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Mid-UV studies of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states

Mid-UV studies of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states
Mid-UV studies of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states
We report mid-UV (MUV) observations taken with HST/WFC3, Swift/UVOT and GALEX/NUV of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states. Both systems were detected in our images and showed MUV variability. At similar orbital phases, the MUV luminosities of both pulsars are comparable. This suggests that the emission processes involved in both objects are similar. We estimated limits on the mass ratio, companion's temperature, inclination, and distance to XSS J12270-4859 by using a Markov Chain Monte Carlo algorithm to fit published folded optical light curves. Using the resulting parameters, we modeled MUV light curves in our HST filters. The resulting models failed to fit our MUV observations. Fixing the mass ratio of XSS J12270-4859 to the value reported in other studies, we obtained a distance of ~3.2 kpc. This is larger than the one derived from radio measurements (~1.4 kpc). Assuming a uniform prior for the mass ratio, the distance is similar to that from radio measurements. However, it requires an undermassive companion (~0.01 M_sun). We conclude that a direct heating model alone can not fully explain the observations in optical and MUV. Therefore, an additional radiation source is needed. The source could be an intrabinary shock which contributes to the MUV flux and likely to the optical one as well. During the radio pulsar state, the MUV orbital variations of PSR J1023+0038 detected with GALEX, suggests the presence of an asymmetric intrabinary shock.
astro-ph.HE, astro-ph.SR
0035-8711
1086-1099
Sandoval, L.E. Rivera
865a4448-dae0-4dfb-a0d1-24863891459e
Santisteban, J.V. Hernandez
a2d27157-6438-4256-85c2-7978e3106f68
Degenaar, N.
54149051-d74e-4e43-a7cd-501ec4023511
Wijnands, R.
382893ee-0e03-45e3-9321-db8b9fc74914
Knigge, C.
ac320eec-631a-426e-b2db-717c8bf7857e
Miller, J.M.
29683965-a939-4107-bcd0-de1109154e7c
Reynolds, M.
321eb5ea-deac-484a-97eb-193c3e03248e
Altamirano, D.
d5ccdb09-0b71-4303-9538-05b467be075b
Berg, M. van den
a26a14f7-7078-4654-932f-0a31c2629263
Hill, A.
b1007941-b5b1-47cd-8476-7c6b9c57f347
Sandoval, L.E. Rivera
865a4448-dae0-4dfb-a0d1-24863891459e
Santisteban, J.V. Hernandez
a2d27157-6438-4256-85c2-7978e3106f68
Degenaar, N.
54149051-d74e-4e43-a7cd-501ec4023511
Wijnands, R.
382893ee-0e03-45e3-9321-db8b9fc74914
Knigge, C.
ac320eec-631a-426e-b2db-717c8bf7857e
Miller, J.M.
29683965-a939-4107-bcd0-de1109154e7c
Reynolds, M.
321eb5ea-deac-484a-97eb-193c3e03248e
Altamirano, D.
d5ccdb09-0b71-4303-9538-05b467be075b
Berg, M. van den
a26a14f7-7078-4654-932f-0a31c2629263
Hill, A.
b1007941-b5b1-47cd-8476-7c6b9c57f347

Sandoval, L.E. Rivera, Santisteban, J.V. Hernandez, Degenaar, N., Wijnands, R., Knigge, C., Miller, J.M., Reynolds, M., Altamirano, D., Berg, M. van den and Hill, A. (2018) Mid-UV studies of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states. Monthly Notices of the Royal Astronomical Society, 476 (1), 1086-1099. (doi:10.1093/mnras/sty291).

Record type: Article

Abstract

We report mid-UV (MUV) observations taken with HST/WFC3, Swift/UVOT and GALEX/NUV of the transitional millisecond pulsars XSS J12270-4859 and PSR J1023+0038 during their radio pulsar states. Both systems were detected in our images and showed MUV variability. At similar orbital phases, the MUV luminosities of both pulsars are comparable. This suggests that the emission processes involved in both objects are similar. We estimated limits on the mass ratio, companion's temperature, inclination, and distance to XSS J12270-4859 by using a Markov Chain Monte Carlo algorithm to fit published folded optical light curves. Using the resulting parameters, we modeled MUV light curves in our HST filters. The resulting models failed to fit our MUV observations. Fixing the mass ratio of XSS J12270-4859 to the value reported in other studies, we obtained a distance of ~3.2 kpc. This is larger than the one derived from radio measurements (~1.4 kpc). Assuming a uniform prior for the mass ratio, the distance is similar to that from radio measurements. However, it requires an undermassive companion (~0.01 M_sun). We conclude that a direct heating model alone can not fully explain the observations in optical and MUV. Therefore, an additional radiation source is needed. The source could be an intrabinary shock which contributes to the MUV flux and likely to the optical one as well. During the radio pulsar state, the MUV orbital variations of PSR J1023+0038 detected with GALEX, suggests the presence of an asymmetric intrabinary shock.

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Mid-UV Studies of the Transitional Millisecond Pulsars - Accepted Manuscript
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Submitted date: 23 August 2017
Accepted/In Press date: 30 January 2018
e-pub ahead of print date: 5 February 2018
Published date: May 2018
Keywords: astro-ph.HE, astro-ph.SR

Identifiers

Local EPrints ID: 413617
URI: http://eprints.soton.ac.uk/id/eprint/413617
ISSN: 0035-8711
PURE UUID: dccde1f3-df76-4f80-b67f-ac51d773a310
ORCID for D. Altamirano: ORCID iD orcid.org/0000-0002-3422-0074
ORCID for A. Hill: ORCID iD orcid.org/0000-0003-3470-4834

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Date deposited: 30 Aug 2017 16:31
Last modified: 17 Dec 2019 01:48

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Contributors

Author: L.E. Rivera Sandoval
Author: J.V. Hernandez Santisteban
Author: N. Degenaar
Author: R. Wijnands
Author: C. Knigge
Author: J.M. Miller
Author: M. Reynolds
Author: D. Altamirano ORCID iD
Author: M. van den Berg
Author: A. Hill ORCID iD

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