Short-term variability of the transitional pulsar candidate CXOU J110926.4-650224 from X-rays to infrared

F. Coti Zelati; D. de Martino; V. S. Dhillon; T. R. Marsh; F. Vincentelli; S. Campana; D. F. Torres; A. Papitto; M. C. Baglio; A. Miraval Zanon; N. Rea; J. Brink; D. A. H. Buckley; P. D'Avanzo; G. Illiano; A. Manca; A. Marino

doi:10.1051/0004-6361/202450915

Short-term variability of the transitional pulsar candidate CXOU J110926.4-650224 from X-rays to infrared

F. Coti Zelati, D. de Martino, V. S. Dhillon, T. R. Marsh, F. Vincentelli, S. Campana, D. F. Torres, A. Papitto, M. C. Baglio, A. Miraval Zanon, N. Rea, J. Brink, D. A. H. Buckley, P. D'Avanzo, G. Illiano, A. Manca, A. Marino

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

CXOU J110926.4-650224 is a candidate transitional millisecond pulsar (tMSP) with X-ray and radio emission properties reminiscent of those observed in confirmed tMSPs in their X-ray 'subluminous' disc state. We present the results of observing campaigns that, for the first time, characterise the optical and near-infrared variability of this source and establish a connection with the mode-switching phenomenon observed in X-rays. The optical emission exhibited flickering activity, frequent dipping episodes where it appeared redder, and a multi-peaked flare where it was bluer. The variability pattern was strongly correlated with that of the X-ray emission. Each dip matched an X-ray low-mode episode, indicating that a significant portion of the optical emission originates from nearly the same region as the X-ray emission. The near-infrared emission also displayed remarkable variability, including a dip of 20 min in length during which it nearly vanished. Time-resolved optical spectroscopic observations reveal significant changes in the properties of emission lines from the disc and help infer the spectral type of the companion star to be between K0 and K5. We compare the properties of CXOU J110926.4-650224 with those of other tMSPs in the X-ray subluminous disc state and discuss our findings within the context of a recently proposed scenario that explains the phenomenology exhibited by the prototypical tMSP PSR J1023+0038.

Original language	English
Article number	A220
Number of pages	11
Journal	Astronomy & Astrophysics
Volume	690
Early online date	18 Sept 2024
DOIs	https://doi.org/10.1051/0004-6361/202450915
Publication status	Published - 10 Oct 2024
Externally published	Yes

Bibliographical note

Publisher Copyright:
© The Authors 2024.

Funding

We thank the referee for their valuable comments, which helped improve the manuscript. We are grateful to Paranal Science Operations for allowing us to reschedule the VLT observations. We acknowledge excellent support from the ESO observing staff in Paranal, in particular Fuyan Bian, Jonathan Smoker and Luca Sbordone. FCZ is supported by a Ramón y Cajal fellowship (grant agreement RYC2021-030888-I). FCZ, NR and A. Marino are supported by the H2020 ERC Consolidator Grant ‘MAGNESIA’ under grant agreement No. 817661 and from grant SGR2021-01269 (PI: Graber/Rea). FCZ, DdM, PDA, SC, AP and GI acknowledge financial support from the Italian National Institute for Astrophysics (INAF) Research Grant “Uncovering the optical beat of the fastest magnetised neutron stars” (FANS; PI: AP). AP and GI also acknowledge financial support from the Italian Ministry of University and Research (MUR) under PRIN 2020 grant No. 2020BRP57Z ‘Gravitational and Electromagnetic wave Sources in the Universe with current and nextgeneration detectors (GEMS)’. GI is also supported by the AASS Ph.D. joint research program between the University of Rome ‘Sapienza’ and the University of Rome ‘Tor Vergata’, with the collaboration of INAF. VSD and ULTRACAM operations are funded by the Science and Technology Facilities Council (grant ST/V000853/1). DAHB is supported by the National Research Foundation (NRF) of South Africa. PDA and SC acknowledge support from ASI grant I/004/11/5. DFT is supported by the grant PID2021-124581OB-I00 funded by MCIU/AEI/10.13039/501100011033 and 2021SGR00426 of the Generalitat de Catalunya. AMZ is supported by PRIN-MIUR 2017 UnIAM (Unifying Isolated and Accreting Magnetars; PI: S. Mereghetti). This work was also supported by the Spanish program Unidad de Excelencia María de Maeztu CEX2020-001058-M and by MCIU with funding from European Union NextGeneration EU (PRTR-C17.I1) We also acknowledge the support of the PHAROS COST Action (CA16214). This work is based on observations collected at the European Southern Observatory under ESO programmes 0103.D-0241 and 105.20UV.001 and at the South African Astronomical Observatory under programmes 2018-2-LSP-001 and 2020-2-SCI-027. XMM-Newton is an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. The ULTRACAM data can be obtained by contacting the corresponding author or the ULTRACAM team (V. S. Dhillon). The XMM-Newton data (obs. ID: 0864190201) are publicly available at the European Space Agency (ESA) archive ( http://nxsa.esac.esa.int/nxsa-web ). The VLT data can be accessed on the ESO online data archive ( http://archive.eso.org/ ). This research has made use of the following software: ASTROPY v.6.0.1 (Price-Whelan 2013); astropy:2018; astropy:2022, ESO HAWKI instrument pipeline v.2.4.13 ( https://www.eso.org/sci/software/pipelines/hawki/hawki-pipe-recipes.html ), HEASOFT v.6.33.2 ( https://heasarc.gsfc.nasa.gov/lheasoft ), HiPERCAM data reduction pipeline v.1.2.0 ( https://github.com/HiPERCAM/hipercam ), IRAF v.2.18 ( https://github.com/iraf-community/iraf ), MATPLOTLIB v.3.8 (Hunter 2007), NUMPY v.1.26.0 (Harris et al. 2020), PYSALT (Crawford et al. 2010), SAOImageDS9 v.8.6 (Joye & Mandel 2003), SAS v.21.0.0 (Gabriel et al. 2004), SCIPY v.1.13.0 (Virtanen et al. 2020), Stingray v.2.0.0 (Huppenkothen et al. 2019a,b; Bachetti et al. 2021), The Joker v.1.3.0 (Price-Whelan et al. 2017), XRONOS v.5.22 (Stella & Angelini 1992), XSPEC v.12.14.0 (Arnaud 1996). We thank the referee for their valuable comments, which helped improve the manuscript. We are grateful to Paranal Science Operations for allowing us to reschedule the VLT observations. We acknowledge excellent support from the ESO observing sta in Paranal, in particular Fuyan Bian, Jonathan Smoker and Luca Sbordone. FCZ is supported by a Ramón y Cajal fellowship (grant agreement RYC2021-030888-I). FCZ, NR and A. Marino are supported by the H2020 ERC Consolidator Grant 'MAGNESIA' under grant agreement No. 817661 and from grant SGR2021-01269 (PI: Graber/Rea). FCZ, DdM, PDA, SC, AP and GI acknowledge financial support from the Italian National Institute for Astrophysics (INAF) Research Grant "Uncovering the optical beat of the fastest magnetised neutron stars" (FANS; PI: AP). AP and GI also acknowledge financial support from the Italian Ministry of University and Research (MUR) under PRIN 2020 grant No. 2020BRP57Z 'Gravitational and Electromagnetic wave Sources in the Universe with current and nextgeneration detectors (GEMS)'. GI is also supported by the AASS Ph.D. joint research program between the University of Rome 'Sapienza' and the University of Rome 'Tor Vergata', with the collaboration of INAF. VSD and ULTRACAM operations are funded by the Science and Technology Facilities Council (grant ST/V000853/1). DAHB is supported by the National Research Foundation (NRF) of South Africa. PDA and SC acknowledge support from ASI grant I/004/11/5. DFT is supported by the grant PID2021-124581OB-I00 funded by MCIU/AEI/10.13039/501100011033 and 2021SGR00426 of the Generalitat de Catalunya. AMZ is supported by PRIN-MIUR 2017 UnIAM (Unifying Isolated and Accreting Magnetars; PI: S. Mereghetti). This work was also supported by the Spanish program Unidad de Excelencia María de Maeztu CEX2020-001058-M and by MCIU with funding from European Union NextGeneration EU (PRTR-C17.I1) We also acknowledge the support of the PHAROS COST Action (CA16214). This work is based on observations collected at the European Southern Observatory under ESO programmes 0103.D-0241 and 105.20UV.001 and at the South African Astronomical Observatory under programmes 2018-2-LSP-001 and 2020-2-SCI-027. XMM-Newton is an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. The ULTRACAM data can be obtained by contacting the corresponding author or the ULTRACAM team (V. S. Dhillon). The XMM-Newton data (obs. ID: 0864190201) are publicly available at the European Space Agency (ESA) archive (http://nxsa.esac.esa.int/nxsa-web). The VLT data can be accessed on the ESO online data archive (http://archive.eso.org/). This research has made use of the following software: ASTROPY v.6.0.1 (Price-Whelan 2013, 2018, 2022), ESO HAWKI instrument pipeline v.2.4.13 (https://www.eso.org/sci/software/ pipelines/hawki/hawki-pipe-recipes.html), HEASOFT v.6.33.2 (https://heasarc.gsfc.nasa.gov/lheasoft), HiPERCAM data reduction pipeline v.1.2.0 (https://github.com/HiPERCAM/hipercam), IRAF v.2.18 (https://github.com/iraf-community/iraf), MATPLOTLIB v.3.8 (Hunter 2007), NUMPY v.1.26.0 (Harris et al. 2020), PYSALT (Crawford et al. 2010), SAOImageDS9 v.8.6 (Joye & Mandel 2003), SAS v.21.0.0 (Gabriel et al. 2004), SCIPY v.1.13.0 (Virtanen et al. 2020), Stingray v.2.0.0 (Huppenkothen et al. 2019a,b; Bachetti et al. 2021), The Joker v.1.3.0 (Price-Whelan et al. 2017), XRONOS v.5.22 (Stella & Angelini 1992), XSPEC v.12.14.0 (Arnaud 1996).

Funders	Funder number
Generalitat de Catalunya
Sapienza University of Rome
National Institute for Astrophysics
National Research Foundation
Ministry of Science, Innovation and Universities
Science and Technology Facilities Council (STFC)	ST/V000853/1
European Southern Observatory	RYC2021-030888-I
European Union	2020-2-SCI-027, PRTR-C17, 2018-2-LSP-001, CA16214, 105.20UV.001
Ministero dell’Istruzione, dell’Università e della Ricerca	2020BRP57Z
European Space Agency	12.14.0, 2017, 2.4.13, 2021, 2010, 2020, 2019a
Horizon Europe	817661, SGR2021-01269
NASA	0864190201
Agenzia Spaziale Italiana	MCIU/AEI/10.13039/501100011033, I/004/11/5, PID2021-124581OB-I00, 2021SGR00426

Keywords

Accretion, accretion disks
Methods: data analysis
Methods: observational
Techniques: photometric
Techniques: radial velocities
Techniques: spectroscopic

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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aa50915-24Final published version, 25.6 MBLicence: CC BY
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Zelati, F. C., de Martino, D., Dhillon, V. S., Marsh, T. R., Vincentelli, F., Campana, S., Torres, D. F., Papitto, A., Baglio, M. C., Zanon, A. M., Rea, N., Brink, J., Buckley, D. A. H., D'Avanzo, P., Illiano, G., Manca, A., & Marino, A. (2024). Short-term variability of the transitional pulsar candidate CXOU J110926.4-650224 from X-rays to infrared. Astronomy & Astrophysics, 690, Article A220. https://doi.org/10.1051/0004-6361/202450915

Zelati, FC, de Martino, D, Dhillon, VS, Marsh, TR, Vincentelli, F, Campana, S, Torres, DF, Papitto, A, Baglio, MC, Zanon, AM, Rea, N, Brink, J, Buckley, DAH, D'Avanzo, P, Illiano, G, Manca, A & Marino, A 2024, 'Short-term variability of the transitional pulsar candidate CXOU J110926.4-650224 from X-rays to infrared', Astronomy & Astrophysics, vol. 690, A220. https://doi.org/10.1051/0004-6361/202450915

@article{256d8bb8001746689f88d6040edcf6c1,

title = "Short-term variability of the transitional pulsar candidate CXOU J110926.4-650224 from X-rays to infrared",

abstract = "CXOU J110926.4-650224 is a candidate transitional millisecond pulsar (tMSP) with X-ray and radio emission properties reminiscent of those observed in confirmed tMSPs in their X-ray 'subluminous' disc state. We present the results of observing campaigns that, for the first time, characterise the optical and near-infrared variability of this source and establish a connection with the mode-switching phenomenon observed in X-rays. The optical emission exhibited flickering activity, frequent dipping episodes where it appeared redder, and a multi-peaked flare where it was bluer. The variability pattern was strongly correlated with that of the X-ray emission. Each dip matched an X-ray low-mode episode, indicating that a significant portion of the optical emission originates from nearly the same region as the X-ray emission. The near-infrared emission also displayed remarkable variability, including a dip of 20 min in length during which it nearly vanished. Time-resolved optical spectroscopic observations reveal significant changes in the properties of emission lines from the disc and help infer the spectral type of the companion star to be between K0 and K5. We compare the properties of CXOU J110926.4-650224 with those of other tMSPs in the X-ray subluminous disc state and discuss our findings within the context of a recently proposed scenario that explains the phenomenology exhibited by the prototypical tMSP PSR J1023+0038.",

keywords = "Accretion, accretion disks, Methods: data analysis, Methods: observational, Techniques: photometric, Techniques: radial velocities, Techniques: spectroscopic",

author = "Zelati, \{F. Coti\} and \{de Martino\}, D. and Dhillon, \{V. S.\} and Marsh, \{T. R.\} and F. Vincentelli and S. Campana and Torres, \{D. F.\} and A. Papitto and Baglio, \{M. C.\} and Zanon, \{A. Miraval\} and N. Rea and J. Brink and Buckley, \{D. A. H.\} and P. D'Avanzo and G. Illiano and A. Manca and A. Marino",

note = "Publisher Copyright: {\textcopyright} The Authors 2024.",

year = "2024",

month = oct,

day = "10",

doi = "10.1051/0004-6361/202450915",

language = "English",

volume = "690",

journal = "Astronomy \& Astrophysics",

issn = "0004-6361",

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T1 - Short-term variability of the transitional pulsar candidate CXOU J110926.4-650224 from X-rays to infrared

AU - Zelati, F. Coti

AU - de Martino, D.

AU - Dhillon, V. S.

AU - Marsh, T. R.

AU - Vincentelli, F.

AU - Campana, S.

AU - Torres, D. F.

AU - Papitto, A.

AU - Baglio, M. C.

AU - Zanon, A. Miraval

AU - Rea, N.

AU - Brink, J.

AU - Buckley, D. A. H.

AU - D'Avanzo, P.

AU - Illiano, G.

AU - Manca, A.

AU - Marino, A.

PY - 2024/10/10

Y1 - 2024/10/10

N2 - CXOU J110926.4-650224 is a candidate transitional millisecond pulsar (tMSP) with X-ray and radio emission properties reminiscent of those observed in confirmed tMSPs in their X-ray 'subluminous' disc state. We present the results of observing campaigns that, for the first time, characterise the optical and near-infrared variability of this source and establish a connection with the mode-switching phenomenon observed in X-rays. The optical emission exhibited flickering activity, frequent dipping episodes where it appeared redder, and a multi-peaked flare where it was bluer. The variability pattern was strongly correlated with that of the X-ray emission. Each dip matched an X-ray low-mode episode, indicating that a significant portion of the optical emission originates from nearly the same region as the X-ray emission. The near-infrared emission also displayed remarkable variability, including a dip of 20 min in length during which it nearly vanished. Time-resolved optical spectroscopic observations reveal significant changes in the properties of emission lines from the disc and help infer the spectral type of the companion star to be between K0 and K5. We compare the properties of CXOU J110926.4-650224 with those of other tMSPs in the X-ray subluminous disc state and discuss our findings within the context of a recently proposed scenario that explains the phenomenology exhibited by the prototypical tMSP PSR J1023+0038.

AB - CXOU J110926.4-650224 is a candidate transitional millisecond pulsar (tMSP) with X-ray and radio emission properties reminiscent of those observed in confirmed tMSPs in their X-ray 'subluminous' disc state. We present the results of observing campaigns that, for the first time, characterise the optical and near-infrared variability of this source and establish a connection with the mode-switching phenomenon observed in X-rays. The optical emission exhibited flickering activity, frequent dipping episodes where it appeared redder, and a multi-peaked flare where it was bluer. The variability pattern was strongly correlated with that of the X-ray emission. Each dip matched an X-ray low-mode episode, indicating that a significant portion of the optical emission originates from nearly the same region as the X-ray emission. The near-infrared emission also displayed remarkable variability, including a dip of 20 min in length during which it nearly vanished. Time-resolved optical spectroscopic observations reveal significant changes in the properties of emission lines from the disc and help infer the spectral type of the companion star to be between K0 and K5. We compare the properties of CXOU J110926.4-650224 with those of other tMSPs in the X-ray subluminous disc state and discuss our findings within the context of a recently proposed scenario that explains the phenomenology exhibited by the prototypical tMSP PSR J1023+0038.

KW - Accretion, accretion disks

KW - Methods: data analysis

KW - Methods: observational

KW - Techniques: photometric

KW - Techniques: radial velocities

KW - Techniques: spectroscopic

UR - https://www.scopus.com/pages/publications/85207632327

U2 - 10.1051/0004-6361/202450915

DO - 10.1051/0004-6361/202450915

M3 - Article

SN - 0004-6361

VL - 690

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A220

ER -

Short-term variability of the transitional pulsar candidate CXOU J110926.4-650224 from X-rays to infrared

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