2014A&A...566A..94K


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.10CEST03:12:37

2014A&A...566A..94K - Astronomy and Astrophysics, volume 566A, 94-94 (2014/6-1)

Feedback by massive stars and the emergence of superbubbles. II. X-ray properties.

KRAUSE M., DIEHL R., BOEHRINGER H., FREYBERG M. and LUBOS D.

Abstract (from CDS):

In a previous paper we investigated the energy transfer of massive stars to the interstellar medium (ISM) as a function of time and the geometrical configuration of three massive stars via 3D-mesh-refining hydrodynamics simulations, following the complete evolution of the massive stars and their supernovae with the exception of non-thermal processes. To compare our results against observations we derive thermal X-ray properties of the ISM from our simulations and compare them to observations of superbubbles in general, to the well-studied nearby Orion-Eridanus superbubble and to the diffuse soft X-ray emission of nearby galaxies. We analysed our ISM simulation results with the help of spectra for plasma temperatures between 0.1 and 10keV and computed the spectral evolution and the spatio-temporal distribution of the hot gas. Despite significant input of high-temperature gas from supernovae and fast stellar winds, the resulting thermal X-ray spectra are generally very soft, with most of the emission well below 1keV. We show that this is due to mixing triggered by resolved hydrodynamic instabilities. Supernovae enhance the X-ray luminosity of a superbubble by 1-2 orders of magnitude for a time span of about 0.1Myr; which is longer if a supernova occurs in a larger superbubble and shorter in higher energy bands. Peak superbubble luminosities of the order of 1036erg/s are reproduced well. The strong decay of the X-ray luminosity is due to bubble expansion, hydrodynamic instabilities related to the acceleration of the superbubble's shell thanks to the sudden energy input, and subsequent mixing. We also find global oscillations of our simulated superbubbles, which produce spatial variations of the X-ray spectrum, similar to what we see in the Orion-Eridanus cavity. We calculated the fraction of energy emitted in X-rays and find that with a value of a few times 10–4, it is about a factor of ten below the measurements for nearby galaxies. Our models explain the observed soft spectra and peak X-ray luminosities of individual superbubbles. Each supernova event inside a superbubble produces a fairly similar heating-entrainment-cooling sequence, and the energy content of superbubbles is always determined by a specific fraction of the energy released by one supernova. For a given superbubble, soft X-rays trace the internal energy content well with moderate scatter. Some mechanism seems to delay the energy loss in real superbubbles compared to our simulations. Alternatively, some mechanism other than thermal emission of superbubbles may contribute to the soft X-ray luminosity of star-forming galaxies.

Abstract Copyright:

Journal keyword(s): ISM: bubbles - ISM: structure - galaxies: ISM - hydrodynamics - instabilities - X-rays: ISM

Errata: + corrigendum vol. 570, p. C3

Simbad objects: 15

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Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9446 1
2 NAME Eridanus Shell sh 02 17 31 +07 49.6           ~ 45 0
3 NAME Eri Bubble HI 03 52 -02.0           ~ 86 0
4 NAME Eridanus Cavity reg 04 28 36.88 -17 03 24.9           ~ 9 1
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14832 1
6 NAME Barnard's Loop HII 05 27.5 -03 58           ~ 104 1
7 LHA 120-N 154 HII 05 35 04.8 -69 43 25           ~ 43 0
8 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1736 1
9 NGC 3372 HII 10 44 19.0 -59 53 21           ~ 888 2
10 NGC 4945 Sy2 13 05 27.279 -49 28 04.44   9.31 14.40 7.55   ~ 1265 2
11 Cl Westerlund 1 OpC 16 47 04.00 -45 51 04.9           ~ 464 0
12 NGC 6888 ISM 20 12 07 +38 21.3   7.44       WN6b(h) 257 1
13 NAME Cyg Superbubble PoC 20 47 +41.2           ~ 73 1
14 NAME MW Group GrG ~ ~           ~ 14 0
15 NAME Ori-Eri reg ~ ~           ~ 18 0

    Equat.    Gal    SGal    Ecl

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2020.07.10-03:12:38

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