Probing the formation of planetesimals in the Galactic Centre using Sgr A* flares

Abstract

Flares in X-ray and near infrared are observed above the quiescent emission of the supermassive black hole (SBH) in the Galactic Centre (GC) at a rate of approximately once per day. One proposed energy source for these flares is the tidal disruption of planetesimals with radius $\gtrsim 10$ km passing within $\sim$ 1 AU of the SBH. Very little is known about the formation and evolution of planetesimals in galactic nuclei such as the GC, making predictions for flaring event rates uncertain. We explore two scenarios for the formation of planetesimals in the GC: (1) in a large-scale cloud bound to the SBH, and (2) in debris discs around stars. We model their orbital evolution around the SBH using the Fokker-Planck equation and investigate the effect of gravitational interactions with various relevant perturbers. Our predicted flaring rate, $\approx 0.6\mathrm{da}{\mathrm{y}}^{-1}$, is nearly independent of the distribution of perturbers. Moreover, it is insensitive to scenarios (1) or (2). The assumed number of planetesimals per star is consistent with debris discs around stars in the Solar neighbourhood. In scenario (1) this implies that the number of planetesimals formed in the large-scale cloud is strongly correlated with the number of stars, and this requires finetuning for our results to be consistent with the observed flaring rate. We favour the alternative explanation that planetesimals in the GC are formed in debris discs around stars, similar to the Solar neighbourhood.

Accepted for publication in MNRAS. 21 pages, 12 figures

References in corpus (9)

• The structure of the nuclear stellar cluster of the Milky Way
• Kinematics of the old stellar population at the Galactic Center
• Evidence for a Long-Standing Top-Heavy IMF in the Central Parsec of the Galaxy
• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• Collisionally Regenerated Dark Matter Structures in Galactic Nuclei
• Dynamical and evolutionary constraints on the nature and origin of hypervelocity stars
• Resonant relaxation near a massive black hole: the dependence on eccentricity
• Tidal disruption of a super-Jupiter by a massive black hole

Cited by in corpus (1)

• Formation and evolution of nuclear star clusters with in-situ star-formation: Nuclear cores and age segregation