Cosmology Archives

August 4, 2020 by Brian Koberlein

The Universe is the Same, Everywhere We Look. Even More than Cosmologists Predicted

Several superclusters revealed by the 2dF Galaxy Redshift Survey. This contains the structure known as the "Sloan Great Wall". Courtesy 2dF Galaxy Redshift Survey.

No matter which direction you look in the Universe, the view is basically the same if you look far enough. Our local neighborhood is populated with bright nebulae, star clusters, and dark clouds of gas and dust. There are more stars toward the center of the Milky Way than there are in other directions. But across millions, and billions, of light-years, galaxies cluster evenly in all directions, and everything starts to look the same. In astronomy, we say the Universe is homogeneous and isotropic. Put another way, the Universe is smooth.

August 3, 2020 by Brian Koberlein

How Loop Quantum Gravity Could Match Anomalies in the CMB with Large Structures in the Modern Universe

Map of the cosmic microwave background (CMB) sky produced by the Planck satellite. The Cold Spot is shown in the inset, with coordinates and the temperature difference in the scale at the bottom. Credit: ESA/Durham University.

Our universe is best described by the LCDM model. That is an expanding universe filled with dark energy (Lambda), and dense clumps of cold dark matter (CDM). It is also sprinkled with regular matter that makes up planets, stars, and us, but that only makes up about 4% of the cosmos. While we don’t know what dark matter and dark energy are, we know how they behave, so the ?CDM model works exceptionally well. There’s just one small problem.

July 27, 2020July 27, 2020 by Matt Williams

According to Globular Clusters, the Universe is 13.35 Billion Years Old

This dazzling image shows the globular cluster Messier 69, or M 69 for short, as viewed through the NASA/ESA Hubble Space Telescope. Globular clusters are dense collections of old stars. In this picture, foreground stars look big and golden when set against the backdrop of the thousands of white, silvery stars that make up M 69. Another aspect of M 69 lends itself to the bejewelled metaphor: As globular clusters go, M 69 is one of the most metal-rich on record. In astronomy, the term “metal” has a specialised meaning: it refers to any element heavier than the two most common elements in our Universe, hydrogen and helium. The nuclear fusion that powers stars created all of the metallic elements in nature, from the calcium in our bones to the carbon in diamonds. Successive generations of stars have built up the metallic abundances we see today. Because the stars in globular clusters are ancient, their metallic abundances are much lower than more recently formed stars, such as the Sun. Studying the makeup of stars in globular clusters like M 69 has helped astronomers trace back the evolution of the cosmos. M 69 is located 29 700 light-years away in the constellation Sagittarius (the Archer). The famed French comet hunter Charles Messier added M 69 to his catalogue in 1780. It is also known as NGC 6637. The image is a combination of exposures taken in visible and near-infrared light by Hubble’s Advanced Camera for Surveys, and covers a field of view of approximately 3.4 by 3.4 arcminutes.

It is a widely-accepted theory today that when the first stars formed in our Universe (ca. over 13 billion years ago), they quickly came together to form globular clusters. These clusters then coalesced to others to form the first galaxies, which have been growing through mergers and evolving ever since. For this reason, astronomers have long-suspected that the oldest stars in the Universe are to be found in globular clusters.

The study of stars in these clusters is therefore a means of determining the age of the Universe, which is still subject to some guesswork. In this vein, an international team of astronomers and cosmologists recently conducted a study of globular clusters in order to infer the age of the Universe. Their results indicate that the Universe is about 13.35 billion years old, a result that could help astronomers learn more about the expansion of the cosmos.

July 27, 2020July 27, 2020 by Matthew Cimone

Take a Flight Through the Most Detailed 3D Map of the Universe Ever Made

The most detailed map of the universe ever made

Once I accidentally took a photo of one of the most important stars in the Universe…

Andromeda Galaxy imaged at the SFU Trotter Observatory processed by Matthew Cimone

That star highlighted in the photo is called M31_V1 and resides in the Andromeda Galaxy. The Andromeda – AKA M31- is the closest galaxy to our own Milky Way. But before it was known as a galaxy, it was called the Andromeda Nebula. Before this particular star in Andromeda was studied by Edwin Hubble, namesake of the Hubble Space Telescope, we didn’t actually know if other galaxies even existed. Think about that! As recently as a hundred years ago, we thought the Milky Way might be the ENTIRE Universe. Even then…that’s pretty big. The Milky Way is on the order of 150,000 light years across. A light year is about 10 TRILLION kilometers so even at the speed of light it would take nearly the same length of time to cross the Milky Way as humans have existed on planet Earth. M31_V1 changed all that.

July 14, 2020July 14, 2020 by Evan Gough

Astronomers Have Mapped Out an Enormous Structure in the Universe Called the South Pole Wall

A projection of the South Pole Wall in celestial coordinates. Image Credit: Pomarède et al, 2020.

Galaxies aren’t spread evenly throughout space. They exist in groups, clusters, and superclusters. Our own Milky Way galaxy exists in an impossibly vast structure called the Laniakea supercluster. Laniakea was defined in 2014, and it contains over 100,000 galaxies.

Now a team of astronomers have discovered another immense feature beyond Laniakea, called the South Pole Wall.

July 9, 2020July 10, 2020 by Matt Williams

A Giant Galaxy Seen Lighting Up the Universe Shortly After the Big Bang

An illustration of cosmic expansion. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab

About 370,000 years after the Big Bang, the Universe experienced a period that cosmologists refer to as the “Cosmic Dark Ages.” During this period, the Universe was obscured by pervasive neutral gas that obscured all visible light, making it invisible to astronomers. As the first stars and galaxies formed over the next few hundred millions of years, the radiation they emitted ionized this plasma, making the Universe transparent.

One of the biggest cosmological mysteries right now is when “cosmic reionization” began. To find out, astronomers have been looking deeper into the cosmos (and farther back in time) to spot the first visible galaxies. Thanks to new research by a team of astronomers from University College London (UCL), a luminous galaxy has been observed that was reionizing the intergalactic medium 13 billion years ago.

June 17, 2020June 17, 2020 by Matt Williams

Searching for the End of the Universe’s “Dark Age”

A ‘radio colour’ view of the sky above the Murchison Widefield Array radio telescope, part of the International Centre for Radio Astronomy Research (ICRAC). Credit: Radio image by Natasha Hurley-Walker (ICRAR/Curtin) and the GLEAM Team. MWA tile and landscape Credit: ICRAR/Dr John Goldsmith/Celestial Visions

According to the most widely accepted cosmological theories, the first stars in the Universe formed a few hundred million years after the Big Bang. Unfortunately, astronomers have been unable to “see” them since their emergence coincided during the cosmological period known as the “Dark Ages.” During this period, which ended about 13 billion years ago, clouds of gas filled the Universe that obscured visible and infrared light.

However, astronomers have learned that light from this era can be detected as faint radio signals. It’s for this reason that radio telescopes like the Murchison Widefield Array (MWA) were built. Using data obtained by this array last year, an international team of researchers is scouring the most precise radio data to date from the early Universe in an attempt to see exactly when the cosmic “Dark Ages” ended.

June 15, 2020June 15, 2020 by Brian Koberlein

Evidence is Building that the Standard Model of the Expansion of the Universe Needs some new Ideas

Artist's conception illustrating a disk of water-bearing gas orbiting the supermassive black hole at the core of a distant galaxy. Credit: Sophia Dagnello, NRAO/AUI/NSF

Once again a new measurement of cosmic expansion is encouraging astronomers to reconsider the standard cosmological model. The problem is the Hubble constant and dark energy. While we have a broad understanding of dark energy, pinning down the value of the Hubble constant has been a problem, since different measurements keep getting different results. Now a new study has been published which further complicates things.

June 6, 2020June 6, 2020 by Evan Gough

A New Telescope is Ready to Start Searching for Answers to Explain Dark Energy

Back in 2015, construction began on a new telescope called the Dark Energy Spectroscopic Instrument (DESI). Later this year, it will begin its five-year mission. Its goal? To create a 3D map of the Universe with unprecedented detail, showing the distribution of matter.

That detailed map will allow astronomers to investigate important aspects of cosmology, including dark energy and its role in the expansion of the Universe.

June 5, 2020June 5, 2020 by Brian Koberlein

A New Test Confirms Dark Energy and the Expansion of the Universe

A map of galaxy clustering in the universe. Credit: Seshadri Nadathur

In the standard model of cosmology, dark energy fills the universe. It causes the universe to expand at an ever-increasing rate, and it makes up more than 70% of the cosmos. But there’s a problem. When we measure the rate of cosmic expansion in different ways, we get results that disagree with each other.