The Magnetar at the Heart of the Milky Way

A long time ago, I wrote a story called “Magnetar the Magnificent”.  It was about these weird things called neutron stars that have extremely strong magnetic fields. They’re a step in the evolution of massive stars, which explode as supernovae and leave behind these giant balls of neutrons held together by a strong gravitational pull. They are actually an interesting form of pulsars, which spin rapidly and emit radiation. In the story, I introduced the concept. It also became a podcast about for the old 365 Days of Astronomy project.

At the AAS last week, we heard some more about these objects. The latest story focuses on one that astronomers have detected at the heart of the Milky Way Galaxy. It’s the object shown in this artist’s conception. Basically, the object is a rotating neutron star with very powerful magnetic fields.

Magnetars give off radio emissions which can be studied with telescopes here on Earth. That’s just what people from CalTech and JPL did, using one of NASA’s deep-space network dishes in Australia, and it had been observed previously by NASA’s Swift X-Ray Telescope and the Nuclear Spectroscopic Array (NuSTAR).

About PSR J1745-2900

So, the magnetar has a catalog name full of numbers and letters PSR J1745-2900. It puts out fast bursts of radio emissions (called FRBs). That caught the attention of astronomers trying to figure out the mechanism behind other FRBs in the universe. It will take time to establish any link, and there are a number of scientific issues to solve. But, it does look like an interesting research direction

Even more interestingly, this magnetar is actually the closest known such object to live near a supermassive black hole. And, it’s still around to tell about it. PSR J1445 -2900 is in a stable orbit around the black hole region. That offers astronomers a chance to use it as a probe of conditions around the black hole.

For example, the emissions can reveal the material in the region around the black hole, either by “illuminating it” or by blocking certain wavelengths or frequencies. In addition, the activity of the magnetar may reveal something about its relationship with the black hole. Is there a link between its outbursts, its connection to the black hole, and FRBs? That’s what astronomers want to know. If they can establish a link between the black hole and the magnetar, that would be a fascinating new step in the research.

Radio Studies

The current research has identified characteristics in the emissions from the magnetar that are similar to those of FRBs. It’s not a new idea, but this work is studying its radio pulses and analyzing individual ones. The timing and frequency of these pulses seems to suggest something like clumps of plasma moving past the magnetar. Or, it could also be something that’s going on inside the magnetar itself. These dead stars spin very fast, and occasionally a surface disturbance causes strong emissions like the ones the scientists are detecting.

The current view of magnetars is that they are probably fairly young pulsars and that all pulsars go through a magnetar phase. The story of this one, which lies only three-tenths of a light-year away from Sagittarius A*, will likely get more interesting as astronomers do more studies of it.

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