The 2005 outburst of the halo black hole X - ray transient XTE
نویسندگان
چکیده
We present optical and infrared monitoring of the 2005 outburst of the halo black hole X-ray transient XTE J1118+480. We measured a total outburst amplitude of ∼ 5.7±0.1 mag in the R band and ∼ 5 mag in the infrared J, H and K s bands. The hardness ratio HR2 (5-12 keV/3-5 keV) from the RXTE/ASM data is 1.53±0.02 at the peak of the outburst indicating a hard spectrum. Both the shape of the light curve and the ratio L X (1-10 keV)/L opt resemble the mini-outbursts observed in GRO J0422+32 and XTE J1859+226. During early decline, we find – 3 – a 0.02-mag amplitude variation consistent with a superhump modulation, like the one observed during the 2000 outburst. Similarly, XTE J1118+480 displayed a double-humped ellipsoidal modulation distorted by a superhump wave when settled into a near-quiescence level, suggesting that the disk expanded to the 3:1 resonance radius after outburst where it remained until early quiescence. The system reached quiescence at R = 19.02±0.03 about three months after the onset of the outburst. The optical rise preceded the X-ray rise by at most 4 days. The spectral energy distributions (SEDs) at the different epochs during outburst are all quasi-power laws with F ν ∝ ν α increasing toward the blue. At the peak of the outburst we derived α = 0.49 ± 0.04 for the optical data alone and α = 0.1 ± 0.1 when fitting solely the infrared. This difference between the optical and the in-frared SEDs suggests that the infrared is dominated by a different component (a jet?) whereas the optical is presumably showing the disk evolution.
منابع مشابه
Correlation between Hard X-ray Peak Flux and Soft X-ray Peak Flux in the Outburst Rise of Low Mass X-ray Binaries
We have analyzed Rossi X-ray timing explorer (RXTE) pointed observations of the outbursts of black hole and neutron star soft X-ray transients in which an initial low/hard state or ‘island’ state, followed by a transition to a softer state, was observed. In three sources, the black hole transient XTE J1550-564, the neutron star transient Aquila X-1 and a quasi-persistent neutron star low mass X...
متن کاملLooking for black-holes in X-ray binaries with XMM-Newton: XTE J1817-330 and XTE J1856+053
The X-ray binary XTE J1817-330 was discovered in outburst on 26 January 2006 with RXTE/ASM. One year later, another X-ray transient discovered in 1996, XTE J1856+053, was detected by RXTE during a new outburst on 28 February 2007. We triggered XMM-Newton target of opportunity observations on these two objects to constrain their parameters and search for a stellar black holes. We summarize the p...
متن کاملXmm-newton Observations of Xte J1817-330 and Xte J1856+053
The black hole candidate XTE J1817-330 was discovered in outburst on 26 January 2006 with RXTE/ASM. One year later, on 28 February 2007, another X-ray transient discovered in 1996, XTE J1856+053, was detected by RXTE during a new outburst. We report on the spectra obtained by XMM-Newton of these two black hole candidates.
متن کاملA highly polarised radio jet during the 1998 outburst of the black hole transient XTE J 1748 − 288
XTE J1748-288 is a black hole X-ray transient which went into outburst in 1998 June. The X-ray lightcurves showed canonical morphologies, with minor variations on the “Fast Rise Exponential Decay” profile. The radio source, however, reached an unusually high flux density of over 600 mJy. This high radio flux was accompanied by an exceptional (> 20%) fractional linear polarisation, the variabili...
متن کاملThe faint 2005 hard state outburst of Aquila X - 1 seen by INTEGRAL and RXTE
We report on the spectral analysis of RXTE and INTEGRAL data of the 2005 April outburst of the transient Atoll source Aql X-1. Although this outburst is one of the faintest ever detected for this source in the soft X-rays (RXTE /ASM), one of our INTEGRAL observations, taken close to the soft X-ray peak, shows that the source flux was quite high, with a 20-200 keV flux of 2.05 × 10 −9 erg cm −2 ...
متن کامل