HSC-XD 52: An X-Ray Detected AGN in a Low-mass Galaxy at z ∼ 0.56

• Published in: Astrophysical journal. Letters 2019-11, Vol.885 (1), p.L3
• Main Authors: Halevi, Goni, Goulding, Andy, Greene, Jenny, Coupon, Jean, Golob, Anneya, Gwyn, Stephen, Johnson, Sean D., Moutard, Thibaud, Sawicki, Marcin, Suh, Hyewon, Toba, Yoshiki
• Format: Article
• Language: English
• Subjects: Active galactic nuclei; Astronomical models; Black holes; Dwarf galaxies; Galactic evolution; Luminosity; Red shift; Spectral energy distribution; Stars & galaxies; Stellar mass; Supermassive black holes; X ray sources; X-ray active galactic nuclei
• ISSN: 2041-8205; 2041-8213
• DOI: 10.3847/2041-8213/ab4b4f

The properties of low-mass galaxies hosting central black holes provide clues about the formation and evolution of the progenitors of supermassive black holes. In this Letter, we present HSC-XD 52, a spectroscopically confirmed low-mass active galactic nucleus (AGN) at an intermediate redshift of z ∼ 0.56. We detect this object as a very luminous X-ray source coincident with a galaxy observed by the Hyper Suprime-Cam (HSC) as part of a broader search for low-mass AGN. We constrain its stellar mass through spectral energy distribution modeling to be LMC-like at M 3 × 109M , placing it in the dwarf regime. We estimate a central black hole mass of MBH ∼ 106M . With an average X-ray luminosity of , HSC-XD 52 is among the most luminous X-ray selected AGN in dwarf galaxies. The spectroscopic and photometric properties of HSC-XD 52 indicate that it is an intermediate-redshift counterpart to local low-mass AGN.