{"id":212200,"date":"2025-05-07T06:24:24","date_gmt":"2025-05-06T20:24:24","guid":{"rendered":"https:\/\/www.nasa.gov\/?p=860443"},"modified":"2025-05-07T06:24:24","modified_gmt":"2025-05-06T20:24:24","slug":"nasas-ixpe-reveals-x-ray-generating-particles-in-black-hole-jets-2","status":"publish","type":"post","link":"https:\/\/www.vibewire.com.au\/?p=212200","title":{"rendered":"NASA\u2019s IXPE Reveals X-ray-Generating Particles in Black Hole Jets"},"content":{"rendered":"
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5 min read<\/p>\n

Preparations for Next Moonwalk Simulations Underway (and Underwater)<\/h1>\n<\/div>\n<\/div>\n<\/div>\n

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?<\/p>\n

NASA\u2019s IXPE (Imaging X-ray Polarimetry Explorer<\/a>) collaborated with radio and optical telescopes to find answers. The results (preprint available here<\/a>), 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. <\/p>\n

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This artist\u2019s 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\u2019s 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\u2019s 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.<\/div>\n
NASA\/Pablo Garcia<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

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.<\/p>\n

If the X-rays in a black hole\u2019s 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\u2019s photons. If the X-rays have a lower polarization degree, it would suggest that electron-photons interactions lead to X-ray production.  <\/p>\n

IXPE, which launched Dec. 9, 2021, is the only satellite flying today that can make such a polarization measurement. <\/p>\n

\u201cThis was one of the biggest mysteries about supermassive black hole jets\u201d said Iv\u00e1n Agudo, lead author of the study and astronomer at the Instituto de Astrof\u00edsica de Andaluc\u00eda – CSIC in Spain. \u201cAnd IXPE, with the help of a number of supporting ground-based telescopes, finally provided us with the tools to solve it.\u201d<\/p>\n

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. <\/p>\n

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%. <\/p>\n

\u201cThis 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!\u201d said Ioannis Liodakis, one of the primary authors of the study and astrophysicist at the Institute of Astrophysics \u2013 FORTH in Greece. <\/p>\n

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. <\/p>\n

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The fact that optical polarization was so much higher than in the X-rays can only be explained by Compton scattering.<\/span><\/h2>\n<\/p><\/div>\n
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\"Steven<\/figure>\n<\/div>\n
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Steven Ehlert<\/p>\n

Project Scientist for IXPE at Marshall Space Flight Center<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/div>\n

\u201cThe fact that optical polarization was so much higher than in the X-rays can only be explained by Compton scattering\u201d, said Steven Ehlert, project scientist for IXPE and astronomer at the Marshall Space Flight Center. <\/p>\n

\u201cIXPE has managed to solve another black hole mystery\u201d said Enrico Costa, <\/strong>astrophysicist in Rome at the Istituto di Astrof\u00edsica e Planetologia Spaziali of the Istituto Nazionale di Astrof\u00edsica. 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\u2019s first principal investigator. \u201cIXPE’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.\u201d<\/p>\n

What\u2019s next for the blazar research?<\/p>\n

\u201cOne thing we\u2019ll want to do is try to find as many of these as possible,\u201d Ehlert said. \u201cBlazars change quite a bit with time and are full of surprises.\u201d<\/p>\n

More about IXPE<\/strong><\/p>\n

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\u2019s Marshall Space Flight Center in Huntsville, Alabama. BAE Systems, Inc., headquartered in Falls Church, Virginia, manages spacecraft operations together with the University of Colorado\u2019s Laboratory for Atmospheric and Space Physics in Boulder. Learn more about IXPE\u2019s ongoing mission here:<\/p>\n

https:\/\/www.nasa.gov\/ixpe<\/a><\/p>\n

Elizabeth Landau
<\/strong>NASA Headquarters
elizabeth.r.landau@nasa.gov<\/a>
202-358-0845<\/p>\n

Lane Figueroa
<\/strong>Marshall Space Flight Center, Huntsville, Ala.
lane.e.figueroa@nasa.gov<\/a>
256.544.0034\u00a0<\/p>\n

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