ASCA observation of Henize 2-10

Spectral observations of low-mass X-ray binaries (LMXBs) show that the soft component usually dominates over the hard one. These results provide additional support to an interpretation based on models of LMXBs in which the neutron star while, on the average, spinning up, is also experiencing a spinning down torque. Under these conditions, a fraction of the luminosity associated with the gravitational release of energy on the surface of the accreting neutron star may manifest itself as luminosity originating in the inner part of the accretion disk. It is probably possible to separate the two contributions; the stellar luminosity can be associated with the hard component of the spectrum and the disk luminosity, related to the exchange of energy due to the torque between the rapidly spinning neutron star and the accretion disk, can be associated with the soft spectral component.

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Correlated X-ray and Millimetre Variability of the Blazar 3C273

Symposium - International Astronomical Union ◽

10.1017/s0074180900175023 ◽

1994 ◽

Vol 159 ◽

pp. 193-196 ◽

Cited By ~ 1

Author(s):

I M McHardy ◽

I Papadakis ◽

C M Leach ◽

E I Robson ◽

W Junor ◽

...

Keyword(s):

Power Law ◽

Soft Component ◽

Hard Component ◽

X Ray ◽

Simple Extrapolation

We present the results of X-ray and millimetre monitoring of the blazar 3C273 at 1–2 day intervals over the period 12 December 1992 to 24 January 1993. No large flares are seen in this period but variations in both wavebands of ∼ 30% on few day timescales are apparent. The ROSAT PSPC X-ray spectrum consists of 2 power-law components with the harder component dominating above 0.5 keV. There is very little correlation between the variability of the soft and hard components. The soft component does not correlate with the millimetre variations, but the hard component correlates reasonably well and leads the millimetre variations by about 10 days. These results show that the hard X-ray component cannot be a simple extrapolation of the millimetre/IR synchrotron component but may be explained as a self-Compton component in a shocked jet.

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Observations of SN 1987A from Ginga

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000022670 ◽

1988 ◽

Vol 7 (4) ◽

pp. 479-485

Author(s):

H. Inoue

Keyword(s):

Energy Spectrum ◽

Time Variable ◽

Soft Component ◽

X Rays ◽

Hard Component ◽

X Ray ◽

Sn 1987A

AbstractResults of the observations of SN 1987A from Ginga are presented. The first detection of X-rays from the SN 1987A was July, 1987. The energy spectrum is quite unnusual for any of the known classes of X-ray sources, and apparently consists of two seperate components; a soft and a hard component. The soft component is significantly time-variable, and also showed a flarelike increase in January, 1988. Whereas, the intensity of the hard component has remained fairly stationary for more than 300 days. The origins of the two components are also discussed.

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X-Ray Observation of SN1987A from Ginga

International Astronomical Union Colloquium ◽

10.1017/s025292110009415x ◽

1988 ◽

Vol 108 ◽

pp. 399-405

Author(s):

Y. Tanaka

Keyword(s):

Energy Spectrum ◽

Time Variable ◽

Soft Component ◽

Hard Component ◽

X Ray

AbstractAn unusual hard X-ray source was discovered in an error box of 0.2° × 0.3° including SN1987A from the X-ray astronomy satellite Ginga. The energy spectrum is quite unusual for any known classes of X-ray source, and apparently consists of two separate components, a soft component and a very hard component. This source is considered to be identified with SN1987A. The X-ray emergence occurred in July, 1987, or possibly even earlier. The soft component is significantly time-variable and also showed a flare-like increase in January, 1988, while the intensity of the hard component has remained relatively unchanged for more than 200 days.

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X-ray evidence for wind-wind collision in the Wolf-Rayet binary V444 Cygni

Symposium - International Astronomical Union ◽

10.1017/s0074180900205925 ◽

1999 ◽

Vol 193 ◽

pp. 398-399

Author(s):

Jun Yokogawa ◽

Katsuji Koyama ◽

Yoshitomo Maeda ◽

Steve L. Skinner

Keyword(s):

Soft Component ◽

X Rays ◽

Plasma Model ◽

Temperature Plasma ◽

Absorption Column ◽

Hard Component ◽

Eclipsing Binary ◽

X Ray ◽

The Individual ◽

Two Temperature

We present results on the eclipsing binary V444 Cyg (WN5+O6) with the X-ray satellite ASCA. The observations were performed at orbital phases 0.0, 0.25 and 0.5 (the 06 star is in front at phase 0.5 and vice versa at phase 0.0). Two-temperature plasma model could reproduce X-ray spectra in each phase. The temperature of the soft component is lower (kT ≃ 0.6 keV), which is attributed to the individual O6/WN5 stars. The temperature of the hard component is higher (kT ≃ 2 keV), which exhibited phase-related time-variabilities in absorption column NH and luminosity LX; NH was maximal at phase 0.0 while LX was minimal at phase 0.5. These variabilities are consistent with the scenario that X-rays are emitted from plasma heated-up by wind-wind collision near the surface of the O6 star.

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3.10. X-ray constraints on accretion and starburst processes in galactic nuclei

Symposium - International Astronomical Union ◽

10.1017/s0074180900084230 ◽

1998 ◽

Vol 184 ◽

pp. 109-110

Author(s):

A. Ptak ◽

P. Serlemitsos ◽

T. Yaqoob ◽

R. Mushotzky ◽

Y. Terashima ◽

...

Keyword(s):

Power Law ◽

Galactic Nuclei ◽

Seyfert Galaxies ◽

Soft Component ◽

Short Term ◽

Hard Component ◽

X Ray ◽

Ngc 6946 ◽

Process Elements ◽

Low Activity

Although the galaxies in our sample are heterogenous in their optical classifications (LLAGN: M51, NGC 3147, NGC 4258; LINER: NGC 3079, NGC 3310, NGC 3998, NGC 4579, NGC 4594; starburst: M82, NGC 253, NGC 3628, NGC 6946), they are fit well by a “canonical” spectrum with a hot, optically-thin thermal component with T ~ 8 × 106 K and an absorbed (NH ~ 1022 cm−2) power-law with an energy index α ~ 0.7–0.8. Both the “soft” component, most likely due to SN or superwind-heated ISM, and the “hard” power-law, most likely due to a micro-AGN and/or blackhole candidates, appear to be common in low-activity galaxies. If the soft component is associated with a superwind outflow, than ~ 10% of the X-ray emission is due to “swept-up” ISM rather than superwind emission. The abundance of Fe relative to α-process elements tends to be sub-solar, possibly due to dust-depletion and/or type-II SN enrichment. The lack of short-term variability in the hard component suggests that if it is due to an AGN, then the mode of accretion is probably fundamentally different from “normal” Seyfert galaxies.

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XMM-Newton observations of the symbiotic recurrent nova T CrB: evolution of X-ray emission during the active phase

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2329 ◽

2019 ◽

Vol 489 (2) ◽

pp. 2930-2940 ◽

Cited By ~ 1

Author(s):

Svetozar A Zhekov ◽

Toma V Tomov

Keyword(s):

Active Phase ◽

Soft Component ◽

X Rays ◽

Rotational Period ◽

Hard Component ◽

X Ray ◽

Quiescent Phase ◽

Recurrent Nova ◽

First Time ◽

Thin Plasma

ABSTRACT We present an analysis of the XMM-Newton observations of the symbiotic recurrent nova T CrB, obtained during its active phase which started in 2014–2015. The XMM-Newton spectra of T CrB have two prominent components: a soft one (0.2–0.6 keV), well represented by blackbody emission, and a heavily absorbed hard component (2–10 keV), well matched by optically-thin plasma emission with high temperature (kT ≈ 8 keV). The XMM-Newton observations reveal evolution of the X-ray emission from T CrB in its active phase. Namely, the soft component in its spectrum is decreasing with time, while the opposite is true for the hard component. Comparison with data obtained in the quiescent phase shows that the soft component is typical only for the active phase, while the hard component is present in both phases but it is considerably stronger in the quiescent phase. Presence of stochastic variability (flickering) on time-scales of minutes and hours is confirmed both in X-rays and UV (UVM2 filter of the XMM-Newton optical monitor). On the other hand, periodic variability of 6000–6500 s is found for the first time in the soft X-ray emission (0.2–0.6 keV) from T CrB. We associate this periodic variability with the rotational period of the white dwarf in this symbiotic binary.

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Hot gaseous atmospheres of rotating galaxies observed with XMM–Newton

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3182 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5163-5174

Author(s):

A Juráňová ◽

N Werner ◽

P E J Nulsen ◽

M Gaspari ◽

K Lakhchaura ◽

...

Keyword(s):

Angular Momentum ◽

Active Galactic Nuclei ◽

Spiral Galaxy ◽

Galactic Nuclei ◽

X Ray ◽

Hot Gas ◽

Heating And Cooling ◽

Theoretical Predictions ◽

Central Regions ◽

Gaseous Atmospheres

ABSTRACT X-ray emitting atmospheres of non-rotating early-type galaxies and their connection to central active galactic nuclei have been thoroughly studied over the years. However, in systems with significant angular momentum, processes of heating and cooling are likely to proceed differently. We present an analysis of the hot atmospheres of six lenticulars and a spiral galaxy to study the effects of angular momentum on the hot gas properties. We find an alignment between the hot gas and the stellar distribution, with the ellipticity of the X-ray emission generally lower than that of the optical stellar emission, consistent with theoretical predictions for rotationally supported hot atmospheres. The entropy profiles of NGC 4382 and the massive spiral galaxy NGC 1961 are significantly shallower than the entropy distribution in other galaxies, suggesting the presence of strong heating (via outflows or compressional) in the central regions of these systems. Finally, we investigate the thermal (in)stability of the hot atmospheres via criteria such as the TI- and C-ratio, and discuss the possibility that the discs of cold gas present in these objects have condensed out of the hot atmospheres.

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The Hot Universe with XRISM and Athena

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318007792 ◽

2018 ◽

Vol 14 (S342) ◽

pp. 29-36

Author(s):

M. Guainazzi ◽

M. S. Tashiro

Keyword(s):

Electromagnetic Radiation ◽

Large Scale ◽

Cosmological Evolution ◽

X Ray ◽

Hot Gas ◽

Cosmic Vision ◽

Esa Cosmic Vision ◽

The Universe

AbstractX-ray spectroscopy is key to address the theme of “The Hot Universe”, the still poorly understood astrophysical processes driving the cosmological evolution of the baryonic hot gas traceable through its electromagnetic radiation. Two future X-ray observatories: the JAXA-led XRISM (due to launch in the early 2020s), and the ESA Cosmic Vision L-class mission Athena (early 2030s) will provide breakthroughs in our understanding of how and when large-scale hot gas structures formed in the Universe, and in tracking their evolution from the formation epoch to the present day.

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Tracing interactions in HCGs through the H I

International Astronomical Union Colloquium ◽

10.1017/s0252921100054944 ◽

2000 ◽

Vol 174 ◽

pp. 167-173 ◽

Cited By ~ 3

Author(s):

L. Verdes-Montenegro ◽

M. S. Yun ◽

B. A. Williams ◽

W. K. Huchtmeier ◽

A. Del Olmo ◽

...

Keyword(s):

Velocity Dispersion ◽

Group Velocity Dispersion ◽

Dynamical Evolution ◽

Compact Groups ◽

High Group ◽

X Ray ◽

Hot Gas ◽

Isolated Galaxies ◽

Global Study ◽

Hickson Compact Groups

AbstractWe present a global study of Hɪ spectral line mapping for 16 Hickson Compact Groups (HCGs) combining new and unpublished VLA data, plus the analysis of the Hɪ content of individual galaxies. Sixty percent of the groups show morphological and kinematical signs of perturbations (from multiple tidal features to concentration of the Hɪ in a single enveloping cloud) and sixty five of the resolved galaxies are found to be Hɪ deficient with respect to a sample of isolated galaxies. In total, 77% of the groups suffer interactions among all its members which provides strong evidence of their reality. We find that dynamical evolution does not always produce Hɪ deficiency, but when this deficiency is observed, it appears to correlate with a high group velocity dispersion and in some cases with the presence of a first-ranked elliptical. The X-ray data available for our sample are not sensitive enough for a comparison with the Hɪ mass; however this study does suggest a correlation between Hɪ deficiency and hot gas since velocity dispersions are known from the literature to correlate with X-ray luminosity.

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