A recent study utilized NASA’s IXPE (Imaging X-ray Polarized Explorer) to analyze a highly relativistic jet originating from the Blazar Bl Lacertae, a supermassive black hole surrounded by luminous discs.
This artist’s rendering illustrates the core area of Blazar Bl Lacertae, featuring an ultra-massive black hole surrounded by bright discs and Earth-directed jets. Image credit: NASA/Pablo Garcia.
Astrophysicists elucidated a highly relativistic jet, proposing two competing theories regarding an X-ray component made up of protons and electrons.
Each theory presents a distinct signature in the polarization characteristics of the X-ray light.
Polarized light signifies the average direction of the electromagnetic waves comprising light.
When X-rays in a black hole’s jets are highly polarized, it indicates production from protons that circulate within the magnetic field of the jet or protons interacting with the jet’s photons.
Conversely, low polarization in X-rays implies that the generation of X-rays occurs through electron-photon interactions.
The IXPE is the sole satellite capable of making such polarization measurements.
“This was one of the greatest mysteries involving supermassive black hole jets,” remarks Dr. Ivan Agdo, an astronomer at Astrophicidae Athtrophicidae and Andocia-CSIC.
“Thanks to numerous supporting ground telescopes, IXPE equipped us with the necessary tools to ultimately resolve this issue.”
Astronomers concluded that electrons are likely the source, through a process known as Compton scattering.
This phenomenon, also referred to as the Compton effect, occurs when photons lose or gain energy through interactions with charged particles (primarily electrons).
Within the jets of a supermassive black hole, electrons move at speeds approaching that of light.
IXPE enabled researchers to determine that, in Blazar jets, electrons possess enough energy to scatter infrared photons into the X-ray spectrum.
Bl Lacertae, one of the earliest discovered Blazars, was initially thought to be a kind of star in the Lacerta constellation.
IXPE monitored Bl Lacertae for seven days in November 2023, in conjunction with several ground-based telescopes also measuring optical and radio polarization.
Interestingly, during the X-ray polarization observations, Bl Lacertae’s light polarization peaked at 47.5%.
“This marks not only the most polarized BL Lacertae has been in the past 30 years, but indeed the highest ever recorded,” states Dr. Ioannis Riodakis, an astrophysicist at the Institute of Astrophysics.
Researchers noted that X-rays are significantly less polarized than optical light.
They were unable to detect strong polarized signals and ascertained that the X-rays could not exceed 7.6% polarization.
This finding confirms that electron interactions with photons via the Compton effect must account for the X-ray emissions.
“The fact that optical polarization is considerably higher than that of X-rays can only be explained by Compton scattering,” he added.
“IXPE has solved yet another mystery surrounding black holes,” claimed Dr. Enrico Costa, an astrophysicist associated with the planet spaziali of astituto to astituto to n diastrofísica.
“IXPE’s polarized X-ray capabilities have unraveled several long-standing mysteries, which is a significant achievement.
“In other instances, IXPE’s results challenged previously held beliefs, opening up new questions, but that’s the essence of science, and certainly IXPE excels in its scientific contributions.”
Survey results will be published in Astrophysics Journal Letter.
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Ivan Agd et al. 2025. The height of X-ray and X-ray polarization reveals Compton scattering of BL Lacertae jets. apjl in press; doi: 10.3847/2041-8213/ADC572
Source: www.sci.news
