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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It Could be Possible to see Gravitational Wave Lenses

In February 2016, LIGO detected gravity waves for the first time. As this artist's illustration depicts, the gravitational waves were created by merging black holes. The third detection just announced was also created when two black holes merged. Credit: LIGO/A. Simonnet.

Gravitational-wave astronomy is very different from that of electromagnetic light. While gravitational waves are faint and difficult to detect, they also pass through matter with little effect. In essence, the material universe is transparent to gravitational waves. This makes gravitational wave astronomy a powerful tool when studying the universe. But it’s still in the early stages, and there is much to learn about how gravitational waves behave.

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Gaia Might Even be Able to Detect the Gravitational Wave Background of the Universe

Embry-Riddle researchers used data captured by the Gaia satellite (shown here in an artist’s impression) to determine the ages of stars. Credit: European Space Agency – D. Ducros, 2013

The Gaia spacecraft is an impressive feat of engineering. Its primary mission is to map the position and motion of more than a billion stars in our galaxy, creating the most comprehensive map of the Milky Way thus far. Gaia collects such a large amount of precision data that it can make discoveries well beyond its main mission. For example, by looking at the spectra of stars, astronomers can measure the mass of individual stars to within 25% accuracy. From the motion of stars, astronomers can measure the distribution of dark matter in the Milky Way. Gaia can also discover exoplanets when they pass in front of a star. But one of the more surprising uses is that Gaia could help us detect cosmic gravitational waves.

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A new Technique Could use Quasars to Directly Measure the Expansion Rate of the Universe

One of the biggest challenges to measuring the expansion of the universe is the fact that many of the methods we use are model-dependent. The most famous example is the use of distant supernovae, where we compare the standard brightness of a Type Ia supernova with their apparent brightness to find their distance. But knowing the standard brightness depends upon comparing them to the brightness of Cepheid variables which is in turn determined by measuring the distances of nearby stars via parallax. Every step of this cosmic distance ladder depends upon the step before it.

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You Thought Black Hole Event Horizons Looked Strange. Check out Binary Black Hole Event Horizons

One of the strangest predictions of general relativity is that gravity can deflect the path of light. The effect was first observed by Arthur Eddington in 1919. While the bending effect of the Sun is small, near a black hole light deflection can be significant. So significant that you need a powerful supercomputer to calculate how light will behave.

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Gaia Finds 12 Examples of Einstein Crosses; Galaxies Being Gravitationally Lensed so we see Them Repeated 4 Times

In 1915, Einstein put the finishing touches on his Theory of General Relativity (GR), a revolutionary new hypothesis that described gravity as a geometric property of space and time. This theory remains the accepted description of gravitation in modern physics and predicts that massive objects (like galaxies and galaxy clusters) bend the very fabric of spacetime.

As result, massive objects (like galaxies and galaxy clusters) can act as a lens that will deflect and magnify light coming from more distant objects. This effect is known as “gravitational lensing,” and can result in all kinds of visual phenomena – not the least of which is known as an “Einstein Cross.” Using data from the ESA’s Gaia Observatory, a team of researchers announced the discovery of 12 new Einstein Crosses.

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An Intermediate-Mass Black Hole Discovered Through the Gravitational Lensing of a Gamma-ray Burst

Black holes come in three sizes: small, medium, and large. Small black holes are of stellar mass. They form when a large star collapses at the end of its life. Large black holes lurk in the centers of galaxies and are millions or billions of solar masses. Middle-sized black holes are those between 100 to 100,000 solar masses. They are known as Intermediate Mass Black Holes (IMBHs), and they are the kind we least understand.

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Dark Energy Survey Finds Hundreds of New Gravitational Lenses

It’s relatively rare for a magical object from fantasy stories to have a analog in real life.  A truly functional crystal ball (or palantir) would be useful for everything from military operations to checking up on grandma. While nothing exists to be able to observe the mundanities of everyday life, there is something equivalent for extraordinarily far away galaxies: gravitational lenses.  Now a team led by Xiaosheng Huang from Lawrence Berkeley National Laboratory (LBNL) and several universities around the world have published a list of more than 1200 new gravitational lensing candidates.

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One of the Largest, Most Complete Einstein Rings Ever Seen. Astronomers Call it the “Molten Ring”

A very rare astronomical phenomenon has been in the headlines a lot recently, and for good reason.  It will be hundreds of years until we can see Jupiter and Saturn this close to one another again.  However, there are some even more “truly strange and very rare phenomena” that can currently be observed in our night sky.  The only problem is that in order to observe this phenomena, you’ll need access to Hubble.

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