Unknown Radio Signal from Space Repeats Every Hour -- Usually

[Tom.G]

"The signal first appeared in data gathered by the ASKAP radio telescope in Australia, which watches a big swath of sky at once for transient pulses. Officially designated ASKAP J1935+2148, the signal seems to repeat every 53.8 minutes.

Whatever it is, the signal cycles through three different states. Sometimes it shoots out bright flashes that last between 10 and 50 seconds and have a linear polarization, meaning the radio waves all “point” in the same direction. Other times, its pulses are much weaker with a circular polarization, lasting just 370 milliseconds. And sometimes, the object misses its cue and stays silent."

Short news announcement:
https://newatlas.com/space/radio-signal-space-repeats-hour-neutron-star-white-dwarf/

Research Article:
https://www.nature.com/articles/s41550-024-02277-w

Cheers,
Tom

 

[JLowe]

 

[Klystron]

Other times, its pulses are much weaker with a circular polarization, lasting just 370 milliseconds.

I tend to associate circular polarization with lenses or some lensing effect. I have not read the second paper (PDF) yet but would like to know associated wavelength and pulse information.

 

[Vanadium 50]

I think the word "source" fits better than "signal", which can imply a signal-er.

 

[Nik_2213]

Pulsars and similar 'compact objects' may spin very rapidly, down to milliseconds.
As I understand it, takes accretion from a binary partner to 'spin up' the most rapid sources.
There seems no evidence of such here...
Uh, how rapidly could a compact object precess ??

As isolated 'compact objects' 'spin down' due magnetic field 'dragging', that 'hour' implies tired, old object...

An 'hour' rotation of 'evolved' object, in old binary approaching 'common envelope' like repeating nova ??

Hopefully, patient monitoring will reveal any Doppler shift, or if such accretion is fuelling 'spin-up'...

 

[Klystron]

From the Nature paper

However, coherent and highly polarized radio emission has been detected in cataclysmic variables which are close binary systems containing a white dwarf primary accreting matter from a low-mass M-dwarf companion. In all detection cases, the radio emission appears to arise from the lower corona of the magnetically active M-dwarf and is attributed to the electron cyclotron maser instability.

Granted my experience lies in artificial signal sources, cycloid rotation of electrons in a strong magnetic field produce pulses similar to #2 pulses described. The paper goes on to describe plausible mechanisms for highly magnetic object surfaces to induce electron cycloid emmisions. Instability is certainly a major design factor for practical (artificial) masers and cavity magnetrons.

I think the word "source" fits better than "signal", which can imply a signal-er.

Concur. This distinction often arises in electronic engineering threads. People who spend careers deep in RF electronics tend to regard label repetitive pulsed emmissions as "signals" without implying agency or information content.

[Edit: upon reflection, replaced vague term 'regard' with 'label'.]

 

[Baluncore]

People who spend careers deep in RF electronics tend to regard repetitive pulsed emmissions as "signals" without implying agency or information content.

The Australian Square Kilometre Array Pathfinder (ASKAP) is a synthetic aperture array that has as many beams as it has correlators. The results are generated by numerical signal processing, by searching for signals in the noise. That is why they are referred to as signals. The IF quadrature signals, received from up to 36 antennas, are processed to provide the sum of all correlates from that beam direction. A signal is extracted that comes from that beam area, so there is no one source being observed. The signal will depend on the beam resolution and the sources in that field.

The increased sensitivity, and the ability to observe and image large areas of the sky, increases the type and the number of things that can be detected. Also, because it is in an isolated, protected and radio-quiet zone, it can make reliable observations in the VHF and UHF spectrum, free from TV, mobile phone and WiFi interference.

There is a tendency for each step forward in instrumentation, built to test some previous hypothesis, will yield data that was unexpected, and will open new avenues for hypothetical models and further research. A one-hour periodic signal would once not have been identified near a big city, because in a single channel receiver, it could so easily be dismissed as an artefact of the railway timetable. It seems, the most surprising discoveries in Radio Astronomy are always yet to come.