X-ray emission from star-forming galaxies - II. Hot interstellar medium

Abstract

We study the emission from the hot interstellar medium in a sample of nearby late type galaxies defined in Paper I. Our sample covers a broad range of star formation rates, from ~0.1 Msun/yr to ~17 Msun/yr and stellar masses, from ~3x10^8 Msun to ~6x10^10 Msun. We take special care of systematic effects and contamination from bright and faint compact sources. We find that in all galaxies at least one optically thin thermal emission component is present in the unresolved emission, with the average temperature of <kT>= 0.24 keV. In about ~1/3 of galaxies, a second, higher temperature component is required, with the <kT>= 0.71 keV. Although statistically significant variations in temperature between galaxies are present, we did not find any meaningful trends with the stellar mass or star formation rate of the host galaxy. The apparent luminosity of the diffuse emission in the 0.5-2 keV band linearly correlates with the star formation rate with the scale factor of Lx/SFR\approx 8.3x10^38 erg/s per Msun/yr, of which in average ~30-40% is likely produced by faint compact sources of various types. We attempt to estimate the bolometric luminosity of the gas and and obtained results differing by an order of magnitude, log(Lbol/SFR)\sim39-40, depending on whether intrinsic absorption in star-forming galaxies was allowed or not. Our theoretically most accurate, but in practice the most model dependent result for the intrinsic bolometric luminosity of ISM is Lbol/SFR\sim 1.5x10^40 erg/s per Msun/yr. Assuming that core collapse supernovae are the main source of energy, it implies that \epsilon_SN\sim5x10^-2 (E_SN/10^51)^-1 of mechanical energy of supernovae is converted into thermal energy of ISM.Comment: 15 pages, 8 figures, 3 tables - Accepted for publication in MNRA

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

“…This is for both APEC components combined, but is dominated by a factor of 4 by the lower temperature component. Using the relation for star-forming galaxies by Mineo, Gilfanov & Sunyaev (2012) between the thermal component luminosity and the star formation rate (SFR), we estimate an X-ray-derived SFR X−ray ≈ 9 × 10 3 M yr −1 .…”

Gas around galaxy haloes - III: hydrogen absorption signatures around galaxies and QSOs in the Sherwood simulation suite

“…It receives additional support from x-ray measurements. The measured linear proportionality of the diffuse soft x-ray luminosity of galaxies with the star formation rate (Mineo et al 2012), is matched in an energy-driven wind model for an asymptotic wind velocity that scales approximately asṀ 1/6 * (Meiksin 2016). For a star-formation rate scaling approximately like the stellar mass (e.g.…”

XMM-Newtonobservation of the interacting galaxies NGC 1512 and NGC 1510

“…The resulting plasma temperature for the truly diffuse emission is kT = 0.68 (0.31−0.87) keV and L X,0.3−10 keV = 1.3 × 10 38 erg s −1 . Mineo et al (2012b) determined from a sample of nearby star-forming galaxies that the 0.5−2 keV luminosity of diffuse X-ray emission from the ISM is linearly correlated with the SFR of that galaxy as L X,0.5−2 keV (erg s −1 ) ≈ (8.3 ± 0.1) × 10 38 SFR (M yr −1 ). Because the SFR of NGC 1512 is 0.22 M yr −1 (Koribalski & López-Sánchez 2009), we expect L X,0.5−2 keV to be ∼2 ×10 38 erg s −1 .…”