THE X-RAY SPECTRAL ANALYSIS OF DWARF NOVA WZ Sge OBSERVED WITH ROSAT IN QUIESCENCE

2005 ◽  
Vol 14 (07) ◽  
pp. 1185-1193 ◽  
Author(s):  
GÜLNUR İKİS GÜN
Keyword(s):  
Spectral Analysis ◽  
Column Density ◽  
Evaporation Rate ◽  
Accretion Rate ◽  
Spectral Parameters ◽  
X Ray ◽  
Viscosity Parameter ◽  
Spectral Models ◽  
Mass Evaporation ◽  
Best Fit

X-ray spectral parameters were determined for WZ Sge observed with the ROSAT PSPC. The raw data were fitted with various spectral models and the best fit spectral models are found to be that of Raymond–Smith and Thermal Bremsstrahlung. The best fit temperature was estimated to be kT ~ 2.17 keV while the column density was found to be NH ~ 2.8 × 1020 cm -2. The estimated 0.1–2.4 keV flux was in the range of log F = -12 ergs cm -2 s -1. WZ Sge stars show long outburst recurrence times and weak X-ray emissions during the quiescence states. It is possible to lengthen repetition cycles by decreasing the viscosity parameter (α); however there still remains the question why α is so small, specifically for these objects. The Coronal Siphon Model of Meyer and Meyer–Hofmeister1 can explain these phenomenons successfully. For this reason, the equations of this model were applied to the results of spectral analysis. Using this model, the mass accretion rate, mass evaporation rate in corona and the radius of the corona were calculated to be 1014.48 gr yr-1, 10-5.4 gr cm-2 s-1 and 109.7 cm, respectively. The obtained values suggest that the corona model can indeed operate in WZ Sge system.

X-RAY SPECTRAL ANALYSIS OF SU UMa TYPE DWARF NOVAE OBSERVED WITH ROSAT

2003 ◽  
Vol 12 (04) ◽  
pp. 739-755 ◽  
Author(s):  
GÜLNUR ÝKİS GÜN ◽  
E. NİHAL ERCAN
Keyword(s):  
Spectral Analysis ◽  
Quiescent State ◽  
X Rays ◽  
Dwarf Novae ◽  
Spectral Parameters ◽  
X Ray ◽  
Spectral Models ◽  
Accretion Rates ◽  
Mass Evaporation ◽  
Best Fit

X-ray spectral parameters were determined for eight SU UMa type Dwarf Novae observed with the ROSAT PSPC. The raw data were fitted with various spectral models and the best fit spectral models are found to be that of Raymond–Smith and Thermal Bremsstrahlung. The best fit temperatures were estimated to be between kT ~ 1.1-1.8 keV while the Column Densities were found to be between NH ~ 2.4×1020-4.1×1020 cm -2. The estimated 0.1-2.4 keV fluxes were in the range of log FX=-13 to -11 ergs cm-2 s-1. FX/F UV and FX/F opt rates were calculated to be between ~0.09 and ~0.37. This shows that most of the energy is radiated in the Optical and Ultraviolet band from the accretion disk in the quiescent state. Many of the SU UMa type Dwarf Novae show an Ultraviolet lag in their outburst spectrum, the Coronal Siphon Flow Model of Meyer and Meyer-Hofmeister may explain this phenomenon. This model proposes a corona at the boundary layer of a system when it is a quiescent state and suggests that some parts of the X-rays come from the corona. For these reasons, the equations of this model were applied to the results of the spectral analysis. Using this model, the mass accretion rates, the mass evaporation rates, and the radii of the coronas were calculated to be ~10-12.3-10-11.3 M⊙ yr -1, ~10-6.5-10-5.5 g cm -2 s -1 and ~109.1-109.9 cm , respectively. The pressures in the coronas were less than ~1200 g cm -2 s -1 for (z) up to ~10×109 cm . The obtained values suggest that the Corona model can indeed operate in SU UMa type Dwarf Novae.

scholarly journals The 3C Chandra snapshot survey

2014 ◽  
Vol 10 (S313) ◽  
pp. 305-306
Author(s):  
Alessandro Paggi ◽  
F. Massaro ◽  
D. E. Harris
Keyword(s):  
Spectral Analysis ◽  
Detailed Analysis ◽  
Hot Spots ◽  
Column Density ◽  
Radio Sources ◽  
Energy Bands ◽  
Complete Sample ◽  
X Ray ◽  
Pile Up ◽  
Best Fit

AbstractWe present a uniform analysis of Chandra archival observations of a complete sample of ~ 200 3C sources at z < 0.5. We measured the X-ray intensity of the nuclei and of any radio hot spots and jet features with associated X-ray emission. X-ray fluxes in three energy bands, i.e., soft, medium, and hard, for all the sources analyzed are also reported. For the stronger nuclei, we also applied the standard spectral analysis, which provides the best-fit values of the X-ray spectral index and absorbing column density. In addition, a detailed analysis of bright X-ray nuclei that could be affected by pile-up has been performed. X-ray emission was detected for all the nuclei of the radio sources in our sample.

scholarly journals XMM-Newton Observation of SNR RX J1713.7–3946

2004 ◽  
Vol 218 ◽  
pp. 73-76 ◽  
Author(s):  
G. Cassam-Chenaï ◽  
A. Decourchelle ◽  
J. Ballet ◽  
J.-L. Sauvageot ◽  
G. Dubner
Keyword(s):  
Column Density ◽  
Supernova Remnant ◽  
Synchrotron Emission ◽  
Spectral Parameters ◽  
X Ray ◽  
First Results ◽  
Photon Index

We present the first results of the observations of the supernova remnant RX J1713.7–3946 (also known as G347.3–0.5) obtained with the EPIC instrument on board the XMM-Newton satellite. We show a 5-pointings mosaiced image of the X-ray synchrotron emission. We characterize this emission by mapping its spectral parameters (absorbing column density NH and photon index γ). The synchrotron spectrum is flat at the shock and steep in the interior of the remnant. NH is well correlated with the X-ray brightness. A strong NH is found in the southwest rim of RX J1713.7–3946. We suggest that the SNR is interacting with a HI region there.

scholarly journals Monitoring PSR B1509–58 with RXTE: Spectral analysis 1996–2010

10.14311/1474 ◽  
2011 ◽  
Vol 51 (6) ◽  
Author(s):  
E. Litzinger ◽  
K. Pottschmidt ◽  
J. Wilms ◽  
S. Suchy ◽  
R. E. Rothschild ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Power Law ◽  
Pulse Period ◽  
Spectral Parameters ◽  
High Significance ◽  
X Ray ◽  
Pulse Phase ◽  
Absorbed Power ◽  
The Stability ◽  
Over Time

We present an analysis of the X-ray spectra of the young, Crab-like pulsar PSR B1509–58 (pulse period P ~ 151ms) observed by RXTE over 14 years since the beginning of the mission in 1996. The uniform dataset is especially well suited for studying the stability of the spectral parameters over time as well as for determining pulse phase resolved spectral parameters with high significance. The phase averaged spectra as well as the resolved spectra can be well described by an absorbed power law.

scholarly journals Revisiting the X-ray emission of the asynchronous polar V1432 Aql

2022 ◽  
Vol 21 (12) ◽  
pp. 315
Author(s):  
Qi-Shan Wang ◽  
Sheng-Bang Qian ◽  
Li-Ying Zhu
Keyword(s):  
Magnetic Field ◽  
Spectral Analysis ◽  
Accretion Rate ◽  
Wide Band ◽  
Reflection Effect ◽  
X Ray ◽  
Low Intensity ◽  
Strong Reflection ◽  
Orbital Modulation ◽  
The Magnetic Field

Abstract As the only eclipsing asynchronous polar, V1432 Aql provides an excellent laboratory to study the interaction between the accreted matter and the magnetic field. Here, we report an analysis of the X-ray data from the contemporaneous NuSTAR and Swift-XRT observations. The X-ray data present a profile with a low-intensity state for almost half an orbital period, a dip at 0.6 phase, and a peak at 0.75 phase, which suggests that there was only one accretion region during the observation and the claim is supported by the spectral analysis. The comparison with the previous data indicates that the X-ray data have an orbital modulation, as the case in BeppoSAX, rather than a spin one observed in ROSAT. We attribute the orbit and spin modulations to the different accretion geometries at work. The spectral analysis of the wide-band data presents a significant reflection effect, a commonly observed soft X-ray temperature, and the energy balance in V1432 Aql. Additionally, we obtained a low total accretion rate of 1.3 × 10−10 M ⊙ yr−1 and a high specific accretion rate of 3.8 g cm−2 s−1 which explains the strong reflection from the surface of the white dwarf. However, due to its complex emission, a more physical understanding of its accretion geometry is still outstanding.

scholarly journals Modelling the Soft X-ray Excess in E1615+061

1994 ◽  
Vol 159 ◽  
pp. 317-317
Author(s):  
M. Bałucińska-Church ◽  
L. Piro ◽  
H. Fink ◽  
F. Fiore ◽  
M. Matsuoka ◽  
...  
Keyword(s):  
Power Law ◽  
Column Density ◽  
High Energy ◽  
X Rays ◽  
Hard Component ◽  
X Ray ◽  
Simple Power ◽  
High Energy Tail ◽  
Photon Index ◽  
Best Fit

SummaryWe report results of an international UV – X-ray campaign in 1990–1992 involving the IUE, Rosat and Ginga satellites to observe E1615+061, a Seyfert 1 galaxy with peculiar spectral and intensity behaviour over the last 20 years. The source has been found to be stable in its medium state during the observations. The Ginga (1–20 keV) spectrum of E1615+061 is adequately represented by a simple power law with a photon index α = 1.8 ± 0.1. However, α ∼ 2, as expected for the intrinsic power law component in a reflection model, cannot be ruled out statistically. The Rosat PSPC (0.1–2 keV) spectra collected during the All Sky Survey and the AO-1 phase can be well-described by a simple power law (α = 2.2 ± 0.1) with cold absorber (NH = 3.5 ± 0.3 · 10λ20 H/cmλ2). Both the photon index being significantly different than that obtained from the Ginga spectrum and the column density being smaller than the galactic column (NH ∼ 4.2 · 10λ20 H/cmλ2) give an indication of a soft excess over and above the hard component seen in the Ginga spectrum. E1615+061 has been observed with IUE in 1990 and in 1992. The source was stable and the colour excess E(B-V) derived from the data = 0.1 is in good agreement with that expected from the galactic absorption.To parameterise the soft excess we fitted the Rosat data with a two-component model consisting of a power law, and a blackbody or thermal bremsstrahlung, with a single galactic absorption term. The column density and the slope of the power law were kept constant. The blackbody temperature was 80 ± 6 eV and 63 ± 12 eV for photon index equal to 1.8 and 2.0, respectively, whereas the bremsstrahlung temperature was 220 ± 40 eV and 115 ± 30 eV for the two cases.An attempt to model the soft excess seen in the Rosat PSPC spectrum has been made assuming that the soft excess is the high energy tail of a disc spectrum which peaks in the UV part of the spectrum. Additionally it was assumed that there is a hard component contributing to the spectrum from UV to X-rays with parameters as described by the Ginga spectrum. The best fit parameters: the mass of the central source and the mass accretion rate were around 5 ± 1 · 10λ6 M⊙ and 0.2 ± 0.04 M⊙/yr, respectively.Our modelling shows that the soft X-ray excess can be described (χredλ2 < 1.2) as the high energy tail of an accretion disk spectrum if the intrinsic power law is quite steep (α = 2). The main contribution to the residuals in the Rosat PSPC range comes from 0.3–0.6 keV, with a tendency for these residuals to increase when the slope gets flatter. The accretion luminosity is ∼ 6.5 · 10λ44 erg/s for the best fit parameters, i.e. about the Eddington luminosity.

scholarly journals Broad-band spectral analysis of LMXB XTE J1710−281 with Suzaku

2020 ◽  
Vol 496 (1) ◽  
pp. 197-205
Author(s):  
Prince Sharma ◽  
Rahul Sharma ◽  
Chetana Jain ◽  
Anjan Dutta
Keyword(s):  
Spectral Analysis ◽  
Broad Band ◽  
Emission Spectra ◽  
Band Spectrum ◽  
Surface Boundary ◽  
Hot Electron ◽  
Spectral Parameters ◽  
Surface Boundary Layer ◽  
X Ray ◽  
Single Temperature

ABSTRACT This work presents the broad-band time-averaged spectral analysis of neutron star (NS) low-mass X-ray binary, XTE J1710−281 by using the Suzaku archival data. The source was in a hard or an intermediate spectral state during this observation. This is the first time that a detailed spectral analysis of the persistent emission spectra of XTE J1710−281 has been done up to 30 keV with improved constraints on its spectral parameters. By simultaneously fitting the X-ray Imaging Spectrometer (0.6–9.0 keV) and the HXD-PIN (15.0–30.0 keV) data, we have modelled the persistent spectrum of the source with models comprising a soft component from accretion disc and/or NS surface/boundary layer and a hard Comptonizing component. The 0.6–30 keV continuum with neutral absorber can be described by a multicolour disc blackbody with an inner disc temperature of kTdisc = 0.28 keV, which is significantly Comptonized by the hot electron cloud with electron temperature of kTe ≈ 5 keV and described by photon index Γ = 1.86. A more complex three-component model comprising a multicolour disc blackbody ≈0.30 keV, single-temperature blackbody ≈0.65 keV, and Comptonization from the disc, partially absorbed (about 38 per cent) by an ionized absorber (log(ξ) ≈ 4) describes the broad-band spectrum equally well.

scholarly journals Revisiting the long term X-ray spectral evolution of Seyfert 1 galaxies

2019 ◽  
Author(s):  
Shan-Shan Weng ◽  
Ying Chen ◽  
Ting-Ting Wang ◽  
Zhen-Yi Cai ◽  
Erlin Qiao ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Power Law ◽  
Order Effect ◽  
Accretion Disc ◽  
Spectral Evolution ◽  
X Ray ◽  
Viscosity Parameter ◽  
Photon Index ◽  
Gaussian Line

Abstract Characterizing the long-term variability of AGNs is a key legacy of RXTE. We carry out a spectral analysis on a sample of 20 Seyfert 1 galaxies, which had been observed by the RXTE for at least 100 times. All 18,335 spectra are fitted in a uniform way using a power-law component plus an additional Gaussian line when necessary. For any source in our sample, we confirm that the spectrum softens or the photon index, Γ, increases with increasing the 2–10 keV luminosity, LX. However, different source holds distinct Γ − LX/LEdd relation, rather than a common one. We also fit the correlation with a function of Γ = C + β × log (flux), where C is a constant and parameter β is the slope of the correlation. In this way, the increase speed of the Γ − LX/LEdd relation can be depicted with the parameter β. Since our sample contains a large sample of long-term monitored sources, it allows us to explore the second order effect of spectral evolution. We find that there is an anti-correlation between β and the X-ray Eddington ratio, LX/LEdd. That is, the increasing tendency of Γ with increasing X-ray luminosity becomes slower when the source has a larger X-ray Eddington ratio. Our results may indicate changes in the geometry and/or the viscosity parameter of the accretion disc at different Eddington ratios.

scholarly journals AstroSat soft X-ray observations of the symbiotic recurrent nova V3890 Sgr during its 2019 outburst

2020 ◽  
Vol 501 (1) ◽  
pp. 36-49
Author(s):  
K P Singh ◽  
V Girish ◽  
M Pavana ◽  
Jan-Uwe Ness ◽  
G C Anupama ◽  
...  
Keyword(s):  
Model Atmosphere ◽  
Local Thermal Equilibrium ◽  
Atomic Data ◽  
Intensity Level ◽  
Spectral Parameters ◽  
X Ray ◽  
Systematic Uncertainties ◽  
Spectral Models ◽  
Non Local ◽  
Recurrent Nova

ABSTRACT Two long AstroSat Soft X-ray Telescope observations were taken of the third recorded outburst of the symbiotic recurrent nova V3890 Sgr. The first observing run, 8.1–9.9 d after the outburst, initially showed a stable intensity level with a hard X-ray spectrum that we attribute to shocks between the nova ejecta and the pre-existing stellar companion. On day 8.57, the first, weak, signs appeared of supersoft source (SSS) emission powered by residual burning on the surface of the white dwarf. The SSS emission was observed to be highly variable on time-scales of hours. After day 8.9, the SSS component was more stable and brighter. In the second observing run, on days 15.9–19.6 after the outburst, the SSS component was even brighter but still highly variable. The SSS emission was observed to fade significantly during days 16.8–17.8 followed by re-brightening. Meanwhile, the shock component was stable, leading to increase in hardness ratio during the period of fading. AstroSat and XMM–Newton observations have been used to study the spectral properties of V3890 Sgr to draw quantitative conclusions even if their drawback is model dependent. We used the xspec to fit spectral models of plasma emission, and the best fits are consistent with the elemental abundances being lower during the second observing run compared to the first for spectra ≥1 keV. The SSS emission is well fitted by non-local thermal equilibrium model atmosphere used for white dwarfs. The resulting spectral parameters, however, are subject to systematic uncertainties such as completeness of atomic data.

scholarly journals An extreme ultraluminous X-ray source X-1 in NGC 5055

2020 ◽  
Vol 642 ◽  
pp. A94
Author(s):  
Samaresh Mondal ◽  
Agata Różańska ◽  
Eleonora Veronica Lai ◽  
Barbara De Marco
Keyword(s):  
Column Density ◽  
Inverse Correlation ◽  
Physical Parameters ◽  
Disk Model ◽  
X Ray ◽  
Hydrogen Column Density ◽  
Spectral Models ◽  
Soft State ◽  
Photon Index ◽  
Positive Correlations

Aims. We analysed multi-epoch X-ray data of the ultraluminous X-ray source NGC 5055 X-1, with luminosity up to 2.32 × 1040 erg s−1, to constrain the physical parameters of the source. Methods. We performed a timing and spectral analysis of Chandra and XMM-Newton observations. We used spectral models that assume the emission is from an accreting black hole system. We fit the data with a multicolour disk combined with a powerlaw or a thermal Comptonization (NTHCOMP) component and compared those fits with a slim disk model. Results. The light curves of the source do not show significant variability. From the hardness ratios (3–10 keV/0.3–3 keV flux), we infer that the source is not spectrally variable. We found that the photon index is tightly, positively correlated with the unabsorbed 0.3–10 keV flux and the hydrogen column density. Furthermore, the temperature emissivity profile indicates a deviation from the standard sub-Eddington thin disk model. The source shows an inverse correlation between luminosity and inner disk temperature in all fitted models. Conclusions. Our analysis favours the source to be in an ultraluminous soft state. The positive correlations between the photon index and the flux as well as between the photon index and the hydrogen column density may suggest the source is accreting at high Eddington ratios and might indicate the presence of a wind. The inverse luminosity relation with the inner disk temperature for all spectral models may indicate that the emission is geometrically beamed by an optically thick outflow.

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