Vivienne Baldassare

We are happy to welcome Vivienne Baldassare as our guest blogger. Vivienne is an Assistant Professor of Physics and Astronomy at Washington State University, and led the paper that is the subject of our latest press release. Her work is mainly focused on searching for the smallest supermassive black holes in order to learn more about black hole formation and growth. Prior to her current position, she was a NASA Einstein fellow at Yale University. She earned her PhD in Astronomy & Astrophysics from the University of Michigan in 2017, and a bachelor's degree in Physics from CUNY Hunter College in 2012.

One of the biggest open questions in astrophysics is “how do massive black holes form?” Our recent research with NASA’s Chandra X-ray Observatory provides support for the theory that massive black holes can form in what astronomers call nuclear star clusters.

While big galaxies have supermassive black holes at their centers, small galaxies often have a nuclear star cluster. Nuclear star clusters are extremely dense, with millions of stars packed into a region that is tens of light years across. It was once suggested that supermassive black holes and nuclear star clusters may be mutually exclusive, with the former residing in big galaxies and the latter occurring in small galaxies. However, some galaxies (like our Milky Way!) have been found to contain both. And excitingly, some theories suggest that nuclear star clusters might be able to form massive black holes.

In my first year of graduate school, I carried out a project studying the properties of nuclear star clusters. After that, I transitioned to studying massive black holes in dwarf galaxies, but have always had a soft spot for these fascinating objects. Our new study brought these two areas together.

Spiderweb Galaxy Field
Credit: X-ray: NASA/CXC/INAF/P. Tozzi et al; Optical (Subaru): NAOJ/NINS; Optical (HST): NASA/STScI

Often, a spiderweb conjures the idea of captured prey soon to be consumed by a waiting predator. In the case of the "Spiderweb" protocluster, however, objects that lie within a giant cosmic web are feasting and growing, according to data from NASA's Chandra X-ray Observatory.

The Spiderweb galaxy, officially known as J1140-2629, gets its nickname from its web-like appearance in some optical light images. This likeness can be seen in the inset box where data from NASA's Hubble Space Telescope shows galaxies in orange, white, and blue, and data from Chandra is in purple. Located about 10.6 billion light years from Earth, the Spiderweb galaxy is at the center of a protocluster, a growing collection of galaxies and gas that will eventually evolve into a galaxy cluster.

PSR J2030+4415
Credit: X-ray: NASA/CXC/Stanford Univ./M. de Vries; Optical: NSF/AURA/Gemini Consortium

This image from NASA's Chandra X-ray Observatory and ground-based optical telescopes shows an extremely long beam, or filament, of matter and antimatter extending from a relatively tiny pulsar, as reported in our latest press release. With its tremendous scale, this beam may help explain the surprisingly large numbers of positrons, the antimatter counterparts to electrons, scientists have detected throughout the Milky Way galaxy.

The panel on the left displays about one third the length of the beam from the pulsar known as PSR J2030+4415 (J2030 for short), which is located about 1,600 light years from Earth. J2030 is a dense, city-sized object that formed from the collapse of a massive star and currently spins about three times per second. X-rays from Chandra (blue) show where particles flowing from the pulsar along magnetic field lines are moving at about a third the speed of light. A close-up view of the pulsar in the right panel shows the X-rays created by particles flying around the pulsar itself. As the pulsar moves through space at about a million miles an hour, some of these particles escape and create the long filament. In both panels, optical light data from the Gemini telescope on Mauna Kea in Hawaii have been used and appear red, brown, and black. The full length of the filament is shown in a separate image.

Cassiopeia A
Credit: NASA/CXC/SAO/IXPE

NASA’s Imaging X-Ray Polarimetry Explorer, which launched into space Dec. 9, 2021, delivered its first imaging data since completing its month-long commissioning phase.

All instruments are functioning well aboard the observatory, which is on a quest to study some of the most mysterious and extreme objects in the universe.

IXPE first focused its X-ray eyes on Cassiopeia A (Cas A), an object consisting of the remains of a star that exploded in the 17th century. The shock waves from the explosion have swept up surrounding gas, heating it to high temperatures and accelerating cosmic ray particles to make a cloud that glows in X-ray light. Other telescopes, including Chandra, have studied Cas A before, but IXPE will allow researchers to examine it in a new way.

The newly-release image combines IXPE and Chandra data of Cas A. The saturation of the magenta color corresponds to the intensity of X-ray light observed by IXPE, which has been overlaid on high-energy X-rays, shown in blue, from Chandra. With different kinds of detectors, Chandra and IXPE have different levels of angular resolution, or sharpness. The IXPE data in this new image contain collected from Jan. 11 to 18, while the Chandra data come from observations over the 22-year mission thus far.

Belinda J. Wilkes
Credit: Center for Astrophysics | Harvard & Smithsonian

The American Association for the Advancement of Science (AAAS), the world's largest general scientific society, has elected Belinda J. Wilkes from the Center for Astrophysics | Harvard & Smithsonian to its newest class of AAAS Fellows.

The 2021 class of AAAS Fellows includes 564 scientists, engineers and innovators spanning 24 scientific disciplines who are recognized for their scientifically and socially distinguished achievements.

"We are incredibly proud of Belinda and her contributions to the field of astronomy," says Mike McCarthy, deputy director of the Center for Astrophysics. "This is one of the most distinct honors a scientist can achieve."

Wilkes is a senior astrophysicist at the Center for Astrophysics who served as director of the Chandra X-Ray Center (CXC) from 2014-2020. There she oversaw science and flight operations of the Chandra X-ray Observatory, one of NASA's flagship space-based telescopes.

An Expanse of Light
Credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI, Palomar Observatory, DSS;
Radio: NSF/NRAO/VLA; H-Alpha: LCO/IMACS/MMTF

The recent launches of the James Webb Space Telescope (Webb) and the Imaging X-ray Polarimetry Explorer (IXPE) by NASA and its international partners are excellent reminders that the universe emits light or energy in many different forms. To fully investigate cosmic objects and phenomena, scientists need telescopes that can detect light across what is known as the electromagnetic spectrum.

This gallery provides examples of the ways that different types of light from telescopes on the ground and in space can be combined. The common thread in each of these selections is data from NASA's Chandra X-ray Observatory, illustrating how X-rays — which are emitted by very hot and energetic processes — are found throughout the Universe.

More videos and information
Video Credit: J. Olmsted, D. Player, L. Hustak, A. Pagan, J. DePasquale, G. Bacon, F. Summers (STScI), R. Hurt (Caltech/IPAC), NASA, ESA; Music: "Sleepy Frieda", Maarten Schellekens, CC BY-NC 4.0;
Image Credit: A. Fujii, J. Morse (BoldlyGo Inst), N. Smith (U Arizona), Hubble SM4 ERO Team, NASA, ESA, STScI, JPL-Caltech, CXC, ESO, NOAO, AURA, NSF

Eta Carinae, or Eta Car, is famous for a brilliant and unusual outburst, called the "Great Eruption", observed in the 1840s. This visualization presents the story of that event and examines the resulting multiwavelength emissions and three-dimensional structures surrounding Eta Car today.

Massive stars are known to have major outbursts. Eta Car, one of the most massive stars known, expelled about 10% of its mass in the Great Eruption, creating a small nebula, called the Homunculus Nebula, around it. Images taken in different wavelengths of light reveal different structures, each providing more information about the outbursts of Eta Car.

For this visualization, astronomers and artists have used NASA observations to model both the close-up and wide views of this massive and eruptive star. The Hubble Space Telescope and the Chandra X-ray Observatory have observed the nested layers of gas and dust around Eta Car using visible, ultraviolet, and X-ray light, as well as in the Hydrogen alpha emission line. The Spitzer Space Telescope provides a larger view of the Carina Nebula, along with Eta Car's dominant position within this star-forming region.

Mrk 462
Credit: X-ray: NASA/CXC/Dartmouth Coll./J. Parker & R. Hickox; Optical/IR: Pan-STARRS

The graphic shows X-rays that NASA's Chandra X-ray Observatory detected from the dwarf galaxy Mrk 462. This X-ray emission (inset) is important because it reveals the presence of a growing supermassive black hole within this relatively small galaxy, as described in our latest press release. The mass contained in this black hole — about 200,000 times the mass of the Sun — provides information to astronomers about how some of the earliest black holes in the Universe may have formed and grown billions of years ago.

The background panel is an optical image from the Pan-STARRS telescope in Hawaii. There are several galaxies that are part of the HCG068 galaxy group on the left-hand side of the image. The galaxy that is emitting copious amounts of X-rays, however, is the much smaller galaxy located to the lower right of the image (marked by the arrow). Mrk 462 is a dwarf galaxy because it contains only a few hundred million stars, which means it holds about a hundred times fewer stars than a galaxy like the Milky Way. Black holes are notoriously hard to find in dwarf galaxies because they are usually too small and dim for optical light telescopes to track the rapid motions of stars in the centers.

Galaxy Cluster RBS 797
Credit: X-ray: NASA/CXC/Univ. of Bologna/F. Ubertosi; Optical: NASA/STScl/M.Calzadilla

Four enormous cavities, or bubbles, have been found at the center of a galaxy cluster using NASA's Chandra X-ray Observatory, as described in our latest press release. The left panel of this graphic shows an optical image of the galaxy cluster called RBS 797, from NASA's Hubble Space Telescope. Hot gas that envelopes the individual galaxies is invisible in optical light, but it is detected in X-rays by Chandra (right). One pair of cavities can be seen towards the left and right of center in the Chandra image as black oval-shaped regions. The other pair is less distinct, but can be found above and below the center of the image.