From NASA Chandra: “Chandra Archive Collection: Combing Through the ‘X-ray Files'”

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From NASA Chandra

October 30, 2019


A new collection of images is being released to recognize Archive month, which is celebrated every October in the US.

These images contain X-rays from Chandra and optical light from the Hubble Space Telescope from data available in public archives.

These new images include five supernova remnants and a region where stars are actively forming.

The data taken by Chandra since 1999 are stored in a digital archive available to professional scientists and members of the public alike.

In its 20 years of operations, NASA’s Chandra X-ray Observatory has observed hundreds of thousands of X-ray sources across the Universe. These data are stored in a public archive where anyone can access them a year after the observations, if not sooner.

Most of the time, the Chandra archive serves the professional astronomical community for their research purposes, but its value extends far beyond. Some members of the public, including amateur astronomers and space enthusiasts, comb through astronomical archives like the one Chandra maintains. Their work has led to the discovery of new objects, investigations of mysterious phenomena, and the creation of stunning images of cosmic objects.

A sample of composite images — that is, those that consist of more than one type of light — using X-ray data from Chandra and optical light from the Hubble Space Telescope is being released today. This image collection, made by “astronomy artist” Judy Schmidt, helps recognize Archive Month, which is celebrated every October in the United States and promotes the contributions of all types of archives. The software tools, instructions, and tutorials on how to make images from Chandra data are free and available in many locations online, including

All of the objects in this new archive collection are located in the Large Magellanic Cloud, or LMC, which is a small satellite galaxy to our Milky Way, located about 150,000 light years away. The images are:

Top row, from left to right:

When a thermonuclear explosion destroyed a white dwarf star (the dense final stage in the evolution of a Sun-like star) in a double star system and produced a supernova, it left behind this glowing debris field, called a supernova remnant. The Chandra X-ray data (most clearly visible on the left side of the remnant in red, green and blue) shows multimillion-degree gas that has been heated by a shock wave produced by the explosion that destroyed the star. An optical light image from the Hubble Space Telescope is brightest on the right side of the image, where the overlap with X-rays is mostly in pink and white.

LHA 120-N 44
This region of star formation features a giant bubble that is blowing out from the middle of this image due to winds flowing off young stars. Chandra data (purple and pink) show this superbubble of hot gas, while Hubble data (orange and light blue) reveals the gas and dust in the system.

After a massive star exploded, it left behind this supernova remnant observed by Chandra and Hubble. The Chandra data (red, green and blue) show multimillion-degree gas and the blast wave from the supernova. The light brown region in the upper right of the remnant is a dense cloud of gas and dust that reflects optical light detected by Hubble.

Bottom row, from left to right:

The Chandra image of this supernova remnant (also known as SNR 0505.7-6752) reveals an inner cloud of glowing iron and silicon (green and blue) surrounded by an outer blast wave (red). The outer blast wave, created during the destruction of the white dwarf star, is also seen in optical data from Hubble (red and white).

SNR J0534.2-7033 (DEM L238)
Another supernova remnant resulting from the explosion of a white dwarf star is revealed in this image of DEM L238, also known as SNR J0534.2-7033. The Chandra image (yellow, green and bright red) shows multimillion-degree gas and the Hubble image shows cooler gas in the system, near the outer border of the remnant in red.

This is the brightest supernova remnant in either the LMC or its galactic cousin, the Small Magellanic Cloud. N132D also stands out because it belongs to a rare class of supernova remnants that have relatively high levels of oxygen. Scientists think most of the oxygen we breathe came from explosions similar to this one. Here, Chandra data are shown in purple and green and Hubble data are shown in red.

For full images credits see the full article.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

#chandra-archive-collection-combing-through-the-x-ray-files, #astronomy, #astrophysics, #basic-research, #cosmology, #nasa-chandra, #x-ray-images

From NASA Chandra: “Behind the Scenes with the Image Makers”

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From NASA Chandra


2019 Chandra Archive Collection Credit: Enhanced Image by Judy Schmidt (CC BY-NC-SA) based on
images provided courtesy of NASA/CXC/SAO & NASA/STScI.

It is both an art and a science to make images of objects from space. Most astronomical images are composed of light that humans cannot detect with their eyes. Instead, the data from telescopes like NASA’s Chandra X-ray Observatory are “translated,” so to speak, into a form that we can understand. This process is done following strict guidelines to ensure scientific accuracy while trying to achieve the highest levels of aesthetics possible.

Over the two decades of the Chandra mission, we have had many talented people who have been involved with making our publicly-released images. We interviewed our current team and share some of their answers to questions posed to all of them below. Kim Arcand is Chandra’s visualization lead and has been with the mission since before launch; Nancy Wolk has been involved with Chandra’s data analysis, software, and spacecraft science operations before joining the image processing team; Lisa Frattare spent years making images from the Hubble Space Telescope before switching career gears but continues to lend her expertise part-time to Chandra’s efforts; Judy Schmidt is a citizen scientist who spends some of her free time using public data to make gorgeous images of space, including those featured in our latest release.

How did you get involved in astronomy and/or astronomical images?

Nancy Wolk
Favorite image processed: NGC 6231

Nancy Wolk: I’ve always wanted to be an astronomer. I studied astronomy and physics in college and completed a Master’s degree in astronomy. After graduation, I moved to the Boston area and started working with data analysis with the Chandra X-ray Observatory (then called AXAF). Over the years, I moved from data analysis to software and then space craft science operations. I’ve been able to talk directly with the observers and help them configure the instruments for them. Most recently, I have been working with preparing images for press releases.

Kim Arcand
Favorite image processed: Tycho’s Supernova Remnant

Kim Arcand: I completed my undergraduate work in molecular biology. My interests then were on bacteria and disease, so I was looking at things like Ixodes Scapularis (the Deer tick) and the spirochaetes that can be transmitted to humans which can cause Lyme Disease. But as I neared the end of my degree I found that I was more attracted to the computer as a tool to tell stories about science than I was to any bugs or bacteria. (The physics and chemistry courses I had to take for that degree, however, would become incredibly useful in my later work.) I moved into a computer science graduate program after completing a degree in biology, and the programming/coding/application development of that was a key tool in my future work with Chandra. I would say it was really the mix of science and computer science that helped move me into astronomical data visualization and related projects.

Judy Schmidt
Favorite image processed: Chamaeleon

Judy Schmidt: I’ve long been interested in astronomy, but what got me hooked on image processing was the European Space Agency (ESA) Hubble’s Hidden Treasure contest in 2012. Prior to that, I had no idea that data from NASA’s Great Observatories are publicly available for anyone in the world to work with. I always wanted to try some astronomical image processing, but I thought I had to buy my own telescope, travel to some dark skies, and capture my own data. Discovering the vast public archives full of professional data changed my life from merely being a casual onlooker to actively participating in a meaningful way within the astronomy community, and I love it.

Lisa Frattare
Favorite image processed: Butterfly Nebula

Lisa Frattare: I have a Master’s in astronomy from Wesleyan University. That landed me working as a data analyst and later, an image processor for the Hubble Space Telescope at Space Telescope Science Institute (STScI) in Baltimore, MD. I worked on the Hubble Project as a member of the news team and Hubble Heritage Project. My main role was to help astronomers make their scientific data into exciting images that would appeal to fellow scientists and the public alike. During my 20-year tenure at STScI, I worked on over 300 Hubble images, observed with the telescope, worked on 3D imaging of several targets which led to two IMAX films, and did a small stint on processing X-ray data for the Chandra X-ray Observatory. I now work directly with the Chandra news and outreach group. Although X-rays look different than optical data, the mechanism of X-ray data processing is the same. Once again, I convert scientific data into an image that is sometimes rendered as just the X-ray data, and other times it is composited with other wavelengths like optical, infrared and radio.

Do you think working with these images requires particular skills or interests?

Kim Arcand: Being curious about a topic seems to get us pretty far in my group. I would say that curiosity is the most important “skill” in working with data like this. The technical aspects can fall into place with a bit of work, but without that first breath of curiosity, I don’t know how rewarding or interesting it would be for someone. That said, the technical skills are certainly useful to have, though there are a range of different software applications and scripting languages that can help depending on what part of the pipeline of image processing someone is interested in. Some of the astronomical packages like ds9/js9/SAO Image are a good place to start. And Photoshop plus FitsLiberator are an “industry standard.” It certainly never hurts to have coding skills in this area, but I also can’t overstate the usefulness of having an overall aesthetic or “eye” for art as well.

Judy Schmidt: I don’t think there is “One True Way,” but a strong familiarity with some kind of digital photo editing software, such as Photoshop, and an understanding of color theory are both essential. My background is in multimedia design, so the astronomy side of things is largely self-taught. This is probably not ideal, but I’ve managed to make it work. There are a lot of resources available online that I am grateful for, and I have been lucky to sometimes receive some helpful tips directly from professionals. I am also privileged enough in life to have a substantial amount of time available to devote to this hobby.

Lisa Frattare: I don’t think there is a single cookie cutter astronomical image processor. Each of us comes to the role with a different level of interest in science, color, patterns, analytical data, photography, astronomical knowledge, experience, academic training, etc. Part of the equation includes trying something new, putting in the time and effort, and knowing when to stop fussing with an image.

Nancy Wolk: I do find that you need a basic understanding of astronomy and how astronomical images are created. Many times, the images are not projected onto a flat surface, which means you need to be careful doing measurements along the areas with the largest changes from flat. Each telescope is different and aligning the images can be difficult at times. In addition, knowing the physics behind the particular image is important to understanding what you want to emphasize. Basic art skills such as understanding color theory helps as well to choose colors that really make the images catch the public’s eye.

Do you think astronomical images resonate with the public in different ways than those from other types of science? If so, why?

Judy Schmidt: Absolutely. Humans have long known that there is something bigger than us out there, and different cultures have so many different stories and metaphors to tell about it, but astronomical images bring us directly in touch with that feeling. It’s like making a connection to some secret hidden truth that perhaps we were never worthy of, but the Universe whispered it to us anyway. There’s just something special about receiving a message that’s thousands, millions, or even billions of years old. And in many cases, it takes little or no special understanding to not only appreciate it, but yearn for more.

Lisa Frattare: There is a feeling of discovery and a sense of wonder that comes from how astronomical images are perceived. From our early photographs of the Moon, to overexposed black and white spirals and ellipticals from early ground-based telescopes, humans have loved viewing and pondering the heavens.

Kim Arcand: I’m a little bit biased here because I come from a place where microscopic images were my first love, and I would like to say they resonate out in the public sphere quite well. I’m also rather loyal to the telescopic images because … well, they’re awesome. So I love the micro and the macro when it comes to imagery. It certainly seems, however (in a non-scientifically assessed way), that the Universe gets more than its fair share of attention with experts and non-experts, and is definitely out in the pop culture world. I’ve found images I or my team have worked on in all sorts of corners of the world, from earrings on Etsy to high-fashion dresses, from album covers to bed covers, in non-astronomy movies and TV/streaming series. It’s always a surprise and a joy to see our data being used in such a way. There’s never enough science imagery for my tastes, but there seems to be a particular appeal to images of the Universe. Perhaps because they seem to hint at answers to those huge questions of where do we come from, who are we, and where are we going?

Nancy Wolk: Many people have a very tenuous relationship with our sky. Living in major cities, many people only see the brightest stars. Bringing people astronomical images really brings the Universe to the people. When we can show images of planets and then some of the more exotic phenomenon in space, we’re opening doors of possibility.

Do you have any advice for anyone who is interested in using astronomical data in public archives for image making or other pursuits?
Lisa Frattare: Observational astronomy is a rocking field. Much of the software needed to analyze telescope data is user friendly and meant to be accessed from anywhere. The NASA Great Observatories Chandra, Hubble and Spitzer, put their data in public online archives. Anyone with a computer and a passion can learn how to process images from the archival data to make incredible pictures of the cosmos. There is also a supportive group of interested, non-professional image processors who share and learn from each other.

Nancy Wolk: I’ve recently had the privilege of working with a young college student in India this past year. We’ve discussed different ways to process X-ray data so that data are both accurate and pretty. He’s asked many questions and I can see how his work has come a long way. I recommend reaching out to the outreach offices at telescopes. That’s why we are here. We want to help people hone their skills and learn how to mix the different wavelengths to gain a better understanding of our universe.

Judy Schmidt: Try not to feel intimidated. I used to worry someone would jump in and tell me I was doing everything wrong and bad, but that never happened. Learning the jargon and getting past the technical parts is worth it. Not a whole lot of people do this work, and there’s no secret club, so try to find us on Twitter or other social networks. I’ve helped a lot of beginners who have asked me questions through email, Twitter, and elsewhere.

Kim Arcand: There are so many different ways to try your hand at imaging the Universe. Here is a brief guide of resources we’ve created or partnered on:

Brand new to this? Start out by learning how computers use red, green and blue to add color to digital images, and try coloring some real NASA data sets at

Next, try watching this TEDx talk to get a brief introduction to what we do at Chandra to visualize the high-energy Universe ( Head over to Vox for a more indepth video on how we color the Universe in different kinds of light (

A good next step would be to take an image using the MicroObservatory (, where you can even submit an image for their NASA data photo challenges. There are a number of good resources to try in here.

After that, a trip through our Open Fits tutorials ( might be a good place to go. “FITS”, which stands for Flexible Image Transport System, is a digital file format used mainly by astronomers. In this section you can download FITS files for some of our favorite Chandra images and learn how to compose your own versions of these high-energy astronomy images with a series of short tutorials.

When you’re ready, dive in to the NASA archives! Each NASA mission has a wealth of data to dig through, and such data is typically public about a year after it’s been taken. For Chandra, there are about 19 years of X-ray data to comb through for treasures ( For Hubble, there’s about 28 years of data ( And that’s just two astronomical missions. All are publicly accessible, ready to be shined up and polished into a gorgeous visual treat.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

#astronomy, #astrophysics, #basic-research, #behind-the-scenes-with-the-image-makers, #cosmology, #judy-schmidt, #kim-arcand, #lisa-frattare, #nancy-wolk, #nasa-chandra

From NASA Chandra: “Chandra Spots a Mega-Cluster of Galaxies in the Making”

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From NASA Chandra

October 24, 2019




A mega-merger of four galaxy clusters in Abell 1758 has been observed by Chandra and other telescopes.

Abell 1758 contains two pairs of galaxy clusters, each with hundreds of galaxies embedded in large amounts of hot gas and unseen dark matter.

Eventually these two pairs of clusters will collide to form one of the most massive objects in the Universe.

The X-rays from Chandra helped astronomers estimate how fast one pair of clusters were moving toward each other.

Astronomers using data from NASA’s Chandra X-ray Observatory and other telescopes have put together a detailed map of a rare collision between four galaxy clusters. Eventually all four clusters — each with a mass of at least several hundred trillion times that of the Sun — will merge to form one of the most massive objects in the universe.

Galaxy clusters are the largest structures in the cosmos that are held together by gravity. Clusters consist of hundreds or even thousands of galaxies embedded in hot gas, and contain an even larger amount of invisible dark matter. Sometimes two galaxy clusters collide, as in the case of the Bullet Cluster, and occasionally more than two will collide at the same time.

The new observations show a mega-structure being assembled in a system called Abell 1758, located about 3 billion light-years from Earth. It contains two pairs of colliding galaxy clusters that are heading toward one another. Scientists first recognized Abell 1758 as a quadruple galaxy cluster system in 2004 using data from Chandra and XMM-Newton, a satellite operated by the European Space Agency (ESA).

ESA/XMM Newton

Each pair in the system contains two galaxy clusters that are well on their way to merging. In the northern (top) pair seen in the composite image, the centers of each cluster have already passed by each other once, about 300 to 400 million years ago, and will eventually swing back around. The southern pair at the bottom of the image has two clusters that are close to approaching each other for the first time.

Labeled image of Abell 1758 system.

X-rays from Chandra are shown as blue and white, depicting fainter and brighter diffuse emission, respectively. This new composite image also includes an optical image from the Sloan Digital Sky Survey.

SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude2,788 meters (9,147 ft)

The Chandra data revealed for the first time a shock wave — similar to the sonic boom from a supersonic aircraft — in hot gas visible with Chandra in the northern pair’s collision. From this shock wave, researchers estimate two clusters are moving about 2 million to 3 million miles per hour (3 million to 5 million kilometers per hour), relative to each other.

Chandra data also provide information about how elements heavier than helium, the “heavy elements,” in galaxy clusters get mixed up and redistributed after the clusters collide and merge. Because this process depends on how far a merger has progressed, Abell 1758 offers a valuable case study, since the northern and the southern pairs of clusters are at different stages of merging.

In the southern pair, the heavy elements are most abundant in the centers of the two colliding clusters, showing that the original location of the elements has not been strongly impacted by the ongoing collision. By contrast, in the northern pair, where the collision and merger has progressed further, the location of the heavy elements has been strongly influenced by the collision. The highest abundances are found between the two cluster centers and to the left side of the cluster pair, while the lowest abundances are in the center of the cluster on the left side of the image.

Collisions between clusters affect their component galaxies as well as the hot gas that surrounds them. Data from the 6.5-meter MMT telescope in Arizona, obtained as part of the Arizona Cluster Redshift Survey, show that some galaxies are moving much faster than others, probably because they have been thrown away from the other galaxies in their cluster by gravitational forces imparted by the collision.

CfA U Arizona Fred Lawrence Whipple Observatory Steward Observatory MMT Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA, Altitude 2,616 m (8,583 ft)

The team also used radio data from the Giant Metrewave Radio Telescope (GMRT), and X-ray data from ESA’s XMM-Newton mission.

Giant Metrewave Radio Telescope, an array of thirty telecopes, located near Pune in India

A paper describing these latest results by Gerrit Schellenberger, Larry David, Ewan O’Sullivan, Jan Vrtilek (all from Center for Astrophysics | Harvard & Smithsonian) and Christopher Haines (Universidad de Atacama, Chile) was published in the September 1st, 2019 issue of The Astrophysical Journal.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

#chandra-spots-a-mega-cluster-of-galaxies-in-the-making, #a-mega-merger-of-four-galaxy-clusters-in-abell-1758-has-been-observed-by-chandra-and-other-telescopes, #astronomy, #astrophysics, #basic-research, #cosmology, #nasa-chandra

From NASA Chandra: “The Clumpy and Lumpy Death of a Star”

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From NASA Chandra

October 17, 2019




A new image of the Tycho supernova remnant from Chanda shows a pattern of bright clumps and fainter holes in the X-ray data.

Scientists are trying to determine if this ‘clumpiness’ was caused by the supernova explosion itself or something in its aftermath.

By comparing Chandra data to computer simulations, researchers found evidence that the explosion was likely the source of this lumpy distribution.

The original supernova was first seen by skywatchers in 1572, including the Danish astronomer Tycho Brahe who the object was eventually named after.

In 1572, Danish astronomer Tycho Brahe was among those who noticed a new bright object in the constellation Cassiopeia. Adding fuel to the intellectual fire that Copernicus started, Tycho showed this “new star” was far beyond the Moon, and that it was possible for the Universe beyond the Sun and planets to change.

Astronomers now know that Tycho’s new star was not new at all. Rather it signaled the death of a star in a supernova, an explosion so bright that it can outshine the light from an entire galaxy. This particular supernova was a Type Ia, which occurs when a white dwarf star pulls material from, or merges with, a nearby companion star until a violent explosion is triggered. The white dwarf star is obliterated, sending its debris hurtling into space.

As with many supernova remnants, the Tycho supernova remnant, as it’s known today (or “Tycho,” for short), glows brightly in X-ray light because shock waves — similar to sonic booms from supersonic aircraft — generated by the stellar explosion heat the stellar debris up to millions of degrees. In its two decades of operation, NASA’s Chandra X-ray Observatory has captured unparalleled X-ray images of many supernova remnants.

Chandra reveals an intriguing pattern of bright clumps and fainter areas in Tycho. What caused this thicket of knots in the aftermath of this explosion? Did the explosion itself cause this clumpiness, or was it something that happened afterward?

This latest image of Tycho from Chandra is providing clues. To emphasize the clumps in the image and the three-dimensional nature of Tycho, scientists selected two narrow ranges of X-ray energies to isolate material (silicon, colored red) moving away from Earth, and moving towards us (also silicon, colored blue). The other colors in the image (yellow, green, blue-green, orange and purple) show a broad range of different energies and elements, and a mixture of directions of motion. In this new composite image, Chandra’s X-ray data have been combined with an optical image of the stars in the same field of view from the Digitized Sky Survey.

By comparing the Chandra image of Tycho to two different computer simulations, researchers were able to test their ideas against actual data. One of the simulations began with clumpy debris from the explosion. The other started with smooth debris from the explosion and then the clumpiness appeared afterwards as the supernova remnant evolved and tiny irregularities were magnified.

A statistical analysis using a technique that is sensitive to the number and size of clumps and holes in images was then used. Comparing results for the Chandra and simulated images, scientists found that the Tycho supernova remnant strongly resembles a scenario in which the clumps came from the explosion itself. While scientists are not sure how, one possibility is that star’s explosion had multiple ignition points, like dynamite sticks being set off simultaneously in different locations.

Understanding the details of how these stars explode is important because it may improve the reliability of the use of Type Ia supernovas “standard candles” — that is, objects with known inherent brightness, which scientists can use to determine their distance. This is very important for studying the expansion of the universe. These supernovae also sprinkle elements such as iron and silicon, that are essential for life as we know it, into the next generation of stars and planets.

A paper describing these results appeared in the July 10th, 2019 issue of The Astrophysical Journal. The authors are Toshiki Sato (RIKEN in Saitama, Japan, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland), John (Jack) Hughes (Rutgers University in Piscataway, New Jersey), Brian Williams, (NASA’s Goddard Space Flight Center), and Mikio Morii (The Institute of Statistical Mathematics in Tokyo, Japan).

3D printed model of Tycho’s Supernova Remnant

Another team of astronomers, led by Gilles Ferrand of RIKEN in Saitama, Japan, has constructed their own three-dimensional computer models of a Type Ia supernova remnant as it changes with time. Their work shows that initial asymmetries in the simulated supernova explosion are required so that the model of the ensuing supernova remnant closely resembles the Chandra image of Tycho, at a similar age. This conclusion is similar to that made by Sato and his team.

A paper describing the results by Ferrand and co-authors appeared in the June 1st, 2019 issue of The Astrophysical Journal.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

#the-clumpy-and-lumpy-death-of-a-star, #astronomy, #astrophysics, #basic-research, #cosmology, #nasa-chandra, #the-tycho-supernova-remnant

From NASA Chandra: “Scientists Discover Black Hole Has Three Hot Meals a Day”

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NASA/Chandra Telescope

From NASA Chandra

September 11, 2019
From Chandra at CfA
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.

From ESA

Giovanni Miniutti
Centro de Astrobiología (CAB, CSIC-INTA)
Madrid, Spain

Richard Saxton
Telespazio-Vega UK for ESA
XMM-Newton Science Operations Centre
European Space Agency

Margherita Giustini
Centro de Astrobiología (CAB, CSIC-INTA)
Madrid, Spain

Norbert Schartel
XMM-Newton project scientist
European Space Agency

X-ray: NASA/CXO/CSIC-INTA/G.Miniutti et al.; Optical: DSS

Evidence for a supermassive black hole consuming large amounts of material about three times a day has been found.

The data come from NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton taken over the span of 54 days beginning in late 2018.

The orbiting X-ray telescopes detected regular outbursts from the black hole at the center of the galaxy called GSN 069.

Astronomers estimate that each “meal” contains the mass about four times that of the Moon.

There’s an adage that it’s not healthy to skip meals. Apparently, a supermassive black hole in the center of a galaxy millions of light years away has gotten the message.

A team of astronomers found X-ray bursts repeating about every nine hours originating from the center of a galaxy called GSN 069. Obtained with NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton, these data indicate that the supermassive black hole located there is consuming large amounts of material on a regular schedule.

XMM-Newton observations

Quasi-periodic eruptions in GSN 069

ESA/XMM Newton

While scientists had previously found two “stellar-mass” black holes (that weigh about 10 times the Sun’s mass) occasionally undergoing regular outbursts before, this behavior has never been detected from a supermassive black hole until now.

The black hole at the center of GSN 069, located 250 million light years from Earth, contains about 400,000 times the mass of the Sun. The researchers estimate that the black hole is consuming about four Moons’ worth of material about three times a day. That’s equivalent to almost a million billion billion pounds going into the black hole per feeding.

“This black hole is on a meal plan like we’ve never seen before,” said Giovanni Miniutti from ESA’s Center for Astrobiology in Spain, the first author of a Nature paper, published today in the September 11, 2019 issue of the journal, describing these results. “This behavior is so unprecedented that we had to coin a new expression to describe it: “X-ray Quasi-Periodic Eruptions”.”

ESA’s XMM-Newton was the first to observe this phenomenon in GSN 069 with the detection of two bursts on December 24, 2018. Miniutti and colleagues then followed up with more XMM-Newton observations on January 16 and 17, 2019, and found five outbursts. Observations by Chandra less than a month later, on February 14, revealed an additional three outbursts.

“By combining data from these two X-ray observatories, we have tracked these periodic outbursts for at least 54 days” said co-author Richard Saxton of the European Space Astronomy Centre in Madrid, Spain. “This gives us a unique opportunity to witness the flow of matter into a supermassive black hole repeatedly speeding up and slowing down.”

During the outbursts the X-ray emission becomes about 20 times brighter than during the quiet times. The temperature of gas falling towards the black hole also climbs, from about one million degrees Fahrenheit during the quiet periods to about 2.5 million degrees Fahrenheit during the outbursts. The temperature of the latter is similar to that of gas found around most actively growing supermassive black holes.

The origin of this hot gas has been a long-standing mystery because it appears to be too hot to be associated with the disk of infalling matter surrounding the black holes. Although its origin is also a mystery in GSN 069, the ability to study a supermassive black hole where hot gas repeatedly forms then disappears may provide important clues.

“We think the origin of the X-ray emission is a star that the black hole has partially or completely torn apart and is slowly consuming bit by bit.” said co-author Margherita Giustini, also of ESA’s Center for Astrobiology. “But as for the repeating bursts, this is a completely different story whose origin needs to be studied with further data and new theoretical models”.

The consumption of gas from a disrupted star by a supermassive black hole has been observed before, but never accompanied by repetitive X-ray bursts. The authors suggest there are two possible explanations for the bursts. One is that the amount of energy in the disk builds up until it becomes unstable and matter rapidly falls into the black hole producing the bursts. The cycle would then repeat. Another is that there is an interaction between the disk and a secondary body orbiting the black hole, perhaps the remnant of the partially disrupted star.

The Chandra data were crucial for this study because they were able to show that the X-ray source is located in the center of the host galaxy, which is where a supermassive black hole is expected to be. The combination of data from Chandra and XMM-Newton implies that the size and duration of the black hole’s meals have decreased slightly, and the gap between the meals has increased. Future observations will be crucial to see if the trend continues.

Supermassive black holes are usually larger than GSN 069, with masses of millions or even billions of suns. The larger the black hole the slower their fluctuations in brightness will be, so instead of erupting every nine hours they should erupt every few months or years which likely explains why quasi-periodic eruptions where never seen before.

Examples of large increases or decreases in the amount of X-rays produced by black holes have been observed in a few cases, using repeated observations over months or even years. The changes in some objects are much faster than expected by standard theory of disks of infalling matter surrounding black holes, but could be naturally accounted for if they were experiencing similar behavior to GSN 069.

Along with data from Chandra and XMM-Newton the international research team used data from NASA’s Swift X-ray observatory, the NASA/ESA Hubble Space Telescope, NRAO’s Karl G. Jansky Very Large Array in New Mexico, USA, CSIRO’s Australia Telescope Compact Array in Australia, and SARAO’s MeerKAT radio telescope in South Africa.

NASA Neil Gehrels Swift Observatory

NASA/ESA Hubble Telescope

NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

CSIRO Australia Compact Array, six radio telescopes at the Paul Wild Observatory, is an array of six 22-m antennas located about twenty five kilometres (16 mi) west of the town of Narrabri in Australia.

SKA Meerkat telescope(s), 90 km outside the small Northern Cape town of Carnarvon, SA

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

#scientists-discover-black-hole-has-three-hot-meals-a-day, #astronomy, #astrophysics, #basic-research, #cosmology, #nasa-chandra, #the-black-hole-at-the-center-of-the-galaxy-called-gsn-069

From NASA Chandra: “The Latest Look at “First Light” from Chandra” Cassiopeia A

NASA Chandra Banner

NASA/Chandra Telescope

From NASA Chandra

Credit: X-ray: NASA/CXC/RIKEN/T. Sato et al.; Optical: NASA/STScI

Located about 11,000 light-years from Earth, Cas A (as it’s nicknamed) is the glowing debris field left behind after a massive star exploded. When the star ran out of fuel, it collapsed onto itself and blew up as a supernova, possibly briefly becoming one of the brightest objects in the sky. (Although astronomers think that this happened around the year 1680, there are no verifiable historical records to confirm this.)

The shock waves generated by this blast supercharged the stellar wreckage and its environment, making the debris glow brightly in many types of light, particularly X-rays. Shortly after Chandra was launched aboard the Space Shuttle Columbia on July 23, 1999, astronomers directed the observatory to point toward Cas A. It was featured in Chandra’s official “First Light” image, released Aug. 26, 1999, and marked a seminal moment not just for the observatory, but for the field of X-ray astronomy. Near the center of the intricate pattern of the expanding debris from the shattered star, the image revealed, for the first time, a dense object called a neutron star that the supernova left behind.

Since then, Chandra has repeatedly returned to Cas A to learn more about this important object. A new video shows the evolution of Cas A over time, enabling viewers to watch as incredibly hot gas — about 20 million degrees Fahrenheit — in the remnant expands outward. These X-ray data have been combined with data from another of NASA’s “Great Observatories,” the Hubble Space Telescope, showing delicate filamentary structures of cooler gases with temperatures of about 20,000 degrees Fahrenheit. Hubble data from a single time period are shown to emphasize the changes in the Chandra data.

The video shows Chandra observations of Cas A from 2000 to 2013. In that time, a child could enter kindergarten and graduate from high school. While the transformation might not be as apparent as that of a student over the same period, it is remarkable to watch a cosmic object change on human time scales.

The blue, outer region of Cas A shows the expanding blast wave of the explosion. The blast wave is composed of shock waves, similar to the sonic booms generated by a supersonic aircraft. These expanding shock waves produce X-ray emission and are sites where particles are being accelerated to energies that reach about two times higher than the most powerful accelerator on Earth, the Large Hadron Collider. As the blast wave travels outwards at speeds of about 11 million miles per hour, it encounters surrounding material and slows down, generating a second shock wave – called a “reverse shock” – that travels backwards, similar to how a traffic jam travels backwards from the scene of an accident on a highway.

These reverse shocks are usually observed to be faint and much slower moving than the blast wave. However, a team of astronomers led by Toshiki Sato from RIKEN in Saitama, Japan, and NASA’s Goddard Space Flight Center, have reported reverse shocks in Cas A that appear bright and fast moving, with speeds between about 5 and 9 million miles per hour. These unusual reverse shocks are likely caused by the blast wave encountering clumps of material surrounding the remnant, as Sato and team discuss in their 2018 study. This causes the blast wave to slow down more quickly, which re-energizes the reverse shock, making it brighter and faster. Particles are also accelerated to colossal energies by these inward moving shocks, reaching about 30 times the energies of the LHC.

Cassiopeia A in X-ray and optical light.

This recent study of Cas A adds to a long collection of Chandra discoveries over the course of the telescope’s 20 years. In addition to finding the central neutron star, Chandra data have revealed the distribution of elements essential for life ejected by the explosion (shown above), have constructed a remarkable three dimensional model of the supernova remnant, and much more.

Scientists also created a historical record in optical light of Cas A using photographic plates from the Palomar Observatory in California from 1951 and 1989 that had been digitized by the Digitized Access to a Sky Century @ Harvard (DASCH) program, located at the Center for Astrophysics | Harvard & Smithsonian (CfA). These were combined with images taken by the Hubble Space Telescope between 2000 and 2011. This long-term look at Cas A allowed astronomers Dan Patnaude of CfA and Robert Fesen of Dartmouth College to learn more about the physics of the explosion and the resulting remnant from both the X-ray and optical data.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

#the-latest-look-at-first-light-from-chandra, #astronomy, #astrophysics, #basic-research, #cassiopeia-a-supernova-remnant, #cosmology, #nasa-chandra

From NASA Chandra Blog: “Exploring New Paths of Study with Chandra”

NASA Chandra Banner

NASA/Chandra Telescope

From NASA Chandra Blog

Peter Edmonds, CXC

We make progress in astrophysics in a variety of ways. There is the sort that starts along a defined path, driven by meticulous proposals for telescope time or detailed science justifications for new missions. The plan is to advance knowledge by traveling further than others, or clearing a broader path. And then there are others.

A big mission like NASA’s Chandra X-ray Observatory begins with plans for investigation along a slew of different directions and lines of study. At the time of Chandra’s launch on July 23rd, 1999, scientists thought these paths would mainly follow studies of galaxy clusters, dark matter, black holes, supernovas, and young stars. Indeed, in the last 20 years we’ve learned about black holes ripping stars apart (reported eg in 2004, 2011 and 2017), about a black hole generating the deepest known note in the universe, about dark matter being wrenched apart from normal matter in the famous Bullet Cluster and similar objects, about the discovery of the youngest supernova remnant in our galaxy, and much more.

Bullet Cluster NASA Chandra NASA ESA Hubble

NASA/ESA Hubble Telescope

Progress in astrophysics can also be made when new paths of study suddenly open up. Three outstanding examples for Chandra are studies of gravitational wave events, dark energy and exoplanets. None of these fields existed before Chandra was conceived or built, but have now delivered some of our most exciting results.

Release: NASA Missions Catch FirstLight from a Gravitational-Wave Event

The newest example is the study of X-rays produced by the aftermath of gravitational wave events. In 1999 the detection of gravitational waves seemed like a distant or even impossible goal for many astronomers. But the LIGO scientists kept improving their remarkably sensitive observatory until September 2015, when they detected a burst of gravitational waves from the merger of two black holes. Two black holes that merge are not expected to produce electromagnetic radiation, but the mergers of two neutron stars are. That is exactly what was as observed for the first time in August 2017 with LIGO and a slew of telescopes.

VIRGO Gravitational Wave interferometer, near Pisa, Italy

Caltech/MIT Advanced aLigo Hanford, WA, USA installation

Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger

Gravity is talking. Lisa will listen. Dialogos of Eide

ESA/eLISA the future of gravitational wave research

Localizations of gravitational-wave signals detected by LIGO in 2015 (GW150914, LVT151012, GW151226, GW170104), more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo came online in August 2018

Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

UC Santa Cruz

UC Santa Cruz

UCSC All the Gold in the Universe

A UC Santa Cruz special report

Tim Stephens

Astronomer Ryan Foley says “observing the explosion of two colliding neutron stars” –the first visible event ever linked to gravitational waves–is probably the biggest discovery he’ll make in his lifetime. That’s saying a lot for a young assistant professor who presumably has a long career still ahead of him.

The first optical image of a gravitational wave source was taken by a team led by Ryan Foley of UC Santa Cruz using the Swope Telescope at the Carnegie Institution’s Las Campanas Observatory in Chile. This image of Swope Supernova Survey 2017a (SSS17a, indicated by arrow) shows the light emitted from the cataclysmic merger of two neutron stars. (Image credit: 1M2H Team/UC Santa Cruz & Carnegie Observatories/Ryan Foley)

Carnegie Institution Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

A neutron star forms when a massive star runs out of fuel and explodes as a supernova, throwing off its outer layers and leaving behind a collapsed core composed almost entirely of neutrons. Neutrons are the uncharged particles in the nucleus of an atom, where they are bound together with positively charged protons. In a neutron star, they are packed together just as densely as in the nucleus of an atom, resulting in an object with one to three times the mass of our sun but only about 12 miles wide.

“Basically, a neutron star is a gigantic atom with the mass of the sun and the size of a city like San Francisco or Manhattan,” said Foley, an assistant professor of astronomy and astrophysics at UC Santa Cruz.

These objects are so dense, a cup of neutron star material would weigh as much as Mount Everest, and a teaspoon would weigh a billion tons. It’s as dense as matter can get without collapsing into a black hole.


Like other stars, neutron stars sometimes occur in pairs, orbiting each other and gradually spiraling inward. Eventually, they come together in a catastrophic merger that distorts space and time (creating gravitational waves) and emits a brilliant flare of electromagnetic radiation, including visible, infrared, and ultraviolet light, x-rays, gamma rays, and radio waves. Merging black holes also create gravitational waves, but there’s nothing to be seen because no light can escape from a black hole.

Foley’s team was the first to observe the light from a neutron star merger that took place on August 17, 2017, and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO).


It turns out that the origins of the heaviest elements, such as gold, platinum, uranium—pretty much everything heavier than iron—has been an enduring conundrum. All the lighter elements have well-explained origins in the nuclear fusion reactions that make stars shine or in the explosions of stars (supernovae). Initially, astrophysicists thought supernovae could account for the heavy elements, too, but there have always been problems with that theory, says Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz.

The violent merger of two neutron stars is thought to involve three main energy-transfer processes, shown in this diagram, that give rise to the different types of radiation seen by astronomers, including a gamma-ray burst and a kilonova explosion seen in visible light. (Image credit: Murguia-Berthier et al., Science)

A theoretical astrophysicist, Ramirez-Ruiz has been a leading proponent of the idea that neutron star mergers are the source of the heavy elements. Building a heavy atomic nucleus means adding a lot of neutrons to it. This process is called rapid neutron capture, or the r-process, and it requires some of the most extreme conditions in the universe: extreme temperatures, extreme densities, and a massive flow of neutrons. A neutron star merger fits the bill.

Ramirez-Ruiz and other theoretical astrophysicists use supercomputers to simulate the physics of extreme events like supernovae and neutron star mergers. This work always goes hand in hand with observational astronomy. Theoretical predictions tell observers what signatures to look for to identify these events, and observations tell theorists if they got the physics right or if they need to tweak their models. The observations by Foley and others of the neutron star merger now known as SSS17a are giving theorists, for the first time, a full set of observational data to compare with their theoretical models.

According to Ramirez-Ruiz, the observations support the theory that neutron star mergers can account for all the gold in the universe, as well as about half of all the other elements heavier than iron.


Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity, but until recently they were impossible to observe. LIGO’s extraordinarily sensitive detectors achieved the first direct detection of gravitational waves, from the collision of two black holes, in 2015. Gravitational waves are created by any massive accelerating object, but the strongest waves (and the only ones we have any chance of detecting) are produced by the most extreme phenomena.

Two massive compact objects—such as black holes, neutron stars, or white dwarfs—orbiting around each other faster and faster as they draw closer together are just the kind of system that should radiate strong gravitational waves. Like ripples spreading in a pond, the waves get smaller as they spread outward from the source. By the time they reached Earth, the ripples detected by LIGO caused distortions of space-time thousands of times smaller than the nucleus of an atom.

The rarefied signals recorded by LIGO’s detectors not only prove the existence of gravitational waves, they also provide crucial information about the events that produced them. Combined with the telescope observations of the neutron star merger, it’s an incredibly rich set of data.

LIGO can tell scientists the masses of the merging objects and the mass of the new object created in the merger, which reveals whether the merger produced another neutron star or a more massive object that collapsed into a black hole. To calculate how much mass was ejected in the explosion, and how much mass was converted to energy, scientists also need the optical observations from telescopes. That’s especially important for quantifying the nucleosynthesis of heavy elements during the merger.

LIGO can also provide a measure of the distance to the merging neutron stars, which can now be compared with the distance measurement based on the light from the merger. That’s important to cosmologists studying the expansion of the universe, because the two measurements are based on different fundamental forces (gravity and electromagnetism), giving completely independent results.

“This is a huge step forward in astronomy,” Foley said. “Having done it once, we now know we can do it again, and it opens up a whole new world of what we call ‘multi-messenger’ astronomy, viewing the universe through different fundamental forces.”


Neutron stars
A team from UC Santa Cruz was the first to observe the light from a neutron star merger that took place on August 17, 2017 and was detected by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)

Graduate students and post-doctoral scholars at UC Santa Cruz played key roles in the dramatic discovery and analysis of colliding neutron stars.Astronomer Ryan Foley leads a team of young graduate students and postdoctoral scholars who have pulled off an extraordinary coup. Following up on the detection of gravitational waves from the violent merger of two neutron stars, Foley’s team was the first to find the source with a telescope and take images of the light from this cataclysmic event. In so doing, they beat much larger and more senior teams with much more powerful telescopes at their disposal.

“We’re sort of the scrappy young upstarts who worked hard and got the job done,” said Foley, an untenured assistant professor of astronomy and astrophysics at UC Santa Cruz.

David Coulter, graduate student

The discovery on August 17, 2017, has been a scientific bonanza, yielding over 100 scientific papers from numerous teams investigating the new observations. Foley’s team is publishing seven papers, each of which has a graduate student or postdoc as the first author.

“I think it speaks to Ryan’s generosity and how seriously he takes his role as a mentor that he is not putting himself front and center, but has gone out of his way to highlight the roles played by his students and postdocs,” said Enrico Ramirez-Ruiz, professor and chair of astronomy and astrophysics at UC Santa Cruz and the most senior member of Foley’s team.

“Our team is by far the youngest and most diverse of all of the teams involved in the follow-up observations of this neutron star merger,” Ramirez-Ruiz added.

Charles Kilpatrick, postdoctoral scholar

Charles Kilpatrick, a 29-year-old postdoctoral scholar, was the first person in the world to see an image of the light from colliding neutron stars. He was sitting in an office at UC Santa Cruz, working with first-year graduate student Cesar Rojas-Bravo to process image data as it came in from the Swope Telescope in Chile. To see if the Swope images showed anything new, he had also downloaded “template” images taken in the past of the same galaxies the team was searching.

Ariadna Murguia-Berthier, graduate student

“In one image I saw something there that was not in the template image,” Kilpatrick said. “It took me a while to realize the ramifications of what I was seeing. This opens up so much new science, it really marks the beginning of something that will continue to be studied for years down the road.”

At the time, Foley and most of the others in his team were at a meeting in Copenhagen. When they found out about the gravitational wave detection, they quickly got together to plan their search strategy. From Copenhagen, the team sent instructions to the telescope operators in Chile telling them where to point the telescope. Graduate student David Coulter played a key role in prioritizing the galaxies they would search to find the source, and he is the first author of the discovery paper published in Science.

Matthew Siebert, graduate student

“It’s still a little unreal when I think about what we’ve accomplished,” Coulter said. “For me, despite the euphoria of recognizing what we were seeing at the moment, we were all incredibly focused on the task at hand. Only afterward did the significance really sink in.”

Just as Coulter finished writing his paper about the discovery, his wife went into labor, giving birth to a baby girl on September 30. “I was doing revisions to the paper at the hospital,” he said.

It’s been a wild ride for the whole team, first in the rush to find the source, and then under pressure to quickly analyze the data and write up their findings for publication. “It was really an all-hands-on-deck moment when we all had to pull together and work quickly to exploit this opportunity,” said Kilpatrick, who is first author of a paper comparing the observations with theoretical models.

César Rojas Bravo, graduate student

Graduate student Matthew Siebert led a paper analyzing the unusual properties of the light emitted by the merger. Astronomers have observed thousands of supernovae (exploding stars) and other “transients” that appear suddenly in the sky and then fade away, but never before have they observed anything that looks like this neutron star merger. Siebert’s paper concluded that there is only a one in 100,000 chance that the transient they observed is not related to the gravitational waves.

Ariadna Murguia-Berthier, a graduate student working with Ramirez-Ruiz, is first author of a paper synthesizing data from a range of sources to provide a coherent theoretical framework for understanding the observations.

Another aspect of the discovery of great interest to astronomers is the nature of the galaxy and the galactic environment in which the merger occurred. Postdoctoral scholar Yen-Chen Pan led a paper analyzing the properties of the host galaxy. Enia Xhakaj, a new graduate student who had just joined the group in August, got the opportunity to help with the analysis and be a coauthor on the paper.

Yen-Chen Pan, postdoctoral scholar

“There are so many interesting things to learn from this,” Foley said. “It’s a great experience for all of us to be part of such an important discovery.”

Enia Xhakaj, graduate student


Scientific Papers from the 1M2H Collaboration

Coulter et al., Science, Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source

Drout et al., Science, Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis

Shappee et al., Science, Early Spectra of the Gravitational Wave Source GW170817: Evolution of a Neutron Star Merger

Kilpatrick et al., Science, Electromagnetic Evidence that SSS17a is the Result of a Binary Neutron Star Merger

Siebert et al., ApJL, The Unprecedented Properties of the First Electromagnetic Counterpart to a Gravitational-wave Source

Pan et al., ApJL, The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source

Murguia-Berthier et al., ApJL, A Neutron Star Binary Merger Model for GW170817/GRB170817a/SSS17a

Kasen et al., Nature, Origin of the heavy elements in binary neutron star mergers from a gravitational wave event

Abbott et al., Nature, A gravitational-wave standard siren measurement of the Hubble constant (The LIGO Scientific Collaboration and The Virgo Collaboration, The 1M2H Collaboration, The Dark Energy Camera GW-EM Collaboration and the DES Collaboration, The DLT40 Collaboration, The Las Cumbres Observatory Collaboration, The VINROUGE Collaboration & The MASTER Collaboration)

Abbott et al., ApJL, Multi-messenger Observations of a Binary Neutron Star Merger


Watch Ryan Foley tell the story of how his team found the neutron star merger in the video below. 2.5 HOURS.

Press releases:

UC Santa Cruz Press Release

UC Berkeley Press Release

Carnegie Institution of Science Press Release

LIGO Collaboration Press Release

National Science Foundation Press Release

Media coverage:

The Atlantic – The Slack Chat That Changed Astronomy

Washington Post – Scientists detect gravitational waves from a new kind of nova, sparking a new era in astronomy

New York Times – LIGO Detects Fierce Collision of Neutron Stars for the First Time

Science – Merging neutron stars generate gravitational waves and a celestial light show

CBS News – Gravitational waves – and light – seen in neutron star collision

CBC News – Astronomers see source of gravitational waves for 1st time

San Jose Mercury News – A bright light seen across the universe, proving Einstein right

Popular Science – Gravitational waves just showed us something even cooler than black holes

Scientific American – Gravitational Wave Astronomers Hit Mother Lode

Nature – Colliding stars spark rush to solve cosmic mysteries

National Geographic – In a First, Gravitational Waves Linked to Neutron Star Crash

Associated Press – Astronomers witness huge cosmic crash, find origins of gold

Science News – Neutron star collision showers the universe with a wealth of discoveries

UCSC press release
First observations of merging neutron stars mark a new era in astronomy


Writing: Tim Stephens
Video: Nick Gonzales
Photos: Carolyn Lagattuta
Header image: Illustration by Robin Dienel courtesy of the Carnegie Institution for Science
Design and development: Rob Knight
Project managers: Sherry Main, Scott Hernandez-Jason, Tim Stephens

Dark Energy Survey

Dark Energy Camera [DECam], built at FNAL

NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

Noted in the video but not in the article:

NASA/Chandra Telescope

NASA/SWIFT Telescope

NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

Prompt telescope CTIO Chile

NASA NuSTAR X-ray telescope

See the full article here

A Chandra observation two days after the merger failed to make a detection, but about a week later a source was discovered. These and additional observations taught us about the behavior and orientation of the jet that the neutron star merger produced.

The interest in this X-ray detection was so intense that there was a race between three different teams to publish the early Chandra observations first. This was accompanied by a rush to publicly announce the full set of results from LIGO and telescopes across the electromagnetic spectrum, before too many smart science writers dug out the news from Twitter and other publicly available information.

Release: All in the Family: Kin ofGravitational-Wave Source Discovered

Chandra detections of two likely neutron star mergers have been reported since August 2017 (in 2018 and 2019). These did not involve a detection of GWs, both because Advanced LIGO wasn’t yet operating, and because the events were likely too distant to be detectable even if it was. When Advanced LIGO and Virgo detect other neutron star mergers, and optical telescopes track them down, Chandra “Target of Opportunity” programs will kick in to study them. (TOOs, as they are called, are special cases made by scientists to interrupt the regularly scheduled observations in favor of one that is time sensitive and/or extremely important.) One is a large proposal and collaboration between three different teams, one aims to take a spectrum, another aims to observe a relatively nearby event, and a fourth involves joint observations with the VLA.

Those who work on Chandra and many in the wider science community were very excited about this detection because it marked the first time that gravitational waves and electromagnetic radiation were observed together, as a new type of “multi-messenger” astrophysics. (Multi-messenger astrophysics involves at least two of the following messengers: electromagnetic radiation, gravitational waves, neutrinos and cosmic rays.) However, it did not represent the first instance of multi-messenger astrophysics, because both electromagnetic radiation and neutrinos had already been observed from the Sun and from Supernova 1987A. Chandra may have already got into the act with the observation of a flare from material very close to the supermassive black hole in the center of our Galaxy, as reported in 2014. An energetic neutrino observed with the IceCube detector may have originated from this flare.

Another exciting new line of study has come from the discovery that the expansion of the universe is accelerating. The two key papers providing the first evidence for this surprising result were published in 1998 and 1999, just before Chandra launched. Both papers used distance measurements to supernova explosions over the last 5 billion or so years to follow the expansion. Since then a set of different techniques have been used to independently confirm and extend these results, including two involving Chandra observations of galaxy clusters. In one of them the distances to galaxy clusters were used to probe the expansion rate of the universe and another involved measuring the effects of accelerating expansion in slowing down the growth rate of galaxy clusters, in a type of cosmic arrested development. As explained in this article, if it wasn’t for accelerating expansion the universe would look very different from how it looks today.

The work measuring the growth rate of galaxy clusters has led to independent tests of Einstein’s General Theory of Relativity over distances that are much greater than those of Earth-orbiting satellites. The confirmation of GR has added to the evidence that a mysterious force called “dark energy” is causing cosmic acceleration.

Release: Astronomers Find Dark EnergyMay Vary Over Time

More recently, Chandra is being used with a new technique to probe cosmic expansion out to greater distances than are possible with supernova data. Astronomers have found tentative evidence that dark energy might be strengthening with time, but this result needs to be confirmed with more extensive use of Chandra data, a study that is currently underway, and independent work.

The recently-launched European mission eROSITA will be taking a sensitive X-ray survey of the complete sky and will discover a huge number of galaxy clusters for follow-up studies of both dark energy and dark matter with Chandra.

eRosita DLR MPG

Release: NASA’s Chandra Sees Eclipsing Planetin X-rays for First Time

Many think the field of exoplanets studies started in 1995 with the detection of a hot Jupiter around the star 51 Pegasus, acclaimed as the first exoplanet discovered around a Sun-like star. (This was about the time that the grinding and polishing of Chandra’s grazing-incidence mirrors was completed.) Chandra observations have shown cases of the tail wagging the dog, where a planet is affecting the star it is orbiting, in one case by making the star appear unusually old, and in others causing it to behave like a much younger star, as reported in 2011 and 2013.

Chandra observations have uncovered multiple examples of planets under assault by outside forces. They’ve found cases where radiation from the host star is evaporating the atmosphere of a close-in planet (from 2011 and 2013), where the powerful gravity of a white dwarf may have ripped a planet apart, a case of possible stellar or planetary cannibalism, and a case where a star may be devouring a young planet. Chandra data was also used to show that young stars much less massive than the Sun can unleash a torrent of X-ray radiation that may significantly shorten the lifetime of planet-forming disks surrounding these stars.

We look forward to reporting more results in these three new fields, along with discoveries from X-ray astronomy’s traditional specialities. We also hope to see new fields appear, for fresh exploration with NASA’s premier X-ray mission.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

#astronomy, #astrophysics, #basic-research, #cfa, #cosmology, #nasa-chandra