Something In Space Has Been Lighting Up Every 20 Minutes Since 1988

Researchers have announced the discovery of an astronomical object called GPM J1839-10, which emits regular bursts of radio energy similar to a pulsar but with a much longer interval between pulses of 21 minutes. The nature and physics behind this behavior remain unknown, as it does not fit into any existing astronomical categories or explanations, making it a unique and enigmatic phenomenon that requires further study and observation. Ars Technica reports: GPM J1839-10 was discovered in a search of the galactic plane for transient objects -- something that's not there when you first look, but appears the next time you check. The typical explanation for a transient object is something like a supernova, where a major event gives something an immense boost in brightness. They're found at the radio end of the spectrum, fast radio bursts, but are also very brief and, so, fairly difficult to spot. In any case, GPM J1839-10 showed up in the search in a rather unusual way: It showed up as a transient item twice in the same night of observation. Rather than delivering a short burst of immense energy, such as a fast radio burst, GPM J1839-10 was much lower energy and spread out over a 30-second-long burst. Follow-on observations showed that the object repeated pretty regularly, with a periodicity of about 1,320 seconds (more commonly known as 22 minutes). There's a window of about 400 seconds centered on that periodicity, and a burst can appear anywhere within the window and will last anywhere from 30 to 300 seconds. While active, the intensity of GPM J1839-10 can vary, with lots of sub-bursts within the main signal. Occasionally, a window will also go by without any bursts. A search through archival data showed that signals had been detected at the site as far back as 1988. So, whatever is producing this signal is not really a transient, in the sense that the phenomenon that's producing these bursts isn't a one-time-only event. The list of known objects that can produce this sort of behavior is short and consists of precisely zero items. [...] So, given that every possible explanation is terrible, where do we go from here? The good news is that these objects will be so difficult to spot that it's possible there are a lot more out there that we've overlooked. The bad news is that they're still hard to spot. The length of the burst -- up to 300 seconds -- and the gap between bursts mean short-cadence observations will likely either see something there the whole time or miss it entirely. We'd really need to have hardware stare at a single area of space for a half-hour or more, and to have its staring divided up into multiple exposures, to be sure we catch it in both its on and off states. And that involves a major commitment of hardware. In the meantime, we can potentially narrow down the location of GPM J1839-10 to try to see if there's anything interesting in other wavelengths. Since this is located within the galactic plane, however, that's going to be challenging as well.

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