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2019年1月25日星期五

來自大型黑洞的射電幾乎直指地球

來自大型黑洞的射電幾乎直指地球
Radio Jet from Massive Black Hole is Pointed Almost Directly at Earth

“This may indicate that the radio emission is produced in a disk of infalling gas rather than by a radio jet. However, that would make Sgr A* an exception compared to other radio-emitting black holes. The alternative could be that the radio jet is pointing almost directly at us.”
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This can’t be good news. Astronomers using a new array of telescopes for the first time managed to get a really good look at the supermassive black hole at the center of our galaxy and discovered that it has its radio jet pointed almost directly at planet Earth. Why? A better question might be “WTF does this mean and shouldn’t we be wearing foil while reading this?”

In a press release from the Max Planck Institute for Radio Astronomy, which participated in this project, Sara Issaoun, a graduate student at the Radboud University Nijmegen in the Netherlands and led author of the study published in the Astrophysical Journal, describes what she noticed when reviewing data collected by the worldwide array of telescopes, including the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, while pointed at the formerly foggy center-of-the-Milky-Way black hole known as Sagittarius A* (Sgr A*). It’s “formerly foggy” because the team used a technique called very long baseline interferometry (VLBI) which allowed them to effectively combine dozens of telescopes (there are 66 in ALMA alone) into one giant virtual telescope the size of the Earth and peer through the fog.
“Even though scattering blurs and distorts the image of Sgr A*, the incredible resolution of these observations allowed us to pin down the exact properties of the scattering. We could then remove most of the effects from scattering and begin to see what things look like near the black hole.”
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Michael Johnson of the Harvard-Smithsonian Center for Astrophysics developed the technique used to remove the scattering — an effect caused by density irregularities in the ionized material along the line of sight between Sgr A* and the Earth. Once the team got a clear view of Sgr A*, they saw that the radio jet spewing material and strong radio waves from the black hole at close to the speed of light was coming from a spot so tiny that the only way it could possibly be seen on Earth is if it was pointed directly or almost directly at us. (See the simulated images with scattering removed here.)


Are we all gonna die? Well, yes … but not from the radio jet pointed at us by the evil Sgr A* black hole. It’s 25,640 light years away, so it’s not going to hurt even if you stare directly at it through the world’s larges telescope without proper eyeshades. However, researchers like Michael Johnson are absolutely giddy over the possibilities.
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“If ALMA has the same success in joining the Event Horizon Telescope at even higher frequencies, then these new results show that interstellar scattering will not stop us from peering all the way down to the event horizon of the black hole.”
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Will they see through the wormhole into a far corner of the universe? Into another dimension? Or will they see another group of researchers from the future peering back at them?

Will those future researchers be pointing and laughing?


https://mysteriousuniverse.org/2019/01/radio-jet-from-massive-black-hole-is-pointed-almost-directly-at-earth/


來自銀河黑洞的射電可能直指地球
Radio jets from the Milky Way’s black hole could be pointing right at Earth

By blocking out scattered light, astronomers were able to study our central black hole's powerful radio jet — which might be looking right at us


http://astronomy.com/news/2019/01/radio-jets-from-the-milky-ways-black-hole-could-be-pointing-right-at-earth







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