1H 0323+342 known as 2MASX J032441.19+341045.9, is a galaxy located in the constellation of Perseus. It is located 831 million light years from Earth.[1] It is classified a gamma-ray emitting narrow-line Seyfert galaxy,[2][3] the nearest known example of this subtype.[4][5]
1H 0323+342 was first discovered by Wood as an astrophysical X-ray source during the HEAO-1 X-ray survey in 1984.[6] At the time of the observation the source had an unknown origin. In 1993, the source was confirmed as a Seyfert type 1 galaxy by Remillard and colleagues, who identified several emission-line AGNs from a further HEAO-1 X-ray survey.[7] This galaxy has since been detected by both the Fermi Gamma-ray Space Telescope and INTEGRAL.[8]
The nucleus of 1H 0323+342 is found to be active. The most likely explanation for this energy source in all active galactic nuclei is a presence of an accretion disk around a supermassive black hole. The mass of the black hole in center of 1H 0323+342 is estimated to be 107Mʘ based on the width and luminosity of a Hβ line and empirical scaling relations,[8] or ~ 2 x 107 Mʘ according to multi-wavelength observations.[9] But later studies shows the mass of the black hole has different estimates. In 2016, a similar mass of (3.4+0.9-0.6) x 107 Mʘ was found from a reverberation study.[10] However, in 2024, the mass is 107.24±0.01 Mʘ according to the galaxy's total flux spectrum.[11] Additionally, the nucleus shows a quasi-stationary feature similar to a HST-1 structure inside the jet of Messier 87.[10]
1H 0323+342 shows some characteristics of blazars, including variable fluxes in optical, radio and X-ray bands as well as a compact bright core.[12] Moreover, the core is revealed to have a two-sided structure measuring ~ 15 kiloparsecs. The galaxy also contains a flat-spectrum radio source with a radio loudness of either R5GHz = 246 or R1.4GHz = 318. A relativistic jet is present in 1H 0323+342[13] although its jet power of 1.0 x 1045 erg s-1 is half the luminosity of its accretion disk.[10]
The host galaxy of 1H 0323+342 is a mystery but it has irregular morphology.[14] There is a peculiar structure in the galaxy. It is either interpreted as a one-armed spiral structure based from an optical image taken by Hubble Space Telescope,[12] or a ring-like structure suggesting a recent galaxy merger.[15]
