Chandra Enters Through the Sidedoor (Podcast)

An artist's drawing of a young Subrahmanyan Chandrasekhar surrounded by ethereal mathematics symbols appearing to leitate an black hole in his out-stretched hand.
Credit: Smithsonian

Did you know that the Smithsonian has a podcast? It’s called Sidedoor and it gives listeners a behind-the-scenes look into the Smithsonian’s museums and research units. One of those research units is the Smithsonian Astrophysical Observatory, which has run NASA’s Chandra X-ray Observatory since before launch and continues to control its flight and science operations to this day.

On the latest episode of Sidedoor, Dr. Kimberly Arcand (Chandra’s visualization scientist and emerging tech lead), along with Dr. Priyamvada Natarajan (astrophysicist, and professor at Yale University) and Dr. Arthur I. Miller, (scientist and author), discuss black holes and the connection to Dr. Subrahmanyan Chandrasekhar, the namesake of the Chandra X-ray Observatory. Listen to the first installment of this two-part journey through the cosmos at

Spotted: 'Death Star' Black Holes in Action

Image of Abell 478 and NGC 5044 in X-ray light.
Black Hole "Death Stars," Abell 478 & NGC 5044
Credit: X-ray: NASA/CXC/Univ. of Chicago/S.C. Mackey et al.; Radio: NRF/SARAO/MeerKAT; Image Processing: NASA/CXC/SAO/N. Wolk

A team of astronomers have studied 16 supermassive black holes that are firing powerful beams into space, to track where these beams, or jets, are pointing now and where they were aimed in the past, as reported in our latest press release. Using NASA’s Chandra X-ray Observatory and the U.S. National Science Foundation (NSF) National Radio Astronomical Observatory’s (NRAO) Very Large Baseline Array (VLBA), they found that some of the beams have changed directions by large amounts.

These two Chandra images show hot gas in the middle of the galaxy cluster Abell 478 (left) and the galaxy group NGC 5044 (right). The center of each image contains one of the sixteen black holes firing beams outwards. Each black hole is in the center of a galaxy embedded in the hot gas.

By mousing over the images, labels and the radio images appear. Ellipses show a pair of cavities in the hot gas for Abell 478 (left) and ellipses show two pairs of cavities for NGC 5044 (right). These cavities were carved out by the beams millions of years ago, giving the directions of the beams in the past. An X shows the location of each supermassive black hole.

NASA's Chandra Notices the Galactic Center is Venting

Image of a region near the center of our galaxy that shows the vent and chimney features.
Galactic Center Vent
Credit: X-ray: NASA/CXC/Univ. of Chicago/S.C. Mackey et al.; Radio: NRF/SARAO/MeerKAT; Image Processing: NASA/CXC/SAO/N. Wolk

These images show evidence for an exhaust vent attached to a chimney releasing hot gas from a region around the supermassive black hole at the center of the Milky Way, as reported in our latest press release. In the main image of this graphic, X-rays from NASA’s Chandra X-ray Observatory (blue) have been combined with radio data from the MeerKAT telescope (red).

Previously, astronomers had identified a “chimney” of hot gas near the Galactic Center using X-ray data from Chandra and ESA’s XMM-Newton. Radio emission detected by MeerKAT shows the effect of magnetic fields enclosing the gas in the chimney.

The evidence for the exhaust vent is highlighted in the inset, which includes only Chandra data. Several X-ray ridges showing brighter X-rays appear in white, roughly perpendicular to the plane of the Galaxy. Researchers think these are the walls of a tunnel, shaped like a cylinder, which helps funnel hot gas as it moves upwards along the chimney and away from the Galactic Center.

The Genesis of Giants: Tracing the Early Development of Supermassive Black Holes

An image of a woman with blonde hair in front of a copper and mirrored wall.
Orsolya Eszter Kovács

We welcome Orsolya Eszter Kovács, a postdoctoral fellow at Masaryk University, Czechia, as our guest blogger. She spent over two years at the Smithsonian Astrophysical Observatory as a pre-doctoral fellow while working on the PhD she obtained from Eötvös Loránd University, Hungary. She is the first author of a recent paper presenting one of the most distant supermassive black holes ever seen.

In the past six months1 Chandra has unveiled two supermassive black holes remarkably close to their formation epoch, only about 500 million years after the big bang. These findings mark some of the most distant supermassive black holes observed to date.

Supermassive black holes, the largest type of black holes, lurk in the heart of most big galaxies. These cosmic behemoths play a central role in the formation and evolution of their hosting galaxies, exerting influence so significant that they can even suppress star formation.

The origin of these giant black holes is a subject of debate. Do they originate from the collapse of the earliest stellar population, known as Population III stars? Although it seems like an obvious explanation, to reach those immense masses observed in their later stages, these “light black hole seeds” need to be fed with an extreme amount of matter in a relatively brief period (through a process that astronomers call “accretion”). Yet, such a high accretion rate seems improbable as a universal solution, because there are physical limits on how quickly material can fall inwards. The outwards pressure from the intense radiation associated with high accretion can overcome the gravitational forces pulling material inwards, causing the material to be pushed away instead.

NASA's Chandra Releases Doubleheader of Blockbuster Hits

Crab Nebula and Cassiopeia A
Credit: Cassiopeia A: X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Image Processing: NASA/CXC/SAO/J. Major, A. Jubett, K. Arcand; Crab Nebula: X-ray: NASA/CXC/SAO; Image processing: NASA/CXC/SAO/J. Schmidt, J. Major, A. Jubett, K. Arcand

New movies of two of the most famous objects in the sky — the Crab Nebula and Cassiopeia A — are being released from NASA’s Chandra X-ray Observatory. Each includes X-ray data collected by Chandra over about two decades. They show dramatic changes in the debris and radiation remaining after the explosion of two massive stars in our galaxy.

The Crab Nebula, the result of a bright supernova explosion seen by Chinese and other astronomers in the year 1054, is 6,500 light-years from Earth. At its center is a neutron star, a super-dense compact object produced by the supernova. As it rotates at about 30 times per second, its beam of radiation passes over the Earth every rotation, like a cosmic lighthouse.

As the young pulsar slows down, large amounts of energy are injected into its surroundings. In particular, a high-speed wind of matter and anti-matter particles plows into the surrounding nebula, creating a shock wave that forms the ring seen in the movie. Jets from the poles of the pulsar spew X-ray emitting matter and antimatter particles in a direction perpendicular to the ring.

New Version of Chandra Source Catalog Released

The Chandra Source Catalog (CSC) is the definitive catalog of X-ray sources detected by the observatory. The latest version, known as CSC 2.1, was released in early April 2024.

Since the Uhuru satellite in the 1970s, X-ray astrophysics missions have a tradition of publishing detailed catalogs of the X-ray sources detected along with a list of key physical properties.

CSC 2.1. carries this tradition forward. Below is an adapted announcement from members of the team who worked on this important resource for the scientific community:

The Chandra X-ray Center (CXC) is pleased to announce the availability of Release 2.1 of the Chandra Source Catalog (CSC 2.1). This catalog covers roughly 730 square degrees of sky and contains 407,806 unique X-ray sources and over 1.3 million individual source detections identified in more than 15,000 Chandra imaging observations released publicly prior to the end of 2021.

Chandra and Voyager: A Robust 3D Experience

Image of a 3D Vela Pulsar model in a computer application
A screenshot from the Smithsonian Voyager 3D platform: Vela Pulsar is shown here with its ejecta and blast wave turned on. Explore the Vela sonification and visual description tour while tumbling around the 3D model and turning the ejecta and blast wave on and off. Download an stl model for 3D printing to hold the Vela Pulsar in your hand.
Credit: INAF-Observatorio Astronomico di Palermo/S.Orlando & NASA/CXC/SAO/A. Jubett et al; Smithsonian Institution/J. Cope, M. Dattoria et al;

The creative team at Chandra X-ray Center has been hard at work on a collaboration with the Smithsonian Institution’s Digitization Program Office (3D SI). Together, our teams have been bringing three-dimensional X-ray datasets to the Voyager platform to offer inclusive, multi-sensory learning experiences.

The Chandra X-ray Observatory is one of NASA's “Great Observatories” (along with the Hubble Space Telescope and the James Webb Telescope). Chandra, the world's most powerful X-ray telescope, is still going strong after 25 years in orbit. The Smithsonian Astrophysical Observatory (SAO) in Massachusetts operates the telescope and runs the science center on behalf of NASA.

In 2021, Chandra and 3D SI released a collection of cosmic models showing various high-energy phenomena in three dimensions including novas, supernovas, pulsars, and the Chandra telescope itself. These 3D representations provided the opportunity for users to tumble around each object and learn about its features and the science behind the model. This has been a huge step in granting greater access to these incredible 3D models and prints for institutions like libraries and museums, as well as the scientific community and individuals in the greater public.

Scientists from Brown, NASA and the Smithsonian Bring Cosmic Explorations to Smartphones

The following press release from Brown University, being released in conjunction with another from the Smithsonian Institution, highlights an exciting new project that brings cosmic objects in 3D to Instagram “experiences.” This project was led by Dr. Kimberly Arcand of the Smithsonian Astrophysical Observatory that runs the Chandra X-ray Center on behalf of NASA. These new Chandra Instagram experiences are the first ever to include sonifications (translations of data into sound) and represent a new way of making astronomical data more accessible.

By using a phone camera and a new set of Instagram augmented reality filters, anyone can dive into the depths of space, encountering nebulae, pulsars and even remnants of exploded stars.

Gaze at the ethereal colors of distant nebulae. Zoom in to the heart of an exploded star. Listen to chimes, bells and electric rhythms representing a celestial object far off in space. Through new Instagram filters, users of the app can now embark on cosmic journeys through their smartphones with space-themed augmented reality experiences.

The filters are fun, for sure — but they’re also grounded in some serious science. The experiences were created by researchers from Brown University, Smithsonian Astrophysical Observatory and NASA to celebrate the 25th anniversary the Chandra spacecraft, NASA’s flagship X-ray telescope. The goals are to engage the public, make images of space more accessible and add new layers of understanding to some of the most well-known and widely studied objects in the sky.

Stunning Echo of 800-year-old Explosion

Image of Supernova remnant 1181
SNR 1181 / Pa 30
Credit: X-ray: (Chandra) NASA/CXC/U. Manitoba/C. Treyturik, (XMM-Newton) ESA/C. Treyturik; Optical: (Pan-STARRS) NOIRLab/MDM/Dartmouth/R. Fesen; Infrared: (WISE) NASA/JPL/Caltech/; Image Processing: Univ. of Manitoba/Gilles Ferrand and Jayanne English

In the year 1181 a rare supernova explosion appeared in the night sky, staying visible for 185 consecutive days. Historical records show that the supernova looked like a temporary ‘star’ in the constellation Cassiopeia shining as bright as Saturn.

Ever since, scientists have tried to find the supernova’s remnant. At first it was thought that this could be the nebula around the pulsar — the dense core of a collapse star — named 3C 58. However closer investigations revealed that the pulsar is older than supernova 1181.

In the last decade, another contender was discovered; Pa 30 is a nearly circular nebula with a central star in the constellation Cassiopeia. It is pictured here combining images from several telescopes. This composite image uses data across the electromagnetic spectrum and shows a spectacular new view of the supernova remnant. This allows us to marvel at the same object that appeared in our ancestors’ night sky more than 800 years ago.

NASA's Chandra Identifies an Underachieving Black Hole

Image of Quasar H1821+643
Quasar H1821+643
Credit: X-ray: NASA/CXC/Univ. of Nottingham/H. Russell et al.; Radio: NSF/NRAO/VLA; Image Processing: NASA/CXC/SAO/N. Wolk

This image shows a quasar, a rapidly growing supermassive black hole, which is not achieving what astronomers would expect from it, as reported in our latest press release. Data from NASA’s Chandra X-ray Observatory (blue) and radio data from the NSF’s Karl G. Jansky’s Very Large Array (red) reveal some of the evidence for this quasar’s disappointing impact on its host galaxy.

Known as H1821+643, this quasar is about 3.4 billion light-years from Earth. Quasars are a rare and extreme class of supermassive black holes that are furiously pulling material inwards, producing intense radiation and sometimes powerful jets. H1821+643 is the closest quasar to Earth in a cluster of galaxies.

Quasars are different than other supermassive black holes in the centers of galaxy clusters in that they are pulling in more material at a higher rate. Astronomers have found that non-quasar black holes growing at moderate rates influence their surroundings by preventing the intergalactic hot gas from cooling down too much. This regulates the growth of stars around the black hole.


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