Zoom in / Most of the explanations for this phenomenon involve neutron stars, as described above. This explanation is amazing.
On Wednesday, researchers announced the discovery of a new astronomical mystery. The new object, GPM J1839–10, behaves much like a pulsar, sending out regular bursts of radio energy. But the physics that power pulsars mean they will stop emitting if they slow down too much, and nearly every pulsar we know of blinks at least once a minute.
GPM J1839–10 takes 22 minutes between pulses. We don’t know what kind of physics or what objects can amplify it.
while persistent
GPM J1839–10 was discovered while searching for transient objects in the galactic plane — something that wasn’t there when you first looked at it, but appeared when you checked again. The typical explanation for a transient object is something like a supernova, in which a massive event gives a huge increase in brightness. They are found at the opposite end of the radio spectrum, fast radio bursts, but also very short, and somewhat difficult to spot.
However, GPM J1839–10 came up in searches in a rather unusual way: it appeared as a transient element twice on the same observation night. Instead of sending out a large burst of energy over a short period of time, like a fast radio burst, the GPM J1839-10 is much lower energy and spreads out for 30 seconds.
Later observations showed that the object rotated regularly, at a periodic rate of about 1320 seconds (more commonly known as 22 minutes). There is a window of about 400 seconds centered around that periodic period, and explosions can appear anywhere within that window and will last anywhere from 30 to 300 seconds. During activity, the intensity of GPM J1839–10 can vary, with many sub-bursts present in the main signal. Occasionally a window would also pass without a pop.
Research through archival data shows that signals have been detected at this location since 1988. So whatever the result of this signal is actually not temporary, in the sense that the phenomenon that produced this burst was not a one-time event – it happened recently.
The list of known objects that can produce this type of behavior is short and consists of zero items.
Not suitable for anything
The most obvious analogue of GPM J1839-10 is a pulsar, a fast rotating magnetic neutron star. These objects release radio energy at their magnetic poles, which may be misaligned with their axis of rotation. As a result, the star’s rotation can sweep the poles through the line of sight to Earth, creating the visualization of radio wave flashes whenever one of the magnetic poles aligns with Earth.
But pulsar flashes reappear quickly, with lags between them from about a minute to milliseconds. More importantly, physics determines the gap he has to be fast. The magnetic field that powers the radio waves is generated by the rotation of stars. If it starts rotating too slowly, the magnetic field will drop to the point where it can no longer produce significant radio emission. In other words, if it slows down, it gets dark, which is why we didn’t see any of them take more than a minute between pulses.
But this doesn’t exclude neutron stars. Another option that includes one is magnetars, which are neutron stars with strong magnetic fields that are prone to energetic explosions. But the explosion also produced more energetic photons, and the researchers examined the GPM J1839-10 site with an X-ray telescope and saw nothing. Also, the magnetar is thought to be rotating faster than the 22-minute lag suggests, so it’s likely that it’s out there too.
Another alternative is a white dwarf with an unusually strong magnetic field. These are much more massive objects, and therefore take longer than a neutron star to rotate. But we’ve observed thousands of them within the Milky Way and we’ve never seen anything like it. Only one has periodic emissions, and produces significantly less energy than the GPM J1839–10.
Even if we expand the list of possible sources to include other organisms we do not understand, we are still lacking. The same team had identified a temporarily slow radio transmitter, GLEAM-X J162759.5-523504.3, several years earlier. But it remained active for about two months before disappearing from view – a far cry from the 35 years in which GPM J1839-10 exploded.
What now?
So, given every possible surprising explanation, where do we go from here? The good news is that these things are so hard to spot that there are probably a lot of things we have overlooked. The bad news is that they are still hard to spot. The duration of the bursts—up to 300 seconds—and the spacing between bursts means short-tempo notes tend to see something there all the time or miss it altogether.
We really need to get the device to stare at one area of space for half an hour or so, and have that stare broken up into multiple exposures, to make sure we capture it both on and off. This involves a significant commitment to hardware.
In the meantime, we can narrow down the location of GPM J1839-10 to try to see if there’s anything interesting out there at other wavelengths. Since this was inside the galactic field, it would also be a challenge.
Alam, 2023. DOI: 10.1038/s41586-023-06202-5 (about DOIs).
2023-07-20 00:52:17
#space #appeared #minutes #Ars #Technica
