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

High-redshift blazar identification for Swift J1656.3-3302
High-redshift blazar identification for Swift J1656.3-3302
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 mag source that shows broad Lyman-, Si IV, He II, C IV, and C III] emission lines at redshift . 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 ) and a hint of spectral curvature below ~2 keV, possibly due to intrinsic absorption ( cm-2) local to the source. Alternatively, a slope change ( ) 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 ~1048 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.
quasars: emission lines, quasars: individual: J1656.3-3302, galaxies: high-redshift, galaxies: active, x-rays: galaxies, astrometry
0004-6361
715-721
Masetti, N.
78166fad-2a82-4de5-9359-25706c0a6e2f
Mason, E.
fc4644d3-13af-477c-ba04-8288aa7e20a5
Landi, R.
b8243478-d7a1-4774-8a66-4158a65a33d3
Giommi, P.
b4aad836-bdcd-453d-b8ca-9b344f13855a
Bassani, L.
07e5602c-f97e-4334-a0fa-c2212431a61a
Malizia, A.
efa63850-cf26-482c-ae3b-54b0c8fb8a87
Bird, A.J.
045ee141-4720-46fd-a412-5aa848a91b32
Bazzano, A.
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Dean, A.J.
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Gehrels, N.
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Palazzi, E.
e9674d6b-8d34-4c1d-8ec0-0dd82392f18b
Ubertini, P.
7035748e-152c-473e-8766-a2fa3ac49fcb
Masetti, N.
78166fad-2a82-4de5-9359-25706c0a6e2f
Mason, E.
fc4644d3-13af-477c-ba04-8288aa7e20a5
Landi, R.
b8243478-d7a1-4774-8a66-4158a65a33d3
Giommi, P.
b4aad836-bdcd-453d-b8ca-9b344f13855a
Bassani, L.
07e5602c-f97e-4334-a0fa-c2212431a61a
Malizia, A.
efa63850-cf26-482c-ae3b-54b0c8fb8a87
Bird, A.J.
045ee141-4720-46fd-a412-5aa848a91b32
Bazzano, A.
8eef0c6e-1a5f-4bcd-a034-9a5c3b29104d
Dean, A.J.
2f9093f2-855c-4769-b1aa-6dd621b5dcf1
Gehrels, N.
4f9b1856-893c-41a0-89a0-ba9e25aacf65
Palazzi, E.
e9674d6b-8d34-4c1d-8ec0-0dd82392f18b
Ubertini, P.
7035748e-152c-473e-8766-a2fa3ac49fcb

Masetti, N., Mason, E., Landi, R., Giommi, P., Bassani, L., Malizia, A., Bird, A.J., Bazzano, A., Dean, A.J., Gehrels, N., Palazzi, E. and Ubertini, P. (2008) High-redshift blazar identification for Swift J1656.3-3302. Astronomy & Astrophysics, 480 (3), 715-721. (doi:10.1051/0004-6361:20078901).

Record type: Article

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 mag source that shows broad Lyman-, Si IV, He II, C IV, and C III] emission lines at redshift . 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 ) and a hint of spectral curvature below ~2 keV, possibly due to intrinsic absorption ( cm-2) local to the source. Alternatively, a slope change ( ) 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 ~1048 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.

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More information

Published date: 4 March 2008
Keywords: quasars: emission lines, quasars: individual: J1656.3-3302, galaxies: high-redshift, galaxies: active, x-rays: galaxies, astrometry

Identifiers

Local EPrints ID: 144821
URI: http://eprints.soton.ac.uk/id/eprint/144821
ISSN: 0004-6361
PURE UUID: 92cfa7d0-dd8d-4d5a-bf95-01405e2b9607
ORCID for A.J. Bird: ORCID iD orcid.org/0000-0002-6888-8937

Catalogue record

Date deposited: 24 May 2010 13:31
Last modified: 09 Nov 2021 02:44

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Contributors

Author: N. Masetti
Author: E. Mason
Author: R. Landi
Author: P. Giommi
Author: L. Bassani
Author: A. Malizia
Author: A.J. Bird ORCID iD
Author: A. Bazzano
Author: A.J. Dean
Author: N. Gehrels
Author: E. Palazzi
Author: P. Ubertini

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