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Evidence for hot clumpy accretion flow in the transitional millisecond pulsar PSR J1023+0038

Evidence for hot clumpy accretion flow in the transitional millisecond pulsar PSR J1023+0038
Evidence for hot clumpy accretion flow in the transitional millisecond pulsar PSR J1023+0038

We present simultaneous optical and near-infrared (IR) photometry of the millisecond pulsar PSR J1023+0038 during its low-mass X-ray binary phase. The r'- and Ks-band light curves show rectangular, flat-bottomed dips, similar to the X-ray mode-switching (active-passive state transitions) behaviour observed previously. The cross-correlation function (CCF) of the optical and near-IR data reveals a strong, broad negative anticorrelation at negative lags, a broad positive correlation at positive lags, with a strong, positive narrow correlation superimposed. The shape of the CCF resembles the CCF of black hole X-ray binaries but the time-scales are different. The features can be explained by reprocessing and a hot accretion flow close to the neutron star's magnetospheric radius. The optical emission is dominated by the reprocessed component, whereas the near-IR emission contains the emission from plasmoids in the hot accretion flow and a reprocessed component. The rapid active-passive state transition occurs when the hot accretion flowmaterial is channelled on to the neutron star and is expelled from its magnetosphere. During the transition the optical reprocessing component decreases resulting in the removal of a blue spectral component. The accretion of clumpy material through the magnetic barrier of the neutron star produces the observed near-IR/optical CCF and variability. The dip at negative lags corresponds to the suppression of the near-IR synchrotron component in the hot flow, whereas the broad positive correlation at positive lags is driven by the increased synchrotron emission of the outflowing plasmoids. The narrow peak in the CCF is due to the delayed reprocessed component, enhanced by the increased X-ray emission.

Binaries: Close, Stars: Fundamental parameters, Stars: Individual: PSR J1023+0038, Stars: Neutron, X-rays: Binaries
0035-8711
566-577
Shahbaz, T.
17cdfe98-d466-40b1-9810-86262df89777
Dallilar, Y.
05fa9bdb-5418-4468-b9e7-b9c0e289d368
Garner, A.
9b6674a0-6493-473c-90dc-1d4148a9782c
Eikenberry, S.
1e439ded-8c26-4664-809a-e817020237c3
Veledina, A.
6235d7df-e2e2-4c4b-907b-a5cafafe60ce
Gandhi, P.
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Shahbaz, T.
17cdfe98-d466-40b1-9810-86262df89777
Dallilar, Y.
05fa9bdb-5418-4468-b9e7-b9c0e289d368
Garner, A.
9b6674a0-6493-473c-90dc-1d4148a9782c
Eikenberry, S.
1e439ded-8c26-4664-809a-e817020237c3
Veledina, A.
6235d7df-e2e2-4c4b-907b-a5cafafe60ce
Gandhi, P.
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9

Shahbaz, T., Dallilar, Y., Garner, A., Eikenberry, S., Veledina, A. and Gandhi, P. (2018) Evidence for hot clumpy accretion flow in the transitional millisecond pulsar PSR J1023+0038. Monthly Notices of the Royal Astronomical Society, 477 (1), 566-577. (doi:10.1093/mnras/sty562).

Record type: Article

Abstract

We present simultaneous optical and near-infrared (IR) photometry of the millisecond pulsar PSR J1023+0038 during its low-mass X-ray binary phase. The r'- and Ks-band light curves show rectangular, flat-bottomed dips, similar to the X-ray mode-switching (active-passive state transitions) behaviour observed previously. The cross-correlation function (CCF) of the optical and near-IR data reveals a strong, broad negative anticorrelation at negative lags, a broad positive correlation at positive lags, with a strong, positive narrow correlation superimposed. The shape of the CCF resembles the CCF of black hole X-ray binaries but the time-scales are different. The features can be explained by reprocessing and a hot accretion flow close to the neutron star's magnetospheric radius. The optical emission is dominated by the reprocessed component, whereas the near-IR emission contains the emission from plasmoids in the hot accretion flow and a reprocessed component. The rapid active-passive state transition occurs when the hot accretion flowmaterial is channelled on to the neutron star and is expelled from its magnetosphere. During the transition the optical reprocessing component decreases resulting in the removal of a blue spectral component. The accretion of clumpy material through the magnetic barrier of the neutron star produces the observed near-IR/optical CCF and variability. The dip at negative lags corresponds to the suppression of the near-IR synchrotron component in the hot flow, whereas the broad positive correlation at positive lags is driven by the increased synchrotron emission of the outflowing plasmoids. The narrow peak in the CCF is due to the delayed reprocessed component, enhanced by the increased X-ray emission.

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Evidence for hot clumpy accretion flow in the transitional millisecond pulsar PSR J1023+0038 - Accepted Manuscript
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Accepted/In Press date: 26 February 2018
e-pub ahead of print date: 9 March 2018
Published date: 11 June 2018
Keywords: Binaries: Close, Stars: Fundamental parameters, Stars: Individual: PSR J1023+0038, Stars: Neutron, X-rays: Binaries

Identifiers

Local EPrints ID: 421434
URI: http://eprints.soton.ac.uk/id/eprint/421434
ISSN: 0035-8711
PURE UUID: c4d256da-1ed6-4187-a0d6-8eeb5214ca1e
ORCID for P. Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

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Date deposited: 11 Jun 2018 16:30
Last modified: 17 Dec 2019 01:34

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