LOFAR detection of faint radio emission from the supernova remnant SRGeJ0023+3625=G116.6-26.1: probing the Milky Way synchrotron halo

Abstract

A supernova remnant (SNR) candidate SRGe~J0023+3625 = G116.6-26.1 was recently discovered in the \textit{SRG}/eROSITA all-sky X-ray survey. This large ($\sim 4$ deg in diameter) SNR candidate lacks prominent counterparts in other bands. Here we report detection of radio emission from G116.6-26.1 in the LOFAR Two-metre Sky Survey (LoTTS-DR2). Radio images show a shell-like structure coincident with the X-ray boundary of the SNR. The measured surface brightness of radio emission from this SNR is very low. Extrapolation of the observed surface brightness to 1~GHz places G116.6-26.1 well below other objects in the $\Sigma -D$ diagram. We argue that the detected radio flux might be consistent with the minimal level expected in the van der Laan adiabatic compression model, provided that the volume emissivity of the halo gas in the LOFAR band is $\sim 10^{-42}\mathrm{W}{\mathrm{m}}^{-3}\mathrm{H}{\mathrm{z}}^{-1}\mathrm{s}{\mathrm{r}}^{-1}$. If true, this SNR can be considered as a prototypical example of an evolved SNR in the Milky Way halo. In the X-ray and radio bands, such SNRs can be used as probes of thermal and non-thermal components constituting the Milky Way halo.

6 pages, submitted to MNRAS Letters

References in corpus (8)

• The eROSITA X-ray telescope on SRG
• The LOFAR Two-metre Sky Survey -- V. Second data release
• The SRG X-ray orbital observatory, its telescopes and first scientific results
• Galactic halo size in the light of recent AMS-02 data
• SRG/eROSITA discovery of a large circular SNR candidate G116.6-26.1: SN Ia explosion probing the gas of the Milky Way halo?
• Hoinga: A supernova remnant discovered in the SRG/eROSITA All-Sky Survey eRASS1
• Radio emission from shell-type supernova remnants
• Updated radio $\Sigma -D$ relation for Galactic supernova remnants -- II

Cited by in corpus (2)

• SRG/eROSITA discovery of a radio faint X-ray candidate supernova remnant SRGe J003602.3+605421=G121.1-1.9
• First optical identification of the SRG/eROSITA-detected supernova remnant G 116.6-26.1 I. Preliminary results