Probing the spectrum of the magnetar 4U 0142+61 with JWST

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Main Authors: Hare, Jeremy, Pavlov, George G., Posselt, Bettina, Kargaltsev, Oleg, Temim, Tea, Chen, Steven
Format: Preprint
Published: 2024
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author Hare, Jeremy
Pavlov, George G.
Posselt, Bettina
Kargaltsev, Oleg
Temim, Tea
Chen, Steven
author_facet Hare, Jeremy
Pavlov, George G.
Posselt, Bettina
Kargaltsev, Oleg
Temim, Tea
Chen, Steven
contents JWST observed the magnetar 4U 0142+61 with the MIRI and NIRCam instruments within a 77 min time interval on 2022 September 20-21. The low-resolution MIRI spectrum and NIRCam photometry show that the spectrum in the wavelength range 1.4-11 $μ$m range can be satisfactorily described by an absorbed power-law model, $f_ν\propto ν^{-α}$, with a spectral slope $α=0.96\pm0.02$, interstellar extinction $A_V= 3.9\pm0.2$, and normalization $f_0 = 59.4\pm 0.5$ $μ$Jy at $λ= 8$ $μ$m. These observations do not support the passive disk model proposed by Wang et al. (2006), based on the Spitzer photometry, which was interpreted as evidence for a fallback disk from debris formed during the supernova explosion. We suggest a nonthermal origin for this emission and source variability as the most likely cause of discrepancies between the JWST data and other IR-optical observing campaigns. However, we cannot firmly exclude the presence of a large disk with a different dependence of the effective disk temperature on distance from the magnetar. Comparison with the power-law fit to the hard X-ray spectrum above 10 keV, measured by NuSTAR contemporaneously with JWST, shows that the X-ray spectrum is significantly harder. This may imply that the X-ray and IR nonthermal emission come from different sites in the magnetosphere of the magnetar.
format Preprint
id arxiv_https___arxiv_org_abs_2405_03947
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Probing the spectrum of the magnetar 4U 0142+61 with JWST
Hare, Jeremy
Pavlov, George G.
Posselt, Bettina
Kargaltsev, Oleg
Temim, Tea
Chen, Steven
High Energy Astrophysical Phenomena
JWST observed the magnetar 4U 0142+61 with the MIRI and NIRCam instruments within a 77 min time interval on 2022 September 20-21. The low-resolution MIRI spectrum and NIRCam photometry show that the spectrum in the wavelength range 1.4-11 $μ$m range can be satisfactorily described by an absorbed power-law model, $f_ν\propto ν^{-α}$, with a spectral slope $α=0.96\pm0.02$, interstellar extinction $A_V= 3.9\pm0.2$, and normalization $f_0 = 59.4\pm 0.5$ $μ$Jy at $λ= 8$ $μ$m. These observations do not support the passive disk model proposed by Wang et al. (2006), based on the Spitzer photometry, which was interpreted as evidence for a fallback disk from debris formed during the supernova explosion. We suggest a nonthermal origin for this emission and source variability as the most likely cause of discrepancies between the JWST data and other IR-optical observing campaigns. However, we cannot firmly exclude the presence of a large disk with a different dependence of the effective disk temperature on distance from the magnetar. Comparison with the power-law fit to the hard X-ray spectrum above 10 keV, measured by NuSTAR contemporaneously with JWST, shows that the X-ray spectrum is significantly harder. This may imply that the X-ray and IR nonthermal emission come from different sites in the magnetosphere of the magnetar.
title Probing the spectrum of the magnetar 4U 0142+61 with JWST
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2405.03947