Deep Chandra observations of diffuse hot plasma in M83

Abstract

It is widely believed that galaxy formation and evolution is regulated by stellar mechanical feedback in forms of fast stellar winds and supernova explosions. However, the coupling of this feedback with the interstellar medium remains poorly understood. We examine how the coupling may be traced by diffuse soft X-ray emission in M83 -a nearby face-on spiral galaxy undergoing active star formation, based chiefly on 729 ks Chandra observations. Our main findings are 1) the X-ray emission is enhanced not only along the galaxy's grand spiral arms, but also clearly in their downstreams; 2) the spectrum of the emission can be well characterized by a super-solar metallicity plasma with a lognormal temperature distribution, plus an X-ray absorption of a lognormal column density distribution; 3) the intensity of the emission is strongly anti-correlated with the dust obscuration seen in optical images of the galaxy. These findings suggest A) the morphology of the X-ray emission is likely due to the convolution of the feedback heating of the plasma with its thermal and dynamical evolution; B) the X-ray emission, accounting for ∼ 10% of the feedback energy input rate, probably traces only the high-energy tail of the radiation from the plasma; C) a good fraction of the recent star forming regions seems sufficiently energetic to produce multi-phased outflows, likely responsible for much of the dust obscuration and X-ray absorption. Direct confrontation of the findings with theories/simulations could help to understand the underlying astrophysics of the coupling and how the hot plasma shapes the interstellar medium.

Elevated Hot Gas and High-Mass X-ray Binary Emission in Low Metallicity Galaxies: Implications for Nebular Ionization and Intergalactic Medium Heating in the Early Universe

“…While we expect that our simple thermal modela two-temperature plasma with absorption by an ISM with solar abundance -will be sufficient to extract a reliable measurement of β gas , we do not assume that our model provides a faithful description of the full physical picture. Detailed studies of resolved nearby galaxies find that distributions of plasma temperatures are inevitably present (e.g., Strickland & Stevens 2000;Strickland et al 2004;Kuntz & Snowden 2010;Lopez et al 2020;Wang et al 2021) and the efficiency of converting mechanical heating of the ISM into hot gas X-ray emission depends on star-formation timescales that are shorter than those measured for typical galaxies (e.g., Mc-Quinn et al 2018;Gilbertson et al 2021). Therefore, it seems plausible that variations in star-formation history and physical environment (e.g., galaxy morphology and gravitational potential) will lead to variations in β gas .…”

disnht: modeling X-ray absorption from distributed column densities

“…An incomplete but instructive list of cases in which this assumption is broken include the spectral analysis of: faint diffuse emission for which collection of photons over a large angular scale is performed to increased the significance of the spectral features (e.g. Muno et al 2009;Masui et al 2009;Yoshino et al 2009;Gupta et al 2012;Ponti et al 2015;Cheng et al 2021;Wang et al 2021); extraction regions holding high (∼ 10 24 cm −2 ) and very high (∼ 10 25 cm −2 ) absorption such as toward dense clouds in the Galactic disc, for which collecting the photons over even a few resolution elements can significantly affect the X-ray spectrum (e.g. Molinari et al 2011); pointlike sources holding column densities variable over the observation timescale, such as for dipping low mass X-ray binaries binaries (Díaz Trigo et al 2006;Ponti et al 2016;Bianchi et al 2017), changing-look active galactic nuclei (Matt et al 2003;Puccetti et al 2007;Bianchi et al 2009;Risaliti et al 2009;Marchese et al 2012;LaMassa et al 2015) and magnetic accreting white dwarfs (Done & Magdziarz 1998).…”

“…Molinari et al 2011); pointlike sources holding column densities variable over the observation timescale, such as for dipping low mass X-ray binaries binaries (Díaz Trigo et al 2006;Ponti et al 2016;Bianchi et al 2017), changing-look active galactic nuclei (Matt et al 2003;Puccetti et al 2007;Bianchi et al 2009;Risaliti et al 2009;Marchese et al 2012;LaMassa et al 2015) and magnetic accreting white dwarfs (Done & Magdziarz 1998). Modeling of the spectral absorption through distribution of column densities has already successfully performed in the past using a power law column density distribution (pwab model, presented in Done & Magdziarz 1998) and more recently using a lognormal distribution (Cheng et al 2021;Wang et al 2021). These examples show the increasing need in the X-ray community of careful and systematic treatment of the absorption when its properties change in a non-negligible way across space or time.…”