X-rays from Low-mass Active Galaxies in the Galaxy And Mass Assembly (GAMA) Survey

@misc{bechtold2026xrays,
  title = {{X-rays from Low-mass Active Galaxies in the Galaxy And Mass Assembly (GAMA) Survey}},
  author = {Stellan Bechtold and Amy Reines and Richard Plotkin and Sheyda Salehirad},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.03820},
  eprint = {2611.03820},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.03820},
}

TY  - UNPB
TI  - X-rays from Low-mass Active Galaxies in the Galaxy And Mass Assembly (GAMA) Survey
AU  - Stellan Bechtold
AU  - Amy Reines
AU  - Richard Plotkin
AU  - Sheyda Salehirad
PY  - 2026
DA  - 2026/11/02
PB  - arXiv
DO  - 10.48550/arxiv.2611.03820
UR  - https://arxiv.org/abs/2611.03820
AB  - We present new Chandra observations of seven broad-line AGNs in low-mass galaxies (M_⋆ < 5 × 10^9 M_⊙) selected from the GAMA sample of Salehirad et al. (2022). X-ray emission is detected in six galaxies, with luminosities spanning log(L_0.5−8 keV/erg s^−1)≈40.5--43.8. Their X-ray luminosities generally exceed predictions for X-ray binary populations, and their proximity to the optical galaxy nuclei favors accreting massive black holes as the dominant emission source. Spectral fits for four sources yield photon indices Γ≈1.7--2.2, with little evidence for intrinsic absorption in most cases. Virial black hole masses and hard X-ray bolometric corrections imply nominal Eddington ratios λ_Edd≈0.004--1.1, although uncertainties are substantial. Optical tracers generally imply higher bolometric luminosities and Eddington ratios, particularly for the X-ray-undetected galaxy. The X-ray-bright sources are broadly consistent with optical AGN scaling relations involving Hα and [O III], whereas most lie below the established X-ray--mid-infrared relation, potentially reflecting host-galaxy contamination. Four sources are consistent with the expected UV-to-X-ray spectral slope relation, while three show evidence for relative X-ray weakness. These results reveal diverse X-ray properties among broad-line AGNs in low-mass galaxies and highlight the importance of multiwavelength diagnostics for understanding black hole accretion and interpreting broad-line AGN candidates at high redshift.
ER  -