Deep X-ray Observations of the Gamma-ray Bright Pulsar Wind Nebula HESS J1303-631
Abstract
HESS J1303−631 is an evolved, TeV-bright pulsar wind nebula (PWN) powered by the energetic radio pulsar PSR~J1301−6305, offset by ≈7' northwest of the TeV centroid, with an energy-dependent gamma-ray morphology. We present new, deep joint Chandra (108 ks) and XMM-Newton (102 ks) observations of this field. High-resolution Chandra ACIS imaging resolves the pulsar from a neighboring point source that XMM-Newton cannot separate. The pulsar's 2-10 keV spectrum is well described by an absorbed power law with Γ=2.02±1.04 and an unabsorbed luminosity of 3.44×1031 erg s−1 at d=4.7 kpc. Chandra also reveals faint diffuse emission east of the pulsar: a clumpy compact nebula on arcsecond scales (Γ=2.98±0.53, LX=4.15×1031 erg s−1) and a fainter extended nebula on arcminute scales (Γ=1.20±1.25, L=4.36×1031 erg s−1). This morphology, the hard GeV counterpart, and the energy-dependent TeV emission together support an evolved, synchrotron-underluminous PWN whose X-ray nebula is far more compact than its TeV nebula. We also serendipitously discovered a transient X-ray source, CXOU~J130131.0−625919, in one of the nine new Chandra observations. Its hard spectrum (Γ=1.4±0.3) and 0.5-7\,keV luminosity of 3.34×1032 erg s−1 at a fiducial distance of 3 kpc, together with a plausible near-infrared counterpart, most closely match a flare from a young pre-main-sequence star, though an active binary or compact-object binary is not excluded. Its large offset from HESS J1303−631 makes association with the TeV source unlikely.
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BibTeX
@misc{gagnon2026deep,
title = {{Deep X-ray Observations of the Gamma-ray Bright Pulsar Wind Nebula HESS J1303-631}},
author = {Seth Gagnon and Oleg Kargaltsev and Yichao Lin and Jeremy Hare and Jordan Eagle},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.26723},
eprint = {2610.26723},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.26723},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Deep X-ray Observations of the Gamma-ray Bright Pulsar Wind Nebula HESS J1303-631
AU - Seth Gagnon
AU - Oleg Kargaltsev
AU - Yichao Lin
AU - Jeremy Hare
AU - Jordan Eagle
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2610.26723
UR - https://arxiv.org/abs/2610.26723
AB - HESS J1303−631 is an evolved, TeV-bright pulsar wind nebula (PWN) powered by the energetic radio pulsar PSR~J1301−6305, offset by ≈7' northwest of the TeV centroid, with an energy-dependent gamma-ray morphology. We present new, deep joint Chandra (108 ks) and XMM-Newton (102 ks) observations of this field. High-resolution Chandra ACIS imaging resolves the pulsar from a neighboring point source that XMM-Newton cannot separate. The pulsar's 2-10 keV spectrum is well described by an absorbed power law with Γ=2.02±1.04 and an unabsorbed luminosity of 3.44×10^31 erg s^−1 at d=4.7 kpc. Chandra also reveals faint diffuse emission east of the pulsar: a clumpy compact nebula on arcsecond scales (Γ=2.98±0.53, L_X=4.15×10^31 erg s^−1) and a fainter extended nebula on arcminute scales (Γ=1.20±1.25, L=4.36×10^31 erg s^−1). This morphology, the hard GeV counterpart, and the energy-dependent TeV emission together support an evolved, synchrotron-underluminous PWN whose X-ray nebula is far more compact than its TeV nebula. We also serendipitously discovered a transient X-ray source, CXOU~J130131.0−625919, in one of the nine new Chandra observations. Its hard spectrum (Γ=1.4±0.3) and 0.5-7\,keV luminosity of 3.34×10^32 erg s^−1 at a fiducial distance of 3 kpc, together with a plausible near-infrared counterpart, most closely match a flare from a young pre-main-sequence star, though an active binary or compact-object binary is not excluded. Its large offset from HESS J1303−631 makes association with the TeV source unlikely.
ER -