Credit: X-ray: NASA/CXC/ICRAR, Curtin Univ./Z. Wang et al.; Radio: SARAO/MeerKAT; Image processing: NASA/CXC/SAO/N. Wolk
Mysterious Signals from Deep Space
A new class of objects called Long-Period Transients, or LPTs for short, has astronomers scratching their heads. These objects show regular, extreme variations in their radio emission, which oscillates on timescales of many minutes. These timescales are much longer than usually seen in other, more common periodic radio variables, like rotating neutron star pulsars or pulsing white dwarf stars. Only a handful of LPTs have been identified. During a radio survey of the southern sky by the Australian Square Kilometer Array Pathfinder radio telescopes, a new bright transient radio source, subsequently called ASKAP J1832-0911, was discovered in outburst. A search of the radio archives showed that previous observations by other radio telescopes between 2013 to 2023 did not show any sign of the source, but followup radio observations showed that the radio emission from ASKAP J1832-0911 varied regularly with a period of about 44 minutes. Coincidently, the Chandra X-ray Observatory was surveying the region of sky containing ASKAP J1832-0911 near the time of the new radio observations. The Chandra observations showed that ASKAP J1832-0911 was also a bright X-ray source an that its X-ray emission oscillated with the same 44 minute period, in tandem with the radio pulses. This makes ASKAP J1832-0911 the first LPT to show coincident X-ray variations, making it the first such source ever detected in the Milky Way, or elsewhere. The source is shown in the circle in the composite X-ray and radio image above. The peculiar characteristics of the source do not match the known properties of "normal" neutron star or white dwarf pulsars, and suggest some new type of here-to-fore unidentified, exotic object.
Published: June 2, 2025
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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 09-Jun-2025 14:01:55 EDT