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arXiv · 1910.02173

HSC-XD 52: An X-ray detected AGN in a low-mass galaxy at $z\sim0.56$

Goni Halevi·Andy Goulding·Jenny Greene·Jean Coupon·Anneya Golob·Stephen Gwyn·Sean D. Johnson·Thibaud Moutard·Marcin Sawicki·Hyewon Suh·Yoshiki Toba
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Abstract

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 $z\sim0.56$. 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 $M_\star \approx 3 \times 10^9 M_\odot$, placing it in the dwarf regime. We estimate a central black hole mass of $M_\mathrm{BH} \sim 10^{6} M_\odot$. With an average X-ray luminosity of $L_X \approx 3.5 \times 10^{43}~\mathrm{erg}~\mathrm{s}^{-1}$, 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.

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Goni Halevi, Andy Goulding, Jenny Greene, Jean Coupon, Anneya Golob, Stephen Gwyn, Sean D. Johnson, Thibaud Moutard, Marcin Sawicki, Hyewon Suh, Yoshiki Toba. 2019-10-04. HSC-XD 52: An X-ray detected AGN in a low-mass galaxy at $z\sim0.56$. https://doi.org/10.3847/2041-8213/ab4b4f

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