Parsec-scale radio emission from the low-luminosity active galactic nucleus in the dwarf starburst galaxy Henize 2-10

AE Reines, AT Deller - The Astrophysical Journal Letters, 2012 - iopscience.iop.org
AE Reines, AT Deller
The Astrophysical Journal Letters, 2012iopscience.iop.org
ABSTRACT A candidate accreting massive black hole (BH) with M BH∼ 10 6 M☉ has
recently been identified at the center of the dwarf starburst galaxy Henize 2-10 (He 2-10).
This discovery offers the first possibility of studying a growing BH in a nearby galaxy
resembling those in the earlier universe, and opens up a new class of host galaxies to
search for the smallest supermassive BHs. Here we present very long baseline
interferometry observations of He 2-10 taken with the Long Baseline Array (LBA) at 1.4 GHz …
Abstract
A candidate accreting massive black hole (BH) with M BH∼ 10 6 M☉ has recently been identified at the center of the dwarf starburst galaxy Henize 2-10 (He 2-10). This discovery offers the first possibility of studying a growing BH in a nearby galaxy resembling those in the earlier universe, and opens up a new class of host galaxies to search for the smallest supermassive BHs. Here we present very long baseline interferometry observations of He 2-10 taken with the Long Baseline Array (LBA) at 1.4 GHz with an angular resolution of∼ 0 farcs 1× 0 farcs 03. A single compact radio source is detected at the precise location of the putative low-luminosity active galactic nucleus. The physical size of the nuclear radio emission is≲ 3 pc× 1 pc, an order of magnitude smaller than previous constraints from the Very Large Array (VLA), and the brightness temperature of T B> 3× 10 5 K confirms a non-thermal origin. These LBA observations indicate that the nuclear radio emission originates from a single object, and exclude the possibility of multiple supernova remnants as the origin of the nuclear radio emission previously detected with the VLA at lower resolution. A weaker, more extended, off-nuclear source is also detected with the LBA and a comparison with multi-wavelength ancillary data indicate that, unlike the nuclear source, the off-nuclear source is co-spatial with a super star cluster, lacks a detectable X-ray point-source counterpart, and is almost certainly due to a supernova remnant in the host star cluster.
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