Abstract: We are less than one year away from the beginning of a revolution in our understanding of the hot, X-ray emitting, plasma of the Milky Way.

The growth of galaxies in the local Universe critically depends on the interplay (via outflows and re-condensation) between the hot plasma with the other phases of the interstellar medium (ISM). As a prototype for typical spiral galaxies, the Milky Way offers the unique opportunity to capture the important details of such feedback all the way from sub-parsec to galactic scales.

In the 90's, the ROSAT all-sky X-ray maps confirmed the existence of a hot component of the ISM, the Galactic corona. However, because of strong obscuration in the soft X-ray energy band, those maps have a limited horizon of ~1 kpc in the Galactic plane. Therefore, despite the fundamental role of the hot ISM phase, its properties are still basically unknown outside the Solar neighbourhood.

My XMM surveys of the Galactic centre (GC) demonstrate that the hot ISM phase can be traced throughout the disc in the harder X-ray band, confirming the feasibility of this ERC project and the strong connection between GC activity and the Galactic corona. Additionally, the hot plasma is a plausible candidate for containing the missing Galactic baryons and a key ingredient for galaxy evolution. However, so far only less than 0.03% of the Milky Way has been covered by the narrow fields of view of current X-ray imaging telescopes.

The eROSITA all-sky survey will rectify this state of affairs. Should this ERC proposal be approved, we will trace the connection and feedback between the Galactic corona and halo with the energetic activity at the GC (e.g., due to cosmic rays, stellar and AGN outflows). This will represent one to two orders of magnitude improvement in sensitivity and/or coverage, compared to current surveys.

Our sensitive X-ray maps will represent an invaluable legacy for future multi-wavelength studies with current and next generation array instruments.

Hot Milk has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 865637.

Dettagli tecnici

PI: Gabriele Ponti

Struttura INAF: OA Brera

Bando: ERC Consolidator Grant 2019

Riferimento contratto n. 865637

Inizio: 01/03/2020

Durata: 60 mesi