Multiwavelength observations of a new black-widow millisecond pulsar PSR J1544−2555

ABSTRACT We report the discovery of a new black-widow millisecond pulsar, PSR J1544–2555, associated with the Fermi-Large Area Telescope (LAT) source 4FGL J1544.2–2554. Optical, radio, and gamma-ray observations confirmed its nature as a compact spider binary system. Optical photometry from ULTRACAM revealed a $\sim$2.7-h orbital period, guiding MeerKAT observations that detected $\sim$2.4-ms radio pulsations. Subsequent timing campaigns using the Murriyang Parkes Telescope, the Effelsberg 100-m Radio Telescope, and the Nançay Radio Telescope allowed us to obtain a preliminary timing solution, which enabled us to find gamma-ray pulsations. The final timing solution, spanning 16 yr of Fermi-LAT gamma-ray data, also displays orbital period variations typical of spider pulsars. X-ray observations from eROSITA indicate non-thermal emission, but the relatively low count rate prohibits the search for X-ray pulsations. Optical light curve modelling using Icarus suggests the asymmetry is best explained by a spot model, where uneven heating creates localized temperature variations on the companion. While the optical spectra we obtained are compatible with the physical properties we infer for the companion star, they were not of sufficient signal-to-noise to allow for radial velocity measurements, thus limiting constraints on the neutron star’s mass. The observed bluer colour near the light curve minimum suggests possible non-thermal emission from intrabinary shocks, supported by the presence of an X-ray source. This discovery exemplifies the proven capability of the Fermi-LAT catalogue in identifying millisecond pulsar candidates and highlights the role of optical surveys in detecting variable sources suitable for radio follow-up.

Authors

Institutions

Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-09-16
DOI
https://doi.org/10.1093/mnras/staf1544
Primary Topic
Pulsars and Gravitational Waves Research
Type
article
Field-Weighted Citation Impact
0.00

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Multiwavelength observations of a new black-widow millisecond pulsar PSR J1544−2555

Sarah Buchner, C. J. Clark, E D Barr, L. Nieder et al.
Monthly Notices of the Royal Astronomical Society
Pulsars and Gravitational Waves Research
article

Multiwavelength observations of a new black-widow millisecond pulsar PSR J1544−2555

Sarah Buchner, C. J. Clark, E D Barr, L. Nieder, E. C. Ferrara, Antonio C. Rodriguez, R. P. Breton, T Thongmeearkom, John A. Paice, Mark R Kennedy, Kaustav K. Das, P V Padmanabh, O G Dodge, M. Kramer, B. W. Stappers, M. Burgay, W. Becker, V. S. Dhillon, R. Karuppusamy, Martin G. F. Mayer, A Phosrisom, J-M Grießmeier
article en

Abstract

ABSTRACT We report the discovery of a new black-widow millisecond pulsar, PSR J1544–2555, associated with the Fermi-Large Area Telescope (LAT) source 4FGL J1544.2–2554. Optical, radio, and gamma-ray observations confirmed its nature as a compact spider binary system. Optical photometry from ULTRACAM revealed a $\sim$2.7-h orbital period, guiding MeerKAT observations that detected $\sim$2.4-ms radio pulsations. Subsequent timing campaigns using the Murriyang Parkes Telescope, the Effelsberg 100-m Radio Telescope, and the Nançay Radio Telescope allowed us to obtain a preliminary timing solution, which enabled us to find gamma-ray pulsations. The final timing solution, spanning 16 yr of Fermi-LAT gamma-ray data, also displays orbital period variations typical of spider pulsars. X-ray observations from eROSITA indicate non-thermal emission, but the relatively low count rate prohibits the search for X-ray pulsations. Optical light curve modelling using Icarus suggests the asymmetry is best explained by a spot model, where uneven heating creates localized temperature variations on the companion. While the optical spectra we obtained are compatible with the physical properties we infer for the companion star, they were not of sufficient signal-to-noise to allow for radial velocity measurements, thus limiting constraints on the neutron star’s mass. The observed bluer colour near the light curve minimum suggests possible non-thermal emission from intrabinary shocks, supported by the presence of an X-ray source. This discovery exemplifies the proven capability of the Fermi-LAT catalogue in identifying millisecond pulsar candidates and highlights the role of optical surveys in detecting variable sources suitable for radio follow-up.

Monthly Notices of the Royal Astronomical SocietyVol. 543(3)
Leibniz University Hannover (DE), California Institute of Technology (US), Université d'Orléans (FR), Centre National de la Recherche Scientifique (FR), Goddard Space Flight Center (US), Friedrich-Alexander-Universität Erlangen-Nürnberg (DE), Durham University (GB), University College Cork (IE), Observatoire de Paris (FR), University of Manchester (GB), Max Planck Institute for Extraterrestrial Physics (DE), Physical Sciences (United States) (US), South African Radio Astronomy Observatory (ZA), Max Planck Institute for Gravitational Physics (DE), Instituto de Astrofísica de Canarias (ES), Astrophysics Science Division (US), Osservatorio Astronomico di Cagliari (IT), Max Planck Institute for Radio Astronomy (DE), Laboratoire de Physique et Chimie de l’Environnement et de l’Espace (FR), University of Maryland, College Park (US), National Astronomical Research Institute of Thailand (TH), University of Sheffield (GB)
National Research Foundation
Openalex Percentile: Top 82%
Pulsars and Gravitational Waves Research
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.