{"id":23687,"date":"2021-03-24T10:00:44","date_gmt":"2021-03-24T14:00:44","guid":{"rendered":"https:\/\/hobbyspace.com\/Blog\/?p=23687"},"modified":"2021-03-23T23:49:12","modified_gmt":"2021-03-24T03:49:12","slug":"eso-magnetic-fields-of-m87s-black-hole-illuminated-by-polarized-light","status":"publish","type":"post","link":"https:\/\/hobbyspace.com\/Blog\/?p=23687","title":{"rendered":"ESO: Magnetic fields of M87’s black hole illuminated by polarized light"},"content":{"rendered":"

A new report from the European Southern Observatory (ESO)<\/a>:<\/p>\n

Astronomers image magnetic fields at the edge of M87\u2019s black hole<\/a><\/strong><\/p>\n

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The Event Horizon Telescope (EHT) collaboration, who produced the first ever image of a black hole released in 2019, has today a new view of the massive object at the centre of the Messier 87 (M87) galaxy: how it looks in polarised light. This is the first time astronomers have been able to measure polarisation, a signature of magnetic fields, this close to the edge of a black hole.\u00a0 This image shows the polarised view of the black hole in M87. The lines mark the orientation of polarisation, which is related to the magnetic field around the shadow of the black hole.<\/figcaption><\/figure>\n

The Event Horizon Telescope (EHT) collaboration, who produced the first ever image of a black hole, has today revealed a new view of the massive object at the centre of the Messier 87 (M87) galaxy: how it looks in polarised light. This is the first time astronomers have been able to measure polarisation, a signature of magnetic fields, this close to the edge of a black hole. The observations are key to explaining how the M87 galaxy, located 55 million light-years away, is able to launch energetic jets from its core.<\/p>\n

\u201cWe are now seeing the next crucial piece of evidence to understand how magnetic fields behave around black holes, and how activity in this very compact region of space can drive powerful jets that extend far beyond the galaxy,\u201d<\/em><\/p>\n

says Monika Mo\u015bcibrodzka, Coordinator of the EHT Polarimetry Working Group and Assistant Professor at Radboud University in the Netherlands.<\/p>\n

https:\/\/cdn.eso.org\/videos\/medium_podcast\/eso2105a.mp4<\/a><\/video><\/div>\n

On 10 April 2019, scientists released the first ever image of a black hole<\/a>, revealing a bright ring-like structure with a dark central region \u2014 the black hole\u2019s shadow<\/a>. Since then, the EHT collaboration has delved deeper into the data on the supermassive object at the heart of the M87 galaxy collected in 2017. They have discovered that a significant fraction of the light around the M87 black hole is polarised.<\/p>\n

\u201cThis work is a major milestone: the polarisation of light carries information that allows us to better understand the physics behind the image we saw in April 2019, which was not possible before,\u201d<\/em><\/p>\n

explains Iv\u00e1n Mart\u00ed-Vidal, also Coordinator of the EHT Polarimetry Working Group and GenT Distinguished Researcher at the University of Valencia, Spain. He adds that<\/p>\n

\u201cunveiling this new polarised-light image required years of work due to the complex techniques involved in obtaining and analysing the data.\u201d<\/em><\/p>\n

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This composite image shows three views of the central region of the Messier 87 (M87) galaxy in polarised light and one view, in the visible wavelength, taken with the Hubble Space Telescope. The galaxy has a supermassive black hole at its centre and is famous for its jets, that extend far beyond the galaxy. The Hubble image at the top captures a part of the jet some 6000 light years in size.
One of the polarised-light images, obtained with the Chile-based Atacama Large Millimeter\/submillimeter Array (ALMA), in which ESO is a partner, shows part of the jet in polarised light. This image captures the part of the jet, with a size of 6000 light years, closer to the centre of the galaxy.
The other polarised light images zoom in closer to the supermassive black hole: the middle view covers a region about one light year in size and was obtained with the National Radio Astronomy Observatory\u2019s Very Long Baseline Array (VLBA) in the US.\u00a0
The most zoomed-in view was obtained by linking eight telescopes around the world to create a virtual Earth-sized telescope, the Event Horizon Telescope or EHT. This allows astronomers to see very close to the supermassive black hole, into the region where the jets are launched.\u00a0
The lines mark the orientation of polarisation, which is related to the magnetic field in the regions imaged. The ALMA data provides a description of the magnetic field structure along the jet. Therefore the combined information from the EHT and ALMA allows astronomers to investigate\u00a0the role of magnetic fields from the vicinity of the event horizon (as probed with the EHT on light-day scales) to far beyond the M87 galaxy along its powerful jets (as probed with ALMA on scales of thousand of light-years).
The values in GHz refer to the frequencies of light\u00a0at which\u00a0the different observations were made. The\u00a0horizontal lines show the scale (in light years) of each of the individual images.<\/figcaption><\/figure>\n

Light becomes polarised when it goes through certain filters, like the lenses of polarised sunglasses, or when it is emitted in hot regions of space where magnetic fields are present. In the same way that polarised sunglasses help us see better by reducing reflections and glare from bright surfaces, astronomers can sharpen their view of the region around the black hole by looking at how the light originating from it is polarised. Specifically, polarisation allows astronomers to map the magnetic field lines present at the inner edge of the black hole.<\/p>\n

\u201cThe newly published polarised images are key to understanding how the magnetic field allows the black hole to ‘eat’ matter and launch powerful jets,\u201d<\/em><\/p>\n

says EHT collaboration member Andrew Chael, a NASA Hubble Fellow at the Princeton Center for Theoretical Science and the Princeton Gravity Initiative in the US.<\/p>\n

https:\/\/cdn.eso.org\/videos\/medium_podcast\/eso2105b.mp4<\/a><\/video><\/div>\n

The bright jets of energy and matter that emerge from M87\u2019s core<\/a> and extend at least 5000 light-years from its centre are one of the galaxy\u2019s most mysterious and energetic features. Most matter lying close to the edge of a black hole falls in. However, some of the surrounding particles escape moments before capture and are blown far out into space in the form of jets.<\/p>\n

Astronomers have relied on different models of how matter behaves near the black hole to better understand this process. But they still don\u2019t know exactly how jets larger than the galaxy are launched from its central region, which is comparable in size to the Solar System, nor how exactly matter falls into the black hole. With the new EHT image of the black hole and its shadow in polarised light, astronomers managed for the first time to look into the region just outside the black hole where this interplay between matter flowing in and being ejected out is happening.<\/p>\n

The observations provide new information about the structure of the magnetic fields just outside the black hole. The team found that only theoretical models featuring strongly magnetised gas can explain what they are seeing at the event horizon.<\/p>\n

\u201cThe observations suggest that the magnetic fields at the black hole\u2019s edge are strong enough to push back on the hot gas and help it resist gravity\u2019s pull. Only the gas that slips through the field can spiral inwards to the event horizon,\u201d<\/em><\/p>\n

explains Jason Dexter, Assistant Professor at the University of Colorado Boulder, US, and Coordinator of the EHT Theory Working Group.<\/p>\n

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This artist\u2019s impression depicts the black hole at the heart of the enormous elliptical galaxy Messier 87 (M87). This black hole was chosen as the object of paradigm-shifting observations by the Event Horizon Telescope. The superheated material surrounding the black hole is shown, as is the relativistic jet launched by M87\u2019s black hole.<\/figcaption><\/figure>\n

To observe the heart of the M87 galaxy, the collaboration linked eight telescopes around the world \u2014 including the northern Chile-based Atacama Large Millimeter\/submillimeter Array (ALMA<\/a>) and the Atacama Pathfinder EXperiment (APEX<\/a>), in which the European Southern Observatory (ESO) is a partner \u2014 to create a virtual Earth-sized telescope, the EHT. The impressive resolution obtained with the EHT is equivalent to that needed to measure the length of a credit card on the surface of the Moon.<\/p>\n

\u201cWith ALMA and APEX, which through their southern location enhance the image quality by adding geographical spread to the EHT network, European scientists were able to play a central role in the research,\u201d\u00a0 … \u201cWith its 66 antennas, ALMA dominates the overall signal collection in polarised light, while APEX has been essential for the calibration of the image.\u201d<\/em><\/p>\n

[says Ciska Kemper, European ALMA Programme Scientist at ESO.]<\/p>\n

“ALMA data were also crucial to calibrate, image and interpret the EHT observations, providing tight constraints on the theoretical models that explain how matter behaves near the black hole event horizon,”<\/em><\/p>\n

adds Ciriaco Goddi, a scientist at\u00a0Radboud University and\u00a0Leiden Observatory, the Netherlands, who led an accompanying study<\/a> that relied only on ALMA observations.<\/p>\n

The EHT setup allowed the team to directly observe the black hole shadow and the ring of light around it, with the new polarised-light image clearly showing that the ring is magnetised. The results are published today in two separate papers in The Astrophysical Journal Letters by the EHT collaboration. The research involved over 300 researchers from multiple organisations and universities worldwide.<\/p>\n

“The EHT is making rapid advancements, with technological upgrades being done to the network and new observatories being added. We expect future EHT observations to reveal more accurately the magnetic field structure around the black hole and to tell us more about the physics of the hot gas in this region,”<\/em><\/p>\n

concludes EHT collaboration member Jongho Park, an East Asian Core Observatories Association Fellow at the Academia Sinica Institute of Astronomy and Astrophysics in Taipei.<\/p>\n

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This image shows the contribution of ALMA and APEX to the EHT. The left hand image shows a reconstruction of the black hole image using the full array of the Event Horizon Telescope (including ALMA and APEX); the right-hand image shows what the reconstruction would look like without data from ALMA and APEX. The difference clearly shows the crucial role that ALMA and APEX played in the observations.<\/figcaption><\/figure>\n

Links<\/strong><\/p>\n

    \n
  • Research papers\n
      \n
    • Paper VII<\/a><\/li>\n
    • Paper VIII<\/a><\/li>\n
    • Goddi et al.<\/a><\/li>\n<\/ul>\n<\/li>\n
    • Additional videos related to the research on the EHT YouTube channel<\/a>\n
        \n
      • What is polarization<\/a><\/li>\n
      • How magnetic fields affect black hole images <\/a><\/li>\n
      • The M87 image as seen with a polarizer<\/a><\/li>\n<\/ul>\n<\/li>\n
      • EHT website<\/a><\/li>\n
      • Images of ALMA<\/a><\/li>\n
      • Images of APEX<\/a><\/li>\n
      • ESO EHT webpage<\/a><\/li>\n
      • ESO blog post on the EHT project<\/a><\/li>\n
      • For scientists: got a story? Pitch your research<\/a><\/li>\n<\/ul>\n

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