from the photo-shows-Maximilian-Schell-looking-back dept.
The Event Horizon Telescope (EHT) is finally ready to take a picture of Sagittarius A*. From April 5th to 14th this year, the virtual telescope that's been in the making for the past two decades will peer into the supermassive black hole in the center of our galaxy. EHT is actually an array of radio telescopes located in different countries around the globe, including the Atacama Large Millimeter/submillimeter Array in Chile.
By using a technique called very-long-baseline interferometry, the EHT team turns all the participating observatories into one humongous telescope that encompasses the whole planet. We need a telescope that big and powerful, because Sagittarius A* is but a tiny pinprick in the sky for us. While scientists believe it has a mass of around four million suns, it also only measures around 20 million km or so across and is located 26,000 light-years away from our planet. The EHT team says it's like looking at a grapefruit or a DVD on the moon from Earth.
To prepare the participating observatories, the team equipped them with atomic clocks for the most precise time stamps and hard-drive modules with enormous storage capacities. Since the scientists are expecting to gather a colossal amount of data, they deployed enough modules to match the capacity of 10,000 laptops. Those hard drives will be flown out to the MIT Haystack Observatory, where imaging algorithms will make sense of EHT's data, once the observation period is done.
Source:
https://www.engadget.com/2017/02/19/event-horizon-telescope-is-ready/
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Black holes are perhaps the strangest objects predicted by Einstein's theory of General Relativity, objects so dense that gravity reigns supreme, and not even light can escape beyond a certain distance, known as the event horizon. The actual existence of black hole event horizons has not been proved, but some clever observations made by astronomers at the University of Texas at Austin and Harvard University have tested the alternative hypothesis: instead of an event horizon, there might instead be a solid surface to a black hole that objects colliding against it will hit. They found results that show that this alternative can't be true, and that an event horizon as predicted by GR is more likely. ScienceDaily has an article:
Astronomers at The University of Texas at Austin and Harvard University have put a basic principle of black holes to the test, showing that matter completely vanishes when pulled in. Their results constitute another successful test for Albert Einstein's General Theory of Relativity.
Most scientists agree that black holes, cosmic entities of such great gravity that nothing can escape their grip, are surrounded by a so-called event horizon. Once matter or energy gets close enough to the black hole, it cannot escape — it will be pulled in. Though widely believed, the existence of event horizons has not been proved.
"Our whole point here is to turn this idea of an event horizon into an experimental science, and find out if event horizons really do exist or not," said Pawan Kumar, a professor of astrophysics at The University of Texas at Austin.
Supermassive black holes are thought to lie at the heart of almost all galaxies. But some theorists suggest that there's something else there instead — not a black hole, but an even stranger supermassive object that has somehow managed to avoid gravitational collapse to a singularity surrounded by an event horizon. The idea is based on modified theories of General Relativity, Einstein's theory of gravity.
While a singularity has no surface area, the noncollapsed object would have a hard surface. So material being pulled closer — a star, for instance — would not actually fall into a black hole, but hit this hard surface and be destroyed.
The team figured out what a telescope would see when a star hit the hard surface of a supermassive object at the center of a nearby galaxy: The star's gas would envelope the object, shining for months, perhaps even years.
Once they knew what to look for, the team figured out how often this should be seen in the nearby universe, if the hard-surface theory is true.
[...] "Given the rate of stars falling onto black holes and the number density of black holes in the nearby universe, we calculated how many such transients Pan-STARRS should have detected over a period of operation of 3.5 years. It turns out it should have detected more than 10 of them, if the hard-surface theory is true," Lu said.
They did not find any.
"Our work implies that some, and perhaps all, black holes have event horizons and that material really does disappear from the observable universe when pulled into these exotic objects, as we've expected for decades," Narayan said. "General Relativity has passed another critical test."
The full text of the original paper "Stellar disruption events support the existence of the black hole event horizon" (DOI: 10.1093/mnras/stx542) is available open access from the Monthly Notices of the Royal Astronomical Society.
Further evidence for or against the existence of black hole event horizons will have to wait for the Event Horizon Telescope, which is due to release its first results later this year.
Event Horizon Telescope captures new view of black hole in polarized light:
Two years ago, the Event Horizon Telescope (EHT) made headlines with its announcement of the first direct image of a black hole. Science magazine named the image its Breakthrough of the Year. Now the EHT collaboration is back with another groundbreaking result: a new image of the same black hole, this time showing how it looks in polarized light. The ability to measure that polarization for the first time—a signature of magnetic fields at the black hole's edge—is expected to yield fresh insight into how black holes gobble up matter and emit powerful jets from their cores. The new findings were described in three papers published in The Astrophysical Journal Letters.
"This work is a major milestone: the polarization 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," said co-author Iván Martí-Vidal, coordinator of the EHT Polarimetry Working Group and a researcher at the University of Valencia, Spain. "Unveiling this new polarized-light image required years of work due to the complex techniques involved in obtaining and analyzing the data."
[...] In much the same way that polarized sunglasses reduce glare from bright surfaces, the polarized light around a black hole provides a sharper view of the region around it. In this case, the polarization of light isn't due to special filters (like the lenses in sunglasses) but the presence of magnetic fields in the hot region of space surrounding the black hole. That polarization enables astronomers to map the magnetic field lines at the inner edge and to study the interaction between matter flowing in and being blown outward.
"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 co-author Jason Dexter of the University of Colorado Boulder, who is also coordinator of the EHT Theory Working Group. That means that only theoretical models that incorporate the feature of a strongly magnetized gas accurately describe what the EHT collaboration has observed.
(Score: -1, Disagree) by Anonymous Coward on Monday February 20 2017, @11:20PM
Could we have fewer submissions about astrology? It gets boring, and no one comments anyway.
(Score: 3, Insightful) by maxwell demon on Monday February 20 2017, @11:24PM
Astrology? I think you are confusing something.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Tuesday February 21 2017, @04:30AM
Maybe he's a steampunk time traveler and isn't aware that astronomy and astrology are different in this era.
(Score: 3, Insightful) by aristarchus on Tuesday February 21 2017, @06:26AM
Two clues: One: misspelled Sagittarius. Two. The distinction between Astronomy and Astrology well predates Steampunk, and STEM, both of which are fictional any way. Real astronomers do it with math!
(Score: 1, Funny) by Anonymous Coward on Monday February 20 2017, @11:55PM
Aquarius- You have an inventive mind and are inclined to be progressive. You lie a great deal, you make the same mistakes repeatedly because you are stupid. Everyone thinks you are a f*&king jerk. You enjoy sucking c*&k.
Pisces--You have a vivid imagination and often think you are being followed by the FBI or CIA. You have minor influence on your friends and people resent you for flaunting what you mistake as power. You lack confidence and are a general dipsh!t.
Aries--You are a pioneer type and think most people are dickheads. You are quick to reprimand, impatient, and scornful of advice. You do nothing but piss off everyone you come into contact wtih. You are a Prick
Taurus-- You are practical and persistent. You have a dogged determination and stick-to-it-iveness because you never do anything right the first time. Most people think you are stubborn and bull headed. You are nothing but a f*^cking asshole.
Gemini--You are a quick and intelligent thinker. People like you because you are bisexual. You are inclined to expect too much for too little. This means u are a cheap bastard. Geminis are notorious for thriving on incest.
Cancer-- You are sympathetic and understanding to other peoples problems which makes you a sucker. You always keep putting things off. Which is why you will always be on welfare and wont be worth a sh!t. Everbody in prison is a cancer
Leo--You consider yourself a born leader, Everone thinks you are an idiot.
Most leos are bullies. You are vain and cannot tolerate honest criticism. You arrogance is disgusting. Leos are thieving mother-f*^ckers and enjoy masturbating more than sex.
Virgo--you are the logical type and hate disorder. Your sh!t picking attitude is sickening to your coworkers. you are cold and unemotional and often fall asleep during sex. Virgos make good bus drivers and pimps
Libra--You are the artistic type and have a difficult time with reality. If you are a male, you are probably gay. Chances for employment and monetary gain are nil. Most libra women are whores. All libras will die of an STD.
Scorpio-The worst of the lot. You are shrewd in business and cannot be trusted. You shall achieve the pinnacle of success because of your total lack of ethics. You are a perfect son-of-a-b!tch. Most scorpios are murdered
Sagitarius--You are optimistic and enthusiastic. You have a reckless tendency to rely on luck-since you have no talent. The majority of Sagitarius's are drunks. Nixon was a sagitarius. You are indeed a worthless piece of sh!t.
Capricorn--You are conservative and are afraid of taking risks. you are basically a chicken sh!t. There has never been a Capricorn of any importance, you should kill yourself now
(Score: 2) by looorg on Monday February 20 2017, @11:29PM
A picture of a black hole in space ... let me guess -- it's going to be fairly black?
(Score: 0) by Anonymous Coward on Tuesday February 21 2017, @12:49AM
They prefer the term afro-American.
(Score: 2) by looorg on Tuesday February 21 2017, @01:41AM
Afro-American-holes? I don't think Hawking discovered those yet.
(Score: 0) by Anonymous Coward on Monday February 20 2017, @11:32PM
> Those hard drives will be flown ...
Too much data for the internet, eh? Tell me again, what is the data rate of a station wagon filled with backup tapes?
(at least that's the way I heard it first, but some of you may go back further...)
The current equivalent might be scores of FedEx packages.
(Score: 4, Informative) by zocalo on Monday February 20 2017, @11:54PM
Working out total storage requirements and using modules that can be shipped around means you only need one set of hard drives (hopefully a including some redundancy against failed/lost modules!) parcelled out to each location to record and do any initial clean-up/compression processing of the raw data. Those can then be shipped back at a reasonably leisurely pace (but *still* probably faster than using the 'net) to be reconnected back at a central facility where the combined data can then be processed. Planning has been years, observation time is going to be ten days, post-processing time is likely to be months, so a day or two in between for airfreight isn't exactly a major issue.
UNIX? They're not even circumcised! Savages!
(Score: 2) by JoeMerchant on Tuesday February 21 2017, @01:26AM
Terabyte drives in a FedEx box can definitely outperform ordinary broadband, even to the opposite side of the planet.
🌻🌻 [google.com]
(Score: 1, Funny) by Anonymous Coward on Tuesday February 21 2017, @12:47AM
(Score: 0) by Anonymous Coward on Tuesday February 21 2017, @01:33AM
Grapefruit is better than DVD, in few years people will ask "Whats a DVD?"
(Score: 0) by Anonymous Coward on Tuesday February 21 2017, @04:52AM
What's a grapefruit?
(Score: 2) by melikamp on Tuesday February 21 2017, @05:51AM
(Score: 0) by Anonymous Coward on Tuesday February 21 2017, @06:06AM
It is a grape that is also a fruit!
(Score: 2) by iWantToKeepAnon on Tuesday February 21 2017, @03:38AM
Couldn't come up with a good car analogy?
"Happy families are all alike; every unhappy family is unhappy in its own way." -- Anna Karenina by Leo Tolstoy
(Score: 2) by mhajicek on Tuesday February 21 2017, @05:25AM
Is that a 2mb laptop pr a 2tb laptop?
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 2) by Scruffy Beard 2 on Tuesday February 21 2017, @05:29AM
I assumed the worst: since the average laptop has a 1TB drive these days, the could have simply said:
10,000TB or 10PB.
(Score: 0) by Anonymous Coward on Tuesday February 21 2017, @11:01AM
Yeah, I remember a documentary some time in the eighties where they talked about the size of the human genome, telling how many PCs you'd need just to store it. Well, even back then it seemed ridiculous to be because, after all, you'd only need the hard disks to store it, instead of the complete PCs, and a hard disk takes much less space. Today, you could put it on a micro-SD card and still would have most of its storage space available for other data. Indeed, with decent compression I'd not be surprised if the genetic data of the complete biosphere would fit on a single card.
(Score: 2) by linkdude64 on Tuesday February 21 2017, @04:19PM
"I assumed the worst"
Good policy.