Title: Fermi -LAT constraints on the pulsar wind nebula nature of HESS J1857+026

Abstract

Since its launch, the Fermi satellite has firmly identified 5 pulsar wind nebulae plus a large number of candidates, all powered by young and energetic pulsars. HESS J1857 + 026 is a spatially extended γ-ray source detected by H.E.S.S. and classified as a possible pulsar wind nebula candidate powered by PSR J1856 + 0245. Here, we search for γ-ray pulsations from PSR J1856+0245 and explore the characteristics of its associated pulsar wind nebula. Using a rotational ephemeris obtained from the Lovell telescope at Jodrell Bank Observatory at 1.5 GHz, we phase-fold 36 months of γ-ray data acquired by the Large Area Telescope (LAT) aboard Fermi. We also perform a complete γ-ray spectral and morphological analysis. No γ-ray pulsations were detected from PSR J1856+0245. But, significant emission is detected at a position coincident with the TeV source HESS J1857 + 026. The γ-ray spectrum is well described by a simple power-law with a spectral index of Γ = 1.53 ± 0.11_stat ± 0.55_syst and an energy flux of G(0.1–100 GeV) = (2.71 ± 0.52_stat ± 1.51_syst) × 10^-11 erg cm^-2 s^-1. The γ-ray luminosity is L_PWN^γ (0.1–100 GeV)=(2.5 ± 0.5_stat ± 1.5_syst) × 10³⁵ (d/9 kpc)² erg s^-1, assuming a distance of 9 kpc. This implies a γ-ray efficiency of ~5% for $$\dot{E}$$ = 4.6 × 10³⁶ erg s^-1, in the range expected for pulsar wind nebulae. This detailed multi-wavelength modeling provides new constraints on its pulsar wind nebula nature.

Authors:

Rousseau, R. ^[1]; Grondin, M. -H. ^[2]; Van Etten, A. ^[3]; Lemoine-Goumard, M. ^[1]; Bogdanov, S. ^[4]; Hessels, J. W. T. ^[5]; Kaspi, V. M. ^[6]; Arzoumanian, Z. ^[7]; Camilo, F. ^[4]; Casandjian, J. M. ^[8]; Espinoza, C. M. ^[9]; Johnston, S. ^[10]; Lyne, A. G. ^[9]; Smith, D. A. ^[1]; Stappers, B. W. ^[9]; Caliandro, G. A. ^[11]

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+ Show Author Affiliations

1. Univ. of Bordeaux (France). Bordeaux Gradignan Centre for Nuclear Research
2. Max Planck Inst. for Nuclear Physics, Heidelberg (Germany); Univ. of Heidelberg (Germany)
3. Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology
4. Columbia Univ., New York, NY (United States)
5. ASRON, Dwingeloo (Netherlands). Netherlands Inst. for Radio Astronomy; Univ. of Amsterdam (Netherlands). Astronomical Inst.
6. McGill Univ., Montreal, QC (Canada)
7. CRESST and NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
8. Univ. of Paris, Saclay (France). CEA Institute of Research into the Fundamental Laws of the Universe (CEA-IRFU)
9. Univ. of Manchester (United Kingdom). Jodrell Bank Centre for Astrophysics
10. Australia Telescope National Facility, Epping, NSW (Australia). CSIRO Astronomy and Space Science
11. Inst. of Space Sciences (IEE-CSIC), Barcelona (Spain)

Publication Date:

Tue Jul 17 00:00:00 EDT 2012

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE

Contributing Org.:

Fermi LAT Collaboration

OSTI Identifier:

1356692

Grant/Contract Number:  

AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

Astronomy and Astrophysics

Additional Journal Information:

Journal Volume: 544; Journal ID: ISSN 0004-6361

Publisher:

EDP Sciences

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; pulsars: general; pulsars: individual: PSR J1856+0245; ISM: individual objects: HESS J1857+026; gamma rays: general