Astronomers Measure the Signal of Dark Matter From 12 Billion Years ago

Visualization of how dark matter lenses distant light. Credit: Reiko Matsushita (Nagoya University)

Although the particles of dark matter continue to allude us, astronomers continue to find evidence of it. In a recent study, they have seen its effect from the edge of visible space, when the universe was just 1.5 billion years old.

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A Mission to Reach the Solar Gravitational Lens in 30 Years

NASA’s Institute for Advanced Concepts is famous for supporting outlandish ideas in the astronomy and space exploration fields. Since being re-established in 2011, the institute has supported a wide variety of projects as part of its three-phase program. However, so far, only three projects have gone on to receive Phase III funding. And one of those just released a white paper describing a mission to get a telescope that could effectively see biosignatures on nearby exoplanets by utilizing the gravitational lens of our own Sun.

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Using the Sun as a Gravitational Lens Would Let Us See Exoplanets With Incredible Resolution

An artist view of countless exoplanets. Credit: NASA/JPL-Caltech

Have you ever seen wispy arcs and rings in astronomical images taken by the Hubble Space Telescope and other observatories? These unusual features are caused by a quirk of nature called gravitational lensing, which occurs when light from a distant object is distorted by a closer massive object along the same line of sight. This distortion effectively creates a giant lens which magnifies the background light source, allowing astronomers to observe objects embedded within those lens-created arcs and rings that are otherwise be too far and too dim to see.

A group of researchers are working on plans to build a spacecraft that could apply this quirk by using our Sun as a gravitational lens. Their goal is to see distant exoplanets orbiting other stars, and to image an Earth-like exoplanet, seeing it in exquisite detail, at a resolution even better than the well-known Apollo 8 Earthrise photo.

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We can Probably Find Supernovae Enhanced by Gravitational Lensing, We Just Need to Look

Using the microlensing metthod, a team of astrophysicists have found the first extra-galactic planets! Credit: NASA/Tim Pyle

Gravitational lensing provides an opportunity to see supernovae and other transients much farther than we normally can. A new research proposal outlines a plan to use a comprehensive catalog of strong gravitational lenses to capture these rare events at extreme distances.

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A New Record! Hubble Detects an Individual Star From a Time When the Universe Was Less Than a Billion Years Old

Gravitationally lensed image of Earendel
The star nicknamed Earendel, indicated by the white arrow, is positioned along a ripple in spacetime toat gives the image extreme magnification. Credit: NASA / ESA / Brian Welch (JHU) / Dan Coe (STScI) / Alyssa Pagan (STScI)

A star that sounds as if it came from “The Lord of the Rings” now marks one of the Hubble Space Telescope’s farthest frontiers: The fuzzy point of light, known as Earendel, has been dated to a mere 900 million years after the Big Bang and appears to represent the farthest-out individual star seen to date.

Based on its redshift value of 6.2, Earendel’s light has taken 12.9 billion years to reach Earth, astronomers report in this week’s issue of the journal Nature. That distance mark outshines Hubble’s previous record-holder for a single star, which registered a redshift of 1.5 and is thought to have existed when the universe was 4 billion years old.

The newly reported record comes with caveats. First of all, we’re talking here about a single star rather than star clusters or galaxies. Hubble has seen agglomerations of stars that go back farther in time.

“Normally at these distances, entire galaxies look like small smudges, with the light from millions of stars blending together,” lead author Brian Welch, an astronomer at Johns Hopkins University, said today in a news release. “The galaxy hosting this star has been magnified and distorted by gravitational lensing into a long crescent that we named the Sunrise Arc.”

A close look at the arc turned up several bright spots, but the characteristics of the light coming from Earendel pointed to a high redshift, which translates into extreme distance. The higher the redshift, the faster the source of the light is receding from us in an ever-more-quickly expanding universe.

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What is Einstein’s Theory of Relativity?

Einstein Lecturing
Albert Einstein during a lecture in Vienna in 1921. Credit: National Library of Austria/F Schmutzer/Public Domain

In the history of science and physics, several scholars, theories, and equations have become household names. In terms of scientists, notable examples include Pythagoras, Aristotle, Galileo, Newton, Planck, and Hawking. In terms of theories, there’s Archimede’s “Eureka,” Newton’s Apple (Universal Gravitation), and Schrodinger’s Cat (quantum mechanics). But the most famous and renowned is arguably Albert Einstein, Relativity, and the famous equation, E=mc2. In fact, Relativity may be the best-known scientific concept that few people truly understand.

For example, Einstein’s Theory of Relativity comes in two parts: the Special Theory of Relativity (SR and the General Theory of Relativity (GR). And the term “Relativity” itself goes back to Galileo Galilee and his explanation for why motion and velocity are relative to the observer. As you can probably tell, explaining how Einstein’s groundbreaking theory works require a deep dive into the history of physics, some advanced concepts, and how it all came together for one of the greatest minds of all time!

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If Alien Probes are Already in the Solar System, Maybe we Could Detect Them Calling Home

Artist's impression of the Milky Way Galaxy. Credit: ESO

It’s been seventy years since physicist Enrico Fermi asked his famous question: “Where is everybody?” And yet, the tyranny of the Fermi Paradox is still with us and will continue to be until definitive evidence of Extraterrestrial Intelligence (ETI) is found. In the meantime, scientists are forced to speculate as to why we haven’t found any yet and (more importantly) what we should be looking for. By focusing our search efforts, it is hoped that we may finally determine that we are not alone in the Universe.

In a recent study, two researchers from the University of Liège and the Massachusetts Institute of Technology (MIT) recommended that we look for evidence of transmissions from our Solar System. Based on the theory that ETIs exist and have already established a communications network in our galaxy, the team identified Wolf 359 as the best place to look for possible interstellar communications from an alien probe.

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Advanced Civilizations Could use Their Stars to Communicate (and as Telescopes)

A schematic of a on-axis stellar relay transmission system, opening angles, distances, and sizes not to scale. The initial unfocused transmission beam may even have an annular pattern to prevent flux from being lost to the disk of the Sun.A reversed arrangement can be used to receive signals from a distant star by focusing rays onto the spacecraft. c. Kerby and Wright 2021

A Long Distance Call

E.T. managed to call home with a Speak and Spell, buzzsaw blade, and an umbrella. The reality of interstellar communication is a bit more complicated. Space is really, really big. The power needed to transmit a signal across the void is huge. However, rather than using super high power transmitters, recent research by Stephen Kerby and Jason T. Wright shows that we could make use of a natural signal gain boost built into solar systems – the gravitational lensing of a solar system’s star. Networking a series of stars as nodes could get signals across vast tracts of the Milky Way. And we may be able to detect if our Sun is already part of an alien galactic communication network.

Distant Satellites at the far reaches of the solar system may use the natural focusing of light by the Sun to communicate across space – c. NASA
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What a Perfect Gravitational Lens

Clustered at the centre of this image are six luminous spots of light, four of them forming a circle around a central pair. Credit: ESA/Hubble & NASA, Acknowledgment: J. Schmidt

A stunning new photograph from the Hubble Space Telescope shows a nearly perfect Einstein Ring, an effect caused by gravitational lensing. This is one of the most complete Einstein Rings ever seen.

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Astronomers saw the Same Supernova Three Times Thanks to Gravitational Lensing. And in Twenty Years They Think They’ll see it one More Time

It is hard for humans to wrap their heads around the fact that there are galaxies so far away that the light coming from them can be warped in a way that they actually experience a type of time delay.  But that is exactly what is happening with extreme forms of gravitational lensing, such as those that give us the beautiful images of Einstein rings.  In fact, the time dilation around some of these galaxies can be so extreme that the light from a single event, such as a supernova, can actually show up on Earth at dramatically different times.  That is exactly what a team led by Dr. Steven Rodney at the University of South Carolina and Dr. Gabriel Brammer of the University of Copenhagen has found. Except three copies of this supernova have already appeared – and the team thinks it will show up again one more time, 20 years from now.

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