On an apparent dearth of recurrent nova super-remnants in the Local Group

Abstract

ABSTRACT The Andromeda Galaxy is home to the annually erupting recurrent nova (RN) M 31N 2008-12a (12a); the first nova found to host a nova super-remnant (NSR). An NSR is an immense structure surrounding a RN, created from many millions of eruptions sweeping up material in the local environment to form a shell tens of parsecs across. Theory has demonstrated that NSRs should be found around all recurrent novae (RNe), even those systems with long periods between eruptions. Befittingly, the second NSR was found around the Galactic classical (and long suspected recurrent) nova, KT Eridani. In this Paper, we aim to find more of these phenomena through conducting the first ever survey for NSRs in M 31 and the Large Magellanic Cloud (LMC). We find that the surroundings of fourteen RNe in M 31 as well as the surroundings of the four RNe in the LMC do not show any evidence of vast parsec-scale structures in narrow-band (H α and $[{\rm S\, {\small II}}]$) images, unlike the one clearly seen around 12a, and therefore conclude that observable NSRs are either rare structures, or they are too faint (or small) to be detected in our existing data sets. Yet, the NSR surrounding 12a would also likely to have been overlooked in our study if it were approximately one magnitude fainter. Searches for NSRs around other RNe ‘masquerading’ as classical novae may prove to be fruitful as would whole surveys of other Local Group galaxies.