Orbital resolved spectroscopy of GX 301–2: wind diagnostics

2018 ◽  
Vol 14 (S346) ◽  
pp. 59-61
Author(s):  
Nazma Islam
Keyword(s):  
Equivalent Width ◽  
Column Density ◽  
High Mass ◽  
Absorption Column ◽  
Iron Line ◽  
X Ray ◽  
Orbital Phase ◽  
Stable Periodic ◽  
Phase Range ◽  
Using Data

AbstractGX 301–2, a bright high-mass X-ray binary with an orbital period of 41.5 days, exhibits stable periodic orbital intensity modulations with a strong pre-periastron X-ray flare. Several models have been proposed to explain the accretion at different orbital phases. In Islam & Paul (2014), we presented results from an orbital resolved spectroscopic study of GX 301–2 using data from MAXI Gas Slit Camera. We have found a strong orbital dependence of the absorption column density and equivalent width of the iron emission line. A very large equivalent width of the iron line along with a small value of the column density in the orbital phase range 0.1–0.3 after the periastron passage indicates the presence of high density accretion stream. We aim to further investigate the characteristics of the accretion stream with an AstroSat observation of the system.

scholarly journals Supergiant fast X-ray transients versus classical supergiant high mass X-ray binaries: Does the difference lie in the companion wind?

2018 ◽  
Vol 610 ◽  
pp. A50 ◽  
Author(s):  
P. Pradhan ◽  
E. Bozzo ◽  
B. Paul
Keyword(s):  
Stellar Wind ◽  
Equivalent Width ◽  
High Mass ◽  
Stellar Winds ◽  
Data Set ◽  
Iron Line ◽  
X Ray ◽  
Eclipse Observations ◽  
The Difference ◽  
X Ray Binaries

We present a comparative study of stellar winds in classical supergiant high mass X-ray binaries (SgXBs) and supergiant fast X-ray transients (SFXTs) based on the analysis of publicly available out-of-eclipse observations performed with Suzaku and XMM-Newton. Our data set includes 55 observations of classical SgXBs and 21 observations of SFXTs. We found that classical SgXBs are characterized by a systematically higher absorption and luminosity compared to the SFXTs, confirming the results of previous works in the literature. Additionally, we show that the equivalent width of the fluorescence Kα iron line in the classical SgXBs is significantly larger than that of the SFXTs (outside X-ray eclipses). Based on our current understanding of the physics of accretion in these systems, we conclude that the most likely explanation of these differences is ascribed to the presence of mechanisms inhibiting accretion most of the time in SFXTs, thereby leading to a much less efficient photoionization of the stellar wind compared to classical SgXBs. We do not find evidence for the previously reported anticorrelation between the equivalent width of the fluorescence iron line and the luminosity of SgXBs.

scholarly journals X-ray reprocessing in accreting pulsar GX 301-2 observed with Insight-HXMT

2020 ◽  
Author(s):  
L Ji ◽  
V Doroshenko ◽  
V Suleimanov ◽  
A Santangelo ◽  
M Orlandini ◽  
...  
Keyword(s):  
Neutron Star ◽  
Equivalent Width ◽  
Column Density ◽  
Absorption Column ◽  
Absorption And Emission ◽  
X Ray ◽  
Absorption Edges

Abstract We investigate the absorption and emission features in observations of GX 301-2 detected with Insight-HXMT/LE in 2017-2019. At different orbital phases, we found prominent Fe Kα, Kβ and Ni Kα lines, as well as Compton shoulders and Fe K-shell absorption edges. These features are due to the X-ray reprocessing caused by the interaction between the radiation from the source and surrounding accretion material. According to the ratio of iron lines (Kα and Kβ), we infer the accretion material is in a low ionisation state. We find an orbital-dependent local absorption column density, which has a large value and strong variability around the periastron. We explain its variability as a result of inhomogeneities of the accretion environment and/or instabilities of accretion processes. In addition, the variable local column density is correlated with the equivalent width of the iron Kα lines throughout the orbit, which suggests that the accretion material near the neutron star is spherically distributed.

scholarly journals X-ray variability of the HMXB Cen X-3: evidence for inhomogeneous accretion flows.

2020 ◽  
Author(s):  
G Sanjurjo-Ferrín ◽  
J M Torrejón ◽  
K Postnov ◽  
L Oskinova ◽  
J J Rodes-Roca ◽  
...  
Keyword(s):  
Equivalent Width ◽  
Compact Star ◽  
Timing Analysis ◽  
Roche Lobe ◽  
The Other ◽  
Emission Lines ◽  
High Mass ◽  
X Ray ◽  
Accretion Flows ◽  
Inner Radius

Abstract Cen X-3 is a compact high mass X-ray binary likely powered by Roche lobe overflow. We present a phase-resolved X-ray spectral and timing analysis of two pointed XMM-Newton observations. The first one took place during a normal state of the source, when it has a luminosity LX ∼ 1036 erg s−1. This observation covered orbital phases φ = 0.00 − 0.37, i.e. the egress from the eclipse. The egress lightcurve is highly structured, showing distinctive intervals. We argue that different intervals correspond to the emergence of different emitting structures. The lightcurve analysis enables us to estimate the size of such structures around the compact star, the most conspicuous of which has a size ∼0.3R*, of the order of the Roche lobe radius. During the egress, the equivalent width of Fe emission lines, from highly ionized species, decreases as the X-ray continuum grows. On the other hand, the equivalent width of the Fe Kα line, from near neutral Fe, strengthens. This line is likely formed due to the X-ray illumination of the accretion stream. The second observation was taken when the source was 10 times X-ray brighter and covered the orbital phases φ = 0.36 − 0.80. The X-ray lightcurve in the high state shows dips. These dips are not caused by absorption but can be due to instabilities in the accretion stream. The typical dip duration, of about 1000 s, is much longer than the timescale attributed to the accretion of the clumpy stellar wind of the massive donor star, but is similar to the viscous timescale at the inner radius of the accretion disk.

scholarly journals Observations of Highly-Ionized Interstellar Iron

1984 ◽  
Vol 81 ◽  
pp. 189-191
Author(s):  
L.M. Hobbs
Keyword(s):  
Radial Velocity ◽  
Absorption Line ◽  
Equivalent Width ◽  
Column Density ◽  
Light Path ◽  
Interstellar Gas ◽  
X Ray ◽  
X Ray Background ◽  
Multi Phase ◽  
No Absorption

AbstractThe spectra of 24 stars, including 5 at distances d < 200 pc, have been observed in the regions of the coronal [Fe X] λ6375 and [Fe XIV] λ5303 lines at detection limits near an equivalent width of 1 mÅ in the best cases. In general agreement with predictions based on a multi-phase model of the interstellar medium, no absorption which can be attributed to Fe X or Fe XIV ions in hot interstellar gas emitting the soft x-ray background is seen in any of these spectra, except for two. Toward λ Cephei an absorption line near λ6375 is measured with an equivalent width of 8.1 ± 2 mÅ, a width corresponding to 20 ± 5 km s-1 or a temperature T ≤ (0.5 ± 0.25) x 106 °K, and, if it is caused by Fe X ions, a radial velocity of -355 km s-1. On that hypothesis, the hot interstellar gas constitutes at least 63% of the column density of gas along this light path.

scholarly journals Iron Line Emission from NGC1068

1989 ◽  
Vol 134 ◽  
pp. 167-172
Author(s):  
Katsuji Koyama
Keyword(s):  
Energy Range ◽  
Power Law ◽  
Equivalent Width ◽  
Line Emission ◽  
X Rays ◽  
Iron Line ◽  
X Ray ◽  
Central Engine ◽  
Photon Index ◽  
The Continuum

X-ray emission in the 2–10 keV energy range was observed with the Ginga satellite from the Seyfert 2 galaxy NGC1068. The continuum spectrum can be described by a power-law of photon index about 1.5. An intense iron line at 6.5 keV with an equivalent width of 1.3 keV was clearly noticed. The X-ray flux was about 6 × 10 −12 erg/sec/cm2 or 3 × 1041 erg/sec, assuming a distance of 22 Mpc. The observed spectrum is consistent with the scattering and reprocessing of X-rays by the gas surrounding the central engine. With this picture we estimate that the X-ray flux of the central engine is about 1043 - 1044 erg/sec, a typical value for a Seyfert 1 galaxy.

scholarly journals Orbital phase spectroscopy of four high mass X-ray binary pulsars to study the stellar wind of the companion

2009 ◽  
Vol 43 (6) ◽  
pp. 900-904 ◽  
Author(s):  
Sachindra Naik ◽  
U. Mukherjee ◽  
B. Paul ◽  
C.S. Choi
Keyword(s):  
Stellar Wind ◽  
High Mass ◽  
X Ray ◽  
Binary Pulsars ◽  
Orbital Phase

scholarly journals The role of molecular gas in the nuclear regions of IRAS 00183-7111

2018 ◽  
Vol 616 ◽  
pp. A127 ◽  
Author(s):  
I. Ruffa ◽  
C. Vignali ◽  
A. Mignano ◽  
R. Paladino ◽  
K. Iwasawa
Keyword(s):  
Column Density ◽  
Broad Band ◽  
Molecular Gas ◽  
Iron Line ◽  
X Ray ◽  
Diagnostic Diagram ◽  
Ultraluminous Infrared Galaxy ◽  
High Ionization ◽  
Nuclear Environment ◽  
Nuclear Regions

Aims. We present a multi-frequency study of the ultraluminous infrared galaxy (ULIRG) IRAS 00183-7111 (z = 0.327), selected from the Spoon diagnostic diagram as a highly obscured active galactic nucleus (AGN) candidate. ALMA millimetre and X-ray observations are used; the main aim is to verify at what level the molecular gas, traced by the CO, may be responsible for the obscuration observed at X-ray energies. Theory and observations both suggest that galaxy-scale absorption may play a role in the AGN obscuration at intermediate (i.e. Compton-thin) column densities. Methods. We calibrated and analysed ALMA archival Cycle 0 data in two bands (Bands 3 and 6). The X-ray properties of IRAS 00183-7111 were studied by reducing and analysing separately archival Chandra and XMM-Newton data; recently acquired NuSTAR spectra were first examined individually and then added to the Chandra and XMM spectra for the broad-band (0.5 − 24 keV, observed frame) analysis. Results. We derived a molecular gas column density of (8.0 ± 0.9) × 1021 cm−2 from the ALMA CO(1−0) detection, while the best-fit column density of cold gas obtained from X-ray spectral fitting is 6.8−1.5+2.1×1022 cm−. The two quantities suggest that the molecular gas may contribute only a fraction of the AGN obscuration; however, the link between them is not straightforward. The nuclear regions of IRAS 00183-7111 are likely stratified into different layers of matter: one inner and highly ionized by the strong radiation field of the AGN (as inferred from the high-ionization iron line found in the X-ray spectra), and one outer and colder, extending more than 5 kpc from the nucleus (as traced by the molecular gas observed with ALMA). The molecular gas regions also give rise to a vigorous starburst with SFR ~260 ± 28 M⊙ yr−1. The complexity of this nuclear environment makes it difficult to identify the origin of the AGN obscuration given the quality of the data currently available. Higher resolution observations in the millimetre regime are needed to deeply investigate this issue.

scholarly journals X-ray Absorption by Ionized Gas in EXOSAT Spectra from the Binary System 4U1700-37/HD153919

1990 ◽  
Vol 115 ◽  
pp. 201-204
Author(s):  
F. Haberl ◽  
T.R. Kallman ◽  
N.E. White
Keyword(s):  
Binary System ◽  
Column Density ◽  
Asymmetric Distribution ◽  
Photoelectric Absorption ◽  
Ionized Gas ◽  
X Ray ◽  
Neutral Gas ◽  
Orbital Phase ◽  
Energy Excess ◽  
X Ray Absorption

AbstractWe observed the 3.41 day eclipsing, massive binary system 4U1700-37/HD153919 with EXOSAT for more than one complete binary period to investigate the spectral variations during the orbital cycle of the neutron star. The spectra show a low energy excess below ~ 3 keV when modelled by a powerlaw spectrum attenuated by photoelectric absorption by neutral gas, suggesting partial ionization of the absorbing gas. The column density derived from spectra above 3 keV shows an asymmetric distribution around orbital phase 0.5 with higher absorption before eclipse ingress. We approximated the with distance to the X-ray source gradually decreasing ionization of the wind by two zones. One of higher ionized wind around the X-ray source for which X-ray opacities of a gas in photoionization equilibrium were used and a zone of neutral gas further away from the X-ray source. We find that our spectra below 3 keV can be well fitted by a powerlaw which is attenuated first by photoelectric absorption of ionized gas and then by neutral gas. Since around phase 0.5 the major contribution of the wind column density along the line of sight arises from the ionized part we found that the total column density can be higher up to a factor of about 4 taking ionization into account.

scholarly journals Probing the nuclear and circumnuclear properties of NGC 6300 using X-ray observations

2020 ◽  
Vol 499 (4) ◽  
pp. 5396-5409
Author(s):  
Arghajit Jana ◽  
Arka Chatterjee ◽  
Neeraj Kumari ◽  
Prantik Nandi ◽  
Sachindra Naik ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Column Density ◽  
Line Emission ◽  
Physical Models ◽  
Line Of Sight ◽  
Physical Parameters ◽  
Energy Bands ◽  
Telescope Array ◽  
Iron Line ◽  
X Ray

ABSTRACT We present the results obtained from a detailed X-ray timing and spectral analysis of the Seyfert 2 galaxy NGC 6300 by using observations from the Suzaku observatory, theChandra X-ray Observatory and the Nuclear Spectroscopic Telescope Array(NuSTAR) mission between 2007 and 2016. We calculate the variance and the rms fractional variability of the source in different energy bands and we find variabilities in various energy bands. Spectral properties of the source are studied by using various phenomenological and physical models. The properties of the Compton clouds, reflection, Fe Kα line emission and soft X-ray excess are studied in detail. Several physical parameters of the source are extracted and investigated to establish the presence/absence of any correlation between them. We also investigate the nature of the circumnuclear ‘torus’ and we find that the torus is not uniform, but clumpy. The observed changes in the line-of-sight column density can be explained in terms of transiting clouds. The iron line-emitting region is found to be different in the different epochs of observations. We also observe that the torus and the nucleus independently evolve over the years.

scholarly journals SALT observations of the supernova remnant MCSNR J0127−7332 and its associated Be X-ray binary SXP 1062 in the SMC

2021 ◽  
Vol 503 (3) ◽  
pp. 3856-3866
Author(s):  
V V Gvaramadze ◽  
A Y Kniazev ◽  
J S Gallagher ◽  
L M Oskinova ◽  
Y-H Chu ◽  
...  
Keyword(s):  
Neutron Star ◽  
Emission Line ◽  
Supernova Remnant ◽  
Supernova Explosion ◽  
High Mass ◽  
Expansion Velocity ◽  
X Ray ◽  
Orbital Phase ◽  
Be Star ◽  
The Moment

ABSTRACT We report the results of optical spectroscopy of the Small Magellanic Cloud supernova remnant (SNR) MCSNR J0127−7332 and the mass donor Be star, 2dFS 3831, in its associated high-mass X-ray binary SXP 1062 carried out with the Southern African Large Telescope. Using high-resolution long-slit spectra, we measured the expansion velocity of the SNR shell of ${\approx} 140 \, {\rm \, km\, s^{-1}}$, indicating that MCSNR J0127−7332 is in the radiative phase. We found that the observed line ratios in the SNR spectrum can be understood if the local interstellar medium is ionized by 2dFS 3831 and/or OB stars around the SNR. We propose that MCSNR J0127−7332 is the result of supernova explosion within a bubble produced by the stellar wind of the supernova progenitor and that the bubble was surrounded by a massive shell at the moment of supernova explosion. We estimated the age of MCSNR J0127−7332 to be ${\lesssim} 10\, 000$ yr. We found that the spectrum of 2dFS 3831 changes with orbital phase. Namely, the equivalent width of the H α emission line decreased by ≈40 per cent in ≈130 d after periastron passage of the neutron star and then almost returned to its original value in the next ≈100 d. Also, the spectrum of 2dFS 3831 obtained closest to the periastron epoch (about 3 weeks after the periastron) shows a noticeable emission line of He ii λ4686, which disappeared in the next 2 weeks. We interpret these changes as a result of the temporary perturbation and heating of the disc as the neutron star passes through it.

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