Author Topic: Event Horizon Telescope ready to image black hole (Read 64509 times)

as58 · « **Reply #20 on:** 04/01/2019 07:20 pm »

Quote from: ugordan on 04/01/2019 06:53 pm

I'm thinking Sgr A*, just because it's a bigger impact as it's in our backyard and not some "random" galaxy out there.

Actually, are there any other plausible targets? Messier 87 is by far the closest of the really massive ones.

ugordan · « **Reply #21 on:** 04/01/2019 07:33 pm »

Quote from: as58 on 04/01/2019 07:20 pm

Quote from: ugordan on 04/01/2019 06:53 pm
I'm thinking Sgr A*, just because it's a bigger impact as it's in our backyard and not some "random" galaxy out there.

Actually, are there any other plausible targets? Messier 87 is by far the closest of the really massive ones.

There's a third one I've seen mentioned in a talk by Avery Broderick (one of the panelists for the press conference), but he said it's not radio-active so we're out of luck. Those two are the best candidates nearby.

Star One · « **Reply #22 on:** 04/01/2019 08:21 pm »

Are there any plans to add the Tianyan radio telescope to this collective?

jgoldader · « **Reply #23 on:** 04/02/2019 01:19 am »

Quote from: as58 on 04/01/2019 07:20 pm

Quote from: ugordan on 04/01/2019 06:53 pm
I'm thinking Sgr A*, just because it's a bigger impact as it's in our backyard and not some "random" galaxy out there.

Actually, are there any other plausible targets? Messier 87 is by far the closest of the really massive ones.

M87 is the best one besides Sgr A*, and I would be surprised if there are many (any?) others that could be resolved. The angular size of the event horizon is proportional to the linear diameter divided by the distance; yet because the linear diameter of the event horizon is proportional to the black hole mass, M87's greater mass almost compensates for its greater distance. The end result is that the angular diameter of the M87 black hole's event horizon should be a little less than that of Sgr A*.

I'm trying not to get too hopeful; the renders in "Interstellar" were based on real physics (tweaked for cinematography) and seeing a ring would be just spectacular.

as58 · « **Reply #24 on:** 04/02/2019 05:06 am »

Quote from: Star One on 04/01/2019 08:21 pm

Are there any plans to add the Tianyan radio telescope to this collective?

No, it works at much longer wavelengths than the telescopes that are used in EHT.

hoku · « **Reply #25 on:** 04/02/2019 10:08 am »

Just a few numbers, which might come in handy for the discussion of the EHT results (of which I do not know anything). The Schwarzschild radius (notice spelling "schild"!) of a black hole is 3 km times the mass of the black hole in solar masses. For a non-rotating black hole this also defines the location of the event horizon.

Sgr A*:
mass: 4.2 million solar masses
RADIUS: 12.5 million km
DIAMETER: 25 million km (15.5 million miles)
angular DIAMETER (for a distance Sun to Sgr A* of 8200 pc): 20 micro-arcsec
RADIUS of innermost stable orbit (for non-rotating black hole): 3 * Scharzschild radius = 30 micro-arcsec

EHT (present configuration?):
observing frequency: 230 GHz (i.e. observing wavelength 1.3mm)
angular resolution EHT for, e.g., Hawaii - ALMA baseline: 28 micro-arcsec
(see https://eventhorizontelescope.org/building-larger-array)

Results of previously highest angular resolution radio (at 86 GHz, i.e. 3.5 millimeter) observations of Sgr A*:
https://www.mpifr-bonn.mpg.de/pressreleases/2019/1

Star One · « **Reply #26 on:** 04/06/2019 12:04 pm »

Documentary to be shown on BBC 4 in the U.K. on the 10th April.

How to See a Black Hole: The Universe’s Greatest Mystery

Quote

Documentary following researchers as they try to take the first-ever picture of a black hole. They must travel the globe to build a revolutionary telescope that spans planet Earth.

Star One · « **Reply #27 on:** 04/06/2019 07:21 pm »

We're About to See The First-Ever Photo of a Black Hole. Here's What It Might Be Like

Recounting the work of Jean-Pierre Luminet amongst others in the depiction of black holes.

eeergo · « **Reply #28 on:** 04/10/2019 01:00 pm »

Press conference event starting (6 different ones going on at the same time in Brussels (English), Shanghai (Mandarin Chinese), Taipei (Mandarin Chinese), Tokyo (Japanese), Santiago de Chile (Spanish) and Washington DC (English); I'm looking at the main one from Europe).

eeergo · « **Reply #29 on:** 04/10/2019 01:08 pm »

M87's black hole (M87*):

eeergo · « **Reply #30 on:** 04/10/2019 01:09 pm »

10^11 (100 billion in English numbering) km diameter.

eeergo · « **Reply #31 on:** 04/10/2019 01:10 pm »

6.5·10^9 (billion in English numbering) times the Sun's mass.

eeergo · « **Reply #32 on:** 04/10/2019 01:13 pm »

Release from NSF: https://www.nsf.gov/news/special_reports/blackholes/

FutureSpaceTourist · « **Reply #33 on:** 04/10/2019 01:14 pm »

https://twitter.com/ESO/status/1115964884892692486

eeergo · « **Reply #34 on:** 04/10/2019 01:15 pm »

Tens of thousands of synthetic images generated to be sure the acquired one really is a BH.

Star One · « **Reply #35 on:** 04/10/2019 01:16 pm »

Any news about the imaging of sagittarius a?

eeergo · « **Reply #36 on:** 04/10/2019 01:19 pm »

Had to wait for all observing sites to have good weather simultaneously to perform the interferometry and get an effective radiotelescope of Earth's size, record everything in hard drives (no fiber optic infrastructure), fly boxes full of HDs (6 m^3 of volume!) to a data processing center where careful checks taking months took place, to arrive to this image.

eeergo · « **Reply #37 on:** 04/10/2019 01:20 pm »

Shadow first seen by individual researchers on their ordinary laptops, while they worked on merging their data to get maximum resolution and reliability.

eeergo · « **Reply #38 on:** 04/10/2019 01:22 pm »

Clockwise rotating hole.

eeergo · « **Reply #39 on:** 04/10/2019 01:23 pm »

6 papers coming out now in astrophysical journals explaining the details.