Volume 450, Number 1, April IV 2006
|Page(s)||77 - 81|
|Published online||03 April 2006|
A short hard X-ray flare from the blazar NRAO 530 observed by INTEGRAL
INAF/IASF-Bologna, via Gobetti 101, 40129 Bologna, Italy e-mail: email@example.com
2 INAF, Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131, Trieste, Italy
3 INAF, Osservatorio Astronomico di Brera, via Bianchi 46, 23807, Merate, Italy
4 INAF, Osservatorio Astronomico di Torino, via Osservatorio 20, 10025, Pino Torinese, Italy
5 Osservatorio Astronomico, Università di Perugia, via B. Bonfigli, 06126 Perugia, Italy
Accepted: 5 January 2006
We report about a short flare from the blazar NRAO 530 occurred on 17 February 2004 and detected serendipitously by the IBIS/ISGRI detector on board INTEGRAL. In the keV energy range, the source, that is otherwise below the detection limit, is detected at a level of ≈2 10-10 erg cm-2 s-1 during a time interval of less than 2000 s, which is about a factor 2 above the detection threshold. At other wavelengths, only nearly-simultaneous radio data are available (1 observation at 2 cm on 11 February 2004), indicating a moderate increase of the polarization. This appears to be the shortest time variability episode ever detected in a high luminosity blazar at hard X-rays, unless the blazar is contaminated by the presence of an unknown unresolved rapidly varying source.
Key words: galaxies: quasars: general / galaxies: quasars: individual: NRAO 530 / X-rays: galaxies
© ESO, 2006
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