X-ray observations of the starburst galaxy M82

Schaaf, R.; Pietsch, W.; Biermann, P. L.; Kronberg, P. P.; Schmutzler, T.

doi:10.1086/167045

Cited by 58 publications

(55 citation statements)

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“…There are further X-ray observations reported by Biermann et al (1985), and Schaaf et al (1987), respectively, with the EINSTEIN and EXOSAT satellites. We make use of the timing of the X-ray eclipses detected with Einstein, the EXOSAT data have a too low count-rate and are not used further in this paper.…”

Section: Rosat Pspcmentioning

confidence: 69%

A multiwavelength timing analysis of the eclipsing polar DP Leo

Schwope

Hambaryan

Schwarz

et al. 2002

A&A

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Abstract.We present an analysis of the X-ray light curves of the magnetic cataclysmic variable DP Leo using recently performed XMM−Newton EPIC and archival published and unpublished ROSAT PSPC observations. We combine the timings of the X-ray eclipses with timings derived from archival HST-observations and new optical observations with the photon counting OPTIMA camera. We determine the eclipse length at X-ray wavelengths to be 235 ± 5 s, slightly longer than at ultra-violet wavelengths, where it lasts 225 s. A new orbital ephemeris is derived which connects the more than 120 000 binary cycles covered since 1979. It has a highly significant quadratic term, implying an orbital period change ofṖ = −4.4 × 10 −12 s s −1 , two orders of magnitude larger than being compatible with braking by gravitational radiation only. Over the last twenty years, the optical and X-ray bright phases display a continuous shift with respect to the eclipse center by ∼2.1• yr −1 . Over the last 8.5 years the shift of the X-ray bright phase is ∼2.5• yr −1 . We interpret this as evidence of an asynchronously rotating white dwarf although synchronization oscillations cannot be ruled out completely. If the observed phase shift continues, a fundamental rearrangement of the accretion geometry must occur on a time-scale of some ten years. Applying model atmosphere spectra to optical/UV eclipse light curves, we determine the temperature and mass of the white dwarf, the temperature and size of the optical/UV emitting spot and the distance to DP Leo to be T wd = 13 500 K, M wd 0.6 M , T spot = 32 000 K, A spot 0.1 A wd , and D = 400 pc, respectively. The implied inclination and mass ratio are i = 79.5• and Q = M wd /M 2 = 6.7. DP Leo is marginally detected at eclipse phase in X-rays. The upper limit eclipse flux is consistent with an origin on the late-type secondary, L X 2.5 × 10 29 ergs s −1 (0.20−7.55 keV), at a distance of 400 pc.

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Section: Rosat Pspcmentioning

confidence: 69%

A multiwavelength timing analysis of the eclipsing polar DP Leo

Schwope

Hambaryan

Schwarz

et al. 2002

A&A

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“…The main consequence of a strong energetic proton component is a higher rate of ionization and heating of ISM, whereas relativistic electrons give rise to more intense synchrotron and Compton emissions. Moreover, the strong FIR emission from warm dust (heated by stellar emission) further intensifies the emission from Compton scattering of the relativistic electrons on the FIR radiation field (Schaaf et al 1989;Rephaeli et al 1991). A detailed convection-diffusion model was proposed for electrons in NGC 253, with the energy density of the electrons normalized by the observed radio flux and estimated mean magnetic field (Goldshmidt & Rephaeli 1995).…”

Section: Compton Scatteringmentioning

confidence: 99%

“…However, the detailed physical characteristics of the gas -in particular its chemical abundanceshave remained unclear because the analysis in the LEX band is complicated by the unknown line-of-sight extinction, the large uncertainties in the theoretical models used (in particular around the FeL-shell energy band), and the presence of multiple temperature components (typically with 0.2 keV < ∼ kT < ∼ 3 keV). At higher energies, available imaging information to date was essentially limited to the EXOSAT observation of M82 (Schaaf et al 1989) and to the ASCA observations of a few X-ray bright SBGs [NGC 253, M82: Ptak et al 1997 (hereafter P97), Moran & Lehnert 1997, DWH98;NGC 3310, NGC 3690: Zezas et al 1998;NGC 1569, NGC4449, NGC2146: Della Ceca et al 1996, 1999. Schaaf et al (1989) found that the ∼1-10 keV spectrum of M82 was equally well fit with a Γ ∼ 2 power-law spectrum or with thermal emission characterized by kT ∼ 9 keV.…”

Section: Introductionmentioning

confidence: 99%

Diffuse thermal emission from very hot gas in starburst galaxies: Spatial results

Cappi¹,

Peršić

Mariani

et al. 1999

Advances in Space Research

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Abstract.BeppoSAX observations of the nearby archetypical starburst galaxies NGC253 and M82 are presented. Spectral analysis shows that the 2-10 keV spectra of both galaxies, extracted from the central 4 ′ regions, are best fitted by a thermal emission model with kT ∼ 6-9 keV and metal abundances ∼ 0.1-0.3 solar. The spatial analysis yields clear evidence that this emission is extended in NGC 253, and possibly also in M82. These results clearly rule out a LLAGN as the main origin of the X-ray emission in NGC 253. For M82, the presence of an Fe-K line at ∼ 6.7 keV, and the convex profile of its 2-10 keV continuum, indicate a significant thermal component. Contributions from point sources (e.g. X-ray binaries, supernova remnants, and/or a LLAGN) and Compton emission are also likely. Altogether, BeppoSAX results provide compelling evidence for the existence of a hot interstellar plasma in both galaxies, possibly in the form of superwind outflows from the disks of these galaxies. Order-of-magnitude estimates and some implications, such as the expelled mass and the energetics of the outflowing gas of this superwind scenario, are discussed. These new results also suggest some similarity between the X-ray emission from these galaxies and that from the Galactic Ridge.

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“…Moreover, since SN remnants are prime sites for shock-acceleration of particles to high energies, Compton scattering of relativistic electrons by the local radiation fields will enhance X-ray emission in a SBG. This expectation is heightened by the fact that in a SBG the energy density of the FIR radiation field can be much higher than that of the cosmic microwave background radiation (Schaaf et al 1989;Rephaeli et al 1991).…”

Section: Introductionmentioning

confidence: 99%

RXTE view of the starburst galaxies M 82 and NGC 253

Rephaeli

Gruber

2002

A&A

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Abstract. The two nearby starburst galaxies M 82 and NGC 253 were observed for ∼100 ksec over a 10-month period in 1997. An increase of the M 82 flux by a factor ∼2 was measured during the period July-November, when compared with the flux measured earlier in 1997. The flux measured in the field centered on M 82 includes ∼38% of the emission from the Seyfert 1 galaxy M 81. The best-fitting model for the earlier emission from M 82 is thermal with kT 6.7 ± 0.1. In the high flux state, the emission additionally includes either an absorbed second thermal component or absorbed power-law component, with the former providing a much better fit. A likely origin for the temporal variability is a single source in M 82. The flux of NGC 253, which did not vary significantly during the period of observations, can be well fit by either a thermal spectrum with kT 3.8 ± 0.3 keV, or by a power law with photon index of 2.7 ± 0.10. We have also attempted fitting the measurements to more realistic composite models with thermal and power-law components, such as would be expected from a dominant contribution from binary systems, or Compton scattering of (far) IR radiation by radio emitting electrons. However, the addition of any amount of a power-law component, even with cutoff at 20 keV, only increases chi-square. The 90% confidence upper limit for power law emission with (photon) index 1.5 is only 2.4% of the 2-10 keV flux of M 82; the corresponding limit for NGC 253, with index 2.0, is 48%.

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X-ray observations of the starburst galaxy M82

Cited by 58 publications

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A multiwavelength timing analysis of the eclipsing polar DP Leo

A multiwavelength timing analysis of the eclipsing polar DP Leo

Diffuse thermal emission from very hot gas in starburst galaxies: Spatial results

RXTE view of the starburst galaxies M 82 and NGC 253

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