Tycho's Supernova Remnant
Credit: X-ray: NASA/CXC/SAO.; Optical: DSS

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.

Ryan W. Pfeifle

We welcome Ryan W. Pfeifle as our guest blogger. He received his B.S. in Physics from George Mason University (GMU) in 2017, and then stayed at GMU to continue onto his Ph.D and work with his current advisor on colliding galaxies and active galactic nuclei (AGNs). He is currently a third-year graduate research assistant in the Department of Physics and Astronomy at GMU. His primary focus is the identification and characterization of dual and triple AGNs in advanced mergers in an effort to understand the relationship between galaxy mergers and black hole growth. He has two recently published papers, one on their dual AGN program (published in April and available here), and one that is the focus of this press release, published in the Astrophysical Journal and available here. In addition to his research work, he is a tour guide at the GMU observatory in Fairfax, VA.

Over the past several decades, we have come to understand that supermassive black holes (SMBHs), with masses in the range of one million to several billion times the mass of our own sun, reside at the centers of most massive galaxies. Not only do we see these SMBHs in nearby galaxies, we also see them in galaxies as early as a few hundred million years after the Big Bang! Astronomers are still struggling to explain how these massive black holes could grow to these immense sizes so quickly, but one possible explanation lies in the interactions between galaxies.

SDSS J084905.51+111447.2
Credit: X-ray: NASA/CXC/George Mason Univ./R. Pfeifle et al.; Optical: SDSS & NASA/STScI

A new study using data from NASA's Chandra X-ray Observatory and other telescopes provides the strongest evidence yet for a system of three supermassive black holes, as described in our latest press release. Astronomers think these triplet collisions, while extremely rare, play a critical role in how the biggest black holes grow over time.

The system is known as SDSS J084905.51+111447.2 (SDSS J0849+1114 for short) and is located a billion light years from Earth. In this graphic, X-rays from Chandra (purple) are shown in the pull-out in comparison with optical light from the Hubble Space Telescope and the Sloan Digital Sky Survey (red, green, and blue) in the main panel.

Credit: Illustration: ESO, ESA/Hubble, M.Kornmesser/N.Bartmann; Labels: NASA/CXC

Recently, we put out a press release about the regular dining habits of a supermassive black hole. Not only was this black hole found to be consuming material, or "eating," it was doing so regularly, about once every nine hours. While scientists had found such regular eating habits of smaller, so-called stellar mass black holes, this is the first evidence of such behavior in the black hole giants that live at the centers of galaxies.

The lead author of the result, which used data from both NASA's Chandra X-ray Observatory and ESA's XMM-Newton, is Giovanni Minuitti of the Center for Astrobiology (CAB, CSIC-INTA) in Spain. Recently, he agreed to answer a series of questions about his work aimed at kids.

How would you explain a supermassive black hole to kids?

Let me start from the beginning.

Any object with mass (a planet, a star, a black hole, and even our own bodies) produces a force — gravity — attracting towards it any other body with mass. Gravity is a force that is proportional to the mass of the object that produces it, and that is stronger if you are closer. Basically, the higher the mass of the body and the closer to the body you are, the stronger the pull you feel.

GSN 069
Credit: X-ray: NASA/CXO/CSIC-INTA/G.Miniutti et al.; Optical: DSS

A supermassive black hole is blasting out X-rays about every nine hours, according to data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton, as described in our latest press release. This indicates that this black hole, containing about 400,000 times the mass of our Sun, is consuming significant amounts of material about three times per day.

The main panel of this graphic is a visible light image taken by the Digitized Sky Survey (DSS) around the galaxy known as GSN 069, located in the center of the image. The inset gives a time-lapse of Chandra data taken over a period of about 20 hours on February 14 and 15, 2019, centered on the X-ray source in the middle of GSN 069. The sequence runs in a loop to show that the X-ray brightness of the source changes regularly and dramatically over the Chandra observation. Three X-ray eruptions are observed. (Note that to clearly show the Chandra source is located in GSN 069, the size of the box in the center of the DSS image is about ten times larger than the Chandra field in the inset.)

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.

Fabio Vito

We are very pleased to welcome Fabio Vito as our guest blogger. Vito is the first author of a paper that is the subject of our latest press release, on the discovery of a distant, cloaked black hole. He obtained his PhD in 2014 at the University of Bologna, Italy, before moving to Penn State as a postdoctoral researcher. He is now a postdoctoral fellow at the Pontificia Universidad Católica de Chile. He mainly works on the properties and evolution of high-redshift AGN, with the final goal of understanding how they formed and grew in the first billion years of the Universe.

Imagine you are a teacher in a kindergarten starting the school year. You enter the classroom, but instead of finding little children, you see fully grown people — men and women — staring at you. Puzzled, you check with the principal, and they confirm that those people are supposed to be the new kindergarteners, just a handful of years old. Two things come to your mind immediately: 1) this is definitely going to be a very long school year, 2) what happened? Why are adults sitting in your kindergarten classroom?

Astrophysicists find themselves in a similar situation today. According to our theoretical knowledge, supermassive black holes (SMBHs) should grow from "seeds" with masses not larger than hundreds of thousands of solar masses. We then use the most powerful telescopes to find the most distant — both in space and in time — growing SMBHs, shining as “quasars,” about 13 billion years ago, when the Universe was just a few hundred million years old. We look for them because astronomers want to study how they grew to become the monsters that populate the older Universe, with masses of billions of solar masses. However, the SMBHs powering the quasars that we find in the kindergarten of the Universe are already fully grown! They are indeed already as massive as the most massive SMBHs in the local Universe.

Illustration: Chandra X-ray Observatory

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.

Beginning in less than a month, we will be celebrating the 20th anniversary of the launch of NASA’s Chandra X-ray Observatory into space. To get Chandra-philes (Chandra-ites?) ready and bring new ones into the fold, we have been busy here at the Chandra X-ray Center preparing a slew of activities, products, and more to usher in our favorite X-ray telescope’s third decade of operation. Here are just a few of the things to look forward to this year:

• Launching with yet more content soon, a special section of the website devoted to the Chandra’s 20thanniversary. (Keep an eye on the calendar of events list for potential opportunities in your area to speak with Chandra scientists.)
• A collection of new Chandra images will be released twenty years to the day – July 23rd– that the Space Shuttle Columbia launched Chandra into orbit.