Hoinga: discovery of the largest SNR in X-rays at high Galactic latitude
Luciano Nicastro (INAF - OAS Bologna)
Tuesday 30/03/2021 @ 14:00, Sala IV piano Battiferro
With a galactic supernovae rate of approximately 2 per century, we can expect to have about 1200 SNRs in our Galaxy. However, only about 300 of them are known to date, with the majority discovered in galactic plane radio surveys. In this talk I'll present the discovery of G249.5+24.5 in the eROSITA all-sky survey data (eRASS1). It is located at a relatively high galactic latitude, where SNRs are not typically found (and searched for) and represents the largest SNR discovered at wavelengths other than the radio. The remnant, dubbed "Hoinga", has a diameter of about 4.4 deg and shows a circularly shaped morphology with diffuse soft X-ray emission filling almost the entire remnant. We estimate a distance of about 500 pc and an age of about 20 kyrs, though further data and studies are needed to confirm these figures. eRASS2/3 data will be investigated to this aim, together with dedicated observations with other facilities.