# The Progenitor Systems of Classical Novae in M31

## TL;DR

This paper identifies two distinct populations of classical nova progenitors in the Andromeda galaxy based on their ages and nova production rates.

## Contribution

The study provides the first statistical characterization of nova progenitor systems in M31 using a delay time distribution.

## Key findings

- A population of nova progenitors aged 2-3.2 Gyr has a nova production rate of ~3.7×10⁻⁹ events per solar mass.
- Another population aged 7.9 Gyr to the age of the Universe has a higher nova production rate of ~4.8×10⁻⁹ events per solar mass.

## Abstract

We present the first characterization of the statistical relationship between a
large sample of novae in M31 and their progenitor stellar populations in the
form of a delay time distribution. To this end, we leverage the spatially
resolved stellar age distribution of the M31 disk derived from deep Hubble Space
Telescope photometry by the Panchromatic Hubble Andromeda Treasury survey and a
large catalog of novae in M31. Our delay time distribution has two statistically
significant detections: one population of nova progenitors with ages between 2
and 3.2 Gyr and an unnormalized rate of (\documentclass[12pt]{minimal}
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${3.7}_{-3.5}^{+6.8}\pm 2.1)\times {10}^{-9}$\end{document}3.7−3.5+6.8±2.1)×10−9 events M⊙−1, and another of ages between 7.9 Gyr
and the age of the Universe with (\documentclass[12pt]{minimal}
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${4.8}_{-0.9}^{+1.0}\pm 0.2)\times {10}^{-9}$\end{document}4.8−0.9+1.0±0.2)×10−9 events M⊙−1 (uncertainties are statistical and
systematic, respectively). Together with the upper limits we derive at other
time bins, these detections are consistent with either a constant production
efficiency or a higher production efficiency of novae at earlier delay
times.