On the radio emission following the August 27 giant flare of SGR 1900+14 € U. Ertan * , K.S. Cheng Department of Physics, The University of Hong Kong, Hong Kong, China Received 26 January 2004; received in revised form 23 February 2004; accepted 24 February 2004 Available online 13 March 2004 Communicated by L.E. Hernquist Abstract By comparing our analytical estimates with the results of the model fits to the radio data of the SGR 1900+14, we show that the radio afterglow of the August 27 giant flare of this source can be accounted for by the outflow of inner disk matter by the flare pressure. Our results are consistent with the observed flare energy and its estimated fraction imparted to the inner disk. Ó 2004 Elsevier B.V. All rights reserved. PACS: 97.60.Gb; 97.60.Jd Keywords: Pulsars: individual: SGR 1900+14; Stars: neutron; X-rays: bursts; Accretion: accretion disks; ISM: jets and outflows 1. Introduction Soft gamma-ray repeaters (SGRs) (see Hurley, 2000 for a review) are characterized by their short ( K 1 s), super-Eddington (E K 10 42 erg) soft c-ray bursts and persistent X-ray luminosities L x  10 34 –10 36 erg s 1 which are much higher than their rotational powers. Their spin periods are clustered in a narrow range (5–12 s). SGRs share all these properties including the bursts with anomalous X-ray pulsars (AXPs) (see Mereghetti et al., 2002 for a review). Over the history of the SGR burst observations, two giant flares were detected from two different sources, SGR 0526-66 (Mazets et al., 1979) and SGR 1900+14 (Hurley et al., 1999). During these flares an initial hard spike (E  10 44 erg) which lasts a small fraction of a second is followed by an oscillating tail which de- cays in a few minutes. Assuming isotropic emission total burst fluences exceed 10 44 erg (Feroci et al., 2001; Hurley et al., 1999; Mazets et al., 1999). The energies and time scales of these bursts can be explained by huge magnetic energy release from inside the neuron star (NS) through instabilities * Corresponding author. Present address: Faculty of Engi- neering and Natural Sciences, Sabanci University, Orhanlı, Tuzla 34956, _ Istanbul, Turkey. Tel.: +90-216-483-9560; fax: +90-216-483-9550. E-mail addresses: unal@sabanciuniv.edu ( € U. Ertan), hrspksc@hkucc.hku.hk (K.S. Cheng). 1384-1076/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.newast.2004.02.005 New Astronomy 9 (2004) 503–507 www.elsevier.com/locate/newast