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TOPIC: SDSS J150243.09+111557.3

Blobrana

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Posts: 131433

Date: Aug 27 06:24 2014

J1502SE/SW	Permalink

Title: Evidence from the Very Long Baseline Array that J1502SE/SW are Double Hotspots, not a Supermassive Binary Black Hole Author: J.M. Wrobel, R.C. Walker, H. Fu SDSS J150243.09+111557.3 is a merging system at z = 0.39 that hosts two confirmed AGN, one unobscured and one dust-obscured, offset by several kiloparsecs. Deane et al. recently reported evidence from the European VLBI Network (EVN) that the dust-obscured AGN exhibits two flat-spectrum radio sources, J1502SE/SW, offset by 26 mas (140 pc), with each source being energized by its own supermassive black hole (BH). This intriguing interpretation of a close binary BH was reached after ruling out a double-hotspot scenario, wherein both hotspots are energized by a single, central BH, a configuration occurring in the well-studied Compact Symmetric Objects. When observed with sufficient sensitivity and resolution, an object with double hotspots should have an edge-brightened structure. We report evidence from the Very Long Baseline Array (VLBA) for just such a structure in an image of the obscured AGN with higher sensitivity and resolution than the EVN images. We thus conclude that a double-hotspot scenario should be reconsidered as a viable interpretation for J1502SE/SW, and suggest further VLBA tests of that scenario. A double-hotspot scenario could have broad implications for feedback in obscured AGNs. We also report a VLBA detection of high-brightness-temperature emission from the unobscured AGN that is offset several kiloparsecs from J1502SE/SW. Read more (28kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Jul 5 18:14 2014

SDSS J150243.09+111557.3	Permalink

Title: A close-pair binary in a distant triple supermassive black-hole system Author: R. P. Deane (1,2), Z. Paragi (3), M. J. Jarvis (4,5), M. Coriat (1,2), G. Bernardi (2,6,7), R. P. Fender (4), S. Frey (8), I. Heywood (9,6), H.-R. Klöckner (10), K. Grainge (11), C. Rumsey (12), ((1) University of Cape Town, (2) Square Kilometre Array South Africa, (3) Joint Institute for VLBI in Europe, (4) University of Oxford, (5) University of the Western Cape, (6) Rhodes University, (7) Harvard-Smithsonian Center for Astrophysics, (8) Satellite Geodetic Observatory, Institute of Geodesy, Cartography and Remote Sensing, (9) CSIRO Astronomy and Space Science, (10) Max-Planck-Institut für Radioastronomie, (11) The University of Manchester, (12) University of Cambridge) Galaxies are believed to evolve through merging, which should lead to multiple supermassive black holes in some. There are four known triple black hole systems, with the closest pair being 2.4 kiloparsecs apart (the third component is more distant at 3 kiloparsecs), which is far from the gravitational sphere of influence of a black hole with mass ~10^9 solar masses (about 100 parsecs). Previous searches for compact black hole systems concluded that they were rare, with the tightest binary system having a separation of 7 parsecs. Here we report observations of a triple black hole system at redshift z=0.39, with the closest pair separated by ~140 parsecs. The presence of the tight pair is imprinted onto the properties of the large-scale radio jets, as a rotationally-symmetric helical modulation, which provides a useful way to search for other tight pairs without needing extremely high resolution observations. As we found this tight pair after searching only six galaxies, we conclude that tight pairs are more common than hitherto believed, which is an important observational constraint for low-frequency gravitational wave experiments. Read more (491kb, PDF) __________________

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