Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624
<jats:title>Abstract</jats:title> <jats:p>We present the first joint NuSTAR and NICER observations of the ultracompact X-ray binary (UCXB) 4U 1543−624 obtained in 2020 April. The source was at a luminosity of <jats:italic>L</jats:italic>...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Astronomical Society
2022
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| Online Access: | https://hdl.handle.net/1721.1/141429 |
| _version_ | 1826193167772286976 |
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| author | Ludlam, RM Jaodand, AD García, JA Degenaar, N Tomsick, JA Cackett, EM Fabian, AC Gandhi, P Buisson, DJK Shaw, AW Chakrabarty, D |
| author_facet | Ludlam, RM Jaodand, AD García, JA Degenaar, N Tomsick, JA Cackett, EM Fabian, AC Gandhi, P Buisson, DJK Shaw, AW Chakrabarty, D |
| author_sort | Ludlam, RM |
| collection | MIT |
| description | <jats:title>Abstract</jats:title>
<jats:p>We present the first joint NuSTAR and NICER observations of the ultracompact X-ray binary (UCXB) 4U 1543−624 obtained in 2020 April. The source was at a luminosity of <jats:italic>L</jats:italic>
<jats:sub>0.5−50 keV</jats:sub> = 4.9(<jats:italic>D</jats:italic>/7 kpc)<jats:sup>2</jats:sup> × 10<jats:sup>36</jats:sup> erg s<jats:sup>−1</jats:sup> and showed evidence of reflected emission in the form of an O <jats:sc>viii</jats:sc> line, Fe K line, and Compton hump within the spectrum. We used a full reflection model, known as <jats:sc>xillverCO</jats:sc>, that is tailored for the atypical abundances found in UCXBs, to account for the reflected emission. We tested the emission radii of the O and Fe line components and conclude that they originate from a common disk radius in the innermost region of the accretion disk (<jats:italic>R</jats:italic>
<jats:sub>in</jats:sub> ≤ 1.07 <jats:italic>R</jats:italic>
<jats:sub>ISCO</jats:sub>). Assuming that the compact accretor is a neutron star (NS) and the position of the inner disk is the Alfvén radius, we placed an upper limit on the magnetic field strength to be <jats:italic>B</jats:italic> ≤ 0.7(<jats:italic>D</jats:italic>/7 kpc) × 10<jats:sup>8</jats:sup> G at the poles. Given the lack of pulsations detected and position of <jats:italic>R</jats:italic>
<jats:sub>in</jats:sub>, it was likely that a boundary layer region had formed between the NS surface and inner edge of the accretion disk with an extent of 1.2 km. This implies a maximum radius of the neutron star accretor of <jats:italic>R</jats:italic>
<jats:sub>NS</jats:sub> ≤ 12.1 km when assuming a canonical NS mass of 1.4 <jats:italic>M</jats:italic>
<jats:sub>⊙</jats:sub>.</jats:p> |
| first_indexed | 2024-09-23T09:35:06Z |
| format | Article |
| id | mit-1721.1/141429 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T09:35:06Z |
| publishDate | 2022 |
| publisher | American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/1414292022-04-01T03:35:44Z Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624 Ludlam, RM Jaodand, AD García, JA Degenaar, N Tomsick, JA Cackett, EM Fabian, AC Gandhi, P Buisson, DJK Shaw, AW Chakrabarty, D <jats:title>Abstract</jats:title> <jats:p>We present the first joint NuSTAR and NICER observations of the ultracompact X-ray binary (UCXB) 4U 1543−624 obtained in 2020 April. The source was at a luminosity of <jats:italic>L</jats:italic> <jats:sub>0.5−50 keV</jats:sub> = 4.9(<jats:italic>D</jats:italic>/7 kpc)<jats:sup>2</jats:sup> × 10<jats:sup>36</jats:sup> erg s<jats:sup>−1</jats:sup> and showed evidence of reflected emission in the form of an O <jats:sc>viii</jats:sc> line, Fe K line, and Compton hump within the spectrum. We used a full reflection model, known as <jats:sc>xillverCO</jats:sc>, that is tailored for the atypical abundances found in UCXBs, to account for the reflected emission. We tested the emission radii of the O and Fe line components and conclude that they originate from a common disk radius in the innermost region of the accretion disk (<jats:italic>R</jats:italic> <jats:sub>in</jats:sub> ≤ 1.07 <jats:italic>R</jats:italic> <jats:sub>ISCO</jats:sub>). Assuming that the compact accretor is a neutron star (NS) and the position of the inner disk is the Alfvén radius, we placed an upper limit on the magnetic field strength to be <jats:italic>B</jats:italic> ≤ 0.7(<jats:italic>D</jats:italic>/7 kpc) × 10<jats:sup>8</jats:sup> G at the poles. Given the lack of pulsations detected and position of <jats:italic>R</jats:italic> <jats:sub>in</jats:sub>, it was likely that a boundary layer region had formed between the NS surface and inner edge of the accretion disk with an extent of 1.2 km. This implies a maximum radius of the neutron star accretor of <jats:italic>R</jats:italic> <jats:sub>NS</jats:sub> ≤ 12.1 km when assuming a canonical NS mass of 1.4 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>.</jats:p> 2022-03-31T12:46:08Z 2022-03-31T12:46:08Z 2021 2022-03-31T12:39:48Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/141429 Ludlam, RM, Jaodand, AD, García, JA, Degenaar, N, Tomsick, JA et al. 2021. "Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624." Astrophysical Journal, 911 (2). en 10.3847/1538-4357/ABEDB0 Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Astronomical Society The American Astronomical Society |
| spellingShingle | Ludlam, RM Jaodand, AD García, JA Degenaar, N Tomsick, JA Cackett, EM Fabian, AC Gandhi, P Buisson, DJK Shaw, AW Chakrabarty, D Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624 |
| title | Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624 |
| title_full | Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624 |
| title_fullStr | Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624 |
| title_full_unstemmed | Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624 |
| title_short | Simultaneous NICER and NuSTAR Observations of the Ultracompact X-Ray Binary 4U 1543–624 |
| title_sort | simultaneous nicer and nustar observations of the ultracompact x ray binary 4u 1543 624 |
| url | https://hdl.handle.net/1721.1/141429 |
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