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

Abstract

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-band 19 mag source that shows broad Lyman-alpha, 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 around 1.6) and a hint of spectral curvature below 2 keV, possibly due to intrinsic absorption (N_H about 7e22 cm-2) local to the source. Alternatively, a slope change (of about 1 in terms of photon index) 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 about 1e48 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.

9 pages, 5 figures, 2 tables. Accepted for publication on Astronomy & Astrophysics, main journal

References in corpus (23)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Swift X-ray Telescope
• The Swift Ultra-Violet/Optical Telescope
• A Unifying View of the Spectral Energy Distributions of Blazars
• A theoretical unifying scheme for gamma-ray bright blazars
• ISGRI: the INTEGRAL Soft Gamma-Ray Imager
• The 3rd IBIS/ISGRI soft gamma-ray survey catalog
• The INTEGRAL/IBIS Scientific Data Analysis
• Dust in active nuclei. II. Powder or gravel?
• XMM-Newton spectroscopy of high-redshift QSOs
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. V. Identification and properties of 21 southern hard X-ray sources
• The Blazar Sequence: Validity and Predictions
• SWIFT observations of TeV BL Lac objects
• Empirical Uncertainty Estimators for Astrometry from Digital Databases
• PMN J0525-3343: soft X-ray spectral flattening in a blazar at z=4.4
• A refined position catalog of the Swift XRT afterglows
• Low energy cut-offs and hard X-ray spectra in high-z radio-loud quasars: the Suzaku view of RBS315
• Swift observations of high-redshift radio-loud quasars
• IGR J22517+2218=MG3 J225155+2217: a new gamma-ray lighthouse in the distant Universe
• Discovery of an Extreme MeV Blazar with the Swift Burst Alert Telescope
• X-ray spectral properties of high-redshift radio-loud quasars beyond redshift 4--first results
• Radio and X-ray observations of an exceptional radio flare in the extreme z=4.72 blazar GB B1428+4217
• ROXA J081009.9+384757.0: a $10^{47}$ erg/s blazar with hard X-ray synchrotron peak or a new type of radio loud AGN?

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• The fraction of Compton-thick sources in an INTEGRAL complete AGN sample
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VI. A multi-observatory identification campaign
• The Central Engines of Fermi Blazars
• The INTEGRAL/IBIS AGN catalogue I: X-ray absorption properties versus optical classification
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VII. Identification of 20 Galactic and extragalactic hard X-ray sources
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VIII. Identification of 44 newly detected hard X-ray sources
• Correlation of Fermi-LAT sources with the AT20GHz radio survey
• TANAMI Blazars in the IceCube PeV Neutrino Fields
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. X. A new multi-year, multi-observatory campaign
• Broadband Observations of High Redshift Blazars
• INTEGRAL: science highlights and future prospects
• INTEGRAL view of AGN
• The changing look of PKS 2149-306
• 15 years of Galactic surveys and hard X-ray Background measurements
• Soft gamma-ray sources detected by INTEGRAL
• Breaks in the X-ray spectra of high redshift blazars and the intervening medium