APOD: EHT Resolves Central Jet from Black... (2021 Aug 04)

[APOD Robot]

EHT Resolves Central Jet from Black Hole in Cen A

Explanation: How do supermassive black holes create powerful jets? To help find out, the Event Horizon Telescope (EHT) imaged the center of the nearby active galaxy Centaurus A. The cascade of featured inset images shows Cen A from it largest, taking up more sky than many moons, to its now finest, taking up only as much sky as an golf ball on the moon. The new image shows what may look like two jets -- but is actually two sides of a single jet. This newly discovered jet-edge brightening does not solve the jet-creation mystery, but does imply that the particle outflow is confined by a strong pressure -- possibly involving a magnetic field. The EHT is a coordination of radio telescopes from around the Earth -- from the Caltech Submillimeter Observatory in Hawaii USA, to ALMA in Chile, to NOEMA in France, and more. The EHT will continue to observe massive, nearby black holes and their energetic surroundings.

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[shaileshs]

At least to me (to a naked eye, without zoom), comparing center of "right top" zoomed into "right middle" - I'm a bit challenged to see how they are same.. ?

[astraburning62]

I get really tired of descriptions of intergalactic objects such as Centaurus A (which is 13.05million light years away) as being 'nearby'. 13 million lights is not in any human sense of the word, 'nearby'. Sure, in a galactic relativistic sense its closer than most but use of this kind of relativistic language is far from helpful in communicating just how vast interstellar distances actually are. It still stuns me that highly educated intelligent people still have a warped understanding of how truly vast the universe - to me its the flat earth mentality of the era we inhabit. We need to start communicating better the cosmic realities and not cushion people from them. Having said that, very interesting picture, thanks for posting APOD Robot.

[Ann]

I get really tired of descriptions of intergalactic objects such as Centaurus A (which is 13.05million light years away) as being 'nearby'. 13 million lights is not in any human sense of the word, 'nearby'. Sure, in a galactic relativistic sense its closer than most but use of this kind of relativistic language is far from helpful in communicating just how vast interstellar distances actually are. It still stuns me that highly educated intelligent people still have a warped understanding of how truly vast the universe - to me its the flat earth mentality of the era we inhabit. We need to start communicating better the cosmic realities and not cushion people from them. Having said that, very interesting picture, thanks for posting APOD Robot.

Think of it like this. In space almost nothing is nearby, apart from the Moon. That is why people have visited the Moon and come back from it alive.

13 million light-years is actually quite nearby for another galaxy. And Centauri A is the most nearby galaxy that has an actively accreting supermassive central black hole with a jet. So yes, in view of what Centaurus A is, it is nearby.

An aside here: I once created a simple more or less to scale model of the inner Solar system, using a 2 meter in diameter table cloth for the Sun, a 0.02 meter in diameter cotton ball for the Earth, and a yellow pea for the Moon. I also created Mercury (a pea), Venus (a cotton ball) and Mars (another cotton ball), and then I found a long enough straight stretch of walking path in a park, and had other people help me place the objects at the roughly correct distances from each other. It completely boggled my mind to see how far away the planets were from each other and from the Sun. And that was only the inner Solar system.

(But the Moon was ridiculously close to the Earth.)

So I completely agree with you that space is... vast, for the lack of a better word. Space is humongous, to use another puny word for what space really is. I realize that as a human, I can't even begin to picture the "true" distance to Alpha Centauri in my mind. I can (at least in theory) make a model of the nearest stars and place them at more or less correct distances from each other, and I can certainly look at other people's models or drawings of the 3-D relationships between the nearest stars and get a good idea of the relative distances involved, but I absolutely can't picture the true kilometer by kilometer distance to Alpha Centauri in my mind. And I'd say that no one can, because no human brain is equipped to deal with such vastness.

For all of that, Centaurus A is nearby, in view of what sort of object it is.

Ann

[Ann]

At least to me (to a naked eye, without zoom), comparing center of "right top" zoomed into "right middle" - I'm a bit challenged to see how they are same.. ?

They look different, because they have been produced using different telescopes.

Colour composite image of Centaurus A, revealing the lobes and jets emanating from the active galaxy’s central black hole. This is a composite of images obtained with three instruments, operating at very different wavelengths. The 870-micron submillimetre data, from LABOCA on APEX, are shown in orange. X-ray data from the Chandra X-ray Observatory are shown in blue. Visible light data from the Wide Field Imager (WFI) on the MPG/ESO 2.2 m telescope located at La Silla, Chile, show the background stars and the galaxy’s characteristic dust lane in close to 'true colour'.

---

TANAMI radio image of the inner jet of Centaurus A at 8.4 GHz. From Müller et al. (2014).

The picture at left is a composite of submillimetre, X-ray and visible light exposures. The picture at left is a radio image. Therefore they look very different.

Ann

[astrocat]

looks like the 165000 light years in the top left corner is wrong, as scale for the double-ended arrow; should probably be a few light days or so maybe;

as for the "nearby" object, I once read an article about a large black hole that was discovered near Earth! further down it specified that it was really next to earth at 50 million light years; there are lots of galaxies closer than that

[De58te]

Wow. 60 million magnification from top to bottom for the EHT. I wonder what the comparison is to the Hubble Deep Sky Image? (I know I could look it up. I am just a bit lazy this morning.) And I hear that the James Webb when it launches will be 100 times stronger resolution than the Hubble! Gawd it feels like I have been waiting for decades for the James Webb.

[orin stepanek]

Are the jet particles blowing away from or toward the blach hole?

Very studious Kitty

[Chris Peterson]

I get really tired of descriptions of intergalactic objects such as Centaurus A (which is 13.05million light years away) as being 'nearby'.

Because it is. This is an astronomical site, and on an astronomical scale this distance is nearby. And it's important that the descriptions continue to emphasize that point.

[bystander]

viewtopic.php?t=41817

[johnnydeep]

I can't seem to find an explanation for the almost symmetrical huge purple "smoke", aka "jets in the largest scale image. I also find it odd that it's angle doesn't seem to align with either the central jet or the galactic dust disk.

[neufer]

I get really tired of descriptions of intergalactic objects such as Centaurus A (which is 13.05million light years away) as being 'nearby'.

Because it is. This is an astronomical site, and on an astronomical scale this distance is nearby. And it's important that the descriptions continue to emphasize that point.

Any object that is among the nearest dozen objects of its kind is certainly
a nearby object (be it a house, a star or a galactic supercluster).

[johnnydeep]

looks like the 165000 light years in the top left corner is wrong, as scale for the double-ended arrow; should probably be a few light days or so maybe;

Why? 40 times the zoom-in factor of the 4000 ly scale line on the smaller image would make it represent about the same distance as the 165000 ly scale line on the larger image, and both scale lines are the same size. (Man, that tortured sentence was hard to write, and is probably still not very clear...)

EDIT: nope: The box sizes don't seem to represent the same regions. Hopefully someone will set me straight.

[VictorBorun]

viewtopic.php?t=41817

That was my first thought: split jet is in fact a thin-shell cylinder (or a narrow cone), and the thin walls are all we can see at this exposure

Click to view full size image

Thin spherical shells of material in space can look like rings, because we see more material near their edges than through the center, making the edge bright and the middle dimmer. Credit: Phil Plait

In a protostar the accretion disk has an orbital electric current, generating magnetic thorus, its magnetic center hole creating a pair of thin-shell jets, too (called a Herbig Haro object)

Click to view full size image

[VictorBorun]

is not it strange for a giant elliptical galaxy like Centaurus A to have a dusty disk full of young giant stars, too?
A pair of jets is somewhat more typical. M87 has those too.

[neufer]

I can't seem to find an explanation for the almost symmetrical huge purple "smoke", aka "jets in the largest scale image. I also find it odd that it's angle doesn't seem to align with either the central jet or the galactic dust disk.

• There is an apparent slow precession of Centaurus A's accretion disk
  (unrelated to its more distant dust disk)
  resulting in a spiral structure to its distant jet lobes.

A&A 580, L8 (2015) DOI: 10.1051/0004-6361/201526797
c©ESO 2015 : Astronomy&Astrophysics

• Planck revealed bulk motion of Centaurus A lobes
  F. De Paolis1 et al.

Overview over the ~8°radio structure of Centaurus A.

---

<<The elliptical (S0) galaxy NGC 5128 is an example of the family of ellipticals that have an absorbing band of gas and dust projected across the stellar body. The center of this system harbors a supermassive black hole with mass about 10⁷−10⁸ M (see, e.g., Silge et al. 2005; Marconi et al. 2006; Neumayer 2010), which powers two jets, two inner lobes (with size about a few arcmin each), and the two outer giant lobes. The GLN and the northern jet are likely tilted toward the observer and the GLN is thought to be closer to us than the GLS. Indeed, the jets appear clearly in the radio band and are obviously shooting out of Centaurus A, with the radio emission becoming more diffuse at greater distances from the center of the galaxy (Neff et al. 2015). The jets consist of a plasma state, i.e., a high-temperature stream of matter. The jets are also clearly observed in X-rays (see, e.g., Karovska et al. 2002, and references therein). The most prominent feature is the jet extending for about 8 kpc toward the northeast (upper left in the sky), while a less prominent jet extends toward the southwest. The apparent brightness difference between the jets and the proper motion asymmetries of both the jets and the inner lobes (Tingay et al. 2001) are thought to be due to the viewing geometry: the first jet is moving toward us, while the second is moving away (see, e.g., Burns et al. 1983; Israel 1998). This was also suggested by the Faraday depolarization analysis of the southern inner lobe (Clarke et al. 1992).>>

[bystander]

I can't seem to find an explanation for the almost symmetrical huge purple "smoke", aka "jets in the largest scale image. I also find it odd that it's angle doesn't seem to align with either the central jet or the galactic dust disk.

I found the original image, the original CSIRO article on phys.org and a scientific article based on the data. Here is an article on associated gamma-rays from Fermi.

[neufer]

Click to play embedded YouTube video.

is not it strange for a giant elliptical galaxy like Centaurus A to have a dusty disk full of young giant stars, too?

A pair of jets is somewhat more typical. M87 has those too.

[johnnydeep]

I can't seem to find an explanation for the almost symmetrical huge purple "smoke", aka "jets in the largest scale image. I also find it odd that it's angle doesn't seem to align with either the central jet or the galactic dust disk.

I found the original image, the original CSIRO article on phys.org and a scientific article based on the data. Here is an article on associated gamma-rays from Fermi.

Thanks for the links bystander (and neufer). (bystander - your "original image" link is broken.)

[Ann]

is not it strange for a giant elliptical galaxy like Centaurus A to have a dusty disk full of young giant stars, too?
A pair of jets is somewhat more typical. M87 has those too.

Sure it is, but that's because Centaurus A is a collisional product! An elliptical galaxy has collided with a small gas-rich spiral galaxy, and the small spiral has produced the thick dust lane and created all the young blue stars!

No doubt the collision has sent a lot of gas into the supermassive central black hole of the elliptical component, fueling all the fury at the center of the galaxy and being responsible for the launching of the jet.

Ann

[bystander]

Thanks for the links bystander (and neufer). (bystander - your "original image" link is broken.)

Fixed it. Here it is: https://www.scienceimage.csiro.au/libra ... 850//large

[MarkBour]

Click to play embedded YouTube video.

Wow, the EHT is fantastic. 60,000,000 magnification.



While we enjoy these images of black holes and such, I wonder when they're going to get around to using it for the purpose for which it was created (locating Alan Shepard's lost golf ball).

[MarkBour]

https://www.scienceimage.csiro.au/libra ... 850//large

Thanks for this image. A couple of features at the very bottom of it are interesting. If those white dots are distant galaxies, oddly, there appear to be rings of disturbance around a couple of them in the purple of the image. I wonder what causes that?

[neufer]

Wow, the EHT is fantastic. 60,000,000 magnification.

While we enjoy these images of black holes and such, I wonder when they're going to get around to using it for the purpose for which it was created (locating Alan Shepard's lost golf ball).

• The Lunar Reconnaissance Orbiter Camera (LROC) (50 cm/pixel) resolution
  came within a factor of 12 of finding that 4.267 cm ball.

Apollo 14 landing site, 2009 photograph by Lunar Reconnaissance Orbiter

---

<<The Lunar Reconnaissance Orbiter Camera (LROC) comprises a pair of narrow-angle push-broom imaging cameras (NAC) and a single wide-angle camera (WAC). LROC has flown several times over the historic Apollo lunar landing sites at 50 km altitude; with the camera's high (50 cm/pixel) resolution, the Lunar Roving Vehicles and Lunar Module descent stages and their respective shadows are clearly visible, along with other equipment previously left on the Moon.>>

<<Under the rules of golf, a golf ball has a mass no more than 45.93 grams, has a diameter not less than 4.267 cm.>>

[tomatoherd]

overall a ridiculous collage. So the moon is between 250 and 300,000 light years in diameter? that's what in "Moon for scale" in that field implies. Why is it even there? none of the windows are in the range/order of moon measurement. Silly and wrong.