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Starts With A Bang

Black hole caught devouring star for an entire decade

It’s the longest feast we’ve ever seen, and it’s still going on! But why?

“Put two ships in the open sea, without wind or tide, and, at last, they will come together. Throw two planets into space, and they will fall one on the other. Place two enemies in the midst of a crowd, and they will inevitably meet; it is a fatality, a question of time; that is all.” –Jules Verne

When an object passes close to a black hole, it experiences tremendous tidal forces compressing and stretching it, capable of tearing it completely apart.

This artist’s impression depicts a Sun-like star being torn apart by tidal disruption as it nears a black hole. Image credit: ESO, ESA/Hubble, M. Kornmesser.

The parts closest to the black hole experience the greatest gravitational force, fragmenting the object in a tidal disruption event (TDE).

High-resolution image of the fragments of the comet tidally torn apart by Jupiter, prior to the ultimate impact. With a large enough mass, even stars can be torn apart. Image credit: NASA, ESA, and H. Weaver and E. Smith (STScI).

Although most of the matter gets ejected, some gets accelerated towards the black hole, where it heats up, causing an intense emission of X-rays.

Most of the mass from an infalling star onto a black hole gets ejected, creating cosmic spitballs. But the accreted portion may cause incredible black hole growth. Image credit: Mark A. Garlick/CfA.

Normally lasting weeks or months, a new record has just been set for TDEs. XJ1500+0154, 1.8 billion light years away, is the largest, longest-lasting one ever seen.

Our galaxy’s supermassive black hole has witnessed some incredibly bright flares, but none as bright or long-lasting as XJ1500+0154. Image credit NASA/CXC/Stanford/I. Zhuravleva et al.

First detected in July of 2005, the X-rays from this distant source brightened by a factor of 100 over 3 years. They remain bright even today.

High-energy observations of this object from Chandra (blue), XMM-Newton (red) and Swift (green) all indicate that this object brightened and now dims slowly, consistent with a new record for TDEs. Image credit: “A likely decade-long sustained tidal disruption event”, D. Lin et al., Nature Astronomy (2017).

Although dozens of TDEs have been observed since the 1990s, none have lasted this long. It may be caused by the most massive star ever observed creating a TDE.

The supermassive black hole at the center of our galaxy, with an X-ray flare as imaged by Chandra. All other X-ray flares and TDEs pale in comparison to XJ1500+0154. Images credit: X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI.

Chandra’s incredible X-ray eyes can pinpoint this emission to the galaxy’s center: where its supermassive black hole lives.

The X-ray emissions come from the dead center of the galaxy, indicating that the supermassive black hole is the culprit. Image credit: X-ray: NASA/CXC/UNH/D.Lin et al, Optical: CFHT.

This accretion rate is beyond the Eddington limit — the first such observation — and may explain the rapid growth of supermassive black holes.

The Eddington limit defines the maximum accretion rate of a black hole. This incredible brightness is the first observation of a super-Eddington accretion rate, perhaps an indication of how the earliest SMBHs formed. Image credit: ESA/Hubble, ESO, M. Kornmesser.

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