A Centiparsec-scale Compact Radio Core in the Nearby Galaxy M60
Journal article, 2024

M60, an elliptical galaxy located 16.5 Mpc away, has an active nucleus with a very low luminosity and an extremely low accretion rate. Its central supermassive black hole (SMBH) has a mass of M BH ∼ 4.5 × 109 M ⊙ and a Schwarzschild radius corresponding to R S ∼ 5.4 μas. To investigate the nature of its innermost radio nucleus, data from the Very Long Baseline Array (VLBA) at 4.4 and 7.6 GHz were reduced. The VLBA images reveal a compact component with total flux densities of ∼20 mJy at both frequencies, a size of ≤0.27 mas (99.7% confidence level), about 0.022 pc (50 R S) at 7.6 GHz, and a brightness temperature of ≥6 × 109 K. This suggests that the observed centiparsec-scale compact core could be attributed to a nonthermal jet base or an advection-dominated accretion flow (ADAF) with nonthermal electrons. The extremely compact structure also supports the presence of an SMBH in the center. Our results indicate that M60 is a promising target for broadband very long baseline interferometry observations at millimeter wavelengths to probe ADAF scenarios and tightly constrain the potential photon ring (about 28 μas) around its SMBH.

Author

X. F. Li

National Astronomical Data Center

Guangzhou University

Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province

Jun Yang

Chalmers, Space, Earth and Environment, Onsala Space Observatory

X. P. Cheng

Korea Astronomy and Space Science Institute

Mai Liao

Chinese Academy of Sciences

Diego Portales University

Xiaoyu Hong

Shanghai Astronomical Observatory

Chinese Academy of Sciences

ShanghaiTech University

Liming Dou

Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province

National Astronomical Data Center

Guangzhou University

Tianle Zhao

Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province

National Astronomical Data Center

Guangzhou University

Zhongying Fan

National Astronomical Data Center

Guangzhou University

Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province

Fupeng Zhang

Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province

National Astronomical Data Center

Guangzhou University

Weirong Huang

Guangzhou University

Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province

National Astronomical Data Center

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 960 1 1

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

DOI

10.3847/1538-4357/ad0be6

More information

Latest update

1/11/2024