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

TL;DR

This study conducted the first survey for nova super-remnants in M31 and LMC, finding none, suggesting such structures are rare or faint, and highlighting the need for more sensitive future searches.

Contribution

It provides the first systematic search for NSRs in M31 and LMC, expanding understanding of their prevalence and properties in the Local Group.

Findings

No evidence of NSRs around 14 RNe in M31

No evidence of NSRs around 4 RNe in LMC

NSRs are likely rare or too faint to detect with current data

Abstract

The Andromeda Galaxy is home to the annually erupting recurrent nova (RN) M31N 2008-12a (12a); the first nova found to host a nova super-remnant (NSR). A 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 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 M31 and the Large Magellanic Cloud (LMC). We find that the surroundings of fourteen RNe in M31 as well as the surroundings of the four RNe in the LMC do not show any evidence of vast parsec-scale structures in narrowband (H${\alpha}$ and [S 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 datasets. 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.