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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The blazar BL Lacertae, a supermassive black hole surrounded by a bright disk and jets oriented toward Earth, provided scientists with a unique opportunity to answer a longstanding question: How are X-rays generated in extreme environments like this?
NASA’s IXPE (Imaging X-ray Polarimetry Explorer) collaborated with radio and optical telescopes to find answers. The results (preprint available here), to be published in the journal Astrophysical Journal Letters, show that interactions between fast-moving electrons and particles of light, called photons, must lead to this X-ray emission.
This artist’s concept depicts the central region of the blazar BL Lacertae, a supermassive black hole surrounded by a bright disk and a jet oriented toward Earth. The galaxy’s central black hole is surrounded by swirls of orange in various shades representing the accretion disk of material falling toward the black hole. While black holes are known for pulling in material, this accretion process can result in the ejection of jets of electrons at nearly the speed of light. The jet of matter is represented by the cone of light that starts at the center of the black hole and widens out as it reaches the bottom of the image. It is streaked with lines of white, pink and purple which represent helix-shaped magnetic fields. We can observe these jets in many wavelengths of light including radio, optical, and X-ray. NASA’s Imaging X-ray Polarimetry Explorer (IXPE) recently collaborated with radio and optical telescopes to observe this jet and determine how the X-rays are generated in these types of celestial environments.NASA/Pablo Garcia Scientists had two competing possible explanations for the X-rays, one involving protons and one involving electrons. Each of these mechanisms would have a different signature in the polarization of X-ray light. Polarization is a property of light that describes the average direction of the electromagnetic waves that make up light.
If the X-rays in a black hole’s jets are highly polarized, that would mean that the X-rays are produced by protons gyrating in the magnetic field of the jet or protons interacting with jet’s photons. If the X-rays have a lower polarization degree, it would suggest that electron-photons interactions lead to X-ray production.
IXPE, which launched Dec. 9, 2021, is the only satellite flying today that can make such a polarization measurement.
“This was one of the biggest mysteries about supermassive black hole jets” said Iván Agudo, lead author of the study and astronomer at the Instituto de Astrofísica de Andalucía – CSIC in Spain. “And IXPE, with the help of a number of supporting ground-based telescopes, finally provided us with the tools to solve it.”
Astronomers found that electrons must be the culprits through a process called Compton Scattering. Compton scattering (or the Compton effect) happens when a photon loses or gains energy after interacting with a charged particle, usually an electron. Within jets from supermassive black holes, electrons move near the speed of light. IXPE helped scientists learn that, in the case of a blazar jet, the electrons have enough energy to scatter photons of infrared light up to X-ray wavelengths.
BL Lacertae (BL Lac for short) is one of the first blazars ever discovered, originally thought to be a variable star in the Lacerta constellation. IXPE observed BL Lac at the end of November 2023 for seven days along with several ground-based telescopes measuring optical and radio polarization at the same time. While IXPE observed BL Lac in the past, this observation was special. Coincidentally, during the X-ray polarization observations, the optical polarization of BL Lac reached a high number: 47.5%.
“This was not only the most polarized BL Lac has been in the past 30 years, this is the most polarized any blazar has ever been observed!” said Ioannis Liodakis, one of the primary authors of the study and astrophysicist at the Institute of Astrophysics – FORTH in Greece.
IXPE found the X-rays were far less polarized than the optical light. The team was not able to measure a strong polarization signal and determined that the X-rays cannot be more polarized than 7.6%. This proved that electrons interacting with photons, via the Compton effect, must explain the X-rays.
The fact that optical polarization was so much higher than in the X-rays can only be explained by Compton scattering.
Steven Ehlert
Project Scientist for IXPE at Marshall Space Flight Center
“The fact that optical polarization was so much higher than in the X-rays can only be explained by Compton scattering”, said Steven Ehlert, project scientist for IXPE and astronomer at the Marshall Space Flight Center.
“IXPE has managed to solve another black hole mystery” said Enrico Costa, astrophysicist in Rome at the Istituto di Astrofísica e Planetologia Spaziali of the Istituto Nazionale di Astrofísica. Costa is one of the scientists who conceived this experiment and proposed it to NASA 10 years ago, under the leadership of Martin Weisskopf, IXPE’s first principal investigator. “IXPE’s polarized X-ray vision has solved several long lasting mysteries, and this is one of the most important. In some other cases, IXPE results have challenged consolidated opinions and opened new enigmas, but this is how science works and, for sure, IXPE is doing very good science.”
What’s next for the blazar research?
“One thing we’ll want to do is try to find as many of these as possible,” Ehlert said. “Blazars change quite a bit with time and are full of surprises.”
More about IXPE
IXPE, which continues to provide unprecedented data enabling groundbreaking discoveries about celestial objects across the universe, is a joint NASA and Italian Space Agency mission with partners and science collaborators in 12 countries. IXPE is led by NASA’s Marshall Space Flight Center in Huntsville, Alabama. BAE Systems, Inc., headquartered in Falls Church, Virginia, manages spacecraft operations together with the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder. Learn more about IXPE’s ongoing mission here:
https://www.nasa.gov/ixpe
Elizabeth Landau
NASA Headquarters
elizabeth.r.landau@nasa.gov
202-358-0845
Lane Figueroa
Marshall Space Flight Center, Huntsville, Ala.
lane.e.figueroa@nasa.gov
256.544.0034
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Last Updated May 06, 2025 EditorBeth RidgewayContactElizabeth R. Landauelizabeth.r.landau@nasa.govLocationMarshall Space Flight Center Related Terms
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Black Holes Black holes are among the most mysterious cosmic objects, much studied but not fully understood. These objects aren’t…
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By European Space Agency
The European Space Agency's XMM-Newton is playing a crucial role in investigating the longest and most energetic bursts of X-rays seen from a newly awakened black hole. Watching this strange behaviour unfold in real time offers a unique opportunity to learn more about these powerful events and the mysterious behaviour of massive black holes.
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By NASA
Curiosity Navigation Curiosity Home Mission Overview Where is Curiosity? Mission Updates Science Overview Instruments Highlights Exploration Goals News and Features Multimedia Curiosity Raw Images Images Videos Audio Mosaics More Resources Mars Missions Mars Sample Return Mars Perseverance Rover Mars Curiosity Rover MAVEN Mars Reconnaissance Orbiter Mars Odyssey More Mars Missions Mars Home 3 min read
Sols 4498-4499: Flexing Our Arm Once Again
NASA’s Mars rover Curiosity acquired this image using its Left Navigation Camera on March 30, 2025 — Sol 4496, or Martian day 4,496 of the Mars Science Laboratory mission — at 20:12:48 UTC. NASA/JPL-Caltech Written by Conor Hayes, Graduate Student at York University
Earth planning date: Monday, March 31, 2025
Planning today began with two pieces of great news. First, our 50-meter drive (about 164 feet) from the weekend plan completed successfully, bringing us oh-so-close to finally driving out of the small canyon that we’ve been traversing through and toward the “boxwork” structures to our southwest. Second, we passed our “Slip Risk Assessment Process” (SRAP), confirming that all six of Curiosity’s wheels are parked firmly on solid ground. Avid readers of this blog will be familiar with last week’s SRAP challenges, which prevented us from using the rover’s arm for the entire week. With a green light on SRAP, we were finally able to put our suite of contact science instruments back to work today.
The arm gets to work early on the first sol of this plan, with an APXS integration on “Los Osos,” a bedrock target in our workspace, after it has been cleared of the ubiquitous Martian dust by DRT. The rest of our arm activities consist of a series of MAHLI observations later in the afternoon, both of Los Osos and “Black Star Canyon.”
Of course, just because we managed to get contact science in this plan doesn’t mean we’re letting our remote sensing instruments take a break. In fact, we have more than two hours of remote sensing, split between the two sols and the two science teams (Geology and Mineralogy [GEO] and Atmosphere and Environment [ENV]). GEO will be using Mastcam to survey both the highs and the lows of the terrain, with mosaics of “Devil’s Gate” (some stratigraphy in a nearby ledge) and some small troughs close to the rover. We’ll also be getting even more Mastcam images of “Gould Mesa,” an imaging target in many previous plans, as we continue to drive past it. ChemCam gets involved with a LIBS observation of “Fishbowls,” which will also be imaged by Mastcam, a post-drive AEGIS, and two RMI mosaics of Gould Mesa and “Torote Bowl,” which was also imaged over the weekend.
ENV’s activities are fairly typical for this time of year as Curiosity monitors the development of the Aphelion Cloud Belt (ACB) with several Navcam cloud movies, as well as seasonal changes in the amount of dust in and above Gale with Navcam line-of-sight observations and Mastcam taus. We’ll also be taking a Navcam dust devil movie to see if we can catch any cold-weather wind-driven dust movement. ENV also filled this plan with their usual set of REMS, RAD, and DAN observations.
The drive planned today is significantly shorter than the one over the weekend, at just about 10 meters (about 33 feet). This is because we’re driving up a small ridge, which limits our ability to see what’s on the other side. Although our rover knows how to keep itself safe, we still prefer not to drive through terrain that we can’t see in advance, if it can be avoided. Once we’ve got a better eye on what lies in front of us, we will hopefully be able to continue our speedy trek toward the boxwork structures.
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Last Updated Apr 03, 2025 Related Terms
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By NASA
Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Posters Hubble on the NASA App Glossary More 35th Anniversary Online Activities Hubble captured this image of supernova SN 2022abvt (the pinkish-white dot at image center) about two months after it was discovered in 2022. ESA/Hubble & NASA, R. J. Foley (UC Santa Cruz)
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A supernova and its host galaxy are the subject of this NASA/ESA Hubble Space Telescope image. The galaxy in question is LEDA 132905 in the constellation Sculptor. Even at more than 400 million light-years away, LEDA 132905’s spiral structure is faintly visible, as are patches of bright blue stars.
The bright pinkish-white dot in the center of the image, between the bright center of the galaxy and its faint left edge, is a supernova named SN 2022abvt. Discovered in late 2022, Hubble observed SN 2022abvt about two months later. This image uses data from a study of Type Ia supernovae, which occur when the exposed core of a dead star ignites in a sudden, destructive burst of nuclear fusion. Researchers are interested in this type of supernova because they can use them to measure precise distances to other galaxies.
The universe is a big place, and supernova explosions are fleeting. How is it possible to be in the right place at the right time to catch a supernova when it happens? Today, robotic telescopes that continuously scan the night sky discover most supernovae. The Asteroid Terrestrial-impact Last Alert System, or ATLAS, spotted SN 2022abvt. As the name suggests, ATLAS tracks down the faint, fast-moving signals from asteroids close to Earth. In addition to searching out asteroids, ATLAS also keeps tabs on objects that brighten or fade suddenly, like supernovae, variable stars, and galactic centers powered by hungry black holes.
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Media Contact:
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NASA’s Goddard Space Flight Center, Greenbelt, MD
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Last Updated Feb 07, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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