A team of astronomers using the Green Bank Telescope has detected a faint but tantalizing signal from the center of the Milky Way: a possible millisecond pulsar spinning once every 8.19 milliseconds, deep in the gravitational neighborhood of the supermassive black hole Sagittarius A*. The candidate, reported in a paper published February 9, 2026, in The Astrophysical Journal, volume 998, remains unconfirmed but has already reignited debate about what kinds of extreme objects lurk near our galaxy’s core. If verified, the find would join a small but growing roster of magnetically extreme dead stars orbiting dangerously close to a black hole weighing four million times the mass of the Sun.
A Needle in the Galaxy’s Noisiest Haystack
Finding pulsars near Sagittarius A* is one of the hardest observational challenges in radio astronomy. The dense, turbulent plasma between Earth and the Galactic Center scatters radio waves so severely that conventional low-frequency searches are effectively blind. Theoretical work has shown that optimal frequencies for millisecond pulsars in weak-scattering scenarios sit around 8 GHz, well above the bands used in most pulsar surveys. That prediction shaped the design of the new search: a Breakthrough Listen campaign using the Green Bank Telescope’s X-band receiver, operating between 8 and 12 GHz, with observations conducted from 2021 to 2023.
The survey, led by Karen I. Perez and detailed in a recent preprint, represents the deepest search yet for pulsars in this region. Out of the full dataset, a single candidate emerged with a spin period of 8.19 milliseconds and a dispersion measure of approximately 2775 pc cm-3, a value consistent with a source located at or near the Galactic Center. The authors are careful not to claim a confirmed detection. Confirmation requires re-observation at a different epoch to rule out radio-frequency interference and verify that the signal repeats with the expected characteristics. That follow-up work is still pending, leaving the community in a familiar state of cautious anticipation.
The Magnetar Already Living Next Door
The new candidate is not the first sign that magnetically extreme neutron stars inhabit the Galactic Center. In April 2013, the Swift and Chandra X-ray observatories detected an energetic burst from a previously unknown source just 2.4 arcseconds from Sagittarius A* in projected angular separation. That source, designated SGR J1745-2900, turned out to be a magnetar, a type of neutron star with a magnetic field so intense it dwarfs anything else in nature. A magnetar is essentially a compact neutron sphere about 12 miles across wrapped in a field a trillion times stronger than Earth’s, capable of powering bright X-ray and gamma-ray flares.
SGR J1745-2900 sits strikingly close to the black hole. Its physical distance could be as small as 0.3 light years, roughly 2 trillion miles, according to NASA estimates, placing it firmly within the gravitational grip of the four-million-solar-mass black hole. It remains the closest known neutron star to any supermassive black hole. The magnetar’s discovery had an immediate scientific payoff: by measuring how its radio pulses twisted as they traveled through the surrounding plasma, researchers inferred an exceptionally strong magnetic field permeating the immediate environment of Sagittarius A*, a finding that reshaped models of accretion and outflow near the black hole and provided a rare probe of conditions in this otherwise inaccessible region.
Why the Galactic Center Keeps Swallowing Signals
The scarcity of known pulsars near Sagittarius A* is itself a puzzle. Stellar population models predict that hundreds or even thousands of neutron stars should orbit the black hole, yet only one, the 2013 magnetar, has been confirmed. The gap is almost certainly an observational artifact rather than a real absence. Interstellar scattering broadens pulsar signals into smeared blobs at frequencies below a few gigahertz, and the extreme dispersion measures in this region demand long integration times that compound the problem. An 86 GHz search using the Atacama Large Millimeter/submillimeter Array, or ALMA, employed acceleration searches and data segmentation to account for orbital motion but still reported no new pulsars, detecting only the known magnetar’s polarization signature amid the glare of the Galactic Center.
That persistent failure highlights a tension in current search strategies. Moving to higher frequencies reduces scattering but also reduces the intrinsic brightness of most pulsars, whose radio emission fades steeply above a few gigahertz. The Breakthrough Listen survey threaded that needle by working in the 8 to 12 GHz window, where scattering is manageable and millisecond pulsars can still produce detectable flux. The 8.19 ms candidate’s dispersion measure of roughly 2775 pc cm-3 is extremely high, consistent with the known magnetar’s DM and reinforcing the idea that the signal originates from deep within the Galactic Center rather than from a foreground source along the line of sight. If more such objects are uncovered, they would help resolve whether the apparent pulsar deficit is purely a matter of sensitivity and scattering, or whether additional physical processes are suppressing radio emission near the black hole.
What Confirmation Would Actually Mean
If the candidate turns out to be real, it would be far more than a catalog entry. A millisecond pulsar orbiting within a light-year of Sagittarius A* would act as an exquisitely precise clock in a region where gravity is strong enough to noticeably warp spacetime. By tracking the arrival times of its pulses over years, astronomers could measure tiny deviations from perfect periodicity caused by the black hole’s gravity. Those timing residuals would encode information about the black hole’s mass, spin, and quadrupole moment, offering one of the cleanest tests yet of general relativity in the strong-field regime. Previous work on SGR J1745-2900 has already shown that pulsars in this environment can be timed and modeled, with detailed analyses of its radio properties and evolution demonstrating that even heavily scattered signals can yield precise physical insights.
In addition to gravity tests, a confirmed millisecond pulsar near the Galactic Center would open a new window on the local plasma and magnetic field. Each pulse would sample the turbulent medium along the line of sight, allowing researchers to monitor changes in dispersion and scattering as gas flows in and out of the black hole’s vicinity. Combined with X-ray and infrared observations of flares from Sagittarius A*, such timing data could link variations in the pulsar signal to specific episodes of accretion or outflow. Over time, a small ensemble of pulsars in different orbits could map the three-dimensional structure of the central parsec, turning what is now a largely static picture into a dynamic, time-resolved laboratory for high-energy astrophysics.
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*This article was researched with the help of AI, with human editors creating the final content.
