Oral Presentation

Coronal Emission Lines as Tracers of Massive Black Holes in Dwarf Galaxies

Author(s): Jialai Wang (USTC), Weiyu Ding (USTC), Yongquan Xue (USTC), et al.

Presenter: Jialai Wang (University of Science and Technology of China)

Massive black holes (BHs) in dwarf galaxies offer key insights into the origin of BH seeds in the early universe, but they are difficult to detect. Traditional optical indicators of active galactic nuclei (AGNs) preferentially select bright, high-accretion BHs in dwarf galaxies and can be easily diluted by star-forming emission from the host, missing much of the lower-mass, lower-accretion-rate BH population. Coronal emission lines, such as [Fe X] λ6374 and [Ne V] λ3426, require very high ionization energies and could be reliable tracers of AGN activity, as their presence is difficult to explain by stellar processes alone. Using Data Release 1 from the Dark Energy Spectroscopic Instrument (DESI), we identify a sample of dwarf galaxies ($M_\star \leq 3 \times 10^9\,M_\odot$) with detectable coronal line emission. In several cases, we corroborate BH activity through additional multi-wavelength indicators supporting an accretion-powered origin. Combined with legacy samples from SDSS and future surveys including PFS, this growing statistical sample of dwarf AGN candidates will be pivotal for constraining BH seeding mechanisms and advancing our understanding of the co-evolution of galaxies and their central black holes at the low-mass end.