NuSTAR Puts New Spin On Supermassive Black Holes

A supermassive black hole has been found in an unusual spot: an isolated region of space where only small, dim galaxies reside. Image credit: NASA/JPL-Caltech

Checking out the spin rate on a supermassive black hole is a great way for astronomers to test Einstein’s theory under extreme conditions – and take a close look at how intense gravity distorts the fabric of space-time. Now, imagine a monster … one that has a mass of about 2 million times that of our Sun, measures 2 million miles in diameter and rotating so fast that it’s nearly breaking the speed of light.

A fantasy? Not hardly. It’s a supermassive black hole located at the center of spiral galaxy NGC 1365 – and it is about to teach us a whole lot more about how black holes and galaxies mature.

What makes researchers so confident they have finally taken definitive calculations of such an incredible spin rate in a distant galaxy? Thanks to data taken by the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency’s XMM-Newton X-ray satellites, the team of scientists has peered into the heart of NGC 1365 with x-ray eyes – taking note of the location of the event horizon – the edge of the spinning hole where surrounding space begins to be dragged into the mouth of the beast.

“We can trace matter as it swirls into a black hole using X-rays emitted from regions very close to the black hole,” said the coauthor of a new study, NuSTAR principal investigator Fiona Harrison of the California Institute of Technology in Pasadena. “The radiation we see is warped and distorted by the motions of particles and the black hole’s incredibly strong gravity.”

However, the studies didn’t stop there, they advanced to the inner edge to encompass the location of the accretion disk. Here is the “Innermost Stable Circular Orbit” – the proverbial point of no return. This region is directly related to a black hole’s spin rate. Because space-time is distorted in this area, some of it can get even closer to the ISCO before being pulled in. What makes the current data so compelling is to see deeper into the black hole through a broader range of x-rays, allowing astronomers to see beyond veiling clouds of dust which only confused past readings. These new findings show us it isn’t the dust that distorts the x-rays – but the crushing gravity.

Scientists measure the spin rates of supermassive black holes by spreading the X-ray light into different colors. Image credit: NASA/JPL-Caltech
Scientists measure the spin rates of supermassive black holes by spreading the X-ray light into different colors. Image credit: NASA/JPL-Caltech

“This is the first time anyone has accurately measured the spin of a supermassive black hole,” said lead author Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF — Arcetri Observatory.

“If I could have added one instrument to XMM-Newton, it would have been a telescope like NuSTAR,” said Norbert Schartel, XMM-Newton Project Scientist at the European Space Astronomy Center in Madrid. “The high-energy X-rays provided an essential missing puzzle piece for solving this problem.”

Even though the central black hole in NGC 1365 is a monster now, it didn’t begin as one. Like all things, including the galaxy itself, it evolved with time. Over millions of years it gained in girth as it consumed stars and gas – possibly even merging with other black holes along the way.

“The black hole’s spin is a memory, a record, of the past history of the galaxy as a whole,” explained Risaliti.

“These monsters, with masses from millions to billions of times that of the sun, are formed as small seeds in the early universe and grow by swallowing stars and gas in their host galaxies, merging with other giant black holes when galaxies collide, or both,” said the study’s lead author, Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and the Italian National Institute for Astrophysics.

This new spin on black holes has shown us that a monster can emerge from “ordered accretion” – and not simply random multiple events. The team will continue their studies to see how factors other than black hole spin changes over time and continue to observe several other supermassive black holes with NuSTAR and XMM-Newton.

“This is hugely important to the field of black hole science,” said Lou Kaluzienski, NuSTAR program scientist at NASA Headquarters in Washington, D.C. “NASA and ESA telescopes tackled this problem together. In tandem with the lower-energy X-ray observations carried out with XMM-Newton, NuSTAR’s unprecedented capabilities for measuring the higher energy X-rays provided an essential, missing puzzle piece for unraveling this problem.”

Original Story Source: JPL/NASA News Release.

New Bright and Blue Supernova in NGC 1365

Supernova 2012fr in NGC 1365. It is the bright blue “star” directly below the galaxy core. Credit: Rolf Wahl Olsen. Click the image for larger version.

A very bright supernova has shown up in NGC 1365, the galaxy also known as the Great Barred Spiral Galaxy, visible now for southern hemisphere observers. This already elegant galaxy lies about 56 million light-years away in the constellation Fornax. The supernova, a type Ia, was discovered by Alain Klotz with the TAROT telescope at the La Silla Observatory in Chile on October 27, 2012. “The supernova is a very nice addition to the already highly photogenic galaxy,” said Rolf Wahl Olsen, who took the gorgeous image above. “I’m amazed by how blue it is; it’s really intense.”

Supernova 2012fr is the bright and intensely blue star directly below the galaxy core. Olsen said that as of November 10, 2012 the supernova appeared to be nearing its peak, with an R magnitude of 11.90.

“To get an idea of how bright this event is we can calculate the absolute magnitude M of the supernova using the following formula where m is the apparent magnitude and D the distance in parsecs: M = m – 5(log10(D) – 1),” Olsen wrote. “This gives an absolute magnitude of -19.27 for SN2012fr. This means that if the supernova had occurred at a distance to us similar to Betelgeuse (643 light years), then its apparent magnitude would be -12.80, same as the full Moon!”

Details about Olsen’s image:
Date: 7th and 9th November 2012
Exposure: LRGB: 205:57:56:51m, total 6hrs 9mins @ -30C
Telescope: 10″ Serrurier Truss Newtonian f/5
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon LRGB E-Series Gen 2
Taken from his observatory in Auckland, New Zealand

See more of Olsen’s astrophotography at his Flickr page.