Cosmology Archives

July 23, 2024July 23, 2024 by Mark Thompson

New Horizons Measures the Background Light of the Universe

The locations of the NCOB, DCAL, SCAL, and IPD fields are shown on the IRIS full-sky 100 µm map in Galactic coordinates.

Think about background radiation and most people immediately think of the cosmic background radiation and stories of pigeon excrement during its discovery. That’s for another day though. Turns out that the universe has several background radiations, such as infrared and even gravitational wave backgrounds. NASA’s New Horizons is far enough out of the Solar System now that it’s in the perfect place to measure the cosmic optical background (COB). Most of this light comes from the stars in galaxies, but astronomers have always wondered if there are other sources of light filling our night sky. New Horizons has an answer. No!

June 30, 2024June 30, 2024 by Carolyn Collins Petersen

Galaxies Filled With Old Stars Seen Shortly After the Big Bang

Astronomers used JWST to investigate three mysterious objects in the very early Universe. These little red dots contain extremely ancient stars and supermassive black holes. Courtesy JWST/Penn State University.

How can young galaxies in the early Universe have ancient stars? That’s the question a team of astronomers set out to answer using JWST as a probe. They first spotted the massive objects in 2022 and are still working to explain what these things are.

June 27, 2024June 27, 2024 by Evan Gough

Webb Sees Globular Clusters Forming in the Early Universe

The Cosmic Gems arc as observed by the JWST. The clusters have the attributes of gravitationally-bound proto-Globular Clusters. Credit: ESA/Webb, NASA & CSA, L. Bradley (STScI), A. Adamo (Stockholm University) and the Cosmic Spring collaboration.

Picture the Universe’s ancient beginnings. In the vast darkness, light was emitted from a particular galaxy only 460 million years after the Big Bang. On the way, the light was shifted into the infrared and magnified by a massive gravitational lens before finally reaching the James Webb Space Telescope.

The galaxy is called the Cosmic Gems arc, and it held some surprises for astronomers.

June 17, 2024June 17, 2024 by Andy Tomaswick

Baby Stars are Swarming Around the Galactic Center

The vicinity of Sagittarius A* (Sgr A*), the supermassive black hole at the Milky Way’s center, is hyperactive. Stars, gas, and dust zip around the black hole’s gravitational well at thousands of kilometers per hour. Previously, astronomers thought that only mature stars had been pulled into such rapid orbits. However, a new paper from the University of Cologne and elsewhere in Europe found that some relatively young stars are making the rounds rather than older ones, which raises some questions about the models predicting how stars form in these hyperactive regions.

June 17, 2024June 17, 2024 by Andy Tomaswick

Rotation Curves of Galaxies Stay Flat Indefinitely

In his classic book On the Structure of Scientific Revolutions, the philosopher Thomas Kuhn posited that, for a new scientific framework to take root, there has to be evidence that doesn’t sit well within the existing framework. For over a century now, Einstein’s theory of relativity and gravity has been the existing framework. However, cracks are starting to show, and a new paper from researchers at Case Western Reserve University added another one recently when they failed to find decreasing rotational energy in galaxies even millions of light years away from the galaxy’s center.

June 15, 2024June 15, 2024 by Matt Williams

New Simulation Explains how Supermassive Black Holes Grew so Quickly

Supermassive Black Hole Survey. Credit: ESA/XMM-Newton/PSU/F. Zou et al./N.Trehnl/The TNG Collaboration

One of the main scientific objectives of next-generation observatories (like the James Webb Space Telescope) has been to observe the first galaxies in the Universe – those that existed at Cosmic Dawn. This period is when the first stars, galaxies, and black holes in our Universe formed, roughly 50 million to 1 billion years after the Big Bang. By examining how these galaxies formed and evolved during the earliest cosmological periods, astronomers will have a complete picture of how the Universe has changed with time.

As addressed in previous articles, the results of Webb‘s most distant observations have turned up a few surprises. In addition to revealing that galaxies formed rapidly in the early Universe, astronomers also noticed these galaxies had particularly massive supermassive black holes (SMBH) at their centers. This was particularly confounding since, according to conventional models, these galaxies and black holes didn’t have enough time to form. In a recent study, a team led by Penn State astronomers has developed a model that could explain how SMBHs grew so quickly in the early Universe.

June 10, 2024June 10, 2024 by Evan Gough

If Gravity Can Exist Without Mass, That Could Explain Dark Matter

Researchers are making progress mapping dark matter, but they don't know what it is. This is a 3D density map of dark matter in the local universe, with the Milky Way marked by an X. Dots are galaxies, and the arrows indicate the directions of motion derived from the reconstructed gravitational potential of dark matter. Image Credit: Hong et al., doi: 10.3847/1538-4357/abf040.

Dark Matter is Nature’s poltergeist. We can see its effects, but we can’t see it, and we don’t know what it is. It’s as if Nature is playing tricks on us, hiding most of its mass and confounding our efforts to determine what it is.

June 5, 2024June 5, 2024 by Evan Gough

Primordial Black Holes Can Only Explain a Fraction of Dark Matter

This artist's illustration shows what primordial black holes might look like. In reality, the black holes would struggle to form accretion disks, as shown. Image Credit: NASA’s Goddard Space Flight Center

What is Dark Matter? That question is prominent in discussions about the nature of the Universe. There are many proposed explanations for dark matter, both within the Standard Model and outside of it.

One proposed component of dark matter is primordial black holes, created in the early Universe without a collapsing star as a progenitor.

June 5, 2024June 5, 2024 by Evan Gough

The JWST is Re-Writing Astronomy Textbooks

The first JWST Deep Field Image, showing large distant galaxies. The telescope's observations are revealing the previously unseen and are forcing a re-write of astronomy textbooks. Image Credit: NASA, ESA, CSA, STScI

When the James Webb Space Telescope was launched at the end of 2021, we expected stunning images and illuminating scientific results. So far, the powerful space telescope has lived up to our expectations. The JWST has shown us things about the early Universe we never anticipated.

Some of those results are forcing a rewrite of astronomy textbooks.

May 13, 2024May 13, 2024 by Andy Tomaswick

Some Clever Ways to Search for Primordial Black Holes

Primordial Black Holes (PBHs) have recently received much attention in the physics community. One of the primary reasons is the potential link to dark matter. In effect, if PBHs can be proven to exist, there’s a very good chance that they are what dark matter, the invisible thing that makes up 85% of the universe’s mass, is made of. If proven, that would surely be a Nobel-level discovery in astrophysics.