A Radio Transient 0.1 pc from Sagittarius A*

Geoffrey C. Bower(1), Doug A. Roberts(2,3), Farhad Yusef-Zadeh(3), Donald C. Backer(1), W.D. Cotton(4), W. M. Goss(5), Cornelia C. Lang(6), Yoram Lithwick(1)

(1)Astronomy Department & Radio Astronomy Laboratory, University of California, Berkeley
(2) Adler Planetarium and Astronomy Museum, Chicago
(3) Department of Physics and Astronomy, Northwestern University, Evanston
(4) National Radio Astronomy Observatory, Charlottesville
(5) National Radio Astronomy Observatory, Socorro
(6) Department of Physics and Astronomy, University of Iowa, Iowa City

Paper: ApJ, in press


We report the discovery of a transient radio source 2.7 arcsec (0.1 pc projected distance) South of the Galactic Center massive black hole, Sagittarius A*. The source flared with a peak of at least 80 mJy in March 2004. The source was resolved by the Very Large Array into two components with a separation of 0.7 arcsec and characteristic sizes of 0.2 arcsec. The two components of the source faded with a power-law index of 1.1 +/- 0.1. We detect an upper limit to the proper motion of the Eastern component of 3 * 103 km s-1 relative to Sgr A*. We detect a proper motion of 104 km s-1 for the Western component relative to Sgr A*. The transient was also detected at X-ray wavelengths with the Chandra X-ray Observatory and the XMM-Newton telescope and given the designation CXOGC J174540.0-290031. The X-ray source falls in between the two radio components. The maximum luminosity of the X-ray source is 1036 erg s-1, significantly sub-Eddington. The radio jet flux density predicted by the X-ray/radio correlation for X-ray binaries is orders of magnitude less than the measured flux density. We conclude that the radio transient is the result of a bipolar jet originating in a single impulsive event from the X-ray source and interacting with the dense interstellar medium of the Galactic Center.

Preprints available from the authors at gbower@astron.Berkeley.EDU , or the raw TeX (no figures) if you click here.

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