2025/11/18 by Roychowdhury, Tamojeet, von Fellenberg, Sebastiano D., Michail, Joseph M. +14
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Astronomy and Astrophysical Research
paper · doi:10.48550/arxiv.2511.14856
JWST/MIRI observations can place photometric limits on the presence of an intermediate-mass black hole (IMBH) near the Galactic Centre. The stellar complex IRS 13E, a co-moving conglomerate of young and massive stars, is a prime location to study because it has been speculated to be bound by an IMBH. Assuming a standard radiatively inefficient accretion flow (RIAF) and a minimum fractional variability of 10% of intrinsic luminosity, the wavelength of peak emission in the spectral energy distribution for an IMBH would lie in the mid-infrared (∼ 5-25 μm), and variability would be detectable in MIRI time-series observations. Monitoring fails to detect such variable emission (other than from Sgr A*) in and around the IRS 13E complex, and upper limits on a putative IMBH's intrinsic variability on timescales of minutes to about 1 hour are \lesssim1 mJy at 12 μm and \lesssim2 mJy at 19 μm. These translate to luminosities \lesssim 25 × 1032 erg/s. The resulting limits on the IMBH mass and accretion rate rule out any IMBH with mass \gtrsim 103 M_\odot accreting at \gtrsim 10-6 times Eddington rate at the location of IRS 13E. Further, the observations rule out an IMBH anywhere in the central 6" × 6" region that is more massive than ≈ 2 × 103 M_\odot and accreting at \gtrsim 10-6 of the Eddington rate. Assuming Bondi accretion scaled to typical RIAF-accretion efficiencies, albeit somewhat uncertain, also allows us to rule out IMBHs moving with typical velocities of about 200 km/s and masses \gtrsim 2 × 103 M_\odot. These methods showcase the effectiveness of photometric variability measurements in constraining the presence of accreting black holes in Galactic centre-like environments.