MAXI/GSC detection of short intense flare from GRS 1915+105
ATel #12787; W. Iwakiri (Chuo U.), H. Negoro (Nihon U.), N. Kawai, M. Sugizaki(Tokyo Tech),K. Yamaoka (Nagoya U.), Y. Ueda(Kyoto U.), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), S. Nakahira, T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), M. Oeda, K. Shiraishi (Tokyo Tech), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai, M. Tominaga (JAXA), A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), Y. Kawakubo (LSU) report on behalf of the MAXI team:
on 21 May 2019; 07:53 UT
Credential Certification: Wataru Iwakiri (wataru.iwakiri@riken.jp)
Subjects: X-ray, Binary, Black Hole, Transient, Variables
The MAXI/GSC nova alert system triggered on the X-ray flare from GRS 1915+105
at 2019-05-21 00:16 (UT). The spectrum is well reproduced by absorbed powerlaw
model with a photon index of 1.8 +/- 0.3 and the hydrogen
column density of 8.0 (+2.9, -2.3) x 1022 cm-2.
The estimated absorbed X-ray flux in the 2-20 keV
is 3.9 (+0.3, -1.5) x 10-8 ergs/cm2/s.
Assuming the distance of 8.6 kpc (Reid et al, 2014 ApJ,796,2),
the absorbed luminosity is 3.5 (+0.2, -0.9) x 1038 erg/s (2-20 keV).
All errors are at 90% confidence level.
There are no significant X-ray signal at the preceding and following scan transits
of MAXI that occured 92 minutes before and after the trigger.
The 3 sigma upper limits for the both preceding
and following scan transits in the 2 - 10 keV band are 2 x 10-9 ergs/cm2/s.
This is the second X-ray flare after the previous one reported in ATel #12761,
with an interval of 7 days, which was followed by activities in NIR (ATel #12769),
radio (ATel #12773), X-ray halo (Atel #12770) and dimming (Atel #12772).
These short intense flares suggests that GRS 1915+105
is in a new activity state characterized by sporadic massive accretion
and/or ejection overlaid on a very low persistent emission.
We strongly encourage multi-wavelength observations of GRS 1915+105.
MAXI lightcurve of GRS 1915+105