Vivienne Baldassare

We are very pleased to welcome Vivienne Baldassare as a guest blogger today. Vivienne is the first author of a paper that is the subject of our latest press release, about an exceptionally small supermassive black hole. She is a PhD candidate and National Science Foundation Graduate Research Fellow in the University of Michigan Department of Astronomy. Vivienne obtained her undergraduate degree in physics from Hunter College, where she was also a member of the Macaulay Honors College.

It is well established that most, if not all, massive galaxies host supermassive black holes at their centers − our own Milky Way houses a several million solar mass black hole in its core. Little is known, however, about the population of black holes in the centers of dwarf galaxies. I study the centers of small galaxies to see how many host supermassive black holes and if those black holes interact with their galaxies in the same way as bigger supermassive black holes.

Though dwarf galaxies are more common than large galaxies, it is more difficult to determine whether they host black holes. When galaxies are large and nearby, we can find central black holes by studying the motions of stars in the region dominated by the gravity of the black hole. Since smaller black holes influence smaller regions, this method would only work for dwarf galaxies in our cosmological back yard. Instead, we must search for active black holes in dwarf galaxies, i.e. black holes that are voraciously consuming material, releasing large amounts of light from the galaxy’s center.

Astronomers using NASA's Chandra X-ray Observatory and the 6.5-meter Clay Telescope in Chile have identified the smallest supermassive black hole ever detected in the center of a galaxy, as described in our latest press release. This oxymoronic object could provide clues to how much larger black holes formed along with their host galaxies 13 billion years or more in the past.

Jeremy Hare

We are very pleased to welcome Jeremy Hare as a guest blogger today. Jeremy is a co-author of a study led by George Pavlov from Pennsylvania Statue University and Oleg Kargaltsev from George Washington University that is the subject of our most recent press release, on a binary system named LS 2883. Jeremy is about to begin his fourth year of graduate school at GWU working under Oleg Kargaltsev. He studies high-mass gamma-ray binaries, mainly in X-rays, and the classification of X-ray sources using machine learning. He tells us that LS 2883 was the first research project he worked on in graduate school and that it has been “very exciting to study!”

High mass gamma-ray binaries are rare objects in the Galaxy. These binaries consist of a massive star (usually with a mass greater than 10 solar masses) and a compact object, a neutron star or black hole. Many high-mass stars have a disk of material around them, which the compact object can interact with as it nears the star in its (often elliptical) orbit. High-mass gamma-ray binaries can accelerate particles to extreme energies of 10 TeV (=1012 electron volts, or eV) or higher, which is comparable to the energies that are currently being produced at the Large Hadron Collider. These particles then scatter off of lower energy photons (packets of electromagnetic energy that make up light) produced by the star, transferring some of their energy and boosting the photon’s energy to the GeV (109 eV) and TeV energy range.

More information at http://chandra.harvard.edu/16th/index.html

Today we are celebrating the “sweet 16th” birthday not of a person, but of NASA's Chandra X-ray Observatory. On July 23, 1999, Chandra was launched into space aboard the Space Shuttle Columbia and has been working diligently to explore the high-energy Universe ever since.

On July 14th, the New Horizons spacecraft will fly by Pluto during its unprecedented mission to the outer Solar System. In addition to the data gathered by New Horizons and its suite of instruments, other telescopes – including the Chandra X-ray Observatory – will be pitching in to help astronomers learn more about this distant and icy world.

Artist conception of New Horizons Spacecraft.
Credits: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

While fireworks only last a short time here on Earth, a bundle of cosmic sparklers in a nearby cluster of stars will be going off for a very long time. NGC 1333 is a star cluster populated with many young stars that are less than 2 million years old, a blink of an eye in astronomical terms for stars like the Sun expected to burn for billions of years.

We are pleased to welcome guest blogger Sebastian Heinz, a Professor in the Astronomy Department at the University of Wisconsin-Madison. Sebastian led the team that discovered light echoes around Circinus X-1, the subject of our latest press release. He received his Ph.D. at the University of Colorado at Boulder. He studies relativistic jets − a phenomenon observed around black holes and neutron stars and started investigating the neutron star Circinus X-1 star when he was a Chandra Postdoctoral Fellow at MIT.

Some astronomical discoveries are straightforward − you observe something and it is immediately clear what you have found and what the consequences are. Often, though, astronomy requires the combination of different people’s skills and different kinds of data to solve a puzzle. This was definitely one of those puzzles.

When we downloaded the data from our long Chandra observation of the neutron star Circinus X-1 in early 2014, it was immediately clear that we were looking at an exceptionally bright light echo. Light echoes are created just like sound echoes, when light waves bounce off an obstacle (in this case dust clouds). Because their path has a kink in it, the bounced light waves take longer to arrive at the telescope than the waves that didn't bounce. Our echo resulted from a two-month long huge X-ray outburst Circinus X-1 had had in late 2013 (see the X-ray movie from MAXI included here), making it the largest, brightest, most spectacular set of X-ray rings to date, which is why we jokingly call Circinus X-1 the "Lord of the Rings".

Data from NASA's Chandra X-ray Observatory has helped provide a rare opportunity to determine the distance to an object on the other side of the Milky Way galaxy, as described in our latest press release

Astronomers have used NASA's Chandra X-ray Observatory to show that multiple eruptions from a supermassive black hole over 50 million years have rearranged the cosmic landscape at the center of a group of galaxies.

Scientists discovered this history of black hole eruptions by studying NGC 5813, a group of galaxies about 105 million light years from Earth. These Chandra observations are the longest ever obtained of a galaxy group, lasting for just over a week. The Chandra data are shown in this new composite image where the X-rays from Chandra (purple) have been combined with visible light data (red, green and blue).