galactic evolution Archives

January 31, 2024January 31, 2024 by Brian Koberlein

Even Early Galaxies Grew Hand-in-Hand With Their Supermassive Black Holes

An artist’s impression of a quasar. Credit: NASA / ESA / J. Olmsted, STScI

Within almost every galaxy there is a supermassive black hole. This by itself implies some kind of formative connection between the two. We have also observed how gas and dust within a galaxy can drive the growth of galactic black holes, and how the dynamics of black holes can both drive star formation or hinder it depending on how active a black hole is. But one area where astronomers still have little information is how galaxies and their black holes interacted in the early Universe. Did black holes drive the formation of galaxies, or did early galaxies fuel the growth of black holes? A recent study suggests the two evolved hand in hand.

January 24, 2024January 24, 2024 by Brian Koberlein

Webb Sees Dozens Of Young Quasars in the First Billion Years of the Universe

Artist's impression of blue quasar in the early universe. Credit: S. Munro / CC BY 4.0

Within almost every galaxy is a supermassive black hole. Millions, sometimes billions of solar masses locked within an event horizon of space and time. They can power luminous quasars, drive star formation, and change the evolution of a galaxy. Because of their size and abundance, supermassive black holes must have formed early in cosmic history. But how early is still an unanswered question. It’s a focus of a recent study on the arXiv.

January 15, 2024January 15, 2024 by Brian Koberlein

Gigantic Galaxy Clusters Found Just Before They're Awash in Star Formation

This panchromatic view of galaxy cluster MACS0416 was created by combining infrared observations from the NASA/ESA/CSA James Webb Space Telescope with visible-light data from the NASA/ESA Hubble Space Telescope. Credit: NASA/ESA/CSA/STScI

One of the central factors in the evolution of galaxies is the rate at which stars form. Some galaxies are in a period of active star formation, while others have very little new stars. Very broadly, it’s thought that younger galaxies enter a period of rapid star formation before leveling off to become a mature galaxy. But a new study finds some interesting things about just when and why stars form.

December 29, 2023December 29, 2023 by Brian Koberlein

The Early Universe Was Surprisingly Filled With Spiral Galaxies

The bluish-white spiral galaxy NGC 1376 hangs delicately in the cold vacuum of space. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

If we could travel far beyond our galaxy, and look back upon the Milky Way, it would be a glorious sight. Luminous spirals stretching from a central core, with dust and nebulae scattered along the spiral edges. When you think about a galaxy, you probably imagine a spiral galaxy like the Milky Way, but spirals make up only about 60% of the galaxies we see. That’s because spiral galaxies only form when smaller galaxies collide and merge over time. Or so we thought, as a new study suggests that isn’t the case.

November 6, 2023November 9, 2023 by Matt Williams

Supermassive Black Holes Shut Down Star Formation During Cosmic Noon

Artist’s impression of a quasar. These all have supermassive black holes at their hearts. Credit: NOIRLab/NSF/AURA/J. da Silva

Since it became operational almost two years ago, the James Webb Space Telescope (JWST) has produced countless breathtaking images of the Universe and enabled fresh insights into how it evolved. In particular, the telescope’s instruments are optimized for studying the cosmological epoch known as Cosmic Dawn, ca. 50 million to one billion years after the Big Bang when the first stars, black holes, and galaxies in the Universe formed. However, astronomers are also getting a better look at the epoch that followed, Cosmic Noon, which lasted from 2 to 3 billion years after the Big Bang.

During this time, the first galaxies grew considerably, most stars in the Universe formed, and many galaxies with supermassive black holes (SMBHs) at their centers became incredibly luminous quasars. Scientists have been eager to get a better look at galaxies dated to this period so they can see how SMBHs affected star formation in young galaxies. Using near-infrared data obtained by Webb, an international team of astronomers made detailed observations of over 100 galaxies as they appeared 2 to 4 billion years after the Big Bang, coinciding with Cosmic Noon.

September 19, 2023September 19, 2023 by Brian Koberlein

Polar Ring Galaxies Are Bizarre and Rare. Astronomers Just Found Two More

A galaxy with a polar ring of hydrogen gas, known as a polar ring galaxy. Credit: Jayanne English, Nathan Deg & WALLABY Survey, CSIRO/ASKAP, NAOJ/Subaru Telescope

Galaxies come in a range of shapes, from elegant spirals to egg-shaped ellipticals. We often categorize galaxies by their shape, which was traditionally done based on what we could observe in the visual spectrum. But as we expanded astronomy into radio, infrared, ultraviolet, and x-ray light, learned that often galaxies have structures invisible to our eyes. Take, for example, an odd type of galaxy known as polar ring galaxies (PRGs).

September 17, 2023September 17, 2023 by Brian Koberlein

The Milky Way's Disk is Warped. Is That Because our Dark Matter Halo is Tilted?

Illustration of the Milky Way's warped shape. Credit: ESA/Stefan Payne-Wardenaar

It’s difficult to determine the shape of our galaxy. So difficult that only in the last century did we learn that the Milky Way is just one galaxy among billions. So it’s not surprising that despite all our modern telescopes and spacecraft we are still mapping the shape of our galaxy. And one of the more interesting discoveries is that the Milky Way is warped. One explanation for this is that our galaxy has undergone collisions, but a new study argues that it’s caused by dark matter.

August 27, 2023August 27, 2023 by Brian Koberlein

The Early Universe Should Be Awash in Active Galaxies, but JWST Isn't Finding Them

Artist view of an active black hole in the early universe. Credit: Boston University/Cosmovision

For decades the most distant objects we could see were quasars. We now know they are powerful active black holes. Active galactic nuclei so distant that they resemble star-like points of light. It tells us that supermassive black holes in the early Universe can be powerful monsters that drive the evolution of their galaxies. We had thought most early supermassive black holes went through such an active phase, but a new study suggests most supermassive black holes don’t.

August 9, 2023August 9, 2023 by Brian Koberlein

Could This Supermassive Black Hole Only Have Formed by Direct Collapse?

Artist's impression of an active supermassive black hole in the early universe. Credit: NOIRLab/NSF/AURA/J. da Silva

Nearly every galaxy in the universe contains a supermassive black hole. Even galaxies that are billions of light years away. This means supermassive black holes form early in the development of a galaxy. They are possibly even the gravitational seeds around which a galaxy forms. But astronomers are still unclear about just how these massive gravitational beasts first appeared.

June 28, 2023June 28, 2023 by Brian Koberlein

What Would the Milky Way Look Like From Afar?

A view of the Milky Way from Paranal, Chile. Credit: ESO/Y. Beletsky

Our understanding of galaxies is rooted in the fact that we can see so many of them. Some, such as the Andromeda and Pinwheel galaxies are fairly close, and others are more distant, but all of them give a unique view. Because of this, we can see how the various types of galaxies appear from different points of view, from face-on to edge-on and all angles in between. But there is one galaxy that’s a bit harder to map out, and that’s our own. Because we are in the galactic plane of the Milky Way, it can be difficult to create an accurate bird’s-eye view of our home galaxy. That’s where a recent study in Nature Astronomy comes in.