We welcome Ian Brunton, a research scientist currently at NASA Johnson Space Center in the Astromaterials Research and Exploration Science Division as our guest blogger. In this post, he describes his team’s work below on the effects that a nearby supernova may have on an Earth-like planet and its biosphere. Ian first became involved with this area of research as an astronomy student of Brian Fields at the University of Illinois. He will soon be continuing his academic studies as a PhD student at Caltech in the Division of Geological and Planetary Sciences.
Much has been said about the extraordinary advancements throughout the field of astronomy, particularly regarding the innovative ways in which we can now observe the universe across the electromagnetic spectrum. Chandra has of course been one of the instruments at the forefront of this exploration for the last couple of decades, illuminating the universe in the X-ray band. These new ways of looking at our universe have served to confirm, alter, or entirely upend our prior notions of certain astrophysical processes.
What I personally find most intriguing is how these new observations can then be integrated into the knowledge and pursuits of other scientific disciplines, be it planetary science, atmospheric chemistry, geology, etc.
One of the most fascinating processes (if I may say so myself…) that orbital X-ray telescopes are especially handy for are supernovae, i.e., exploding stars! I’ll elaborate a bit on exactly why below, but first, some background on nearby supernovae and Earth is needed since our project really builds upon a lot of previous work in the field.
Everyone loves a good astronomical explosion, and supernovae — typically characterized by the wondrous spectacle of their initial outbursts — are some of the best explosions in the known universe. In the blink of an eye, these monstrous events can outshine the entire combined output of stars in a galaxy, launching neutrinos, photons, and stellar material out into the abyss of the interstellar medium.
Artist's Illustration of Dual Quasar J0749+2255
Artwork Credit: NASA, ESA, Joseph Olmsted (STScI) Science Credit: NASA, ESA, Yu-Ching Chen (UIUC), Hsiang-Chih Hwang (IAS), Nadia Zakamska (JHU), Yue Shen (UIUC)
Quasars are among the universe's brightest fireworks. Scattered all across the sky, they blaze with the opulence of over 100 billion stars. And, like a brilliant July 4th aerial flare, they are dazzling for a relatively brief time — on cosmic timescales. That's because they're powered by voracious supermassive black holes gobbling up a lot of gas and dust that gets heated to high temperatures. But the quasar food buffet lasts only so long.
This fleeting characteristic of quasars helped astronomers find two quasars on a collision course with each other. They are embedded inside a pair of galaxies that smashed into each other 10 billion years ago. It's rare to find such a dynamic duo in the far universe. The detection yields clues as to how unsettled the cosmos was long ago, when galaxies more frequently collided and black holes were engorged with flotsam and jetsam from the close encounters.
Credit: X-ray: NASA/CXC/The Ohio State Univ/S. Lopez et al.; H-alpha and Optical: NSF/NOIRLab/AURA/KPNO/CTIO; Infrared: NASA/JPL-Caltech/Spitzer/D. Dale et al; Full Field Optical: ESO/La Silla Observatory.
On Earth, wind can transport particles of dust and debris across the planet, with sand from the Sahara ending up in the Caribbean or volcanic ash from Iceland being deposited in Greenland. Wind can also have a big impact on the ecology and environment of a galaxy, just like on Earth, but on much larger and more dramatic scales.
A new study using NASA's Chandra X-ray Observatory shows the effects of powerful winds launched from the center of a nearby galaxy, NGC 253, located 11.4 million light-years from Earth. This galactic wind is composed of gas with temperatures of millions of degrees that glows in X-rays. An amount of hot gas equivalent to about two million Earth masses blows away from the galaxy's center every year.
NGC 253 is a spiral galaxy, making it similar to our Milky Way. However, stars are forming in NGC 253 about two to three times more quickly than in our home galaxy. Some of these young stars are massive and generate a wind by ferociously blowing gas from their surfaces. Even more powerful winds are unleashed when, later in their relatively short lives, these stars explode as supernovae, and hurl waves of material out into space.
R Aquarii, All Wavelengths
Credit: X-ray: NASA/CXC/SAO/R. Montez et al.; Optical: Data: NASA/ESA/STScI, Enhanced processing by Judy Schmidt (CC BY-NC-SA). X-ray/Optical composite processing by CXC/N. Wolk & K.Arcand; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)
The system called R Aquarii unfolds dramatically through the eyes of NASA’s Chandra X-ray Observatory (purple) and Hubble Space Telescope (red and blue). The spectacular structures outlined in the Hubble data are old notes, or in other words, evidence from outbursts generated by a pair of stars buried at the center of the image. X-rays from Chandra reveal how a jet from one of these stars — a cool stellar ember known as a white dwarf — is banging into the material surrounding it. This high-powered flow creates shock waves, similar to sonic booms from planes that move faster than the speed of sound. The other player with the white dwarf in this interstellar duet is a red giant star. As they orbit each other, the white dwarf pulls material from the red giant onto its surface. Over time, enough of this material accumulates and triggers an explosion. Astronomers have seen such outbursts over recent decades and this dynamic chorus will likely go on for millennia to come.
We are happy to welcome Valentina Missaglia as a guest blogger. She is the first author of the paper that is the subject of our latest press release. She is currently a postdoctoral researcher at the Institute of Astrophysics — FORTH in Heraklion (Crete) in the SMILE (“Search for Milli-LEnses”) group, recently funded by an ERC grant, that aims at investigating the nature of dark matter through observations of gravitational lenses on milli-arcsecond scales. Valentina earned her Ph.D. from the University of Turin (Italy) and her research focuses on radio and X-ray emission from radio-loud active galactic nuclei (which contain supermassive black holes that are rapidly pulling in material, producing intense radio waves) and how these sources interact with the surrounding medium. Before starting her Ph.D. in 2019, Valentina was a visiting student at the Center of Astrophysics | Harvard & Smithsonian, where she collaborated with Dr. Ralph Kraft on observations of galaxy clusters performed with NASA’s Chandra X-ray Observatory.
Looking at the night sky with the naked eye, we can only see an infinitesimal part of what the Universe contains, and the largest part cannot even be “seen”. Radio wavelengths have gifted us some of the most fascinating astronomical sources: radio-loud active galactic nuclei in the centers of galaxies, which can produce jets that extend way farther out from the optical galaxy itself.
The most powerful radio sources in the northern hemisphere are listed in a well- studied catalog, the Third Cambridge Catalog (3C), which contains the source we investigated with multiwavelength observations: 3C 297. This source appeared very intriguing in observations performed with Chandra in 2016. Therefore, we requested more time to better investigate features that we uncovered thanks to this first short observation, such as hot, X-ray emitting gas around our source.
Tycho's Supernova Remnant
Credit: X-ray (IXPE: NASA/ASI/MSFC/INAF/R. Ferrazzoli, et al.), (Chandra: NASA/CXC/RIKEN & GSFC/T. Sato et al.) Optical: DSS, Image processing: NASA/CXC/SAO/K. Arcand, L. Frattare & N. Wolk
This image provides a new look at the Tycho supernova remnant, named for Danish astronomer Tycho Brahe who noticed the bright glow of this new “star” in the constellation Cassiopeia more than 450 years ago. Astronomers used NASA’S Imaging X-ray Polarimetry Explorer (IXPE) to study polarized light from Tycho, the debris from an exploded star, as described in IXPE’s latest press release. IXPE revealed, for the first time, the geometry of the magnetic fields close to the supernova’s blast wave, which is still propagating from the initial explosion and forms a boundary around the ejected material. Understanding the magnetic field geometry allows scientists to further investigate how particles are accelerated there.
In this composite image, data from IXPE (dark purple and white) have been combined with those from NASA’s Chandra X-ray Observatory (red and blue), which were overlaid with the stars in the field of view seen by the Digitized Sky Survey.
We are pleased to welcome Marko Mićić as a guest blogger. Marko led the study that is the subject of our latest press release [link to PR]. He graduated from the University of Belgrade, Serbia, with a degree in Astronomy and Astrophysics, in 2018. The same year he started a Ph.D. at the University of Alabama, and has been working under Dr. Jimmy Irwin's supervision since then. His research interests include evolution of low-mass galaxies, AGN content of low-mass galaxies, intermediate-mass black holes and gravitational lenses.
Galaxies are made up of billions of stars, interstellar gas and dust, and large amounts of dark matter. Every (or almost every) galaxy is expected to host a supermassive black hole in its center. Galaxies and their central black holes grow and evolve together predominantly through mergers; smaller objects merge to create larger ones over time. However, the earliest stages of galaxy evolution involving the mergers of the first galaxies are poorly understood. It is unclear how the first mergers affected the morphology of ancient galaxies and their star formation. We also do not know how massive the first black holes were that inhabited the first galaxies, nor how the first mergers influenced their ability to accrete – pull in – material.
It is challenging to answer these important questions because the first mergers are too distant and faint to be directly observed. One way to overcome this issue is to look for local analogs. In other words, we need to find pairs of small, dwarf galaxies that have had very quiet lives, with almost no mergers, that have only recently met and started interacting. Such galaxies have experienced little to no evolution so they are analogs of distant, ancient galaxies, and observations of their mergers would represent the local case study that illustrates the hierarchical growth of structures in the early Universe. Their central black holes are also expected not to have grown much and preserve information about primordial seeds, potentially holding the key to resolving the outstanding problem of the origin of supermassive black holes.
Credit: X-ray: Chandra: NASA/CXC/Univ. of Bologna/K. Rajpurohit et al.; XMM-Newton: ESA/XMM-Newton/Univ. of Bologna/K. Rajpurohit et al. Radio: LOFAR: LOFAR/ASTRON; GMRT: NCRA/TIFR/GMRT; VLA: NSF/NRAO/VLA; Optical/IR: Pan-STARRS
Astronomers have captured a spectacular, ongoing collision between at least three galaxy clusters. Data from NASA’s Chandra X-ray Observatory, ESA’s (European Space Agency’s) XMM-Newton, and a trio of radio telescopes is helping astronomers sort out what is happening in this jumbled scene. Collisions and mergers like this are the main way that galaxy clusters can grow into the gigantic cosmic edifices seen today. These also act as the largest particle accelerators in the universe.
The giant galaxy cluster forming from this collision is Abell 2256, located 780 million light-years from Earth. This composite image of Abell 2256 combines X-rays from Chandra and XMM in blue with radio data collected by the Giant Metrewave Radio Telescope (GMRT), the Low Frequency Array (LOFAR), and the Karl G. Jansky Very Large Array (VLA) all in red, plus optical and infrared data from Pan-STARRs in white and pale yellow.
SDSS J011522.18+001518.5 and SDSS J155627.74+241758.9
Credit: X-ray: NASA/CXC/SAO/D. Kim et al.; Optical/IR: Legacy Surveys/D. Lang (Perimeter Institute)
This panel of images represents a survey that used data from NASA’s Chandra X-ray Observatory to uncover hundreds of previously “hidden” black holes. This result helps astronomers conduct a more accurate census of supermassive black holes that exist in the centers of most large galaxies, as reported in our latest press release.
This graphic shows two of the galaxies from the new study, with Chandra X-ray data in purple and optical data from the Sloan Digital Sky Survey (SDSS) in red, green and blue. These black holes were found in galaxies that are dim in optical light, but bright in X-rays. Astronomers have dubbed these “XBONGs” (for X-ray bright, optically normal galaxies). While scientists have been aware of XBONGs for several decades, an explanation for their unusual properties has been unclear.
When Dr. Leisa Townsley passed away this summer, the scientific community lost a brilliant researcher, teacher, and mentor. She was all of those things, but we wanted to feature some of the pivotal and critical ways that she helped the Chandra X-ray Observatory, specifically our Communications and Public Engagement work.
Chandra was launched into space in 1999 and with the beginning of its successful operations, a new era in high-energy astrophysics was born. For certain deep space objects that emitted enough X-ray photons, Chandra brought, for the first time, the ability to create richly detailed, high-resolution images. These X-ray images, however, were different in many ways from the images of its previously-launched sister Great Observatory, the Hubble Space Telescope.
Establishing a visual identity for Chandra, both on its own and in collaboration with other telescopes that study different kinds of light, including Hubble, was no small challenge. Our Chandra group was responsible for finding the best way to show X-ray data, which often looks completely different from optical data. Would traditional techniques used for visible light data be suitable to process X-ray data? Would new processes and tactics need to be developed to make X-ray data more accessible, easier to understand and process?
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