Transient events in archival very large array observations of the galactic center
- Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, M/S 138-308, 4800 Oak Grove Dr., Pasadena, CA 91109 (United States)
- Department of Physics, University of Wisconsin-Milwaukee, 3135 N Maryland Ave., Milwaukee, WI 53201 (United States)
- Academia Sinica Institute for Astronomy and Astrophysics (ASIAA), 645 N. Aohoku Pl, Hilo, HI 96720 (United States)
- University of California, Berkeley, Department of Astronomy, 501 Campbell Hall #3411, Berkeley, CA 94720 (United States)
The Galactic center has some of the highest stellar densities in the Galaxy and a range of interstellar scattering properties, which may aid in the detection of new radio-selected transient events. Here, we describe a search for radio transients in the Galactic center, using over 200 hr of archival data from the Very Large Array at 5 and 8.4 GHz. Every observation of Sgr A* from 1985 to 2005 has been searched using an automated processing and detection pipeline sensitive to transients with timescales between 30 s and 5 minutes with a typical detection threshold of ∼100 mJy. Eight possible candidates pass tests to filter false-positives from radio-frequency interference, calibration errors, and imaging artifacts. Two events are identified as promising candidates based on the smoothness of their light curves. Despite the high quality of their light curves, these detections remain suspect due to evidence of incomplete subtraction of the complex structure in the Galactic center, and apparent contingency of one detection on reduction routines. Events of this intensity (∼100 mJy) and duration (∼100 s) are not obviously associated with known astrophysical sources, and no counterparts are found in data at other wavelengths. We consider potential sources, including Galactic center pulsars, dwarf stars, sources like GCRT J1745−3009, and bursts from X-ray binaries. None can fully explain the observed transients, suggesting either a new astrophysical source or a subtle imaging artifact. More sensitive multiwavelength studies are necessary to characterize these events, which, if real, occur with a rate of 14{sub −12}{sup +32} hr{sup −1} deg{sup −2} in the Galactic center.
- OSTI ID:
- 22868396
- Journal Information:
- Astrophysical Journal, Vol. 833, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Soft gamma-ray repeaters and anomalous X-ray pulsars as highly magnetized white dwarfs
GCRT J1742-3001: A NEW RADIO TRANSIENT TOWARD THE GALACTIC CENTER