scholarly journals Revisiting BeppoSAX and NuSTAR observations of KS 1947+300 and the missing cyclotron line

2020 ◽  
Vol 493 (3) ◽  
pp. 3442-3448
Author(s):  
R Doroshenko ◽  
S Piraino ◽  
V Doroshenko ◽  
A Santangelo
Keyword(s):  
Cyclotron Resonance ◽  
Broad Band ◽  
Resonance Scattering ◽  
Continuum Models ◽  
Line Detection ◽  
Soft Component ◽  
Additional Absorption ◽  
X Ray ◽  
Two Component ◽  
Cyclotron Line

ABSTRACT Motivated by the alleged detection of a cyclotron resonance scattering feature in the X-ray spectrum of the Be-transient KS 1947+300 with NuSTAR, not observed with other observatories, we have revisited the available observations of the source to clarify the origin of the reported feature. We focus on the analysis of observations obtained with the BeppoSAX observatory during the 2001 outburst, and by NuSTAR in 2013, when the discovery of the line was reported. We find that in both cases, the source broad-band X-ray continuum can be well described with a two-component Comptonization model, which does not require an additional absorption-like feature. In addition, we show that low-significance residuals mimicking the line, which appear using different continuum models, are consistent with known calibration uncertainties. We therefore conclude that the reported cyclotron line detection is largely questionable, and thus the question on the strength of the source magnetic field remains open. We briefly discuss the origin of the observed broad-band continuum in the context of the pulse-phase-resolved analysis conducted for BeppoSAX data and speculate that the soft component may be associated with the emission from polar areas of the pulsar irradiated by the accretion column.

scholarly journals Constraining X-ray emission in HBL blazars using multiwavelength observations

2020 ◽  
Vol 496 (2) ◽  
pp. 1295-1306
Author(s):  
Alicja Wierzcholska ◽  
Stefan J Wagner
Keyword(s):  
Spectral Energy Distribution ◽  
Broad Band ◽  
Neutral Hydrogen ◽  
High Energy ◽  
Host Galaxy ◽  
Spectral Energy ◽  
Additional Absorption ◽  
X Ray ◽  
Uv Excess ◽  
Survey Results

ABSTRACT The X-ray spectrum of extreme high-energy peaked BL Lac-type blazars is located in the synchrotron branch of the broad-band spectral energy distribution (SED), at energies below the peak. A joint fit of the extrapolated X-ray spectra together with a host galaxy template allows characterizing the synchrotron branch in the SED. The X-ray spectrum is usually characterized either with a pure or a curved power-law model. In the latter case, however, it is hard to distinguish an intrinsic curvature from excess absorption. In this paper, we focus on five well-observed blazars: 1ES 0229+200, PKS 0548−322, RX J 1136+6737, 1ES 1741+196, and 1ES 2344+514. We constrain the infrared to X-ray emission of these five blazars using a model that is characterized by the host galaxy, spectral curvature, absorption, and ultraviolet (UV) excess to separate these spectral features. In the case of four sources, namely 1ES 0229+200, PKS 0548−322, 1ES 1741+196, and 1ES 2344+514, the spectral fit with the atomic neutral hydrogen from the Leiden Argentina Bonn Survey results in a significant UV excess present in the broad-band SED. Such excess can be interpreted as an additional component, for example, a blue bump. However, in order to describe spectra of these blazars without such excess, additional absorption to the atomic neutral hydrogen from the Leiden Argentina Bonn Survey is needed.

Discovery of a Cyclotron Resonance Scattering Feature in the X-Ray Spectrum of XTE J1946+274

2001 ◽  
Vol 563 (1) ◽  
pp. L35-L39 ◽  
Author(s):  
W. A. Heindl ◽  
W. Coburn ◽  
D. E. Gruber ◽  
R. E. Rothschild ◽  
I. Kreykenbohm ◽  
...  
Keyword(s):  
Cyclotron Resonance ◽  
Resonance Scattering ◽  
X Ray

scholarly journals Discovery of a Third Harmonic Cyclotron Resonance Scattering Feature in the X-Ray Spectrum of 4U 0115+63

1999 ◽  
Vol 521 (1) ◽  
pp. L49-L53 ◽  
Author(s):  
W. A. Heindl ◽  
W. Coburn ◽  
D. E. Gruber ◽  
M. R. Pelling ◽  
R. E. Rothschild ◽  
...  
Keyword(s):  
Cyclotron Resonance ◽  
Resonance Scattering ◽  
Third Harmonic ◽  
X Ray

scholarly journals NuSTAR view of Be/X-ray binary pulsar 2S 1417−624 during 2018 giant outburst

2019 ◽  
Vol 490 (2) ◽  
pp. 2458-2466 ◽  
Author(s):  
Shivangi Gupta ◽  
Sachindra Naik ◽  
Gaurava K Jaisawal
Keyword(s):  
Broad Band ◽  
Gaussian Function ◽  
Physical Models ◽  
Spectral Studies ◽  
Band Spectrum ◽  
X Ray ◽  
Binary Pulsar ◽  
Double Peak Structure ◽  
Peak Structure ◽  
Cyclotron Line

ABSTRACT We report the results obtained from a detailed timing and spectral studies of Be/X-ray binary pulsar 2S 1417−624 using data from Swift and NuSTAR observatories. The observations were carried out at the peak of a giant outburst of the pulsar in 2018. X-ray pulsations at ∼17.475 s were detected in the source light curves up to 79 keV. The evolution of the pulse profiles with energy was found to be complex. A four-peaked profile at lower energies gradually evolved into a double-peak structure at higher energies. The pulsed fraction of the pulsar, calculated from the NuSTAR observation was found to follow an anticorrelation trend with luminosity as observed during previous giant X-ray outburst studies in 2009. The broad-band spectrum of the pulsar is well described by a composite model consisting of a cut-off power-law model modified with the interstellar absorption, a thermal blackbody component with a temperature of ≈1 keV, and a Gaussian function for the 6.4 keV iron emission line. Though the pulsar was observed at the peak of the giant outburst, there was no signature of presence of any cyclotron line feature in the spectrum. The radius of the blackbody emitting region was estimated to be ≈2 km, suggesting that the most probable site of its origin is the stellar surface of the neutron star. Physical models were also explored to understand the emission geometry of the pulsar and are discussed in the paper.

scholarly journals New measurements of the cyclotron line energy in Cen X-3

2020 ◽  
Vol 500 (3) ◽  
pp. 3454-3461
Author(s):  
Gunjan Tomar ◽  
Pragati Pradhan ◽  
Biswajit Paul
Keyword(s):  
Broad Band ◽  
Resonant Scattering ◽  
High Energy ◽  
Emission Lines ◽  
Power Law Model ◽  
Pulse Profile ◽  
Line Energy ◽  
X Ray ◽  
Cyclotron Absorption ◽  
Cyclotron Line

ABSTRACT We report results from the analysis of data from two observations of the accreting binary X-ray pulsar Cen X-3 carried out with the broad-band X-ray observatories Suzaku and NuSTAR. The pulse profile is dominated by a broad single peak and show some energy dependence with two additional weak pulse peaks at energies below 15 and 25 keV, respectively. The broad-band X-ray spectrum for 0.8–60.0 keV for Suzaku  and 3.0–60.0 keV for NuSTAR is fitted well with high-energy cut-off power-law model along with soft-excess, multiple iron emission lines and a cyclotron absorption. The cyclotron line energy is found to be $30.29^{+0.68}_{-0.61}$ and $29.22^{+0.28}_{-0.27}$ keV, respectively, in the Suzaku  and NuSTAR  spectra. We make a comparison of these two measurements with four previous measurements of Cyclotron Resonant Scattering Feature (CRSF) in Cen X-3  obtained with Ginga, BeppoSAX,  and RXTE. We find no evidence for a dependence of the CRSF on luminosity. Except for one CRSF measurement with BeppoSAX , the remaining measurements are consistent with a CRSF energy in the range of 29.5–30.0 keV over a luminosity range of 1.1–5.4 × 1037 erg s−1 different from several other sources that show considerable CRSF variation in the same luminosity range.

An Australian Broad-band Satellite for X-ray Astronomy

1985 ◽  
Vol 6 (2) ◽  
pp. 186-194 ◽  
Author(s):  
J. G. Greenhill ◽  
K. B. Fenton ◽  
R. K. Sood ◽  
I. R. Tuohy
Keyword(s):  
Broad Band ◽  
High Sensitivity ◽  
Wide Energy Range ◽  
Line Production ◽  
Power Sources ◽  
X Ray ◽  
Wide Energy ◽  
X Ray Background ◽  
Cyclotron Line ◽  
Better Than

AbstractA broad-band (2-190 keV) Australian X-ray satellite could provide a spectral sensitivity substantially better than HEAO-1 or any presently approved spacecraft. It would be virtually unique by providing simultaneously data over a wide energy range with high sensitivity and energy resolution in the little measured region above 30 keV. These measurements are vital to our understanding of such diverse topics as the cyclotron line production mechanism in binary sources, the structure of the magnetosphere of neutron stars, the origin of the diffuse cosmic X-ray background and the nature of the giant power sources in active galaxies and stellar black holes. Details of the proposed spacecraft and scientific objectives are given.

scholarly journals The X-ray Astronomy Satellite SAX

1990 ◽  
Vol 115 ◽  
pp. 302-306
Author(s):  
R.C. Butler
Keyword(s):  
Energy Range ◽  
Scintillation Counter ◽  
Broad Band ◽  
Wide Energy Range ◽  
Wide Field ◽  
X Ray ◽  
Wide Energy ◽  
Cyclotron Line ◽  
Galactic Sources

AbstractThe SAX satellite is forseen for launch at the end of 1992 to study the X-ray emission from galactic and extra-galactic sources in the energy range 0.1-200 keV. The payload consists of four concentrator/spectrometer systems (3 units 1-10keV, 1 unit 0.1-10keV), a high pressure gas scintillation proportional counter (3-120keV), a phoswich scintillation counter (15-200keV), and two wide field cameras (2-30keV). Together these instruments will perform the following:- - Broad band spectroscopy (E/ΔE=12) in the energy range 0.1-10 keV with imaging resolution of 1 arcmin- Continuum and cyclotron line spectroscopy (E/ΔE=5-20) in the wide energy range 3-200 keV- Variability studies of bright source energy spectra on time scales from milliseconds to days and months- Systematic long term source variability studies in selected regions of the sky down to a source intensity of 1 mCrab.

scholarly journals Broad-band X-ray characteristics of the transient pulsar GRO J2058+42

2020 ◽  
Vol 497 (1) ◽  
pp. 1059-1065
Author(s):  
Sanhita Kabiraj ◽  
Biswajit Paul
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Broad Band ◽  
High Energy ◽  
Energy Bands ◽  
X Ray ◽  
Energy Cutoff ◽  
Cyclotron Line ◽  
Energy Dependent

ABSTRACT The Be X-ray binary GRO J2058+42 recently went through a Type-II outburst during 2019 March–April lasting for about 50 d. This outburst was detected with the operating all sky X-ray monitors like the Fermi-GBM, Swift-BAT, and MAXI-GSC. Two Nuclear Spectroscopic Telescope Array(NuSTAR) observations were also made, one during the rise and other during the decay of the outburst. It gave us the unique opportunity to analyse the broad-band characteristics of the pulsar for the first time and accretion torque characteristics of the pulsar over a range of X-ray luminosity. The pulse profiles are strongly energy-dependent, with at least four different pulse components at low energy (< 20 keV), which evolves to a single-peaked profile at high energy (> 30 keV). In each of the narrow energy bands, the pulse profiles are nearly identical in the two NuSTAR observations. The spectra from both the observations are fitted well to a power-law with a Fermi–Dirac-type high-energy cutoff. We ruled out presence of a cyclotron line in the pulse phase averaged X-ray spectrum in the NuSTAR band with an optical depth greater than 0.15. An iron emission line is detected in both the NuSTAR spectra with an equivalent width of about 125 eV. We looked at the dependence of the spin-up rate on the luminosity and estimated the magnetic field strength from that, which came out to be much higher compared to other known BeXRB pulsars. Lastly, we discussed the inadequacy of the torque–luminosity relation for determination of magnetic field strength of neutron stars.

scholarly journals POSSIBLE DETECTION OF A CYCLOTRON RESONANCE SCATTERING FEATURE IN THE X-RAY PULSAR 4U 1909+07

2013 ◽  
Vol 779 (1) ◽  
pp. 54 ◽  
Author(s):  
Gaurava K. Jaisawal ◽  
Sachindra Naik ◽  
Biswajit Paul
Keyword(s):  
Cyclotron Resonance ◽  
Resonance Scattering ◽  
X Ray

scholarly journals A full characterization of the supermassive black hole in IRAS 09149–6206

2020 ◽  
Vol 499 (1) ◽  
pp. 1480-1498
Author(s):  
D J Walton ◽  
W N Alston ◽  
P Kosec ◽  
A C Fabian ◽  
L C Gallo ◽  
...  
Keyword(s):  
Black Hole ◽  
Broad Band ◽  
Seyfert Galaxy ◽  
Type I ◽  
Additional Absorption ◽  
X Ray ◽  
Full Characterization ◽  
Supermassive Black Hole ◽  
First Time

ABSTRACT We present new broad-band X-ray observations of the type-I Seyfert galaxy IRAS 09149–6206, taken in 2018 with XMM–Newton, NuSTAR, and Swift. The source is highly complex, showing a classic ‘warm’ X-ray absorber, additional absorption from highly ionized iron, strong relativistic reflection from the innermost accretion disc and further reprocessing by more distant material. By combining X-ray timing and spectroscopy, we have been able to fully characterize the supermassive black hole in this system, constraining both its mass and – for the first time – its spin. The mass is primarily determined by X-ray timing constraints on the break frequency seen in the power spectrum, and is found to be log [MBH/M⊙] = 8.0 ± 0.6 (1σ uncertainties). This is in good agreement with previous estimates based on the H α and H β line widths, and implies that IRAS 09149–6206 is radiating at close to (but still below) its Eddington luminosity. The spin is constrained via detailed modelling of the relativistic reflection, and is found to be $a^* = 0.94^{+0.02}_{-0.07}$ (90 per cent confidence), adding IRAS 09149–6206 to the growing list of radio-quiet active galactic nuclei (AGNs) that host rapidly rotating black holes. The outflow velocities of the various absorption components are all relatively modest (vout ≲ 0.03c), implying these are unlikely to drive significant galaxy-scale AGN feedback.

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