The Two Sided Parsec Scale Structure of the Low Luminosity Active Galactic Nucleus in NGC 4278

Technical Report · Fri Jan 07 04:00:00 EST 2005

DOI:https://doi.org/10.2172/839633· OSTI ID:839633

Giroletti, M ^[1]

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1. SLAC

We present new Very Long Baseline Interferometry observations of the LINER galaxy NGC 4278. The observations were taken with the Very Long Baseline Array (VLBA) and a single antenna of the Very Large Array (VLA) at 5 GHz and 8.4 GHz and have a linear resolution of {approx}< 0.1 pc. Our radio data reveal a two sided structure, with symmetric S-shaped jets emerging from a flat spectrum core. We fit the jet brightness with gaussian components, which we identify from a previous observation taken five years before. By comparing the positions of the components in the two epochs, we measure motions between 0.45 {+-} 0.14 and 3.76 {+-} 0.65 mas, corresponding to apparent velocities {approx}< 0.2 c, and to ages in the range 8.3-65.8 years. Assuming that the radio morphology is intrinsically symmetric and its appearance is governed by Doppler beaming effects, we find that NGC 4278 has mildly relativistic jets ({beta} {approx} 0.75), closely aligned to the line-of-sight (2{sup o} {le} {theta} {le} 4{sup o}). Alternatively, the source could be oriented at a larger angle and asymmetries could be related to the jet interaction with the surrounding medium. We also present new simultaneous VLA observations between 1.4 and 43 GHz, and a 5 GHz light curve between 1972 and 2003. The radio spectrum can be fit by a relatively steep power-law ({alpha} = 0.54). We find significant variability at 5 GHz. All these arguments indicate that the radiation from NGC 4278 is emitted via the synchrotron process by relativistic particles accelerated by a supermassive black hole. Despite a much lower power, this is the same process that takes place in ordinary radio loud AGNs.

• Research Organization: Stanford Linear Accelerator Center (SLAC), Menlo Park, CA
• Sponsoring Organization: SC
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 839633
• Report Number(s): SLAC-PUB-10890
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ANTENNAS
BLACK HOLES
BRIGHTNESS
INTERFEROMETRY
LINERS
LUMINOSITY
MORPHOLOGY
RADIATIONS
RESOLUTION
SYNCHROTRONS