2018A&A...617A..78T


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.03CEST21:17:10

2018A&A...617A..78T - Astronomy and Astrophysics, volume 617A, 78-78 (2018/9-1)

Disentangling multiple high-energy emission components in the Vela X pulsar wind nebula with the Fermi Large Area Telescope.

TIBALDO L., ZANIN R., FAGGIOLI G., BALLET J., GRONDIN M.-H., HINTON J.A. and LEMOINE-GOUMARD M.

Abstract (from CDS):


Context. Vela X is a pulsar wind nebula in which two relativistic particle populations with distinct spatial and spectral distributions dominate the emission at different wavelengths. An extended 2°x3° nebula is seen in radio and GeV gamma rays. An elongated cocoon prevails in X-rays and TeV gamma rays.
Aims. We use ∼9.5yr of data from the Fermi Large Area Telescope (LAT) to disentangle gamma-ray emission from the two components in the energy range from 10GeV to 2TeV, bridging the gap between previous measurements at GeV and TeV energies.
Methods. We determine the morphology of emission associated to Vela X separately at energies <100 and >100GeV, and compare it to the morphology seen at other wavelengths. Then, we derive the spectral energy distribution of the two gamma-ray components over the full energy range.
Results. The best overall fit to the LAT data is provided by the combination of the two components derived at energies <100 and >100GeV. The first component has a soft spectrum, spectral index 2.19±0.16–0.22+0.05, and extends over a region of radius 1.36±0.04°, consistent with the size of the radio nebula. The second component has a harder spectrum, spectral index 0.9±0.3–0.1+0.3, and is concentrated over an area of radius 0.63±0.03°, coincident with the X-ray cocoon that had already been established as accounting for the bulk of the emission at TeV energies.
Conclusions. The spectrum measured for the low-energy component corroborates previous evidence for a roll-over of the electron spectrum in the extended radio nebula at energies of a few tens of GeV possibly due to diffusive escape. The high-energy component has a very hard spectrum: if the emission is produced by electrons with a power-law spectrum, the electrons must be uncooled, and there is a hint that their spectrum may be harder than predictions by standard models of Fermi acceleration at relativistic shocks.

Abstract Copyright: © ESO 2018

Journal keyword(s): stars: winds, outflows - gamma rays: stars - pulsars: individual: PSR J0835-4510 - acceleration of particles - radiation mechanisms: non-thermal

Simbad objects: 2

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Number of rows : 2

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Vela X Psr 08 33 08.880 -45 11 24.36           ~ 242 1
2 NAME Vela Pulsar Psr 08 35 20.65525 -45 10 35.1545           ~ 2056 1

    Equat.    Gal    SGal    Ecl

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2020.07.03-21:17:10

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