Here is a concise summary of the text:
**Event Description**
* A tidal disruption event (TDE) occurred on Nov 22, 2014, where a star was consumed by a supermassive black hole (SMBH) ~290 million light-years away.
* The event was detected by ASASSN and observed by three X-ray telescopes, revealing a regular X-ray pulse every 131 seconds.
**Black Hole Spin Measurement**
* Measuring black hole spin is challenging, but crucial for understanding their growth.
* Three methods to measure spin:
1. Analyzing the accretion disk's black-body radiation (limited applicability).
2. Examining broadened iron emission lines (requires a bright iron line).
3. Identifying periodic oscillations in data (like the observed 131-second X-ray pulse).
**Key Finding**
* The observed X-ray pulse is attributed to a white dwarf, illuminated by the TDE's accretion disk, orbiting the SMBH.
* This event enabled the first spin measurement using a TDE, suggesting a spin parameter of at least 0.7 (possibly up to 0.998).
**Implications**
* This method may allow for spin measurements of dormant SMBHs (~95% of all SMBHs).
* Understanding SMBH spin can provide insights into their growth mechanisms (e.g., steady feeding vs. mergers) and galaxy evolution.
Here are the key facts extracted from the text, numbered and in short sentences:
**Event Details**
1. A burst of X-rays was detected by ASASSN on November 22, 2014.
2. The signal came from the center of a galaxy approximately 290 million light-years away.
3. The event was likely a star being consumed by a supermassive black hole.
**Tidal Disruption Events**
4. Tidal Disruption Events (TDEs) occur when a star approaches a black hole too closely.
5. TDEs are thought to be rare, happening maybe once every 10,000 to 100,000 years in a galaxy.
6. The event formed an accretion disk, emitting visible light, UV, and X-rays.
**Black Hole Characteristics**
7. Black holes are characterized by two main attributes: Mass and Spin.
8. Mass can be determined by measuring gravitational effects on nearby objects.
9. Black hole masses range from a few times that of our Sun (stellar-mass) to billions of solar masses (supermassive).
10. Supermassive black holes are generally found at the centers of most galaxies, including our own.
**Measuring Black Hole Spin**
11. The innermost stable circular orbit (r-isco) depends on a black hole's spin.
12. Faster-spinning black holes have smaller r-isco radii.
13. Three methods to measure spin:
a. Analyzing black-body radiation from the accretion disk.
b. Examining broadened iron emission lines.
c. Observing periodic oscillations in X-ray data.
**Specific Event Findings**
14. The observed X-ray pulse (every 131 seconds) was likely caused by a white dwarf orbiting the black hole.
15. The measured spin parameter for this black hole was at least 0.7, possibly up to the theoretical maximum of 0.998.
16. This event provided the first measurement of spin made possible by a Tidal Disruption Event.
**Broader Implications**
17. Measuring black hole spin helps understand their origins.
18. Spin measurements can indicate whether supermassive black holes grow mainly by feeding on galaxy matter or by merging with other black holes.
19. Understanding black hole growth informs our understanding of galaxy formation and evolution.