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Hitomi X-ray observation of the pulsar wind nebula G21.5−0.9

Hitomi X-ray observation of the pulsar wind nebula G21.5−0.9
Hitomi X-ray observation of the pulsar wind nebula G21.5−0.9
We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5−0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8–80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Γ1 = 1.74 ± 0.02 and Γ2 = 2.14 ± 0.01 below and above the break at 7.1 ± 0.3 keV, which is significantly lower than the NuSTAR result (∼9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833−1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 σ. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.
0004-6264
1-16
Aharonian, Felix
bde3f58c-9dfc-4915-a977-34168a2f734e
Akamatsu, Hiroki
ebeb105d-7906-4b7b-a0f0-b59f3283b313
Akimoto, Fumie
7cf2e818-44f0-4b56-92fe-ecd40e2a3ed0
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Hitomi Collaboration
Aharonian, Felix
bde3f58c-9dfc-4915-a977-34168a2f734e
Akamatsu, Hiroki
ebeb105d-7906-4b7b-a0f0-b59f3283b313
Akimoto, Fumie
7cf2e818-44f0-4b56-92fe-ecd40e2a3ed0
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9

Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie and Gandhi, Poshak , Hitomi Collaboration (2018) Hitomi X-ray observation of the pulsar wind nebula G21.5−0.9. Publications of the Astronomical Society of Japan, 70 (3), 1-16. (doi:10.1093/pasj/psy027).

Record type: Article

Abstract

We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5−0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8–80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Γ1 = 1.74 ± 0.02 and Γ2 = 2.14 ± 0.01 below and above the break at 7.1 ± 0.3 keV, which is significantly lower than the NuSTAR result (∼9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833−1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 σ. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.

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More information

e-pub ahead of print date: 3 April 2018
Published date: June 2018

Identifiers

Local EPrints ID: 424593
URI: https://eprints.soton.ac.uk/id/eprint/424593
ISSN: 0004-6264
PURE UUID: 0298def0-6ca4-49ae-8fd1-46bb48e8eeb9
ORCID for Poshak Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

Catalogue record

Date deposited: 05 Oct 2018 11:39
Last modified: 14 Mar 2019 01:32

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