scholarly journals Possible Detection of X-Ray Emitting Circumstellar Material in the Synchrotron-dominated Supernova Remnant RX J1713.7−3946

2021 ◽  
Vol 923 (2) ◽  
pp. 187
Author(s):  
Dai Tateishi ◽  
Satoru Katsuda ◽  
Yukikatsu Terada ◽  
Fabio Acero ◽  
Takashi Yoshida ◽  
...  
Keyword(s):  
Supernova Remnant ◽  
Thermal Emission ◽  
Abundance Ratio ◽  
Emission Lines ◽  
Emission Model ◽  
X Ray ◽  
Circumstellar Material ◽  
Elemental Abundances ◽  
Reflection Grating ◽  
Rayet Star

Abstract We report on a discovery of an X-ray emitting circumstellar material (CSM) knot inside the synchrotron dominant supernova remnant RX J1713.7−3946. This knot was previously thought to be a Wolf–Rayet star (WR 85), but we realized that it is in fact ∼40″ away from WR 85, indicating no relation to WR 85. We performed high-resolution X-ray spectroscopy with the Reflection Grating Spectrometer (RGS) on board XMM-Newton. The RGS spectrum clearly resolves a number of emission lines, such as N Lyα, O Lyα, Fe xviii, Ne x, Mg xi, and Si xiii. The spectrum can be well represented by an absorbed thermal-emission model with a temperature of k B T e = 0.65 ± 0.02 keV. The elemental abundances are obtained to be N / H = 3.5 ± 0.8 N / H ⊙ , O / H = 0.5 ± 0.1 O / H ⊙ , Ne / H = 0.9 ± 0.1 Ne / H ⊙ , Mg / H = 1.0 ± 0.1 Mg / H ⊙ , Si / H = 1.0 ± 0.2 Si / H ⊙ , and Fe / H = 1.3 ± 0.1 Fe / H ⊙ . The enhanced N abundance with others being about the solar values allows us to infer that this knot is CSM ejected when the progenitor star evolved into a red supergiant. The abundance ratio of N to O is obtained to be N / O = 6.8 − 2.1 + 2.5 N / O ⊙ . By comparing this to those in outer layers of red supergiant stars expected from stellar evolution simulations, we estimate the initial mass of the progenitor star to be 15 M ⊙ ≲ M ≲ 20 M ⊙.

scholarly journals Deciphering the nature of the pulsar wind nebula CTB 87 with XMM–Newton

2019 ◽  
Vol 491 (2) ◽  
pp. 3013-3021 ◽  
Author(s):  
B Guest ◽  
S Safi-Harb ◽  
A MacMaster ◽  
R Kothes ◽  
B Olmi ◽  
...  
Keyword(s):  
Supernova Remnant ◽  
Thermal Emission ◽  
Plasma Temperature ◽  
Evolutionary Stage ◽  
Reverse Shock ◽  
X Ray ◽  
Upper Limit ◽  
Supernova Shell ◽  
Pulsar Wind ◽  
Hydrodynamical Simulations

ABSTRACT CTB 87 (G74.9+1.2) is an evolved supernova remnant (SNR) which hosts a peculiar pulsar wind nebula (PWN). The X-ray peak is offset from that observed in radio and lies towards the edge of the radio nebula. The putative pulsar, CXOU J201609.2+371110, was first resolved with Chandra and is surrounded by a compact and a more extended X-ray nebula. Here, we use a deep XMM–Newton observation to examine the morphology and evolutionary stage of the PWN and to search for thermal emission expected from a supernova shell or reverse shock interaction with supernova ejecta. We do not find evidence of thermal X-ray emission from the SNR and place an upper limit on the electron density of 0.05 cm−3 for a plasma temperature kT ∼ 0.8 keV. The morphology and spectral properties are consistent with a ∼20-kyr-old relic PWN expanding into a stellar wind-blown bubble. We also present the first X-ray spectral index map from the PWN and show that we can reproduce its morphology by means of 2D axisymmetric relativistic hydrodynamical simulations.

scholarly journals A new possible accretion scenario for ultra-luminous X-ray sources

2019 ◽  
Vol 489 (1) ◽  
pp. 366-384 ◽  
Author(s):  
Shogo B Kobayashi ◽  
K Nakazawa ◽  
K Makishima
Keyword(s):  
Emission Lines ◽  
Emission Model ◽  
Massive Black Holes ◽  
X Ray ◽  
Local Structures ◽  
Upper Limits ◽  
Nearby Galaxies ◽  
Model Independent ◽  
Spectral States ◽  
Spectral State

ABSTRACT Using archival data from Suzaku, XMM–Newton, and NuSTAR, nine representative ultra-luminous X-ray sources (ULXs) in nearby galaxies were studied. Their X-ray spectra were all reproduced with a multicolour disc emission model plus its Comptonization. However, the spectral shapes of individual sources changed systematically depending on the luminosity, and defined three typical spectral states. These states differ either in the ratio between the Comptonizing electron temperature and the innermost disc temperature, or in the product of Compton y-parameter and fraction of the Comptonized disc photons. The luminosity range at which a particular state emerges was found to scatter by a factor of up to 16 among the eight ULXs. By further assuming that the spectral state is uniquely determined by the Eddington ratio, the sample ULXs are inferred to exhibit a similar scatter in their masses. This gives a model-independent support to the interpretation of ULXs in terms of relatively massive black holes. None of the spectra showed noticeable local structures. Especially, no Fe K-shell absorption/emission lines were detected, with upper limits of 30–40 eV in equivalent width from the brightest three among the sample: NGC 1313 X-1, Holmberg IX X-1, and IC 342 X-1. These properties disfavour ordinary mass accretion from a massive companion star, and suggest direct Bondi–Hoyle accretion from dense parts of the interstellar medium.

scholarly journals The first broad-band X-ray view of the narrow-line Seyfert 1 Ton S180

2020 ◽  
Vol 497 (2) ◽  
pp. 2352-2370 ◽  
Author(s):  
G A Matzeu ◽  
E Nardini ◽  
M L Parker ◽  
J N Reeves ◽  
V Braito ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Outer Part ◽  
Spectral Energy ◽  
X Rays ◽  
Narrow Line ◽  
X Ray ◽  
Extreme Uv ◽  
Reflection Grating

ABSTRACT We present joint XMM–Newton and NuSTAR observations of the ‘bare’ narrow-line Seyfert 1 Ton S180 (z = 0.062), carried out in 2016 and providing the first hard X-ray view of this luminous galaxy. We find that the 0.4–30 keV band cannot be self-consistently reproduced by relativistic reflection models, which fail to account simultaneously for the soft and hard X-ray emission. The smooth soft excess prefers extreme blurring parameters, confirmed by the nearly featureless nature of the Reflection Grating Spectrometer (RGS) spectrum, while the moderately broad Fe K line and the modest hard excess above 10 keV appear to arise in a milder gravity regime. By allowing a different origin of the soft excess, the broad-band X-ray spectrum and overall spectral energy distribution (SED) are well explained by a combination of (a) direct thermal emission from the accretion disc, dominating from the optical to the far/extreme UV; (b) Comptonization of seed disc photons by a warm (kTe ∼ 0.3 keV) and optically thick (τ ∼ 10) corona, mostly contributing to the soft X-rays; (c) Comptonization by a standard hot ($kT_{\rm \mathrm{ e}}\gtrsim 100$ keV) and optically thin (τ < 0.5) corona, responsible for the primary X-ray continuum; and (d) reflection from the mid/outer part of the disc. The two coronae are suggested to be rather compact, with $R_{\rm hot}\lesssim R_{\rm warm}\lesssim 10\, r_{\rm g}$. Our SED analysis implies that Ton S180 accretes at super-Eddington rates. This is a key condition for the launch of a wind, marginal (i.e. 3.1σ significance) evidence of which is indeed found in the RGS spectrum.

scholarly journals Infrared spectroscopy of Be/X-ray binaries

1994 ◽  
Vol 162 ◽  
pp. 204-205
Author(s):  
C. Everall ◽  
M.J. Coe ◽  
P. Roche ◽  
A. J. Norton ◽  
S. J. Unger
Keyword(s):  
Emission Lines ◽  
Circumstellar Disk ◽  
Density Structure ◽  
X Ray ◽  
Circumstellar Material ◽  
Field Temperature ◽  
Be Star ◽  
Ir Emission ◽  
X Ray Binaries ◽  
Depth Effects

We present infrared spectra of 4 Be/X-ray binaries in the K band, and 4 spectra in the J, H and K bands of 2 more sources. The HI IR emission lines are useful determinators of the conditions in the inner regions of the circumstellar disk about the Be star, due to optical depth effects. These are preliminary results, and hope to be followed up by high resolution echelle spectra, where we wish to estimate the velocity field, temperature and density structure of the circumstellar material.

scholarly journals Multiwavelength observations of the Be-star/X-ray binary EXO2030+375 during outburst

1994 ◽  
Vol 162 ◽  
pp. 206-207
Author(s):  
A.J. Norton ◽  
M.J. Coe ◽  
C. Everall ◽  
P. Roche ◽  
L. Bildsten ◽  
...  
Keyword(s):  
Neutron Star ◽  
Emission Lines ◽  
Be Stars ◽  
Infrared Excess ◽  
X Ray ◽  
Circumstellar Material ◽  
Spin Period ◽  
Be Star ◽  
Star Surface ◽  
X Ray Binaries

EXO2030+375 consists of a neutron star in an eccentric 46 day orbit around a 20th magnitude Be-star companion (Coe et al., 1988; Parmar et al., 1989; Stollberg et al., 1993). The Be-star is thought to be surrounded by a shell/disc of material which is responsible for the infrared excess and Balmer emission lines which are characteristic of Be-stars in general. At periastron, the neutron star passes through this circumstellar material, giving rise to enhanced accretion onto the neutron star surface. As a result of this, the X-ray emission (pulsed at the neutron star spin period of 41.8s) increases dramatically, so producing the transient, outburst behaviour which is commonly seen in Be-star / X-ray binaries.

scholarly journals X-Ray Line Emission from Supernova Remnants and Models for Nonequilibrium Ionization

1983 ◽  
Vol 101 ◽  
pp. 109-111
Author(s):  
Craig L. Sarazin ◽  
Andrew J. S. Hamilton ◽  
Roger A. Chevalier
Keyword(s):  
Supernova Remnants ◽  
Thermal Emission ◽  
Thermal Structure ◽  
Line Emission ◽  
Type I ◽  
Emission Model ◽  
Ionization State ◽  
Severe Problem ◽  
X Ray ◽  
Nonequilibrium Ionization

An extensive grid of nonequilibrium ionization models for the X-ray spectra of adiabatic supernova remnants (SNRs) is described. The models are compared to the SSS spectra of remnants in the LMC, the Tycho SNR, and SNR 1006. In Tycho, we show that the observed spectrum requires significantly enhanced abundances of Si and S, and that this conclusion is independent of the detailed ionization and thermal structure in the remnant. We find that the SSS spectrum of SNR 1006 can be fit reasonably by a thermal emission model with abundances of about one half solar. In this model, the weak line emission results from the very low ionization state in the remnant, and not because the X-ray emission is non-thermal. We argue that the failure to detect strong Fe line emission in young Type I SNRs poses a severe problem for models of Type I SN, which predict that most of the ejecta be iron. Finally, the results of UV observations of a star behind SNR 1006 are mentioned; these observations show that the remnant contains a large amount of rapidly moving, cold iron.

ON THE X-RAY PROPERTIES OF H2O MASER HOST GALAXIES

2009 ◽  
Vol 18 (09) ◽  
pp. 1367-1379 ◽  
Author(s):  
QIAN GUO ◽  
JIANG-SHUI ZHANG ◽  
JUN-HUI FAN
Keyword(s):  
Emission Line ◽  
Thermal Emission ◽  
Accretion Rate ◽  
Line Emission ◽  
Special Kind ◽  
Seyfert Galaxies ◽  
Emission Model ◽  
Host Galaxies ◽  
Iron Line ◽  
X Ray

All galaxies beyond the Magellanic clouds with detected H 2 O maser emission so far are investigated and their X-ray observations are collected in detail to probe the X-ray properties of this special kind of galaxies. The soft excess and the strong iron emission line are commonly presented in their X-ray spectrum. Similar to the spectra of normal Seyfert 2 galaxies, the X-ray soft components are usually explained well by two alternative models or their combination: the absorbed power law model and the thermal emission model. The hard X-ray continua are usually flat, which should be caused by the increase of the reflection component, with the increase of the absorbing material density. Modeling their X-ray spectra shows that high absorbing column density is prevalent in our H 2 O megamaser host AGNs. Further, we investigate a possible relation between the iron line emission and the nuclear X-ray emission. It shows no significant correlation between the equivalent width (EW) of the neutral Fe Kα emission line (~ 6.4 keV) and the intrinsic nuclear X-ray luminosity. However, one trend appears clearly — the EW of the iron line decreases with the increase of the observed X-ray luminosity for our H 2 O maser galaxies. We also estimate the accretion rate of H 2 O maser host AGNs and the results show that maser galaxies may have a higher accretion rate than nonmaser Seyfert galaxies. In addition, possible relations between the EW of the iron line with the accretion rate and the central black hole mass are investigated and no significant trend of correlation can be found between them.

scholarly journals X-ray Observations of SN 1993J

2005 ◽  
Vol 192 ◽  
pp. 53-58
Author(s):  
H.-U. Zimmermann
Keyword(s):  
Energy Band ◽  
Thermal Emission ◽  
Emission Model ◽  
Ionization Equilibrium ◽  
X Ray ◽  
General Decline ◽  
Shock Models

SummaryIn April 2001 SN1993J was observed with both the PN and MOS cameras of the XMM-Newton observatory. A 2-component thermal emission model assuming ionization equilibrium provides a good fit to the spectrum in the 0.3 to 11 keV energy band, but fits to shock models show also acceptable results. The development of the X-ray temperatures over the first 8 years after the explosion is discussed in the light of the standard SN model. The long term X-ray lightcurve shows a general decline of the luminosity with Lx ∝ t−0.30.

scholarly journals Emission Lines From Hot Astrophysical Plasmas

1990 ◽  
Vol 115 ◽  
pp. 1-10 ◽  
Author(s):  
John C. Raymond
Keyword(s):  
Spectral Lines ◽  
Emission Lines ◽  
Physical Parameters ◽  
Relative Importance ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
Elemental Abundances ◽  
Computer Codes ◽  
Measurement Uncertainties ◽  
Ionization Balance

AbstractThe spectral lines which dominate the X-ray emission of hot, optically thin astrophysical plasmas reflect the elemental abundances, temperature distribution, and other physical parameters of the emitting gas. The accuracy and level of detail with which these parameters can be inferred are limited by the measurement uncertainties and uncertainties in atomic rates used to compute the model spectrum. This paper discusses the relative importance and the likely uncertainties in the various atomic rates and the likely uncertainties in the overall ionization balance and spectral line emissivities predicted by the computer codes currently used to fit X-ray spectral data.

scholarly journals Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431

2019 ◽  
Vol 489 (4) ◽  
pp. 4589-4605 ◽  
Author(s):  
Prakash Arumugasamy ◽  
Dipanjan Mitra
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Thermal Emission ◽  
Emission Peak ◽  
Emission Model ◽  
Polar Cap ◽  
Thermal Component ◽  
X Ray ◽  
Surface Magnetic Field ◽  
Photon Index

ABSTRACT PSR J0108–1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modelled with a power law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the presence of phase-separated thermal and non-thermal components. The spectrum extracted from half the rotational phase away from the X-ray peak fits well with either a single blackbody (BB) or a neutron star atmosphere (NA) model, whereas the spectrum from the rest of the phase range is dominated by a PL. From Bayesian analysis, the estimated BB area is smaller than the expected polar cap area for a dipolar magnetic field with a probability of 86 per cent, whereas the area estimate from the NA model is larger with a probability of 80 per cent. Due to the ambiguity in the thermal emission model, the polar cap area cannot be reliably estimated and hence cannot be used to understand the nature of the surface magnetic field. Instead, we can infer the presence of multipolar magnetic field from the misalignment between the pulsar’s thermal X-ray peak and the radio emission peak. For J0108–1431, we estimated a phase-offset Δϕ > 0.1 between the thermal polar cap emission peak and the radio emission peak and argue that this is best explained by the presence of a multipolar surface magnetic field.

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