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Wide-field EVN imaging of the Perseus Cluster core and the detection of an over-massive black hole in NGC 1277

Submitter: Jun Yang (for Songyoun Park)
Description: The above figure shows the 1.4 GHz wide-field EVN imaging results of the radio sources in the core of the Perseus Cluster. The background image is the optical g-band image from SDSS (Sloan Digital Sky Survey), the green contours show the WSRT map of the region (Sijbring et al. 1993). The five radio sources targeted by the EVN have total flux densities of 2-11 mJy. Using the multi-phase center correlation capability of the EVN Software Correlator at JIVE (SFXC), we placed small viewing windows on the targets surrounding Perseus A (also known as NGC 1275, or 3C 84). All these sources are detected with a good signal-to-noise ratio at very high resolution. Besides the central calibrator, we used a relatively bright background quasar, J0320+412 to verify the correlation procedure and the calibration quality of the field sources.

Compact radio emission in the centre of galaxies is usually a sign of activity related to the central massive black hole. Active galactic nuclei (AGN) are typically bright in the hard X-rays and show strong optical emission lines as well. Due to the low luminosity of the field sources shown above, and because of the very crowded field, there has been so far very little information about the central activity in these systems. Thanks to the great sensitivity and superior resolution of the EVN, we detect radio emission on very small angular scales, that most likely originates in low-luminosity AGNs. One of the sources is of particular interest: NGC 1277 is claimed to harbour an extremely massive black hole of 10 billion Solar masses, but NGC 1270 is also a suspect to possess an over-massive BH (Van den Bosch et al. 2012, Nature).

This study suggests that LLAGN may be more common than envisaged from optical or X-ray observations alone. The work was carried out by Songyoun Park (South Korea) during the JIVE/Astron Summer Student Programme in 2013. Her supervisors were Jun Yang, Raymond Oonk and Zsolt Paragi.
Copyright: JIVE
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