Issue |
A&A
Volume 696, April 2025
|
|
---|---|---|
Article Number | A121 | |
Number of page(s) | 16 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/202452211 | |
Published online | 10 April 2025 |
The middle-aged pulsar PSR J1741–2054 and its bow-shock nebula in the far-ultraviolet⋆
1
Ioffe Institute, Politekhnicheskaya 26, St. Petersburg, 195251
Russia
2
Pennsylvania State University, Department of Astronomy & Astrophysics, 525 Dave Lab., University Park, PA, 16802
USA
3
Oxford Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH
UK
4
The George Washington University, Department of Physics, 725 21st Street, NW, Washington, DC, 20052
USA
⋆⋆ Corresponding authors; vadab2077@gmail.com, ggp1@psu.edu
Received:
11
September
2024
Accepted:
2
March
2025
Context. Far-ultraviolet (FUV) observations of pulsars allow us to measure surface temperatures of neutron stars and study their thermal evolution. Some pulsars can exhibit FUV bow-shock nebulae (BSNe), providing an additional tool for probing the interstellar medium and studying the pulsar’s properties. The nearby middle-aged gamma-ray pulsar J1741–2054 and its pulsar wind nebula (PWN) have been studied in X-rays, and its BSN has been investigated in the Balmer lines, but they have never been observed in the FUV.
Aims. To further study the thermal and magnetospheric emission from PSR J1741–2054 and the BSN properties, we observed them in the FUV range with the Hubble Space Telescope (HST).
Methods. We imaged the target in two FUV filters of the HST ACS/SBC detector. We also reanalyzed previous optical observations of the pulsar and its BSN. We fit the pulsar’s FUV-optical spectrum separately and together with its X-ray spectrum.
Results. We found that the pulsar’s FUV-optical spectrum consists of a thermal and a nonthermal component. A joint fit of the FUV-optical and X-ray spectra with combinations of the nonthermal and thermal components showed a hard optical nonthermal spectrum with a photon index Γopt ≈ 1.0–1.2 and a softer X-ray component, ΓX ≈ 2.6–2.7. The thermal emission is dominated by the cold component with the temperature kTcold ≈ 40–50 eV and emitting sphere radius Rcold ≈ 8–15 km, at d = 270 pc. An additional hot thermal component, with kThot ∼ 80 eV and Rhot ∼ 1 km, is also possible. Such a spectrum resembles the spectra of other middle-aged pulsars, but it shows a harder (softer) optical (X-ray) nonthermal spectrum. We detected the FUV BSN, the first one associated with a middle-aged pulsar. Its closed-shell morphology is similar to the Hα BSN morphology, while its FUV flux, ∼10−13 erg cm−2 s−1, is a factor of ∼4 higher than the Hα flux. This FUV BSN has a higher surface brightness than the two previously known BSNe.
Key words: shock waves / stars: neutron / pulsars: individual: PSR J1741–2054
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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