Category: Galaxies

Dwarf galaxy mergers generate star formation

Dwarf galaxies have abundant levels of hydrogen gas, the fuel that drives star birth.

Dwarf galaxies such as the Large and Small Magellanic Clouds have abundant hydrogen gas, which plays a key role in star formation.

When two dwarf galaxies merge with one another or one dwarf galaxy merges with a larger, parent galaxy, this hydrogen gas is dispersed within the new combined galaxy, where it acts as fuel to generate the birth of new stars.

“You have this enormous reserve of star formation fuel sitting there ready to be stripped by another system,” explained Mary Putnam of Columbia University, who took part in a study on the role of hydrogen gas in galaxy mergers.

Both the Large and Small Magellanic Clouds are dwarf galaxy satellites of the much larger Milky Way. The two were in the process of  merging when they were gravitationally pulled into the Milky Way’s orbit. Between them, there is enough hydrogen gas to replenish around half of the Milky Way’s star-formation fuel.

Much dimmer than their larger spiral counterparts, dwarf galaxies are filled with swirling hydrogen gas.

Led by then-Columbia graduate student Sarah Pearson, now at the Flatiron Institute‘s Center for Computational Astrophysics, a team of researchers observed two distant dwarf galaxies, NGC 4490 and NGC 4485, both located approximately 23 million light years away, to learn more about the role hydrogen gas in dwarf galaxies plays in creating new stars. NGC 4490 is several times larger than its partner.

Unlike the Magellanic Clouds, these two dwarf galaxies are not bound to a larger spiral galaxy like the Milky Way, so scientists can observe their merging without the influence of a larger parent galaxy.

By inputting data about the two dwarf galaxies into a computer simulation, the researchers modeled their merger, focusing on the subsequent expansion of their hydrogen gas over five billion years. By that time, “tails” of hydrogen gas stretched more than a million light years.

“After five billion years, 10 percent of the gas envelope still resides more than 260,000 light years from the merged remnant, suggesting it takes a very long time before all the gas falls back to the merged remnant,” Pearson said.

Over time, the gas clouds became more and more extended, thinning them out and making it easier for any nearby large galaxies to absorb them. This phenomenon likely makes it easy for the Milky Way to absorb gas from the Magellanic Clouds.

To better understand these dynamics, the researchers plan to study other pairs of dwarf galaxies.

A paper on the study has been published in Monthly Notices of the Royal Astronomical Society.

Opaque universe gives insight into galaxy formation

A new study sheds light on both the cosmic web, as well as what the universe was like when the first galaxies formed.

Researchers from numerous California universities found that 12.5 billion years ago the most opaque place in the universe had almost no matter, a new study in the Astrophysical Journal reports.

Almost all of the universe contains a vast, web-like network of dark matter and gas. Known as the “cosmic web,” that lattice accounts for most of the matter in the universe.

Though the gas within the network is almost completely transparent because it is kept ionized by ultraviolet radiation, it was not always that way.

Researchers first found that information roughly 10 years ago, when they realized 1 billion years after the Big Bang the gas hanging throughout the cosmos was not only opaque as a result of ultraviolet light, but also that its transparency changed greatly from region to region.

Then, a few years past that finding, the team behind the recent research found that the differences in opacity were so large that either the amount of gas — or the radiation in which it sits — also shifted in each area.

“Today, we live in a fairly homogeneous universe,” said lead author George Becker, a researcher from the University of California, Irvine, according to Science Daily. “If you look in any direction you find, on average, roughly the same number of galaxies and similar properties for the gas between galaxies, the so-called intergalactic gas. At that early time, however, the gas in deep space looked very different from one region of the universe to another.”

To take a closer look at the notable differences, scientists used the Subaru telescope in Hawaii to search for galaxies in a vast, 300-light-year stretch of the universe where intergalactic gas was extremely opaque.

In terms of the cosmic web, more opacity typically equals more gas, which means more galaxies. However, in the study the team found the exact opposite. The region they analyzed, despite being opaque, had much less galaxies on average.

Though they are not sure why that is, the researchers postulate it is because UV light could not travel very far in the early universe. As a result, any section with only a few galaxies would look much darker than one with more activity.  

This discovery is important because it could help scientists gain insight into the first billion years after the Big Bang, when ultraviolet light from the first galaxies filled the universe and permanently transformed the gas in deep space. In addition, analyzing deep space galaxies may also shed light on how the cosmic web first came to be. 

“There is still a lot we don’t know about when the first galaxies formed and how they altered their surroundings,” said Becker, according to SciTechDaily.

The universe appears to expand at different rates, study reports

New measurements show that modern physics cannot succinctly understand the rate at which the universe expands.

Astronomers from John Hopkins University have found new evidence that furthers the idea that the universe expands at different speeds depending on what part is observed, according to new research in The Astrophysical Journal. 

Many recent studies on the topic have found numerous discrepancies in how fast the universe moves out to distant locations.

In fact, the “tension” could reveal that scientists need to revise the modern understanding of how physics structures the universe and change ideas surround dark matter and dark energy.

Measurements gathered from the Hubble and Gaia space telescopes revealed that the universe expands at a rate of 45.6 miles per second per megaparsec. In other words, every 3.3 million light-years a galaxy is away from Earth, it appears to move 45 miles faster.

However, previous research from the Planck telescope shows that the more distant background universe moves at a slower 41.6 miles per second per megaparsec.

The difference between both of those measurements continues to grow as researchers refine measurements over time. In fact, the data from the new study reveals a gap that is four times the size of their combined uncertainty — a value that reflects researchers’ level of confidence in the results of a trial.

“At this point, clearly it’s not simply some gross error in any one measurement,” said lead author Adam Riess, an astronomy and physics professor at Johns Hopkins University, in a statement. “It’s as though you predicted how tall a child would become from a growth chart, and then found the adult he or she became greatly exceeded the prediction. We are very perplexed.”

Nobody can explain why the universe accelerates as it expands. Some believe it may be the result of dark matter or dark energy, while others suggest that it may be the result of a yet undiscovered particle.

While researchers are still analyzing the measurements from the recent study, they will likely help scientists better predict how the early universe have evolved into the expansion rate noted today.

“The tension seems to have grown into a full-blown incompatibility between our views of the early and late time universe,” added Riess, according The Independent. “At this point, clearly it’s not simply some gross error in any one measurement.

Telescope gives glimpse of Milky Way’s center

The MeerKAT telescope provides astronomers with a brand new glimpse of the center of the Milky Way.

A brand new mega-telescope has taken the best picture of the Milky Way’s center on record.

The new technology — known as MeerKAT radio telescope — is made up of 64 small dishes that work to detect radio waves. All of the devices sit in the Karoo region of South Africa and are much more sensitive than any other similar object.

That extra sensitivity is key because it allowed MeerKAT to image the region around the supermassive black hole at the center of our galaxy — which sits 25,000 light-years away — in great detail.

The colors in the image reveal the brightness of the radio waves detected, and they range from red to orange to white.

While the picture seems like nothing more than a giant fireball at first glance, it reveals may new features.

For example, it shows compact sources of the long, magnetized filaments that come off the Milky Way’s central region, and it also provides a new look into previously unknown supernova remnants and star-forming regions.

The filaments are particularly important because, while researchers have spent decades analyzing them, nobody understands why they are only near the black hole.

“This image is remarkable,”said Farhad Yusef-Zadeh, a researcher at Northwestern University, according to Newsweek. “It shows so many features never before seen, including compact sources associated with some of the filaments, that it could provide the key to cracking the code and solve this three-decade riddle.”

Another reason the image is so special is because the center of the Milky Way is notoriously hard to photograph. Not only is it incredibly far away, but it also sits behind the constellation Sagittarius, which hides it from optical telescopes.

MeerKAT gets around that because it is able to detect certain radio wavelengths that other machines cannot.

“We wanted to show the science capabilities of this new instrument,” said Fernando Camilo, chief scientist of the South African Radio Astronomy Observatory (SARAO), which built and operates MeerKAT, according to Science Alert. “The center of the galaxy was an obvious target: unique, visually striking and full of unexplained phenomena – but also notoriously hard to image using radio telescopes … Although it’s early days with MeerKAT, and a lot remains to be optimised, we decided to go for it – and were stunned by the results.”

New radio telescope images Galactic Center

World’s most sensitive radio telescope will one day be part of larger, intercontinental facility.

A new radio telescope described as the most sensitive of its kind in the world has captured an image of the Milky Way’s Galactic Center.

Located in South Africa, MEERKAT, an interferometer made up of 64 separate dishes designed to produce detailed maps of normally invisible regions of space, captured a panoramic view of the the Galactic Center using infrared, radio, and X-ray wavelengths, which enabled it to penetrate gas and dust that gets in the way of conventional telescopes.

The stunning image shows the sources of magnetized filament structures close to the galaxy’s central supermassive black hole, an image that could help scientists decipher the filaments’ origins.

MEERKAT is part of an even larger project, the Square Kilometer Array (SKA), a radio telescope that will be linked with 130 dishes in South Africa and as many as 130,000 antennas in Australia. The folding of MEERKAT into SKA is expected to begin in 2020.

Actual scientific experiments with the South-African funded $331 million MEERKAT are scheduled to begin in approximately two months.

Two MEERKAT research projects are already in progress. The first will use the telescope’s full capacity to study hydrogen levels in galaxies. Scientists believe data from this project will provide crucial insight into the universe’s history.

The second project will study fast radio bursts and similar, transient phenomena that are currently not well understood.

Future plans call for eight large survey projects to operate using MEERKAT, with each research team given a total of 1,000 hours on the telescope over a period of five years.

For many astronomers, engineers, and data scientists who would otherwise have to use instruments based in the US, Europe, or Australia for their research projects, MEERKAT provides an alternate, ideal option.

“With this new instrument, South Africa stands poised to be at the forefront of astronomy and data science. The anticipated success of the SKA relies heavily on MEERKAT,” noted SKA organization director-general Phil Diamond.

Michael Kramer, director of the Max Planck Institute for Radio Astronomy in Bonn, Germany, praised the early data returned by MEERKAT as “better than we expected.”

An article on MEERKAT’s imaging of the Galactic Center and plans for the telescope’s future has been published in the journal Nature.

Bright quasar dates back to early universe

Discovery could help scientists better understand how the universe’s first galaxies formed.

The brightest quasar or active galactic nucleus ever detected dates back nearly 13 billion years, meaning it originated in the early universe and could potentially aid scientists in understanding the formation process of the first galaxies.

Quasars are extremely luminous super-massive black holes at the centers of galaxies. These black holes are active, meaning they are devouring large amounts of matter that form an accretion disk spiraling toward their centers. The most luminous, powerful, and remote energy sources in existence, quasars emit as much as one thousand times the energy output of the Milky Way galaxy across the entire electromagnetic spectrum.

A research team led by Eduardo Banadas of the Carnegie Institution for Science discovered the quasar PSO J1352.4034-15.3373 emitting the brightest radio emission ever detected as a result of high-speed jets shooting out of it towards Earth.

His discovery was confirmed by Emmanuel Momjian of the National Radio Astronomy Observatory, who, along with his science team, was able to view the jet emitted by the quasar with an unprecedented level of detail.

The researchers found the jets have been traveling for 13 billion years, making this quasar the first known to have been spewing jets within the first billion years of the universe’s 13.8-billion-year existence.

Unlike most quasars, this one does more than suck matter into its black hole. It also emits jets of plasma that travel at almost the speed of light. This makes the jets appear extremely bright when viewed with radio telescopes.

Approximately 10 percent of quasars are known to emit strong radio jets.

“There is a dearth of known strong radio emitters from the universe’s youth, and this is the brightest radio quasar at that epoch by any order of magnitude,” Banados stated.

Following the Big Bang, the universe was dark as it expanded and cooled into neutral hydrogen gas, with few sources of brightness. Approximately 800 million years after the Big Bang, gravity condensed matter into the first galaxies and stars, which released energy, causing the neutral hydrogen to lose an electronic and become ionized, generating light.

“The jet from this quasar could serve as an important calibration tool to help future projects penetrate the dark ages and perhaps reveal how the earliest galaxies came into being,” Banados emphasized.

Findings of the study have been published in two separate papers in The Astrophysical Journal.

Cosmic rays traced back to massive black hole

For the first time ever researchers have found an origin of the mysterious cosmic rays that come to Earth from outer space.

A team of international scientists have confirmed the source of ultra high-energy cosmic rays that beam to Earth from space, according to a new study published in the journal Science

Occasionally, our planet gets hit with protons and atomic nuclei that shoot out of space with energy so high that scientists cannot replicate it. Researchers first discovered those “cosmic rays” over 100 years ago, but they never knew where they came from until now.

In the new study, the team combined data from light and a single high-energy neutrino particle and found that the rays originate from a blazar — a supermassive black hole at the center of a galaxy.

That discovery could open up new insight into the universe and provide a brand new way to study the cosmos.

“We have been looking for the sources of cosmic rays for more than a century, and we finally found one,” study co-author Francis Halzen, lead scientist at the IceCube Neutrino Observatory and a professor of physics at the University of Wisconsin-Madison, told Space.com.

This finding came about when the IceCube detector at the South Pole spotted a neutrino particle that had an incredible amount of energy. The detector’s computers quickly calculated where it came from and sent the coordinates to astronomers across the globe.

Six days later, the Fermi Large Area Telescope found a distant blazer known as TXS 0506+056 in the same spot.

Further research showed the blazar is able to produce high-energy protons and nuclei, which then creates neutrinos. In that way, it can create the ultra high-energy cosmic rays that have eluded astronomers for the past century.

That is an exciting discovery, but it is just one source. As a result, more research needs to be done to explain all cosmic rays and how they get made.

“We clearly need more data. One source is not enough,” study co-author Spencer Klein, a physicist at Lawrence Berkeley National Lab, told Gizmodo. “Now that we found one accelerator, we’d like to find more and find out how they work.”