Category: chandra

Shredded Star Leads to Important Black Hole …

Shredded Star Leads to Important Black Hole Discovery

This artist’s illustration shows the region around a supermassive black hole after a star wandered too close and was ripped apart by extreme gravitational forces. Some of the remains of the star are pulled into an X-ray-bright disk where they circle the black hole before passing over the “event horizon,” the boundary beyond which nothing, including light, can escape. The elongated spot depicts a bright region in the disk, which causes a regular variation in the X-ray brightness of the source, allowing the spin rate of the black hole to be estimated. The curved region in the upper left shows where light from the other side of the disk has been curved over the top of the black hole.

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This event was first detected by a network of optical telescopes called the All-Sky Automated Survey for Supernovae (ASASSN) in November 2014. Astronomers dubbed the new source ASASSN14-li and traced the bright flash of light to a galaxy about 290 million light years from Earth. They also identified it as a “tidal disruption” event, where one cosmic object is shredded by another through gravity.

Astronomers then used other telescopes including a flotilla of high-energy telescopes in space — NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton and NASA’s Neil Gehrels Swift observatory — to study the X-rays emitted as the remains of a star swirled toward the black hole at the center of the galaxy.

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The tidal disruption in ASASSN-14li is intriguing because it allowed astronomers to measure the spin rate of the black hole. A black hole has two fundamental properties: mass and spin. While it has been relatively easy for astronomers to determine the mass of black holes, it has been much more difficult to get accurate measurements of their spins.

This debris from the shredded star gave astronomers an avenue to get a direct measure of the black hole’s spin in ASASSN-14li. They found that the event horizon around this black hole is about 300 times the diameter of the Earth, yet rotates once every two minutes (compared to the 24 hours it takes to complete one rotation). This means that the black hole is spinning at least half as fast as the speed of light.

Scientists have determined spin rates for some stellar-mass black holes (those that typically weigh between 5 and 30 solar masses) in our Milky Way galaxy by observing rapid and regular variations in their X-ray brightness. A few supermassive black holes have shown similar variations, but they were only observed to repeat over a few cycles, rather than the 300,000 cycles seen for ASASSN-14li. With only a few cycles, the association of the variations with the spin of the black hole is not secure.

These results will likely encourage astronomers to observe future tidal disruption events for long durations to look for similar, regular variations in their X-ray brightness. source

Spiral galaxy ESO 137-001 hurtles through ma…

Spiral galaxy ESO 137-001 hurtles through massive galaxy cluster Abell 3627 some 220 million light years away. The distant galaxy is seen in this colorful Hubble/Chandra composite image through a foreground of the Milky Way’s stars toward the southern constellation Triangulum Australe. As the spiral speeds along at nearly 7 million kilometers per hour, its gas and dust are stripped away when ram pressure with the cluster’s own hot, tenuous intracluster medium overcomes the galaxy’s gravity. Evident in Hubble’s near visible light data, bright star clusters have formed in the stripped material along the short, trailing blue streaks. Chandra’s X-ray data shows off the enormous extent of the heated, stripped gas as diffuse, darker blue trails stretching over 400,000 light-years toward the bottom right. The significant loss of dust and gas will make new star formation difficult for this galaxy. A yellowish elliptical galaxy, lacking in star forming dust and gas, is just to the right of ESO 137-001 in the frame.

Image Credit: NASA, ESA, CXC

Gravitational Wave Event Likely Signaled Creat…

The spectacular merger of two neutron stars that generated gravitational waves announced last fall likely did something else: birthed a black hole. This newly spawned black hole would be the lowest mass black hole ever found, as described in our latest press release.

After two separate stars underwent supernova explosions, two ultra-dense cores (that is, neutron stars) were left behind. These two neutron stars were so close that gravitational wave radiation pulled them together until they merged and collapsed into a black hole. The artist’s illustration shows a key part of the process that created this new black hole, as the two neutron stars spin around each other while merging. The purple material depicts debris from the merger.

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An additional illustration shows the black hole that resulted from the merger, along with a disk of infalling matter and a jet of high-energy particles.

A new study analyzed data from NASA’s Chandra X-ray Observatory taken in the days, weeks, and months after the detection of gravitational waves by the Laser Interferometer Gravitational Wave Observatory (LIGO) and gamma rays by NASA’s Fermi mission on August 17, 2017.

X-rays from Chandra are critical for understanding what happened after the two neutron stars collided. The question is: did the merged neutron star form a larger, heavier neutron star or a black hole?

Chandra observed GW170817 multiple times. An observation two to three days after the event failed to detect a source, but subsequent observations 9, 15 and 16 days after the event, resulted in detections (bottom left). The source went behind the Sun soon after, but further brightening was seen in Chandra observations about 110 days after the event (bottom right), followed by comparable X-ray intensity after about 160 days.

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If the neutron stars merged and formed a heavier neutron star, then astronomers would expect it to spin rapidly and generate a very strong magnetic field. This, in turn, would have created an expanding bubble of high-energy particles that would result in bright X-ray emission. Instead, the Chandra data show levels of X-rays that are a factor of a few to several hundred times lower than expected for a rapidly spinning, merged neutron star and the associated bubble of high-energy particles, implying a black hole likely formed instead.

By comparing the Chandra observations with those by the NSF’s Karl G. Jansky Very Large Array (VLA), researchers explain the observed X-ray emission as being due entirely to the shock wave – akin to a sonic boom from a supersonic plane – from the merger smashing into surrounding gas.  There is no sign of X-rays resulting from a neutron star. Thus, the researchers in this study claim this is a strong case for the merger of two neutron stars merging to then produce bursts of radiation and form a black hole.

source: nasa.gov

A movie showing the dynamics of the inner part of the Crab…

A movie showing the dynamics of the inner part of the Crab Nebula made using the Chandra X-ray Observatory.

Credit: NASA/CXC/ASU/J.Hester et al.

M83 spiral galaxy as seen by Chandra and Hubble. This galaxy is…

M83 spiral galaxy as seen by Chandra and Hubble. This galaxy is located about 15 million light years from Earth. In 2012, using Chandra X-ray Observatory, astronomers discovered an ultraluminous X-ray source (ULX), this source came from a black hole that devoured a giant red star.

Read more at: Chandra X-ray Observatory

Chandra Samples Galactic Goulash What would happen if you…

Chandra Samples Galactic Goulash

What would happen if you took two galaxies and mixed them together over millions of years? A new image including data from NASA’s Chandra X-ray Observatory reveals the cosmic culinary outcome.

Arp 299 is a system located about 140 million light years from Earth. It contains two galaxies that are merging, creating a partially blended mix of stars from each galaxy in the process.

However, this stellar mix is not the only ingredient. New data from Chandra reveals 25 bright X-ray sources sprinkled throughout the Arp 299 concoction. Fourteen of these sources are such strong emitters of X-rays that astronomers categorize them as “ultra-luminous X-ray sources,” or ULXs.

These ULXs are found embedded in regions where stars are currently forming at a rapid rate. Most likely, the ULXs are binary systems where a neutron star or black hole is pulling matter away from a companion star that is much more massive than the Sun. These double star systems are called high-mass X-ray binaries.

Such a loaded buffet of high-mass X-ray binaries is rare, but Arp 299 is one of the most powerful star-forming galaxies in the nearby Universe. This is due at least in part to the merger of the two galaxies, which has triggered waves of star formation. The formation of high-mass X-ray binaries is a natural consequence of such blossoming star birth as some of the young massive stars, which often form in pairs, evolve into these systems.

Read more at: chandra.harvard.edu (View Wavelengths Composite X-ray Optical)

Image credit: raio-X: NASA / CXC / Univ. De Crete / K. Anastasopoulou et ai, NASA / NuSTAR / GSFC / A. Ptak et ai; Óptica: NASA / STScI | (ESO)