MIT: Scientists Identify a Black Hole Choking on Stardust

[bystander]

Scientists Identify a Black Hole Choking on Stardust
Massachusetts Institute of Technology | 2017 Mar 15

In this artist's rendering, a thick accretion disk has formed around a supermassive black hole following the tidal disruption of a star that wandered too close. Stellar debris has fallen toward the black hole and collected into a thick chaotic disk of hot gas. Flashes of X-ray light near the center of the disk result in light echoes that allow astronomers to map the structure of the funnel-like flow, revealing for the first time strong gravity effects around a normally quiescent black hole. Image Credit: NASA/Swift/Aurore Simonnet, Sonoma State University

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Data suggest black holes swallow stellar debris in bursts.

In the center of a distant galaxy, almost 300 million light years from Earth, scientists have discovered a supermassive black hole that is “choking” on a sudden influx of stellar debris.

In a paper published today in Astrophysical Journal Letters, researchers from MIT, NASA’s Goddard Space Flight Center, and elsewhere report on a “tidal disruption flare” — a dramatic burst of electromagnetic activity that occurs when a black hole obliterates a nearby star. The flare was first discovered on Nov. 11, 2014, and scientists have since trained a variety of telescopes on the event to learn more about how black holes grow and evolve.

The MIT-led team looked through data collected by two different telescopes and identified a curious pattern in the energy emitted by the flare: As the obliterated star’s dust fell into the black hole, the researchers observed small fluctuations in the optical and ultraviolet (UV) bands of the electromagnetic spectrum. This very same pattern repeated itself 32 days later, this time in the X-ray band. ...

Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li - Dheeraj R. Pasham et al

• Astrophysical Journal Letters 837(2):L30 (2017 Mar 10) DOI: 10.3847/2041-8213/aa6003
  arXiv.org > astro-ph > arXiv:1703.07024 > 21 Mar 2017

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[bystander]

Swift Maps a Star's 'Death Spiral' into a Black Hole
NASA | GSFC | Swift | 2017 Mar 20

Click to play embedded YouTube video.

This animation illustrates how debris from a tidally disrupted star collides with itself,
creating shock waves that emit ultraviolet and optical light far from the black hole.
According to Swift observations of ASASSN-14li, these clumps took about a month to
fall back to the black hole, where they produced changes in the X-ray emission that
correlated with the earlier UV and optical changes.
Credits: NASA, Goddard Space Flight Center, Scientific Visualization Studio

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Some 290 million years ago, a star much like the Sun wandered too close to the central black hole of its galaxy. Intense tides tore the star apart, which produced an eruption of optical, ultraviolet and X-ray light that first reached Earth in 2014. Now, a team of scientists using observations from NASA’s Swift satellite have mapped out how and where these different wavelengths were produced in the event, named ASASSN-14li, as the shattered star’s debris circled the black hole.

“We discovered brightness changes in X-rays that occurred about a month after similar changes were observed in visible and UV light,” said Dheeraj Pasham, an astrophysicist at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, and the lead researcher of the study. “We think this means the optical and UV emission arose far from the black hole, where elliptical streams of orbiting matter crashed into each other.”

Astronomers think ASASSN-14li was produced when a Sun-like star wandered too close to a 3-million-solar-mass black hole similar to the one at the center of our own galaxy. For comparison, the event horizon of a black hole like this is about 13 times bigger than the Sun, and the accretion disk formed by the disrupted star could extend to more than twice Earth’s distance from the Sun. ...