Discovery of a new subparsec counterjet in NGC 1275: the inclination angle and the environment

作者：Fujita Yutaka^*; Nagai Hiroshi

来源：Monthly Notices of the Royal Astronomical Society, 2017, 465(1): L94-L98.

DOI：10.1093/mnrasl/slw217

• galaxies: active
• galaxies: individual: 3C 84
• galaxies: individual: NGC 1275
• galaxies: jets
• radio continuum: galaxies

We report on the detection of a new feature at the centre of NGC 1275 in the Perseus cluster, hosting the radio source 3C 84. This feature emerges similar to 2 mas (similar to 0.8 pc) north of the central core in recent 15- and 43-GHz Very Long Baseline Array images, and it seems to be the counterjet to a known radio jet expanding to the south of the core. Apparently, the two jets were born through an outburst around 2005. From the ratio of the apparent lengths of the two jets from the core, we have found that the jet angle to the line of sight is theta = 65 degrees +/- 16 degrees, which is not much different from the angle of the outer jets generated by an activity around 1959 and constrains theories on gamma-ray emission from jets. The new northern jet has a strongly inverted spectrum in contrast to the southern jet. This suggests that the central black hole is surrounded by a subparsec-scale accretion disc with the density of greater than or similar to 10(5) cm(-3). The brightness of the counterjet suggests that the disc is highly inhomogeneous. The ambient gas density in the direction of the jet is similar to 8 cm(-3) if the current jet activity is similar to the past average.

• 出版日期2017-2
• 单位中国科学院国家天文台