The Swift X-Ray Telescope

Burrows, D. N.; Hill, J. E.; Nousek, J. A.; Kennea, J. A.; Wells, A.; Osborne, J. P.; Abbey, A. F.; Beardmore, A. P.; Mukerjee, K.; Short, A.; Chincarini, G.; Campana, S.; Citterio, O.; Moretti, A.; Pagani, C.; Tagliaferri, G.; Giommi, P.; Capalbi, M.; Tamburelli, F.; Angelini, L.; Cusumano, G.; Bräuninger, H.; Burkert, Wolfgang; Hartner, Gisela

doi:10.1007/s11214-005-5097-2

Cited by 2,583 publications

(2,190 citation statements)

References 23 publications

Supporting

Mentioning

2,179

Contrasting

Unclassified

Order By: Relevance

“…The source flux was variable by a factor of as high as 4. Subsequent pointed observations with Swift/XRT (Burrows et al 2005) performed in June 2006 located the X-ray counterpart at a position RA = 16 h 56 m 16. s 56, Dec = −33 • 02 09. 3 (J2000), with an uncertainty of 3.…”

Section: Previous Information On Swift J16563-3302mentioning

confidence: 99%

See 1 more Smart Citation

High-redshift blazar identification for Swift J1656.3-3302

Masetti

Mason

Landi

et al. 2008

A&A

Self Cite

View full text Add to dashboard Cite

We report on the high-redshift blazar identification of a new gamma-ray source, Swift J1656.3−3302, detected with the BAT imager onboard the Swift satellite and the IBIS instrument on the INTEGRAL satellite. Follow-up optical spectroscopy has allowed us to identify the counterpart as an R ∼ 19 mag source that shows broad Lyman-α, Si iv, He ii, C iv, and C iii] emission lines at redshift z = 2.40 ± 0.01. Spectral evolution is observed in X-rays when the INTEGRAL/IBIS data are compared to the Swift/BAT results, with the spectrum steepening when the source gets fainter. The 0.7-200 keV X-ray continuum, observed with Swift/XRT and INTEGRAL/IBIS, shows the power law shape typical of radio loud (broad emission line) active galactic nuclei (with a photon index Γ ∼ 1.6) and a hint of spectral curvature below ∼2 keV, possibly due to intrinsic absorption (N H ∼ 7× 10 22 cm −2 ) local to the source. Alternatively, a slope change (∆Γ ∼ 1) around 2.7 keV can describe the X-ray spectrum equally well. At this redshift, the observed 20-100 keV luminosity of the source is ∼10 48 erg s −1 (assuming isotropic emission), making Swift J1656.3−3302 one of the most X-ray luminous blazars. This source is yet another example of a distant gamma-ray loud quasar discovered above 20 keV. It is also the farthest object, among the previously unidentified INTEGRAL sources, whose nature has been determined a posteriori through optical spectroscopy.

show abstract

Section: Previous Information On Swift J16563-3302mentioning

confidence: 99%

“…The first observation started at 03:32 UT on 9 June 2006, and the second at 16:36 UT on 13 June 2006. The pointings had on-source times of 4.4 and 4.8 ks, respectively, and both were performed in Photon Counting mode (see Burrows et al 2005, for details on this observing mode).…”

Section: X-/gamma-ray Observationsmentioning

confidence: 99%

High-redshift blazar identification for Swift J1656.3-3302

Masetti

Mason

Landi

et al. 2008

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…The source has been observed by Swift (Gehrels et al 2004) on 17 occasions 2011 onwards, with exposure times ranging over ≈ 470-5100 s using the X-Ray Telescope (XRT; Burrows et al 2005) sensitive to photons between ∼0.3 and 10 keV. The individual observations are listed in the Appendix A.…”

Section: Swiftmentioning

confidence: 99%

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

Gandhi

Annuar

Lansbury

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe Kα emission line (equivalent width [EW] of ≈ 0.4 keV) and a strong Fe XXVI ionised line (EW ≈ 0.2 keV). We construct an updated longterm X-ray light curve of NGC 7674 and find that the observed 2-10 keV flux has remained constant for the past ≈ 20 years, following a high flux state probed by Ginga. Light travel time arguments constrain the minimum radius of the reflector to be ∼ 3.2 pc under the switchedoff AGN scenario, ≈ 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density (N H ) of 3 × 10 24 cm −2 at present, and yields an intrinsic 2-10 keV luminosity of (3-5) × 10 43 erg s −1 . Realistic uncertainties span the range of ≈ (1-13) × 10 43 erg s −1 . The source has one of the weakest fluorescence lines amongst bona fide CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionised Fe emission. It exemplifies the difficulty of identification and proper characterisation of distant CTAGN based on the strength of the neutral Fe Kα line.

show abstract

“…Swift slewed immediately to the burst and the X-Ray Telescope (XRT, Burrows et al 2005) began data acquisition at t 0 +86 s in Windowed Timing mode. Between t 0 +99 s and t 0 +1.1 day the XRT was operated in Photon Counting mode.…”

Section: Xrtmentioning

confidence: 99%

A study of the prompt and afterglow emission of the short GRB 061201

Stratta¹,

D’Avanzo

Piranomonte

et al. 2007

A&A

Self Cite

View full text Add to dashboard Cite

Context. Our knowledge of the intrinsic properties of short duration Gamma-Ray Bursts has relied, so far, only upon a few cases for which the estimate of the distance and an extended, multiwavelength monitoring of the afterglow have been obtained. Aims. We carried out multiwavelength observations of the short GRB 061201 aimed at estimating its distance and studying its properties. Methods. We performed a spectral and timing analysis of the prompt and afterglow emission and discuss the results in the context of the standard fireball model. Results. A clear temporal break was observed in the X-ray light curve about 40 min after the burst trigger. We find that the spectral and timing behaviour of the X-ray afterglow is consistent with a jet origin of the observed break, although the optical data can not definitively confirm this and other scenarios are possible. No underlying host galaxy down to R ∼ 26 mag was found after fading of the optical afterglow. Thus, no secure redshift could be measured for this burst. The nearest galaxy is at z = 0.111 and shows evidence of star formation activity. We discuss the association of GRB 061201 with this galaxy and with the ACO S 995 galaxy cluster, from which the source is at an angular distance of 17 and 8.5 , respectively. We also test the association with a possible undetected, positionally consistent galaxy at z ∼ 1. In all these cases, in the jet interpretation, we find a jet opening angle of 1-2 degrees.Key words. gamma rays: bursts IntroductionShort duration Gamma-ray Bursts (GRBs) are historically defined as those GRBs with burst duration less than two seconds and hard spectra (Kouveliotou et al. 1993). As the sample of short GRBs increases, in order to take into account all the spectral and temporal properties of the prompt emission, alternative empirical definitions of short GRBs have been introduced (e.g. Norris & Bonnell 2006;Zhang et al. 2007).The expected progenitor for short GRBs is a merging binary system of compact objects. However, our present knowledge of the intrinsic properties of short bursts mainly relies upon a few cases for which the distance could be derived and an extendedThe results reported in this paper are partially based on observations carried out at ESO telescopes under program 078.D-0809.INAF personnel resident at ASDC. multiwavelength monitoring of the afterglow was carried out.From these it appears that short bursts are less energetic and less collimated than long GRBs (e.g. Fox et al. 2005;Burrows et al. 2006;Soderberg et al. 2006). Intrinsic spectral parameters such as the peak energy E p of the EF(E) spectrum of the burst and the equivalent isotropic energy E iso , do not match the E p − E iso correlation for long GRBs (e.g. Amati 2007).The short bursts for which unambiguous hosts have been found are at redshifts between z = 0.10 and z = 0.55. The optical afterglows of seven short bursts and their likely host galaxies have been recently observed with telescopes such as ESO/VLT, Gemini, Magellan and HST, but no firm estimation of...

show abstract

The Swift X-Ray Telescope

Cited by 2,583 publications

References 23 publications

High-redshift blazar identification for Swift J1656.3-3302

High-redshift blazar identification for Swift J1656.3-3302

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

A study of the prompt and afterglow emission of the short GRB 061201

Contact Info

Product

Resources

About