2004/07/13 by Atsushi Miyazaki, Takahiro Tsutsumi, T. Tsutsumi +1 · 5 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/424004
published as Astrophys.J. 611 (2004) L97-L100 · 13 pages, 3 figures, Accepted for publication in ApJL
arxiv created 2004/07/13 · openalex publication_date 2004/07/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
We have performed the monitoring observations of the flux density of Sagittarius A* at short millimeter wavelengths (100 and 140 GHz bands) for 7 years in the period from 1996 to 2003 using the Nobeyama Millimeter Array. We found intraday variation of Sgr A* in the 2000 March flare. The flux density at the peak of the flares increases 100%-200% at 100 GHz and 200%-400% at 140 GHz (Δ S / S ), respectively. The twofold increase timescale of the flare is estimated to be about 1.5 hr at 140 GHz. The intraday variation at millimeter wavelengths has a similar increase timescale as those in the X-ray and infrared flares but has smaller amplitude. This short timescale variability suggests that the physical size of the emitting region is smaller than 12 AU (≈150 R S ). The decay timescale of the flare was at most 24 hr. Such a light curve with rapid increase and slow decay is similar to that often observed in outburst phenomena with ejections.