[FRIAM] center of the milkyway does containt a blackhole

Fri May 13 02:44:29 EDT 2022

Hi Gil,

Yes, several good questions, some with answers, some not known.

> Ok now that I got that out my system:
> I had wondered if this is the same science stunt we used to image a blackhole...but what are they using as a light source

The light is actually being generated by gas or dust that spirals very fast around the black hole itself.  Things that swirl around a central object don’t move cleanly.  There is a lot of turbulence and collision, and they heat up.  Because the infall around BHs is so fast, they get very hot and glow.

As for what frequencies they use to observe, I think it is an intersection of three considerations: 1) it has to be a wavelength long enough that the telescopes can get phase coherence, which I think means somewhere in the radio (microwave might be possible in principle, but quite difficult); 2) it has to be a wavelength that somewhat gets through all the dust between the center of the galaxy and us (I think this is the main limitation); and 3) it has to be some frequency that the BH actually emits.  Small ones like BHs from single stars might emit in X-rays, but I think the large ones in galaxy centers are mostly radio sources, unless they produce jets that create a secondary source of light.  (Check me on this; I could be way off.)

> and how do decide on the galaxy's center

I think people now believe that most galaxy centers have these large BHs in them.  It’s remarkable that 50 years ago, that had not been suspected.  When I was a kid, I read an old Asimov book “Quasar, quasar, burning bright”, in which none of this was even a main theory.

> was this also created by the sheer weight of the galaxy?

This is the thing nobody knows.  They are so large, and the seem to have formed so early, that it doesn’t seem possible for star-sized BHs to form and then to merge.  BHs tend to clean out the dust from the environments where they are for a long time, and without extra frictions, things just orbit for a long time, but don’t collide.  I don’t know the details on how people think about this in the best version.

> or did a star go kaboom their good knows when and it just happened to be more or less dead center of the galaxy?

It seems people believe that the gathering that forms the galaxy is somehow related to the formation of dense things, and eventually BHs, at the center.  But I don’t know.

> and are they all shaped like a toilet?

They are actually among the roundest things in the universe.  The ring, I think, is a very special kind of orbital effects.

I taught with a physics prof. In Austin who used to explain mechanics to students in a way I liked.  He said “The moon is falling toward the earth, just like an apple would.  It’s just that the moon is moving sideways, so it keeps missing”. And that’s all orbits are.  They’re falling inward, but they keep missing.

Where spacetime starts to tip very strongly near the event horizon, you can do that with light.  There is a certain radius where light, traveling sideways, just goes in an orbit.  A bit further in, light shining directly outward never gets further out (that is the event horizon).  So I think the ring effect isn’t so much that the glowing gas makes any kind of a ring, but because there the light gets condensed into orbits, and when we look at it, it is the light just outside that orbital radius that eventually beams at us.  The orbits can be going all around the BH, covering the sphere in any direction, but where we look at the central region of the disk, it is shining “sideways”, and doesn’t eventually beam out to us in a way that looks like it came from there.

There are images of GR models, some of which got used in that Matthew McConaughey movie, to suggest what it would look like if you were close by, and didn’t have the combination of lensing distortions, dust, and telescope resolution limitations.  I think it gives that ring look from any direction, so this doesn’t have anything to do with rotating disks.  In any case, if there were a disk, we wouldn’t see it face-on, because it would be in the same plane of the galaxy as we are.

Eric

> 
> On Thu, May 12, 2022 at 8:08 PM David Eric Smith <desmith at santafe.edu <mailto:desmith at santafe.edu>> wrote:
> Yeah, good stuff.
> 
> I’m not sure when I first heard about the ALMA upgrade that would give them phase coherence across the telescopes at the frequencies the EHT is using, and data archiving that would allow them to try to coherently register telescopes sited all around the world.  It feels like about a decade ago.  I have been waiting, since that first notice, to see this picture.  The M87 image a couple years ago was the resolution of the real cliffhanger — whether they could get it to work at all — but this one was even 2+ years harder to push through technically.
> 
> I don’t imagine I would want to do that work.  It seems like an incredible tedious grind, made for real professionals.  But I am very glad to be a consumer of the outcome.
> 
> Eric
> 
> 
> 
>> On May 13, 2022, at 11:02 AM, Gillian Densmore <gil.densmore at gmail.com <mailto:gil.densmore at gmail.com>> wrote:
>> 
>> https://www.nytimes.com/2022/05/12/science/black-hole-photo.html <https://www.nytimes.com/2022/05/12/science/black-hole-photo.html>
>> 
>> and it looks a bit like something melting on icecream. fudge or caramel
>> -. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. .
>> FRIAM Applied Complexity Group listserv
>> Fridays 9a-12p Friday St. Johns Cafe   /   Thursdays 9a-12p Zoom  https://linkprotect.cudasvc.com/url?a=https%3a%2f%2f%2f%2fbit.ly%2fvirtualfriam&c=E,1,g4nNB9lId8M23hD2WsamUUHKMiSCjJePmyzMOQcT1owkCEiv33l21SxdXAuWv6NnKPbMuEQEkoMHTtKZmQdubAMCmkFwpBKkaeVptVwgtnIO7FUMXA,,&typo=1 <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2f%2f%2fbit.ly%2fvirtualfriam&c=E,1,g4nNB9lId8M23hD2WsamUUHKMiSCjJePmyzMOQcT1owkCEiv33l21SxdXAuWv6NnKPbMuEQEkoMHTtKZmQdubAMCmkFwpBKkaeVptVwgtnIO7FUMXA,,&typo=1>
>> un/subscribe https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fredfish.com%2fmailman%2flistinfo%2ffriam_redfish.com&c=E,1,tB-5WFDpRpXnEpC__CblcLZYsVkkK_KcQSrz2RFubdvXeUO3mNsX66x1bRINNwyULXBWnuuxT30OrrBQUoWE9bBzCt0yhzfyOkXthh4iKRjM0GTea0mZFpL6Bg,,&typo=1 <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fredfish.com%2fmailman%2flistinfo%2ffriam_redfish.com&c=E,1,tB-5WFDpRpXnEpC__CblcLZYsVkkK_KcQSrz2RFubdvXeUO3mNsX66x1bRINNwyULXBWnuuxT30OrrBQUoWE9bBzCt0yhzfyOkXthh4iKRjM0GTea0mZFpL6Bg,,&typo=1>
>> FRIAM-COMIC https://linkprotect.cudasvc.com/url?a=http%3a%2f%2ffriam-comic.blogspot.com%2f&c=E,1,E9TNNRcyezY-Riuyjhrs0n5KeGguwDXKiSiiMtspnqfNgCgmlFYyf-UHQLcz4Va7UXpP6-TXvUHvgndjZl6bmNjjadexHY7xJyplJe0sVazKrMBEA2qDug,,&typo=1 <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2ffriam-comic.blogspot.com%2f&c=E,1,E9TNNRcyezY-Riuyjhrs0n5KeGguwDXKiSiiMtspnqfNgCgmlFYyf-UHQLcz4Va7UXpP6-TXvUHvgndjZl6bmNjjadexHY7xJyplJe0sVazKrMBEA2qDug,,&typo=1>
>> archives:  5/2017 thru present https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fredfish.com%2fpipermail%2ffriam_redfish.com%2f&c=E,1,2RdcgQPrfWS0dIFzI4AgZcrhu4Z1MTuSaXb_lBaw2mkjtx6IPReajVomwTdtitLSRSNRyllE9Q_1mBoPjNDfKL6dqdT93iJXEX02vjDYG6xOKFHur8IX&typo=1 <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fredfish.com%2fpipermail%2ffriam_redfish.com%2f&c=E,1,2RdcgQPrfWS0dIFzI4AgZcrhu4Z1MTuSaXb_lBaw2mkjtx6IPReajVomwTdtitLSRSNRyllE9Q_1mBoPjNDfKL6dqdT93iJXEX02vjDYG6xOKFHur8IX&typo=1>
>>  1/2003 thru 6/2021  http://friam.383.s1.nabble.com/ <http://friam.383.s1.nabble.com/>
> 
> -. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. .
> FRIAM Applied Complexity Group listserv
> Fridays 9a-12p Friday St. Johns Cafe   /   Thursdays 9a-12p Zoom  bit.ly/virtualfriam
> un/subscribe <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fbit.ly%2fvirtualfriamun%2fsubscribe&c=E,1,Sx3h8uJK34nQWYXVzGsGDxnk0rHQ8vs3rTIXtmjzGTQMWAi7q-PtLzN9gtf6XdpDY3eWfy7Ny2tyK73b9tHFgG_oG0_-4rLIxuMhK8NOKM2txixXZbjWXWW4&typo=1> http://redfish.com/mailman/listinfo/friam_redfish.com <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fredfish.com%2fmailman%2flistinfo%2ffriam_redfish.com&c=E,1,yODfz8ytxLHPLBSlgEnq3--9ZKYJtkmzd1PvZIsBdn_LN6HqcbXDNYHMEfy2r-3_aahs6n6Y649laf79Sx7P9KvRhz9zWxGwqeqiAF5-aVXuLA,,&typo=1>
> FRIAM-COMIC http://friam-comic.blogspot.com/ <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2ffriam-comic.blogspot.com%2f&c=E,1,btLMPsMn6rNtuGbWV3mgDPiRQBjaWp4ylDJmEyfFPw0OI5wpMSHNixvSJAX3yeNgg96XXZORNLhZqOFw5ySogDO2ArNxrXmOidKwwFiXn0oi&typo=1>
> archives:  5/2017 thru present https://redfish.com/pipermail/friam_redfish.com/ <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fredfish.com%2fpipermail%2ffriam_redfish.com%2f&c=E,1,oEL4y-gfeageAoLW48CqJK9RSG3Q-2yZ-F72RCUKtLNYK5hq5feP9XhmQ1fT0nV2gHGj0LzaFBNoSDiAJhRq0mdBPcuHAbjLFHJKHUvBRBk4EVxsi4RDLlc,&typo=1>
>   1/2003 thru 6/2021  http://friam.383.s1.nabble.com/ <http://friam.383.s1.nabble.com/>
> -. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. .
> FRIAM Applied Complexity Group listserv
> Fridays 9a-12p Friday St. Johns Cafe   /   Thursdays 9a-12p Zoom  https://linkprotect.cudasvc.com/url?a=https%3a%2f%2f%2f%2fbit.ly%2fvirtualfriam&c=E,1,-craH6Ofllo6j_c7CFw4Jl4DZKO9ZMnfRDGag8UJEneyEspbe4pdqVcP1mYTXfUZl7yfXsBNwD0T5pSA5XxnU-vuR0Tk1iCuDQo1QCMewEGYNwhEDQ,,&typo=1
> un/subscribe https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fredfish.com%2fmailman%2flistinfo%2ffriam_redfish.com&c=E,1,srn6mFvgclpO3Xlj9XX0x95b2sr8rUKUxz9xbLHGkagWmIZdZKdqRjTbXJ75hZByvGmoLcUxh_ihEMTQN0UGSEz4EswSZtMQg5p8rb7LmN-0lA,,&typo=1
> FRIAM-COMIC https://linkprotect.cudasvc.com/url?a=http%3a%2f%2ffriam-comic.blogspot.com%2f&c=E,1,YP5RESa6jnatzUfnA1Mrjhajyqku4wCQhv68y-n6BGD05sKbhyq8-COKqr4LToHQLEdt6_sL8mAetmPYBKHDlUbIg1u31B3UFw1nFT4uaZ5w_5c5iFgukmqO1A,,&typo=1
> archives:  5/2017 thru present https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fredfish.com%2fpipermail%2ffriam_redfish.com%2f&c=E,1,juyiU48N0DT61UEuODpbAQIYCA30iBr_EoaJP3J-0BDmXATfNPRAdMYBc99rCkMo5KKZ5yD8rAI8ZxJV1Xf7EYVUdadv5gr6EdFaIKj1WVQKDfHu5ek,&typo=1
>  1/2003 thru 6/2021  http://friam.383.s1.nabble.com/

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://redfish.com/pipermail/friam_redfish.com/attachments/20220513/2b5abe7e/attachment-0001.html>