Is the Fermi source 4FGL J1824.2+1231 a transitional millisecond pulsar?
Year: 2025
Type: article
Abstract: Context. Transitional millisecond pulsars (tMSPs) in tight binary systems represent an important evolutionary link between low-mass X-ray binaries and radio millisecond pulsars. To date, only three confirmed tMSPs and a few candidates have been discovered. Most of them are γ-ray sources. For this reason, searching for multi-wavelength counterparts to unassociated Fermiγ-ray sources can help us find new tMSPs. Aims. We investigate whether the unassociated γ-ray source 4FGL J1824.2+1231 belongs to the tMSP family. Methods. To find the counterpart to 4FGL J1824.2+1231, we used data from the SRG/eROSITA and Swift X-ray catalogues and from different optical catalogues. We also performed time-series photometric optical observations of the source with the 2.1 m telescope of the Observatorio Astronómico Nacional San Pedro Mártir, the 1.5 m telescope of the Maidanak Astronomical Observatory, and the 1.5 m Russian-Turkish telescope. In addition, we carried out optical spectroscopic observations with the Russian-Turkish telescope and used archival spectroscopic data obtained with the Gemini-North telescope. Results. Within the position error ellipse of 4FGL J1824.2+1231, we find only one X-ray source that coincides with an optical object. We consider it a likely multi-wavelength counterpart to 4FGL J1824.2+1231. The source shows strong optical variability and significant proper motion. The latter strongly implies that it is a Galactic source. Double-peaked H and He emission lines are detected in its spectrum with a flat continuum, as often observed in accretion disks of compact binary systems. The X-ray spectrum is well fitted by a power law with a photon index of ∼1.7. The derived intrinsic X-ray-to-γ-ray flux ratio is about 0.2. Conclusions. Assuming the X-ray/optical source is the true counterpart to 4FGL J1824.2+1231, all its properties suggest that it is a tMSP in the sub-luminous disk state.
Source: Astronomy and Astrophysics
Authors: D. A. Zyuzin, A. V. Karpova, A. Yu. Kirichenko, Yu. A. Shibanov, I. F. Bikmaev, M. R. Gilfanov, E. N. Irtuganov, M. A. Gorbachev, M. V. Suslikov, R. Karimov, M. M. Veryazov, M. Pereyra
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Science Foundation, Smithsonian Institution, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, California Institute of Technology, Northwestern University, Johns Hopkins University, Drexel University, Space Telescope Science Institute, European Space Agency, University of Warwick, Queen's University Belfast, Durham University, Queen's University, Ministry of Education and Science of the Russian Federation, Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, National Central University, Stockholms Universitet, Eötvös Loránd Tudományegyetem, Kazan Federal University, Ioffe Institute, Max-Planck-Institut für Astronomie, Smithsonian Astrophysical Observatory, Science Mission Directorate, Russian Academy of Sciences, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México, Planetary Science Division, Los Alamos National Laboratory
Awards: Exploring & Exploiting the Dynamic Optical Sky, ZWICKY TRANSIENT FACILITY, G4474636675, G618131832, G6508760690, A NEO SEARCH PROGRAM USING THE PAN-STARRS PS1 TELESCOPETHE GOAL OF THE PROPOSED RESEARCH IS TO USE T, G7187964967, G7746265670, Pan-STARRS1: Operations; Public Data Release; Education and Outreach, G833430883, G8337580908
OpenAlex ID: W4410885151