NASA's Two Sides of the Same Star discusses the relationship between pulsars and magnetars and contains a video also linked below.

At 02:13 it quotes "Tom Prince, a physics professor at the California Institute of Technology and a senior research scientist at NASA's Jet Propulsion Laboratory" as saying:

First, magnetars don't last long — just a year to a few years, before colossal waves of X-rays dissipate the magnetic energy...

The quote is also present in Space.com's Dr. Pulsar and Mr. Magnetar? 2 Star Types May Turn into Each Other

Checking Wikipedia's Magnetar; Description:

The active life of a magnetar is short. Their strong magnetic fields decay after about 10,000 years, after which activity and strong X-ray emission cease.

Now four orders of magnitude is sometimes not a lot in Astrophysics, but the difference between a years and ten thousand years is huge for observational astronomy because the former can be readily measured and verified while the latter would need to be inferred from other observations.

Question: Is "magnetars don't last long — just a year to a few years" really true? Is it a misquote or perhaps taken out of context?

If it's true, are there plots of some observable decaying on this timescale that can verify this?

Related and potentially helpful:

cued at 02:13:


1 Answer 1


It's certainly not true. I've watched the linked video and read the linked articles, and even with that additional context, I don't see a way for the quote to fit with our understanding of the behavior of magnetic fields in magnetars. Since the magnetar model was first proposed (Thompson & Duncan 1995), theory and observations have indicated that these objects should stay in this phase for something like $\sim10^{4\mathrm{-}5}$ years. Their strong magnetic fields allow them to release energy through mechanisms not available to pulsars, including high-energy bursts and giant flares - some of the phenomena which originally motivated the magnetar model. We see rapid spin-down rates because the high magnetic fields allow for stronger magnetic dipole radiation. None of this is in dispute. There are plenty of unknowns when it comes to magnetars (e.g. how they form such high magnetic fields), but timescales are not one of them (Mereghetti 2013).

The only way I can reconcile the quote with magnetar behavior is if somehow it's meant to be applied to magnetar flares or bursts, which do involve x-ray and gamma-ray emission and may have afterglows on the order of months (Kaspi & Beloborodov 2017 is a review article with a nice section on this). Peak energies of $\sim10^{36}$ erg s$^{-1}$ certainly count as "colossal" in my book. If you replace "magnetars" with "magnetar outbursts", then the quote makes more factual sense, although it still doesn't fit well in the Space.com article.


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