Brian Koberlein, Author at Universe Today

November 25, 2023November 25, 2023 by Brian Koberlein

Dark Matter Could Help Solve the Final Parsec Problem of Black Holes

This image is from a simulation of two merging black holes. The upcoming Vera Rubin Observatory should be able to detect binary black holes before they merge. But the vexing problem of false positives needs a solution. Image Credit: Simulating eXtreme Spacetimes (SXS) Project

When galaxies collide, their supermassive black holes enter into a gravitational dance, gradually orbiting each other ever closer until eventually…merging. We know they merge because we see the gravitational beasts that result, and we have detected the gravitational waves they emit as they inspiral. But the details of their final consummation remain a mystery. Now a new paper suggests part of that mystery can be solved with a bit of dark matter.

November 21, 2023November 21, 2023 by Brian Koberlein

CERN Has Joined the Search for Dark Photons

Illustration of two types of long-lived particles decaying into a pair of muons. Credit: CMS/CERN

In the search for dark matter particles, there are two main approaches. The first is to look for particles that happen to decay naturally as they pass by. This typically involves neutrino observatories such as IceCube where a dark matter particle particle colliding with a nuclei might trigger a faint burst of light. So far this has turned up nothing. The second approach is to slam particles together in a particle accelerator. This approach has also failed to find dark matter particles, but there have been enough interesting hints that CERN is having a go. Their latest run is looking for what are known as dark photons.

November 18, 2023November 18, 2023 by Brian Koberlein

The Universe Can't Hide Behind the Zone of Avoidance Any Longer

The central region of the Milky Way, also known as the Zone of Avoidance. Credit: ESO/S. Brunier

Our view of the cosmos is always limited by the fact we are located within a galaxy filled with interstellar gas and dust. This is most dramatically seen in the central region of the Milky Way, which is filled with so much dust that it is sometimes referred to as the Zone of Avoidance. Within this zone, our observations of extragalactic objects are limited, but that is starting to change.

November 13, 2023November 13, 2023 by Brian Koberlein

The Oort Cloud Might be More Active Than We Thought

The paths of hyperbolic-orbit comets. Credit: NAOJ

Every now and then a comet or asteroid comes to our solar system from interstellar space. We have observed two interstellar objects in recent years, Oumuamua in 2017, and Borisov in 2019. One would assume then that in the past at least some interstellar objects have struck Earth. But we’ve never found an interstellar meteorite. A new study argues that this is because the Oort cloud is much more active than we thought.

November 11, 2023November 11, 2023 by Brian Koberlein

If You Account for the Laniakea Supercluster, The Hubble Tension Might Be Even Larger

Illustration of the Laniakea Supercluster. Credit: Andrew Z. Colvin

One of the great unsolved mysteries of cosmology is known as the Hubble tension. It stems from our inability to pin down the precise rate of cosmic expansion. There are several ways to calculate this expansion, from observing distant supernovae to measuring the Doppler shift of maser light near supermassive black holes, and they all give slightly different results. Maybe we don’t fully understand the structure of the Universe, or maybe our view of the heavens is biased given that we are located deep within a galactic supercluster. As a new study shows, the bias problem is even worse than we thought.

November 10, 2023November 10, 2023 by Brian Koberlein

If We Could Find Them, Primordial Black Holes Would Explain a Lot About the Universe

Artist view of small black holes in the accretion disk of a supermassive black hole. Credit: Caltech/R. Hurt (IPAC)

There are three known types of black holes in the Universe: supermassive black holes that lurk in the centers of galaxies, stellar-mass black holes that are the remnants of massive stars, and intermediate-mass black holes that can be found in dense clusters of stars. But there is a fourth, hypothetical type of black hole known as primordial black holes (PBHs). If they exist, they could solve a few cosmological mysteries.

November 2, 2023November 2, 2023 by Brian Koberlein

A Dwarf Galaxy That's Almost All Dark Matter

A simulation of dark matter clusters around the Milky Way. Credit: J. Tumlinson (STScI)

Dark matter is a powerful cosmological model, but it isn’t without its problems. In addition to our inability to detect dark matter particles, one issue deals with the number of dwarf galaxies surrounding the Milky Way. According to the most popular models of dark matter, galaxies should be surrounded by clumps of dark matter within their dark matter halo. Since regular matter tends to gather around dark matter, that means the Milky Way should be surrounded by dwarf galaxies. While there are several known dwarf galaxies near the Milky Way, there are fewer than predicted by dark matter simulations. But perhaps there are many more dwarf galaxies we just haven’t noticed because they are made mostly of dark matter.

October 31, 2023October 31, 2023 by Brian Koberlein

Satellites Make up to 80,000 Flashing Glints Per Hour. It's a Big Problem for Astronomers

Starlink trails cut through this image of the star Albiero, in the Cygnus constellation. Credit: Rafael Schmall

Large-scale sky surveys are set to revolutionize astronomy. Observatories such as Vera Rubin and others will allow astronomers to observe how the sky changes on the scale of days, not weeks or months. They will be able to capture transient events such as supernovae in their earliest stages and will discover near-Earth asteroids we have missed in the past. At the same time, the rise of satellite constellations such as Starlink threatens to overwhelm these surveys with light pollution and could threaten their ability to succeed.

October 30, 2023October 30, 2023 by Brian Koberlein

Want to Find Life? Compare a Planet to its Neighbors

Earth compared to the exoplanet Kepler-186f. Credit: NASA's Goddard Space Flight Center

With thousands of known exoplanets and tens of thousands likely to be discovered in the coming decades, it could be only a matter of time before we discover a planet with life. The trick is proving it. So far the focus has been on observing the atmospheric composition of exoplanets, looking for molecular biosignatures that would indicate the presence of life. But this can be difficult since many of the molecules produced by life on Earth could also be produced by geologic processes. A new study argues that a better approach would be to compare the atmospheric composition of a potentially habitable world with those of other planets in the star system.

October 29, 2023October 29, 2023 by Brian Koberlein

An Asteroid Came Uncomfortably Close to Earth in July. Could we Have Stopped it?

Illustration of the Pulverize It method. Credit: Cohen & Cohen - UCSB

In July of this year, an asteroid roughly 30 to 60 meters across passed Earth to within one-quarter of the distance to the Moon. It posed no threat to our world, but if it had struck Earth it would have created a blast three times greater than the 2013 Chelyabinsk impact. And we only noticed it two days after it passed. It’s a good example of how sizable asteroids still miss detection. Not ones large enough to threaten our extinction, but large enough to threaten millions of lives. If a similar asteroid was detected just days before impact, could we stop it? That’s the question raised by a recent study in the arXiv.