1. To be published in Science today
X-ray pulses detected near event horizon as a black hole devours a star
Dheeraj R. Pasham (MIT)
To be published in Science today
Ronald A. Remillard, P. Chris Fragile, Alessia Franchini, Nicholas C. Stone, Giuseppe Lodato, Jeroen Homan, Deepto Chakrabarty, Frederick K. Baganoff, James F. Steiner, Eric R. Coughlin, Nishanth R. Pasham
Our result is about the discovery of quasi-periodic X-ray pulses from near the event horizon of a black hole after it destroyed a star that passed too close to it.
Abstract#239.07

2. Tidal Disruption Flares
Credit: NASA Goddard Space Flight Center NASA/CXC/U. Michigan/J. Miller et al. NASA/CXC/M. Weiss

3. Tidal Disruption Flares
X-rays
X-ray radiation coming from right next to the black hole encodes information about the spacetime just outside the event horizon!
Credit: NASA Goddard Space Flight Center NASA/CXC/U. Michigan/J. Miller et al. NASA/CXC/M. Weiss

4. X-rays encode information about the spacetime
The dynamics of matter in this region (and thus the variations in the X-ray emission) are dictated by the spacetime defined by three parameters:
black hole’s mass,
black hole spin and
radius from the center
X-rays

5. ASASSN-14li flare detected on Nov. 22 2014
A flare from the center of this galaxy 290 million light years away!
Chandra
Credit: HST/STScI/I. Arcavi

6. ASASSN-14li’s long-term evolution in X-rays

7. Regular X-ray modulation with a period of roughly 130 seconds
X-ray flux
Phase

8. Regular X-ray modulation with a period of roughly 130 seconds
By equating this period to various ways in which particles can move around the black hole we estimated that the black hole is spinning at at least half the speed of light.
X-ray flux
Phase

9. Artist’s impression
Credit: Chandra

10. Comparing to Earth ... >300 times bigger than Earth
Rotates faster than once every two minutes!!
Rotates once every 24 hrs
>300 times bigger than Earth
Not to scale!

11. This is exciting because ….
You are getting information (in the form of radiation) from a region of spacetime that has extreme gravity
More future examples to study strong gravity
A possibility to constrain spins of several supermassive black holes when they disrupt stars
Implications on how black holes grew since the beginning of time

12. Thank you!
Contact info: Or
Paper published in Science