Jiang-Tao Li, Q. Daniel Wang
X-ray-emitting coronae of nearby galaxies are expected to be produced either
by accretion from the intergalactic medium and/or by various galactic feedback.
We herein present a systematical analysis of the Chandra observations of 53
nearby edge-on disk galaxies over a range of 3 orders of magnitude in SFR.
Various coronal properties, such as the luminosity, vertical/horizontal extent,
and other inferred parameters, are characterized for all the sample galaxies.
For galaxies with high enough counting statistics, we also examine the thermal
and chemical states of the coronal gas. Here we concentrate on the coronal
luminosity (Lx), estimated in 0.5-2keV and within 5 times the diffuse X-ray
vertical scale height. We find Lx strongly correlates with the SFR for the
whole sample. But the inclusion of Ia SNe in the total energy input (E_SN)
gives an even tighter correlation, which may be characterized with a linear
relation, Lx=0.5%E_SN, and with a dispersion of 0.45dex. Moreover, the coronal
radiation efficiency (\eta=Lx/E_SN) shows little correlation with either the
stellar mass or the gravitational mass (M_TF, inferred from the rotation
velocity), but is significantly correlated with their ratio (M_TF/M_*), which
may be expressed as a linear scaling relation \eta=0.35%M_TF/M_* for the entire
ranges of galaxy parameters. This joint scaling relation suggests that the
coronae are self-regulated by the combination of gravitational confinement and
feedback. But SN appears to be the primary heating source, because about half
of our galaxies are not massive enough to allow for the accretion to play a
major role. The commonly low \eta further suggests that the bulk of the SN
energy likely flows out into large-scale galactic halos for essentially all the
galaxies. Such ubiquitous outflows could have profound implications for
understanding the ecosystem, hence the evolution of galaxies.
View original:
http://arxiv.org/abs/1201.0551
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