No period change in two long-period AM CVn binaries

Green, MJ ORCID: 0000-0002-0948-4801, Marsh, TR ORCID: 0000-0002-2498-7589, van Roestel, J ORCID: 0000-0002-2626-2872, Wong, TLS, Belloni, D ORCID: 0000-0003-1535-0866, Kilic, M, Breedt, E ORCID: 0000-0001-6180-3438, Brown, A ORCID: 0000-0002-3316-7240, Copperwheat, CM ORCID: 0000-0001-7983-8698, Chakpor, A, Dhillon, VS ORCID: 0000-0003-4236-9642, Segura, NC ORCID: 0000-0002-5870-0443, Dyer, MJ ORCID: 0000-0003-3665-5482, Garbutt, J ORCID: 0009-0007-5535-3312, Jarvis, D, Kengkriangkrai, V, Kennedy, MR ORCID: 0000-0001-6894-6044, Kerry, P, Kupfer, T, Littlefair, SP ORCID: 0000-0001-7221-855X et al (2026) No period change in two long-period AM CVn binaries. Monthly Notices of the Royal Astronomical Society, 548 (3). ISSN 0035-8711

Preview

Text No period change in two long period AM CVn binaries.pdf - Published Version Available under License Creative Commons Attribution. Download (3MB) | Preview

Abstract

Ultracompact binary systems, consisting of two compact objects in an orbit (Formula presented), should exhibit measurable rates of orbital period change ((Formula presented) ) due to the emission of gravitational waves (GWs). Measurements of (Formula presented) have so far been limited to the shortest-period ultracompact binaries ((Formula presented)  min). Among the AM CVn-type subclass, several works have proposed the presence of extra angular momentum loss beyond GW emission, with magnetic braking being a widely discussed mechanism. If present, this magnetic braking would dominate the angular momentum loss of AM CVn-type binaries with orbital periods (Formula presented)  min. In this work, we present a long-term eclipse timing study of two AM CVn-type binaries, YZ LMi and Gaia14aae, with respective orbital periods of 28.3 min and 49.7 min and continuous observations since 2006 and 2015. Both systems show (Formula presented) consistent with zero within (Formula presented). Their (Formula presented) upper limits are (Formula presented) and (Formula presented), respectively. These non-detections are most simply explained by a scenario in which secular angular momentum loss is not substantially stronger than GW emission at all orbital periods, but is combined with deviations from the secular (Formula presented) whose time-scales span decades but whose amplitude is (Formula presented). Our non-detections of (Formula presented) represent a limit on the strength of any enhanced angular momentum loss beyond pure GW emission.

Item Type:	Article
Uncontrolled Keywords:	binaries: close; stars: dwarf novae; novae, cataclysmic variables; white dwarfs; 5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press (OUP)
Date of acceptance:	2 April 2026
Date of first compliant Open Access:	5 June 2026
Date Deposited:	05 Jun 2026 15:03
Last Modified:	05 Jun 2026 15:03
DOI or ID number:	10.1093/mnras/stag673
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28756

View Item