1998/08/04 by D. M. Worrall, M. Birkinshaw, R. A. Remillard +4 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/307074
19 pages, including 10 figures, using emulateapj.sty and apjfonts.sty. To appear in the ApJ
arxiv created 1998/08/04 · openalex publication_date 1999/05/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We present new X-ray, radio, and optical data for the unusual galaxy/cluster system J2310-437. Our results confirm the presence of an active nucleus and suggest an interpretation as an anomalous BL Lac object of bulk relativistic Doppler factor <2, with an optically deficient radio to X-ray spectrum. The radio, optical, and soft X-ray flux densities could lie along a single power-law function, lacking the curvature typical of BL Lac objects. Compared with other known sources that may have comparable multifrequency spectra, J2310-437 is the most extreme. Its low isotropic optical/UV radiation is consistent with the intensity of external photons governing the electron spectral break through Compton cooling; in this source the external photon density would be too low to produce a spectral break below the X-ray.