2020 February 19

Ask Ethan: How Does Very-Long-Baseline Interferometry Allow Us To Image A Black Hole?

“[The Event Horizon Telescope] uses VLBI. So what is interferometry and how was it employed by [the Event Horizon Telescope]? Seems like it was a key ingredient in producing the image of M87 but I have no idea how or why. Care to elucidate?”

If it were easy to network radio telescopes together across the world, we’d have produced an image of a black hole’s event horizon long ago. Well, it’s not easy at all, but it is at least possible! The technique that enabled it is known as VLBI: very-long-baseline interferometry. But there are some critical steps that aren’t very obvious that need to happen in order for this method to succeed. Remarkably, we learned how to do it and have successfully employed it, and the Event Horizon Telescope marks the first time we’ve ever been able to get an image with a telescope that’s effectively the size of planet Earth!

Come get the incredible science behind how the technique of VLBI enabled the Event Horizon Telescope to construct the first-ever image of a black hole’s event horizon!

When Dead Stars Collide!

Gravity has been making waves - literally.  Earlier this month, the Nobel Prize in Physics was awarded for the first direct detection of gravitational waves two years ago. But astronomers just announced another huge advance in the field of gravitational waves - for the first time, we’ve observed light and gravitational waves from the same source.

There was a pair of orbiting neutron stars in a galaxy (called NGC 4993). Neutron stars are the crushed leftover cores of massive stars (stars more than 8 times the mass of our sun) that long ago exploded as supernovas. There are many such pairs of binaries in this galaxy, and in all the galaxies we can see, but something special was about to happen to this particular pair.

Each time these neutron stars orbited, they would lose a teeny bit of gravitational energy to gravitational waves. Gravitational waves are disturbances in space-time - the very fabric of the universe - that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction, like this pair of orbiting neutron stars. However, the gravitational waves are very faint unless the neutron stars are very close and orbiting around each other very fast.

As luck would have it, the teeny energy loss caused the two neutron stars to get a teeny bit closer to each other and orbit a teeny bit faster.  After hundreds of millions of years, all those teeny bits added up, and the neutron stars were *very* close. So close that … BOOM! … they collided. And we witnessed it on Earth on August 17, 2017.  

Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

A couple of very cool things happened in that collision - and we expect they happen in all such neutron star collisions. Just before the neutron stars collided, the gravitational waves were strong enough and at just the right frequency that the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo could detect them. Just after the collision, those waves quickly faded out because there are no longer two things orbiting around each other!

LIGO is a ground-based detector waiting for gravitational waves to pass through its facilities on Earth. When it is active, it can detect them from almost anywhere in space.

The other thing that happened was what we call a gamma-ray burst. When they get very close, the neutron stars break apart and create a spectacular, but short, explosion. For a couple of seconds, our Fermi Gamma-ray Telescope saw gamma-rays from that explosion. Fermi’s Gamma-ray Burst Monitor is one of our eyes on the sky, looking out for such bursts of gamma-rays that scientists want to catch as soon as they’re happening.

And those gamma-rays came just 1.7 seconds after the gravitational wave signal. The galaxy this occurred in is 130 million light-years away, so the light and gravitational waves were traveling for 130 million years before we detected them.

After that initial burst of gamma-rays, the debris from the explosion continued to glow, fading as it expanded outward. Our Swift, Hubble, Chandra and Spitzer telescopes, along with a number of ground-based observers, were poised to look at this afterglow from the explosion in ultraviolet, optical, X-ray and infrared light. Such coordination between satellites is something that we’ve been doing with our international partners for decades, so we catch events like this one as quickly as possible and in as many wavelengths as possible.

Astronomers have thought that neutron star mergers were the cause of one type of gamma-ray burst - a short gamma-ray burst, like the one they observed on August 17. It wasn’t until we could combine the data from our satellites with the information from LIGO/Virgo that we could confirm this directly.

This event begins a new chapter in astronomy. For centuries, light was the only way we could learn about our universe. Now, we’ve opened up a whole new window into the study of neutron stars and black holes. This means we can see things we could not detect before.

The first LIGO detection was of a pair of merging black holes. Mergers like that may be happening as often as once a month across the universe, but they do not produce much light because there’s little to nothing left around the black hole to emit light. In that case, gravitational waves were the only way to detect the merger.

Image Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

The neutron star merger, though, has plenty of material to emit light. By combining different kinds of light with gravitational waves, we are learning how matter behaves in the most extreme environments. We are learning more about how the gravitational wave information fits with what we already know from light - and in the process we’re solving some long-standing mysteries!

Want to know more? Get more information HERE.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Must watch: ATB Future Memories (YouTube) https://youtu.be/QpLrjifXT1w https://www.instagram.com/p/BsPJ-vfH-Jr/?utm_source=ig_tumblr_share&igshid=zd40u6v4m410

Pathway to the Stars: Part 11, A New Day

"If we can love ourselves, we can then truly understand what it means to love others and be kind. There is potential that lies within you and everyone else. It is a potential that has always been meant to exist, to bring something greater to this reality of life."

~ Sky Taylor

This story is the eleventh of the Pathway to the Stars space opera series. Sky journeys with Erin Carter and Joanne Gallant, who are now Pathway's president and vice president. On their adventure, she shows them ways to heal the Earth as well as ourselves so we can promote a healthier form of longevity.

To Sky, there is much we can do to prevent future disasters, but sometimes solutions can involve something as simple as a nice walk. In this case, unfortunately, to help Joanne figure out a mystery weighing upon her.

Meanwhile, Eliza Williams and Yesha Alevtina work for the success of the Universal Party with efforts that will affect the United States, the World, and the mission to span the Cosmos!

LCCN: 2019919255

ISBN: 978-1-951321-15-4

eBook: https://smile.amazon.com/dp/B081XNYSL4

Paperback: https://smile.amazon.com/dp/1951321154

#ScienceFiction #Scifi #SpaceOpera #Fantasy #Author #MatthewJOpdyke #EarthFirst #Preservation #ConsiderationForAllLiving #Biology #Neuroscience #Biotechnology #AI #HBCI

I have really enjoyed my journey on becoming a #newly established #scifiauthor focusing on the #spaceopera genre. I enjoy my fan base and newly created friends and acquaintances. The universe awaits us all and I thank you for your support. V/r, @matthewopdyke #theoreticalphysics #physics #biotechnology #neuroscience #nanotechnology #spacetravel https://www.instagram.com/p/BuKIV3JggkU/?utm_source=ig_tumblr_share&igshid=959w55tkryri

The 4 Scientific Lessons Stephen Hawking Never Learned

“His work, his life, and his scientific contributions made him an inspiration to millions across the world, including to me. But the combination of his achievements and his affliction with ALS — combined with his meteoric fame — often made him immune to justified criticism. As a result, he spent decades making false, outdated, or misleading claims to the general population that permanently harmed the public understanding of science. He claimed to have solutions to problems that fell apart on a cursory glance; he proclaimed doomsday for humanity repeatedly with no evidence to back such claims up; he ignored the good work done by others in his own field. Despite his incredible successes in a number of arenas, there are some major scientific lessons he never learned. Here’s your chance to learn them now.”

Hawking’s contribution to physics, from the existence and meaning of singularities to properties of a black hole’s event horizon, entropy, temperature, and the radiation they generate were remarkable in the 1960s and 1970s. His popularizations of science were groundbreaking, too, exposing a general audience to a wide variety of wild and speculative ideas, igniting an interest in theoretical astrophysics in the minds of millions around the world. But as brilliant as Hawking was, there were a number of lessons about science and humanity that he never learned for himself, from the Big Bang and black holes to lessons about communicating speculative or unproven information as though they were facts. We have a tendency, when we turn people into heroes, to lionize their achievements and ignore their failings, but to do so cheats humanity out of recognizing all the facets of a complicated character.

Come learn, for yourself, the 4 scientific ideas that Stephen Hawking never managed to learn and incorporate while he was still alive.

Merry Christmas! I spent time with my dear and sweet Kim. Let's go #furtherthanbefore with our #pathwaytothestars where get to explore solutions to worldwide issues, directing malcontent toward a refocus of their energies to #longevity and other sciences of #physics #biotechnology and #neuroscience through entertainment that takes us on a #scifi #fantasy journey with #strongfemaleleads #strongmalerolemodels and a beautiful #spaceopera with plenty of #politicalsciencefiction in the mix. (at Gene Leahy Mall) https://www.instagram.com/p/BrUuZFvgda1/?utm_source=ig_tumblr_share&igshid=s26phhseo3jb

Thank you for your endless curiosity Dr. Hawking.

This Amazon/Author Hardcover Giveaway of A Cosmic Legacy: From Earth to the Stars is a compilation of all my publications contained within one text and part of a continuing story. Race to win, or simply buy it, and make this grand literary opus the favorite item in your library, next to your reading corner, on your nightstand, or in your living room, as you settle and read while the days go by.

Enjoy the story of several heroes who do as much as they can to heal the Earth, provide healing to those suffering most, and help humanity get out and into the Cosmos!

The Library of Congress Control Number (LCCN) is 2019911854, and the International Standard Book Number (ISBN) is 978-1-7333131-2-4, which is available on Amazon, Barnes & Noble and other stores online. Conduct a keyword search for the author, Matthew J Opdyke.

Hashtags #SpaceOpera #ScienceFiction #SciFi #Fantasy #Cerebral #Sophisticated #Books #eBooks #MatthewJOpdyke #mjopublications #physics #astronomy #biotech #neurotech #nanotech #spaceexploration #wellbeing #EarthFirst #physiology #neurology #longevity #CRISPR #sociopoliticalscifi #forEveryone

Pretty nice representation of Earth on through to the observable universe

~ wikimedia commons