Pulsed radio emission from a Central Compact Object

Abstract

The high magnetic fields and rapid spins of young pulsars associated with supernova remnants, such as the Crab and the Vela, established the standard pulsar model in which massive stellar explosions produce rapidly rotating, radio-luminous neutron stars. Central Compact Objects (CCOs), identified in X-rays at the centers of other remnants, challenged this view, as decades of searches yielded no radio detections. Here we show that the prototypical young CCO 1E 1207.4-5209 is in fact a faint radio pulsar rotating at the 0.4s X-ray period. Analysis of its polarization indicates that the radio beam intersects our line of sight near the magnetic pole, affirming its radio faintness' being intrinsic. Once its supernova remnant dissipates, this source would be misidentified as an apparently gigayear-old pulsar. The CCO's low radio flux density may explain why many supernova remnants lack detectable radio pulsars and suggests a hidden population of young, slowly rotating neutron stars.

Figures (5)

• Figure 1: Polarization profiles of PSR J1210$-$5226. Integrated polarization profiles from two MeerKAT observations: a 4-hour UHF-band observation (544–1088 MHz) on 2024 January 5 (bottom), and the first 4.25-hour segment of the L-band observation (856–1712 MHz) on 2025 October 18 (top). In each panel, black, red, and blue lines represent the total intensity, linear polarization, and circular polarization, respectively. Black points in the upper panels indicate the polarization position angle (PA) of the linear component.
• Figure 2: Sensitivity curves for the four CCOs observed with a 4-hour MeerKAT integration in the UHF band (544–1088 MHz).Left: Theoretical upper limits on radio flux density for the two CCOs with known X-ray spin periods, plotted as a function of dispersion measure (DM) for various assumed intrinsic duty cycles (d.c.). The red star marks PSR J1210$-$5226 at its observed DM and measured mean flux density from this work. The predicted DMs from Galactic electron density models are 127 and 82 pc cm$^{-3}$ (YMW16, NE2001, respectively) for 1E 1207.4$-$5209, and 157 and 417 pc cm$^{-3}$ for RX J0822.0$-$4300. Right: Theoretical flux density limits for the two CCOs without known spin periods, shown as a function of spin period, assuming a 10% intrinsic duty cycle. In all cases, dispersive smearing is the dominant source of pulse broadening and sensitivity degradation.
• Figure S1: Discovery diagnostic plots of PSR J1210$-$5226 from a 4-hour MeerKAT observation in the UHF band (544–1088 MHz), centered at 816 MHz and conducted on 12 January 2024. Upper panel: (a) and (b) show results from the time-domain periodicity search using the riptide-based pipeline, applied to two consecutive 2-hour segments of the observation. Lower panel: (c) and (d) show results from the Fourier-domain periodicity search using the PRESTO-based pipeline, applied to the same two segments.
• Figure S2: Intensity as a function of time and spin phase for the two MeerKAT observations of PSR J1210$-$5226. (a) Observation on 2024-01-05 using 60 dishes in the UHF band (544–1088 MHz). (b) Observation on 2025-10-18 using 31 dishes in the UHF band. (c) Observation on 2025-10-18 using 30 dishes in the L-band (856–1712 MHz). White horizontal stripes mark intervals excised due to radio frequency interference. The flux-density variations across time are consistent with interstellar scintillation Gitika2023.
• Figure S3: Left: Polarization properties of PSR J1210$-$5226 at 816 MHz. The upper panel presents the position angle swing (P.A.) of the linear polarization as black dots, while the median a-posteriori RVM curve that we fit is shown by the orange curve. The lower panel shows the polarization profile, where the total intensity flux is in black, total linear polarization in red and circular polarization in blue. Right: the two-dimensional posterior distribution for the magnetic inclination angle ($\alpha$) and impact angle between our line of sight and the magnetic axis ($\beta$). The colored contours indicate the 1-$\sigma$ (blue) and 2-$\sigma$ (light blue) confidence intervals. The black contours denote lines of constant emission height in km assuming a filled beam.