2025/05/05 by Jiajun Xian, Fupeng Zhang, Xian, Jiajun +4 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.2505.02596
openalex publication_date 2025/05/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study the secular periodic evolution of quasi-periodic eruptions (QPEs) for GSN069 and eRO-QPE2 assuming that they are driven by star-disc collisions. We set up numerical simulations and compared them with the observed periodic decay of ∼ -3160±720 s yr-1 in GSN069 and ∼ -370±40 s yr-1 in eRO-QPE2. We find that: (1) Stellar mass black holes are unlikely the orbiters in these two sources, as their periodic decay are on the order of <10 s yr-1; (2) A naked degenerate core (including white dwarf) is unlikely the orbiter in GSN069, as the decay is on the order of <200 s yr-1. However, it is possible in eRO-QPE2, although the required surface density of the accretion disc is relatively high (e.g., Σ\gtrsim107∼ 108 g cm-2); (3) Both the orbiters in GSN069 and eRO-QPE2 can be solar-like main-sequence stars (MSs). However, each collision can lead to gradual ablation of the stellar envelope in the order of 10-5∼ 10-3M_\odot. To reproduce the observed decay while surviving for \gtrsim 3 yr, the surface density of the disc needs to be within a certain range. For example, given a 1M_\odot MS orbiter the surface density of the disc gas should be in the range of 3×105∼ 2×106g cm-2 for GSN069 or 5×104∼ 106 g cm-2 for eRO-QPE2. In both of these two sources, the MS can not survive for more than ∼ 12 yr. We expect that future observations of these two sources can help to distinguish whether the orbiters are degenerated compact objects or gaseous stars.