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Incredible new image shows the magnetic fields at the edge of the M87 black hole
The Event Horizon Telescope (EHT) collaboration has published a new view of the black hole at the center of the M87 galaxy. The EHT published the first-ever image of a black hole in 2019. This time, the image shows the black hole in polarized light, which shows the magnetic field surrounding the black hole. This marks the first time astronomers have been able to measure polarization this close to the edge of a black hole.
Polarization is a signature of magnetic fields, and being able to observe the magnetic fields provides scientists important new information and helps explain how the M87 galaxy launches energetic jets from its core. Monika Mościbrodzka, Coordinator of the EHT Polarimetry Working Group and Assistant Professor at Radboud Universiteit in the Netherlands, said, ‘We 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.”
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| ”A view of the M87 supermassive black hole in polarized light: 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 center of the Messier 87 (M87) galaxy: how it looks in polarized light. This is the first time astronomers have been able to measure polarization, a signature of magnetic fields, this close to the edge of a black hole. This image shows the polarized view of the black hole in M87. The lines mark the orientation of polarization, which is related to the magnetic field around the shadow of the black hole.’ Image and caption credit: EHT Collaboration. Click to enlarge. |
In 2019, when EHT scientists released the first image of a black hole, they had not finished digging through the data collected in 2017 on the supermassive object at the center of the M87 galaxy. Since then, researchers have discovered that a ‘significant fraction’ of the light around the M87 black hole is polarized. ”This work is a major milestone: the polarization of light carries information that allows us to understand better the physics behind the image we saw in April 2019, which was not possible before,’ says Iván Martí-Vidal, also Coordinator of the EHT Polarimetry Working Group and GenT Distinguished Researcher at the Universitat de València, Spain. Martí-Vidal continues, ‘Unveiling this new polarized-light image required years of work due to the complex techniques involved in obtaining and analyzing the data.”
Light is polarized when it travels through certain filters, like a circular polarizing filter used on a camera lens to reduce reflections and glare or when light is emitted in hot regions of space that are also magnetized. EHT writes, ‘In the same way polarized sunglasses help us see better by reducing reflections and glare from bright surfaces, astronomers can sharpen their vision of the region around the black hole by looking at how the light originating from there is polarized. Specifically, polarization allows astronomers to map the magnetic field lines present at the inner edge of the black hole.’ The new polarized images are critical to understanding how the magnetic field surrounding the black hole allows the black hole to consume matter and send out jets of energy.
The energy that emerges from M87’s core extends at least 5,000 light-years from its center. Scientists have been working to understand why some matter near the black hole is consumed by it, while other particles escape just before entering the black hole and form the observed jets of energy shooting from the black hole. The new image allows scientists for the first time to look at the region just outside the black hole where there’s a mix of matter flowing in and being ejected from the black hole.
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| An artist’s rendition of the black hole at the center of the M87 galaxy. Image credit: ESO/M. Kornmesser |
” The observations suggest that the magnetic fields at the black hole’s edge are strong enough to push back on the hot gas and help it resist gravity’s pull. Only the gas that slips through the field can spiral inwards to the event horizon,’ said Jason Dexter, Assistant Professor at the University of Colorado Boulder, USA, and coordinator of the EHT Theory Working Group.
If you’d like to learn more about the virtual Earth-sized telescope, the EHT, check out the animated video below.
The European Southern Observatory (ESO) released a neat composite view of the M87 jet in visible and polarized light. There’s a lot of information to digest about the image in the caption, which can be found here. You can also click here to download a larger version.
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| Image credit: EHT Collaboration; ALMA (ESO/NAOJ/NRAO), Goddi et al.; NASA, ESA and the Hubble Heritage Team (STScI/AURA); VLBA (NRAO), Kravchenko et al.; J. C. Algaba, I. Martí-Vidal |
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Pentax K-1 and K-1 II firmware updates include astrophotography features (depending on where you live)
Yesterday, Ricoh quietly released firmware 2.50 for its Pentax K-1 and K-1 II DSLRs. However, the features you can expect to gain from this update may depend on your geography.
Ricoh’s English-language firmware pages for the K-1 and K-1 II state that firmware 2.50 delivers “Improved stability for general performance.”
However, astute Pentax users noted that Ricoh’s Japanese-language firmware pages (translation) indicate that the update also includes a limited feature called “Astronomical Photo Assist,” a collection of three new features designed for astrophotography: Star AF, remote control focus fine adjustment, and astronomical image processing.
Star AF is intended to automate focusing on stars when using autofocus lenses. Rather than manually focusing on a bright star and changing your composition, it promises to let you compose your shot and let the camera focus.
Remote control fine adjustment allows users to adjust focus without touching the lens and requires Pentax’s optional O-RC1 remote. Astronomical image processing will enable users to make in-camera adjustments to astrophotography images, including shading correction, fogging correction, background darkness, star brightness, celestial clarity, and fringe correction.
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| Astronomical image processing on the K-1 and K-1 II will enable users to make in-camera adjustments to astrophotography images, including shading correction, fogging correction, background darkness, star brightness, celestial clarity, and fringe correction. |
According to Ricoh, Astronomical Photo Assist is a premium feature that must be purchased and costs ￥11,000 for an activation key (about $70 at current exchange rates).
Although these astrophotography features appear to be Japan-only for now, a Ricoh representative tells us, “Ricoh Imaging Americas confirmed that the premium firmware features for the PENTAX K-1 and PENTAX K-1 Mark II will eventually be available to US customers.”
Firmware update 2.50 for both the K-1 and K-1 II is available for download from Ricoh’s website.
As part of our twenty fifth anniversary, we’re looking back at some of the most significant cameras launched and reviewed during that period. Today’s pick was launched seven years ago today* and yet we’re only quite recently stepping out of its shadow.
The Nikon D850 is likely to be remembered as the high watermark of DSLR technology. We may yet still see impressive developments from Ricoh in the future (we’d love to see a significantly upgraded Pentax K-1 III), but the D850 was perhaps the green flash as the sun set on the DSLR as the dominant technology in the market.
Click here to read our Nikon D850 review
Why do we think it was such a big deal? Because it got just about everything right. Its 45MP sensor brought dual conversion gain to high pixel count sensors, meaning excellent dynamic range at base ISO and lower noise at high ISOs. Its autofocus system was one of the best we’ve ever seen on a DSLR: easy to use and highly dependable, with a good level of coverage. And then there was a body and user interface honed by years of iterative refinement, that made it easy to get the most out of the camera.
None of this is meant as a slight towards the other late-period DSLRs but the likes of Canon’s EOS 5DS and 5DSR didn’t present quite such a complete package of AF tracking, daylight DR and low-light quality as the Nikon did. With its ability to shoot at up to 9fps (if you used the optional battery grip), the D850 started to chip away at the idea that high megapixel cameras were specialized landscape and studio tools that would struggle with movement or less-than-perfect lighting. And that’s without even considering its 4K video capabilities.
In the seven years since the D850 was launched, mirrorless cameras have eclipsed most areas in which DSLRs once held the advantage. For example, the Z8 can shoot faster, autofocus more with more accuracy and precision, across a wider area of the frame and do so while shooting at much faster rates.
But, even though it outshines the D850 in most regards, the Z8 is still based around what we believe is a (significant) evolution of the same sensor, and its reputation still looms large enough for Nikon to explicitly market the Z8 as its “true successor.”
Nikon D850 sample gallery
*Actually seven years ago yesterday: we had to delay this article for a day to focus on the publishing the Z6III studio scene: the latest cameras taking precedence over our anniversary content.
| Photo: Richard Butler |
We’ve just received a production Nikon Z6III and took it into our studio immediately to get a sense for how the sensor really performs.
Dynamic range tests have already been conducted, but these only give a limited insight into the image quality as a whole. As expected, our Exposure Latitude test – which mimics the effect of reducing exposure to capture a bright sunrise or sunset, then making use of the deep shadows – shows a difference if you use the very deepest shadows, just as the numerical DR tests imply.
Likewise, our ISO Invariance test shows there’s more of a benefit to be had from applying more amplification by raising the ISO setting to overcome the read noise, than there was in the Z6 II. This means there’s a bigger improvement when you move up to the higher gain step of the dual conversion gain sensor but, as with the Z6 II, little more to be gained beyond that.
These are pushing at the extreme of the sensor’s performance though. For most everyday photography, you don’t use the deepest shadows of the Raw files, so differences in read noise between sensors don’t play much of a role. In most of the tones of an image, sensor size plays a huge role, along with any (pretty rare) differences in light capturing efficiency.
As expected, the standard exposures look identical to those of the Z6 II. There are similar (or better) levels of detail at low ISO, in both JPEG and Raw. At higher ISO, the Z6III still looks essentially the same as the Z6II. Its fractionally higher level of read noise finally comes back to have an impact at very, very high ISO settings.
Overall, then, there is a read noise price to be paid for the camera’s faster sensor, in a way that slightly blunts the ultimate flexibility of the Raw files at low ISO and that results in fractionally more noise at ultra-high ISOs. But we suspect most people will more than happily pay this small price in return for a big boost in performance.
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