A FAST search for radio pulsations during the dormant state of the accreting millisecond pulsars IGR J00291+5934 and MAXI J1957+032
Year: 2026
Type: article
Abstract: Accreting millisecond pulsars (AMSPs) and transitional millisecond pulsars (tMSPs) are neutron star low-mass X-ray binaries that can evolve into recycled radio millisecond pulsars. In both types of systems, X-ray pulsations have been detected during phases of X-ray activity when matter accretion through a disc was turned on. On the other hand, when accretion stops, and these systems enter the quiescent low-luminosity X-ray state, and only tMSPs become visible as radio pulsars. Despite several attempts, radio pulsations have never been detected in quiescent AMSPs, except for IGR J18245−2452. We present the results of two observational campaigns performed on the AMSPs IGR J00291+5934 and MAXI J1957+032 with the Five-hundred-meter Aperture Spherical Telescope ( FAST ) in L band (1–1.5 GHz). The two sources have most likely been observed in quiescence, as suggested by the upper limits on their X-ray and optical flux obtained with Swift and the Las Cumbres Observatory, respectively. We performed a deep search for coherent periodicities in radio, but found no significant candidate signal at the known spin frequency of these sources or at other frequencies. Assuming a pulse duty cycle of 10%, we derive upper limits on the pulsed radio flux density of 3.3 μJy and 5.6 μJy for IGR J00291+5934 and MAXI J1957+032, respectively, which are the most stringent limits for any known persistent AMSP so far.
Source: Astronomy and Astrophysics
Institutions: Universidad de Santiago de Chile, Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, National Institute for Astrophysics, Centre National de la Recherche Scientifique, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, Brera Astronomical Observatory, Astronomical Observatory of Rome, University of Cagliari, University of Palermo, Observatoire Midi-Pyrénées, Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, European Space Agency, European Space Astronomy Centre, Chinese Academy of Sciences, Yunnan Observatories, New York University Abu Dhabi, Istituto Universitario di Studi Superiori di Pavia
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: National Aeronautics and Space Administration, New York University Abu Dhabi, Agence Nationale de la Recherche, National Natural Science Foundation of China, Chinese Academy of Sciences, Fondazione Cariplo, Tamkeen, Agencia Nacional de Investigación y Desarrollo, Horizon 2020 Framework Programme, National Astronomical Observatories, Chinese Academy of Sciences, Division of Materials Research
OpenAlex ID: W7167851206