hard power law (Γ ∼ 1.4) modified by complex absorption. A narrow iron Kα line is also clearly detected in all observations, but there is no evidence for relativistic reflection. Conclusions. The extended emission is consistent with originating from extended jets and from jet-triggered shocks in the surrounding medium. The hard power-law emission from the nucleus and the lack of relativistic reflection supports the scenario of inefficient accretion in an advection-dominated accretion flow.

scholarly journals NuSTAR and Swift Observations of the Extragalactic Black Hole X-ray Binaries

2021 ◽  
Author(s):  
Arghajit Jana ◽  
Sachindra Naik ◽  
Debjit Chatterjee ◽  
Gaurava K Jaisawal
Keyword(s):  
Black Hole ◽  
Thermal Emission ◽  
Light Curves ◽  
Telescope Array ◽  
X Ray ◽  
Soft State ◽  
Galactic Black Hole ◽  
Photon Index ◽  
X Ray Binaries ◽  
Emission Fraction

Abstract We present the results obtained from detailed spectral and timing studies of extra-galactic black hole X-ray binaries LMC X–1 and LMC X–3, using simultaneous observations with Nuclear Spectroscopic Telescope Array (NuSTAR) and Neil Gehrels Swift observatories. The combined spectra in the 0.5 − 30 keV energy range, obtained between 2014 and 2019, are investigated for both sources. We do not find any noticeable variability in 0.5 − 30 keV light curves, with 0.1 − 10 Hz fractional rms estimated to be &lt;2 per cent. No evidence of quasi-periodic oscillations is found in the power density spectra. The sources are found to be in the high soft state during the observations with disc temperature Tin ∼ 1 keV, photon index, Γ &gt; 2.5 and thermal emission fraction, fdisc &gt; 80 per cent. An Fe Kα emission line is detected in the spectra of LMC X–1, though no such feature is observed in the spectra of LMC X–3. From the spectral modelling, the spins of the black holes in LMC X–1 and LMC X–3 are estimated to be in the range of 0.92 − 0.95 and 0.19 − 0.29, respectively. The accretion efficiency is found to be, η ∼ 0.13 and η ∼ 0.04 for LMC X–1 and LMC X–3, respectively.

scholarly journals Evolution of the hard X-ray photon index in black-hole X-ray binaries: hints for accretion physics

2019 ◽  
Vol 487 (4) ◽  
pp. 5335-5345 ◽  
Author(s):  
Hao Liu ◽  
AiJun Dong ◽  
ShanShan Weng ◽  
Qingwen Wu
Keyword(s):  
Black Hole ◽  
Spectral Index ◽  
Decay Phase ◽  
X Ray ◽  
Initial Rise ◽  
Photon Index ◽  
Accretion Physics ◽  
Positive Correlations ◽  
X Ray Binaries ◽  
Rise Phase

ABSTRACT Negative and positive correlations between the X-ray photon index and the Eddington-scaled X-ray luminosity were found in the decay phase of X-ray binary outbursts and a sample of active galactic nuclei in former works. We systematically investigate the evolution of the X-ray spectral index, along with the X-ray flux and Eddington ratio, in eight outbursts of four black-hole X-ray binaries, where all selected outbursts have observational data from the Rossi X-ray Timing Explorer in both rise and decay phases. In the initial rise phase, the X-ray spectral index is anticorrelated with the flux and the X-ray spectrum quickly softens when the X-ray flux is approaching the peak value. In the decay phase, the X-ray photon index and the flux follow two different positive correlations and they become anticorrelated again when the X-ray flux is below a critical value, where the anticorrelation part follows the same trend as found in the initial rise phase. Compared with other X-ray binaries, GRO J1655−40 has an evident lower critical Eddington ratio for the anticorrelation and positive transition, which suggests that its black-hole mass and distance are not well constrained, or its intrinsic physics is different.

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