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Spitzer reveals infrared optically thin synchrotron emission from the compact jet of the neutron star x-ray binary 4U 0614+091

Spitzer reveals infrared optically thin synchrotron emission from the compact jet of the neutron star x-ray binary 4U 0614+091
Spitzer reveals infrared optically thin synchrotron emission from the compact jet of the neutron star x-ray binary 4U 0614+091
Spitzer observations of the neutron star (ultracompact) X-ray binary (XRB) 4U 0614+091 with the Infrared Array Camera reveal emission of nonthermal origin in the range 3.5-8 μm. The mid-infrared spectrum is well fit by a power law with spectral index of α = -0.57±0.04 (where the flux density is Fv ∝ vα). Given the ultracompact nature of the binary system, we exclude the possibility that either the companion star or the accretion disk can be the origin of the observed emission. These observations represent the first spectral evidence for a compact jet in a low-luminosity neutron star XRB and furthermore of the presence, already observed in two black hole (BH) XRBs, of a "break" in the synchrotron spectrum of such compact jets. We can derive a firm upper limit on the break frequency of the spectrum of vthin=3.7×1013 Hz, which is lower than that observed in BH XRBs by at least a factor of 10. Assuming a high-energy cooling cutoff at ~1 keV, we estimate a total (integrated up to X-rays) jet power to X-ray bolometric luminosity ratio of ~5%, much lower than that inferred in BHs.
infrared: general, ism: jets and outflows, radiation mechanisms: nonthermal, stars: individual (4U 0614091), X-rays: binaries
L41-L44
Migliari, S.
aa759820-ecfe-416d-87e4-75c3f5b04b3f
Tomsick, J.A.
a9cc3ecb-ac1b-4561-8570-edf46d54cd2f
Maccarone, T.J.
5d8ee27f-a174-424c-b3b7-a6739bfeea50
Gallo, E.
6abacb20-399c-4d71-a4d5-9ef9aedccc67
Fender, R.P.
c802ddfc-25a3-4c0e-899d-11c405c705d1
Nelemans, G.
d8405945-6a36-4e77-9253-167c3dc52e6e
Russell, D.R.
14f672bc-c1b9-4836-b9d4-8cd4533dbae0
Migliari, S.
aa759820-ecfe-416d-87e4-75c3f5b04b3f
Tomsick, J.A.
a9cc3ecb-ac1b-4561-8570-edf46d54cd2f
Maccarone, T.J.
5d8ee27f-a174-424c-b3b7-a6739bfeea50
Gallo, E.
6abacb20-399c-4d71-a4d5-9ef9aedccc67
Fender, R.P.
c802ddfc-25a3-4c0e-899d-11c405c705d1
Nelemans, G.
d8405945-6a36-4e77-9253-167c3dc52e6e
Russell, D.R.
14f672bc-c1b9-4836-b9d4-8cd4533dbae0

Migliari, S., Tomsick, J.A., Maccarone, T.J., Gallo, E., Fender, R.P., Nelemans, G. and Russell, D.R. (2006) Spitzer reveals infrared optically thin synchrotron emission from the compact jet of the neutron star x-ray binary 4U 0614+091. The Astrophysical Journal Letters, 643 (1), L41-L44. (doi:10.1086/505028).

Record type: Article

Abstract

Spitzer observations of the neutron star (ultracompact) X-ray binary (XRB) 4U 0614+091 with the Infrared Array Camera reveal emission of nonthermal origin in the range 3.5-8 μm. The mid-infrared spectrum is well fit by a power law with spectral index of α = -0.57±0.04 (where the flux density is Fv ∝ vα). Given the ultracompact nature of the binary system, we exclude the possibility that either the companion star or the accretion disk can be the origin of the observed emission. These observations represent the first spectral evidence for a compact jet in a low-luminosity neutron star XRB and furthermore of the presence, already observed in two black hole (BH) XRBs, of a "break" in the synchrotron spectrum of such compact jets. We can derive a firm upper limit on the break frequency of the spectrum of vthin=3.7×1013 Hz, which is lower than that observed in BH XRBs by at least a factor of 10. Assuming a high-energy cooling cutoff at ~1 keV, we estimate a total (integrated up to X-rays) jet power to X-ray bolometric luminosity ratio of ~5%, much lower than that inferred in BHs.

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More information

Published date: May 2006
Keywords: infrared: general, ism: jets and outflows, radiation mechanisms: nonthermal, stars: individual (4U 0614091), X-rays: binaries

Identifiers

Local EPrints ID: 79624
URI: http://eprints.soton.ac.uk/id/eprint/79624
PURE UUID: cff152a2-0946-4c37-b8fd-ca867fea4323

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Date deposited: 17 Mar 2010
Last modified: 14 Mar 2024 00:32

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Contributors

Author: S. Migliari
Author: J.A. Tomsick
Author: T.J. Maccarone
Author: E. Gallo
Author: R.P. Fender
Author: G. Nelemans
Author: D.R. Russell

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