Tag Archives: Dark Energy

NASA Space Place – The Loneliest Galaxy In The Universe

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in January, 2016.

By Dr. Ethan Siegel

2013february2_spaceplaceOur greatest, largest-scale surveys of the universe have given us an unprecedented view of cosmic structure extending for tens of billions of light years. With the combined effects of normal matter, dark matter, dark energy, neutrinos and radiation all affecting how matter clumps, collapses and separates over time, the great cosmic web we see is in tremendous agreement with our best theories: the Big Bang and General Relativity. Yet this understanding was only possible because of the pioneering work of Edwin Hubble, who identified a large number of galaxies outside of our own, correctly measured their distance (following the work of Vesto Slipher’s work measuring their redshifts), and discovered the expanding universe.

But what if the Milky Way weren’t located in one of the “strands” of the great cosmic web, where galaxies are plentiful and ubiquitous in many different directions? What if, instead, we were located in one of the great “voids” separating the vast majority of galaxies? It would’ve taken telescopes and imaging technology far more advanced than Hubble had at his disposal to even detect a single galaxy beyond our own, much less dozens, hundreds or millions, like we have today. While the nearest galaxies to us are only a few million light years distant, there are voids so large that a galaxy located at the center of one might not see another for a hundred times that distance.

While we’ve readily learned about our place in the universe from observing what’s around us, not everyone is as fortunate. In particular, the galaxy MCG+01-02-015 has not a single known galaxy around it for a hundred million light years in all directions. Were you to draw a sphere around the Milky Way with a radius of 100 million light years, we’d find hundreds of thousands of galaxies. But not MCG+01-02-015; it’s the loneliest galaxy ever discovered. Our Milky Way, like most galaxies, has been built up by mergers and accretions of many other galaxies over billions of years, having acquired stars and gas from a slew of our former neighbors. But an isolated galaxy like this one has only the matter it was born with to call its own.

Edwin Hubble made his universe-changing discovery using telescope technology from 1917, yet he would have found absolutely zero other galaxies at all were we situated at MCG+01-02-015’s location. The first visible galaxy wouldn’t have shown up until we had 1960s-level technology, and who knows if we’d have continued looking? If we were such a lonely galaxy, would we have given up the search, and concluded that our galaxy encompassed all of existence? Or would we have continued peering deeper into the void, eventually discovering our unusual location in a vast, expanding universe? For the inhabitants of the loneliest galaxy, we can only hope that they didn’t give up the search, and discovered the entire universe.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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Caption: ESA/Hubble & NASA and N. Gorin (STScI); Acknowledgement: Judy Schmidt, of the loneliest void galaxy in the known: MCG+01-02-015.

About NASA Space Place

With articles, activities, crafts, games, and lesson plans, NASA Space Place encourages everyone to get excited about science and technology. Visit spaceplace.nasa.gov (facebook|twitter) to explore space and Earth science!

NASA Space Place – The Heavyweight Champion Of The Cosmos

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in February, 2015.

By Dr. Ethan Siegel

2013february2_spaceplaceAs crazy as it once seemed, we once assumed that the Earth was the largest thing in all the universe. 2,500 years ago, the Greek philosopher Anaxagoras was ridiculed for suggesting that the Sun might be even larger than the Peloponnesus peninsula, about 16% of modern-day Greece. Today, we know that planets are dwarfed by stars, which themselves are bound together by the billions or even trillions into galaxies.

But gravitationally bound structures extend far beyond galaxies, which themselves can bind together into massive clusters across the cosmos. While dark energy may be driving most galaxy clusters apart from one another, preventing our local group from falling into the Virgo Cluster, for example, on occasion, huge galaxy clusters can merge, forming the largest gravitationally bound structures in the universe.

Take the “El Gordo” galaxy cluster, catalogued as ACT-CL J0102-4915. It’s the largest known galaxy cluster in the distant universe. A galaxy like the Milky Way might contain a few hundred billion stars and up to just over a trillion (1012) solar masses worth of matter, the El Gordo cluster has an estimated mass of 3 × 1015 solar masses, or 3,000 times as much as our own galaxy! The way we’ve figured this out is fascinating. By seeing how the shapes of background galaxies are distorted into more elliptical-than-average shapes along a particular set of axes, we can reconstruct how much mass is present in the cluster: a phenomenon known as weak gravitational lensing.

That reconstruction is shown in blue, but doesn’t match up with where the X-rays are, which are shown in pink! This is because, when galaxy clusters collide, the neutral gas inside heats up to emit X-rays, but the individual galaxies (mostly) and dark matter (completely) pass through one another, resulting in a displacement of the cluster’s mass from its center. This has been observed before in objects like the Bullet Cluster, but El Gordo is much younger and farther away. At 10 billion light-years distant, the light reaching us now was emitted more than 7 billion years ago, when the universe was less than half its present age.

It’s a good thing, too, because about 6 billion years ago, the universe began accelerating, meaning that El Gordo just might be the largest cosmic heavyweight of all. There’s still more universe left to explore, but for right now, this is the heavyweight champion of the distant universe!

Learn more about “El Gordo” here: www.nasa.gov/press/2014/april/nasa-hubble-team-finds-monster-el-gordo-galaxy-cluster-bigger-than-thought/

El Gordo is certainly huge, but what about really tiny galaxies? Kids can learn about satellite galaxies at NASA’s Space Place spaceplace.nasa.gov/satellite-galaxies/.

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Image credit: NASA, ESA, J. Jee (UC Davis), J. Hughes (Rutgers U.), F. Menanteau (Rutgers U. and UIUC), C. Sifon (Leiden Observatory), R. Mandelbum (Carnegie Mellon U.), L. Barrientos (Universidad Catolica de Chile), and K. Ng (UC Davis). X-rays are shown in pink from Chandra; the overall matter density is shown in blue, from lensing derived from the Hubble space telescope. 10 billion light-years distant, El Gordo is the most massive galaxy cluster ever found.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

About NASA Space Place

The goal of the NASA Space Place is “to inform, inspire, and involve children in the excitement of science, technology, and space exploration.” More information is available at their website: http://spaceplace.nasa.gov/

TACNY Junior Cafe Scientifique: “The Dark Side of the Universe”

Saturday – September 20, 9:30-11:00am

Milton J Rubenstein Museum of Science & Technology – Syracuse, NY


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We’re back!! Stuff that most of us have seen is made of atoms, tiny particles that cause scientists headaches and lead to inventions like microwaves. However, current observations beyond our planet have led to astonishing mysteries. It seems most of the universe is made of things called dark matter and dark energy. These strange substances are not like anything we have encountered and they imply bizarre consequences for the past and eventual fate of our universe. Dr. Scott Watson will discuss both the evidence and the consequences of nature living on the dark side of the universe.

People interested in learning more about dark matter are invited to attend the free Junior Cafe presentation on Saturday, September 20, from 9:30 a.m. to 11 a.m. at the Milton J. Rubenstein Museum of Science and Technology (MOST) in Syracuse’s Armory Square. Walk-ins are welcome, but we ask that people RSVP by emailing jrcafe@tacny.org by September 17, 2014.

Presenters

Watson _small001Prof. Watson is an assistant professor at Syracuse University, working in the fields of theoretical particle physics and cosmology. He received his doctorate in physics from Brown University under the supervision of Robert Brandenberger. He held research positions at the University of Toronto and the University of Michigan before joining the faculty at Syracuse in 2010. He also holds visiting positions at Cornell University and with Stephen Hawking’s group at Cambridge University in England.

Prof. Watson’s research is focused on fundamental questions related to the origin of the universe and its ultimate fate. How did the universe begin? What is its eventual fate? Do atoms represent all of the stuff making up the universe, or do things like dark energy and dark matter control our ultimate fate? Questions like these are at the center of Prof. Watson’s research. Present theories suggest that the seeds for the growth of structures like galaxies and eventually life resulted from the quantum behavior of particles and fields in the very early universe — when it was less than a fraction of a second old. Such a description requires a quantum understanding of gravity with string theory being our leading candidate for such a theory. And so Prof. Watson’s research is also involved in establishing observational implications of string theory.

TACNY Junior Cafe Scientifique

TACNY Junior Cafe Scientifique, a program for middle-school students founded in 2005, features discussions about topics in the fields of science, technology, engineering and mathematics in an informal atmosphere and seeks to encourage students to consider careers in these areas. Students must be accompanied by an adult and can explore the MOST at no cost after the event.

Technology Alliance of Central New York

Founded in 1903 as the Technology Club of Syracuse, the nonprofit Technology Alliance of Central New York’s mission is to facilitate community awareness, appreciation, and education of technology; and to collaborate with like-minded organizations across Central New York.

For more information about TACNY, visit www.tacny.org.