The Galactic Nova Rate: Estimates from the ASAS-SN and Gaia Surveys

Abstract

We present the first estimate of the Galactic nova rate based on optical transient surveys covering the entire sky. Using data from the All-Sky Automated Survey for Supernovae (ASAS-SN) and \textit{Gaia} -- the only two all-sky surveys to report classical nova candidates -- we find 39 confirmed Galactic novae and 7 additional unconfirmed candidates discovered from 2019--2021, yielding a nova discovery rate of $\approx 14$ yr${}^{-1}$. Using accurate Galactic stellar mass models, three-dimensional dust maps, and incorporating realistic nova light curves, we have built a sophisticated Galactic nova model that allows an estimate of the recovery fraction of Galactic novae from these surveys over this time period. The observing capabilities of each survey are distinct: the high cadence of ASAS-SN makes it sensitive to fast novae, while the broad observing filter and high spatial resolution of \textit{Gaia} make it more sensitive to highly reddened novae across the entire Galactic plane and bulge. Despite these differences, we find that ASAS-SN and \textit{Gaia} give consistent Galactic nova rates, with a final joint nova rate of $26\pm 5$ yr${}^{-1}$. This inferred nova rate is substantially lower than found by many other recent studies. Critically assessing the systematic uncertainties in the Galactic nova rate, we argue that the role of faint fast-fading novae has likely been overestimated, but that subtle details in the operation of transient alert pipelines can have large, sometimes unappreciated effects on transient recovery efficiency. Our predicted nova rate can be directly tested with forthcoming red/near-infrared transient surveys in the southern hemisphere.

24 pages, 9 figures

References in corpus (18)

• The NumPy array: a structure for efficient numerical computation
• The Gaia mission
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment
• Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013)
• Gaia Photometric Science Alerts
• Observations of Galactic and Extragalactic Novae
• Evolution of Cataclysmic Variables and Related Binaries Containing a White-Dwarf
• Palomar Gattini-IR: Survey overview, data processing system, on-sky performance and first results
• A parametric description of the 3D structure of the Galactic Bar/Bulge using the VVV survey
• Highly Enriched 7Be in the ejecta of Nova Sagittarii 2015 No. 2 (V5668 Sgr) and the Galactic Lithium origin
• A population of heavily reddened, optically missed novae from Palomar Gattini-IR: Constraints on the Galactic nova rate
• M31N 2007-11d: A Slowly-Rising, Luminous Nova in M31
• Nova-produced Common Envelope: Source of the Non-solar Abundances and an Additional Frictional Angular Momentum Loss in Cataclysmic Variables
• Classical Novae Masquerading as Dwarf Novae? Outburst Properties of Cataclysmic Variables with ASAS-SN
• Transients from the Cataclysmic Deaths of Cataclysmic Variables
• Population synthesis of accreting white dwarfs: Rates and evolutionary pathways of H and He novae
• The Rate and Spatial Distribution of Novae in M31 as Determined by a Twenty-Year Survey

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