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arXiv · 2312.04452

FRAMEx. V. Radio Spectral Shape at Central Sub-parsec Region of AGNs

Onic I. Shuvo·Megan C. Johnson·Nathan J. Secrest·Mario Gliozzi·Phillip J. Cigan·Travis C. Fischer·Alexander J. Van Der Horst
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Abstract

We present results from the Very Long Baseline Array (VLBA) multi-frequency (1.6, 4.4, 8.6, 22 GHz), high-sensitivity (~25 microJy beam^-1), sub-parsec scale (<1 pc) observations and Spectral Energy Distributions (SEDs) for a sample of 12 local active galactic nuclei (AGNs), a subset from our previous volume-complete sample with hard X-ray (14-195 keV) luminosities above 10^42 erg s^-1, out to a distance of 40 Mpc. All 12 of the sources presented here were detected in the C (4.4 GHz) and X (8.6 GHz) bands, 75% in the L band(1.6 GHz), and 50% in the K band (22 GHz). Most sources showed compact, resolved/slightly resolved, central sub-parsec scale radio morphology, except a few with extended outflow-like features. A couple of sources have an additional component that may indicate the presence of a dual-core, single or double-sided jet or a more intricate feature, such as radio emission resulting from interaction with nearby ISM. The spectral slopes are mostly GHz-peaked or curved, with a few showing steep, flat, or inverted spectra. We found that in the sub-parsec scale, the GHz-peaked spectra belong to the low-accreting, radio-loud AGNs with a tendency to produce strong outflows, possibly small-scale jet, and/or have a coronal origin. In contrast, flat/inverted spectra suggest compact radio emission from highly-accreting AGNs' central region, possibly associated with radio-quiet AGNs producing winds/shocks or nuclear star formation in the vicinity of black holes.

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Onic I. Shuvo, Megan C. Johnson, Nathan J. Secrest, Mario Gliozzi, Phillip J. Cigan, Travis C. Fischer, Alexander J. Van Der Horst. 2023-12-07. FRAMEx. V. Radio Spectral Shape at Central Sub-parsec Region of AGNs. https://arxiv.org/abs/2312.04452

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