Tag: Galaxies

The Fringe Theory That Could Disprove Dark Matter

Quantized Inertia is a type of modified relativity theory that explains inertia as a fundamental force of the universe that could do everything from explain the rotation of galaxies without using Dark Matter, to the expansion of the universe without Dark energy, and may even allow anti-gravity propulsion. If it’s true, that is.

Our bodies Are Made Of Remnants Of Stars And Massive Explosions In The Galaxies

galaxy

It seems natural to assume that the matter from which the Milky Way is made was formed within the galaxy itself, but a series of new supercomputer simulations suggests that up to half of this material could actually be derived from any number of other distant galaxies.

This phenomenon, described in a paper by group of astrophysicists from Northwestern University in the US who refer to it as “intergalactic transfer”, is expected to open up a new line of research into the scientific understanding of galaxy formation.




Led by Daniel Anglés-Alcázar, the astrophysicists reached this intriguing conclusion by implementing sophisticated numerical simulations which produced realistic 3D models of galaxies and followed their formation from shortly after the Big Bang to the present day.

The researchers then employed state-of-the-art algorithms to mine this sea of data for information related to the matter acquisition patterns of galaxies.

Through their analysis of the simulated flows of matter, Anglés-Alcázar and his colleagues found that supernova explosions eject large amounts of gas from galaxies, which causes atoms to be conveyed from one system to the next via galactic winds.

galaxy

In addition, the researchers note that this flow of material tends to move from smaller systems to larger ones and can contribute to up to 50 percent of the matter in some galaxies.

Anglés-Alcázar and his colleagues use this evidence, which is published in Monthly Notices of the Royal Astronomical Society, to suggest that the origin of matter in our own galaxy including the matter that makes up the Sun, the Earth, and even the people who live on it may be far less local than traditionally believed.

galaxy

“It is likely that much of the Milky Way’s matter was in other galaxies before it was kicked out by a powerful wind, traveled across intergalactic space and eventually found its new home in the Milky Way,” Anglés-Alcázar says.

The team of astrophysicists now hopes to test the predictions made by their simulations using real-world evidence collected by the Hubble Space Telescope and other ground-based observatories.

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Scientists Are Tracing the Source of One of the Most Mysterious Signals in Space

Over the past decade, we’ve found out a great deal about what fast radio bursts (FRBs) are — millisecond-long blips of intense radio emissions from deep space — but their origins remain a mystery.

Now, astronomers have tracked a repeating FRB to a dwarf galaxy nearly three billion lightyears from Earth, according to a report.

The international team, which presented its work at the annual American Astronomical Society meeting last January 2018, observed that the radio beam was being contorted by a magnetic field within a cloud of ionized gas, telling us more about the conditions these bursts take place in.




The study detailing the team’s results was recently published in Nature.

We see a sort of ‘twisting’ of the radio bursts caused by an effect known as Faraday rotation,” Jason Hessels, one of the co-authors of the study from the Netherlands Institute for Radio Astronomy, told Futurism.

We hypothesize that the source of the bursts could be a neutron star in the proximity of a massive black hole that is accreting material from its surroundings, or maybe that it is a very young neutron star embedded in a nebula (a sort of cocoon around the source).

We are basically pushing forward and zooming in even further on where these fast radio bursts are coming from,” co-author Shami Chatterjee, a senior research associate from the Cornell Center for Astrophysics and Planetary Science said.

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Early Opaque Universe Linked To Galaxy Scarcity

It has long been known that the universe is filled with a web-like network of dark matter and gas.

This “cosmic web” accounts for most of the matter in the universe, whereas galaxies like our own Milky Way make up only a small fraction.

Today, the gas between galaxies is almost totally transparent because it is kept ionized — electrons detached from their atoms — by an energetic bath of ultraviolet radiation.

Over a decade ago, astronomers noticed that in the very distant past — roughly 12.5 billion years ago, or about 1 billion years after the Big Bang — the gas in deep space was not only highly opaque to ultraviolet light, but its transparency varied widely from place to place, obscuring much of the light emitted by distant galaxies.

Then a few years ago, a team led by Becker, then at the University of Cambridge, found that these differences in opacity were so large that either the amount of gas itself, or more likely the radiation in which it is immersed, must vary substantially from place to place.




To find out what created these differences, the team of University of California astronomers from the Riverside, Santa Barbara, and Los Angeles campuses turned to one of the largest telescopes in the world: the Subaru telescope on the summit of Mauna Kea in Hawaii.

Using its powerful camera, the team looked for galaxies in a vast region, roughly 300 million light years in size, where they knew the intergalactic gas was extremely opaque.

For the cosmic web more opacity normally means more gas, and hence more galaxies. But the team found the opposite: this region contained far fewer galaxies than average.

Because the gas in deep space is kept transparent by the ultraviolet light from galaxies, fewer galaxies nearby might make it murkier.

This discovery, reported in the August 2018 issue of the Astrophysical Journal, may eventually shed light on another phase in cosmic history.

In the first billion years after the Big Bang, ultraviolet light from the first galaxies filled the universe and permanently transformed the gas in deep space.

Astronomers believe that this occurred earlier in regions with more galaxies, meaning the large fluctuations in intergalactic radiation inferred by Becker and his team may be a relic of this patchy process, and could offer clues to how and when it occurred.

By studying both galaxies and the gas in deep space, astronomers hope to get closer to understanding how this intergalactic ecosystem took shape in the early universe.

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From Pancakes To Soccer Balls, New Study Shows How Galaxies Change Shape As They Age

A selection of SAMI galaxies imaged with the Hyper Suprime Cam on the Subaru Telescope in Hawaii. National Astronomical Observatory of Japan (NAOJ), Caroline Foster (The University of Sydney) and Dan Taranu (University of Western Australia)

Galaxies are a fundamental part of the 13.7 billion-year-old universe. Understanding how a system as complex and striking as our own Milky Way galaxy formed after the Big Bang is one of the great themes of modern astronomy.

Our research, published today in Nature Astronomy, has identified a surprising connection between the age of a galaxy and its three-dimensional shape.

As galaxies get older they get rounder, and fall victim to the middle-aged spread that catches many of us humans here on Earth.

We’ve known for a long time that shape and age are linked in very extreme galaxies – that is, very flat ones and very round ones.

But this is the first time we have shown this is true for all kinds of galaxies – all shapes, all ages, all masses.




Unveiling the true face of a galaxy

In this study we calculated both the age and shape of galaxies using different techniques.

Assigning an age to a galaxy is tricky. They don’t have a single birth date for when they suddenly popped into existence.

We assessed the average age of the stars in a galaxy as a measure of the galaxy’s age. Young galaxies have a large fraction of recently formed hot blue stars, whereas old galaxies mostly contain colder red stars formed shortly after the Big Bang.

Spectroscopy — splitting the light from a galaxy into many different colours — allows us to measure the average age of stars in a galaxy.

This technique gives a much higher precision than simply using blue or red images as is typically done.

To measure a galaxy’s true three-dimensional shape and ellipticity, you have to measure how its stars move around.

Ellipticity is simply a measure of how squashed a galaxy is with respect to a perfect sphere. An ellipticity of zero means a galaxy is a perfect sphere like a soccer ball.

But as the measured ellipticity increases from zero towards one, the galaxy becomes more and more squashed – from a roundish pumpkin shape to a thin disk like a pancake.

We see galaxies as two-dimensional images projected onto the sky, but that doesn’t tell us what they really look like in three dimensions.

If we can also measure how the stars in a galaxy are moving we can infer their true, three-dimensional shape.

Spectroscopy lets us do this via the Doppler effect. We can measure shifts in the wavelength of light emitted by stars, which depend on whether those stars are moving towards us or away from us, and so measure their motions.

We did this using SAMI, the Sydney-Australian-Astronomical-Observatory Multi-object Integral-Field Spectrograph, on the 3.9-metre Anglo-Australian Telescope at Siding Spring Observatory.

The SAMI instrument provides 13 optical fibre units that can “dissect” galaxies using spectroscopy, providing unique 3D data.

Over the past couple of years, the SAMI Galaxy Survey team has gathered 3D measurements for more than a thousand galaxies of all kinds, and with a hundred-fold range in mass.

Closer to home

If we look at our own Milky Way galaxy, which is more than 10 billion years old, we can see examples of this story.

The youngest part of the Milky Way, where stars are still being formed, is the thin disk, which has a very squashed, pancake-like shape.

The Milky Way also contains rounder and older components, a thick disk and a bulge, but their origin is still mostly unknown.

We know that eventually the Milky Way will merge with our galactic neighbour, the Andromeda galaxy. Predictions are that this will result in a very round, very old giant elliptical galaxy.

So, by studying the processes that shape other nearby galaxies, we can learn a lot about the past, and the fate of our own.

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The Big Bang Wasn’t The Beginning, After All

A Universe that expands and cools today, like ours does, must have been hotter and denser in the past. Initially, the Big Bang was regarded as the singularity from which this ultimate, hot, dense state emerged. But we know better today.

The Universe began not with a whimper, but with a bang! At least, that’s what you’re commonly told: the Universe and everything in it came into existence at the moment of the Big Bang.

Space, time, and all the matter and energy within began from a singular point, and then expanded and cooled, giving rise over billions of years to the atoms, stars, galaxies, and clusters of galaxies spread out across the billions of light years that make up our observable Universe.

It’s a compelling, beautiful picture that explains so much of what we see, from the present large-scale structure of the Universe’s two trillion galaxies to the leftover glow of radiation permeating all of existence.

Unfortunately, it’s also wrong, and scientists have known this for almost 40 years.

The idea of the Big Bang first came about back in the 1920s and 1930s. When we looked out at distant galaxies, we discovered something peculiar: the farther away from us they were, the faster they appeared to be receding from us.




According to the predictions of Einstein’s General Relativity, a static Universe would be gravitationally unstable; everything needed to either be moving away from one another or collapsing towards one another if the fabric of space obeyed his laws.

The observation of this apparent recession taught us that the Universe was expanding today, and if things are getting farther apart as time goes on, it means they were closer together in the distant past.

An expanding Universe doesn’t just mean that things get farther apart as time goes on, it also means that the light existing in the Universe stretches in wavelength as we travel forward in time.

Since wavelength determines energy (shorter is more energetic), that means the Universe cools as we age, and hence things were hotter in the past.

It’s tempting, therefore, to keep extrapolating backwards in time, to when the Universe was even hotter, denser, and more compact.

First noted by Vesto Slipher, the more distant a galaxy is, on average, the faster it’s observed to recede away from us. For years, this defied explanation, until Hubble’s observations allowed us to put the pieces together: the Universe was expanding.

Theorists thinking about these problems started thinking of alternatives to a “singularity” to the Big Bang, and rather of what could recreate that hot, dense, expanding, cooling state while avoiding these problems.

The conclusion was inescapable: the hot Big Bang definitely happened, but doesn’t extend to go all the way back to an arbitrarily hot and dense state.

Instead, the very early Universe underwent a period of time where all of the energy that would go into the matter and radiation present today was instead bound up in the fabric of space itself.

That period, known as cosmic inflation, came to an end and gave rise to the hot Big Bang, but never created an arbitrarily hot, dense state, nor did it create a singularity.

What happened prior to inflation — or whether inflation was eternal to the past — is still an open question, but one thing is for certain: the Big Bang is not the beginning of the Universe!

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Looks Like The Universe Isn’t As Special As We Thought

There are a few ideas being tossed around perplexing to know what competence be function around these incomparable galaxies. Some of a theories concentration on a thought of tidal army in a formless blank of space.

If we have communication between dual bigger galaxies, afterwards in this communication there will be some bridges or tidal bridges [between a galaxies],” Müller says.

The sobriety of a incomparable star will usually slice out stars and gas identical to a sobriety of a moon, that creates a tides on a Earth.

The ensuing dwarf galaxies would circuit a incomparable ones in a craft and along a same direction, identical to what Müller and colleagues observed.

But researchers have no thought how prolonged these tidal dwarf galaxies would final after a collision, and that does have implications for cosmology.




The thing about tidal dwarf galaxies is that we don’t know how prolonged they live. Can they be stable? This is in contrariety to a customary model, where we consider that a dwarf galaxies are a building blocks of a universe.

“They are a initial galaxies that are combined and they combine [to form incomparable galaxies], so they are a oldest objects. But with tidal dwarf galaxies, they would be a youngest objects,” Müller says.

Going from building retard to afterthought is a lot to reconcile.

People consider we have rescued dark matter, though dim matter is usually a hypothesis,” Müller says. “We are still looking for it.

Dark matter is a vicious member of a customary model, assisting to explain a gravitational lift between objects in a universe, that can’t be explained by a manifest matter in a universe.

This investigate isn’t a genocide knell for a customary cosmological model, that can explain what happened in a star moments after a Big Bang, calculate a series of atoms that were benefaction in a star mins after it started, explain a participation of vast credentials radiation, and explain how matter is distributed in a star today.

It’s a biggest hits list that’s tough to beat.

How to determine a observations with a theory? More calculations, some-more thinking, and some-more data.

For this study, Muller and colleagues looked during a velocities of a satellite galaxies in propinquity to a viewpoint here on Earth to extrapolate some-more fact about their transformation around Centaurus A.

“We’re means to magnitude a velocities of these galaxies along a lines of sight, though we’re not means to magnitude a quickness of a star perpendicular to a line of sight,” Boylan-Kolchin says.

So we don’t know if they’re rotating in planes or if they demeanour like they’re rotating in planes.

There are ways to answer that question. The arriving James Webb Space Telescope, in further to a brave Hubble, could assistance astrophysicists investigate some-more galaxies and their satellites.

By comparing images of a same star taken months or years apart, Boylan-Kolchin says, researchers competence be means to get a improved clarity of how dwarf galaxies are orbiting their hosts, generally if researchers wish to take a demeanour during a circuitously Andromeda.

But it won’t be easy.

It’s like perplexing to magnitude hair expansion on a moon—from Earth. It’s really slow, really excellent measurements, though it should be possible,” Boylan-Kolchin says.

At a really least, these new observations will let people take a closer demeanour during how a galaxies formed.

I consider now people have to take it seriously, some-more severely than before.Müller says.

Before, there was always this guess that we are atypical, we are usually a special box in a universe, that routinely it works.

“But now we have shown that another star organisation circuitously also has this feature, so a village has to figure out how we can make such structures some-more frequently.

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There Might Be More Big Stars In The Universe Than We Thought

A new series of observations suggests that we have underestimated the number of large stars that form in starburst events. If this finding is more than just an exception to the rule, there could be consequences for many astronomical theories.

As reported in Science, an international group of astronomers has studied the stars within 30 Doradus, also known as the Tarantula Nebula, a starburst region in the Large Magellanic Cloud.

The team managed to characterize the properties of 452 stars in 30 Doradus and, out of all of them, 247 were more massive than 15 times our Sun.




There are about 25 to 50 more heavy stars than theoretical predictions, known as the initial mass function (IMF), would expect.

The IMF describes the distribution of masses for any population of stars when it formed. It’s an empirical distribution and is very important. The mass of stars determines their evolution and how they’re going to end their life.

For example, more massive stars mean more supernovae, which leads to more black holes and neutron stars. It also influences the evolution of the stars’ host galaxies as a whole.

And since galaxies have up to 100 billion stars, the IMF is very useful for providing statistics.

Nevertheless, this doesn’t mean that the IMF is perfect. Since its proposal in 1955 by Edwin Salpeter, the IMF has been tweaked to better characterize the low-mass end of star mass distribution.

It turns out that there are a lot more small stars than predicted, and the new study suggests that some tweaking might be necessary for certain environments, even at the high end of mass distribution.

The study raises several questions that will require more observation. Is the excess of massive stars connected to advantageous conditions in the gas clouds?

Is it common during starburst events? Are there other mechanisms at work?

What remains interesting is the presence of some of the most massive stars ever observed, with some weighing over 200 times the mass of the Sun.

The researchers estimate that bigger stars might still exist in the core of the nebular, which was not resolved.

The Tarantula Nebula is the most active and largest (over 600 light-years) starburst region in the local group of galaxies.

Supernova 1987A, the closest supernova observed since the invention of the telescope, occurred on the outskirts of this nebula.

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The Universe May Be Expanding Faster Than We Thought. Does It Mean Something?

At the beginning of time, all the matter in the universe was compressed into an infinitesimally small point. That tiny speck of everything then exploded and formed the universe.

In some sense, it’s still exploding, expanding at an accelerating rate.

In the past, scientists have looked to the radiation left behind from the Big Bang — its smoking gun — to calculate what the rate of the expanding universe ought to be today.

But new evidence, soon to be published in The Astrophysical Journal, suggests these estimates may be wrong, or at least incomplete.

New observations from the Hubble Space Telescope have indicated that the universe may be expanding 5 to 9 percent faster than predicted by the Big Bang.




But how?

Using the Hubble, scientists from across the US were able to painstakingly measure the distance to stars and supernovae in many galaxies.

They then used this data to refine what’s known as the “Hubble constant,” the rate by which the universe expands, as measured by direct observations.

But when this new “Hubble constant” was compared with the estimates from the Big Bang inferences, the numbers just didn’t match.

You start at two ends, and you expect to meet in the middle if all of your drawings are right and your measurements are right,” Adam Riess, the Nobel laureate at the Space Telescope Science Institute and Johns Hopkins University, who led the project, explained Thursday in a statement.

“But now the ends are not quite meeting in the middle and we want to know why.”

Add this to the long list of questions physicists still have about the universe

The prediction based on the Big Bang “should match our measurement,” Lucas Macri, a Texas A&M physicist and one of the study’s co-authors, tells me.

“If they don’t … there must be a physical reason why these two things are not agreeing.”

So what accounts for the discrepancy?

Either there’s something about the Big Bang that previous estimates have not accounted for or there are factors that come into play after the Big Bang that scientist don’t yet understand.

Macri highlights four possible explanations.

The first is related to the Big Bang.

)We’re seeing evidence of a previously unknown subatomic particle that was abundant right after the Big Bang (a.k.a. ‘dark radiation’),” he says.

If you change the assumptions about what was in the primordial soup, things will have shifted a bit.

The other possibilities are related to “dark energy” and “dark matter,” the substances that make up most of the universe yet can’t be directly observed.

2) Dark energy — the mysterious force that opposes gravity and is causing the universe to accelerate — “is growing in strength and ‘pushing’ galaxies apart faster than it did before,” he says.

3) Dark matter — matter that we can’t see but that is theorized to exist and make up most of the matter in the universe — “is even weirder than we thought.

Or it could not so simply be:

4)Our theory of gravity is incomplete.”

He also mentions that their results aren’t set in stone. “There’s one chance in 1,000 that we got this measurement by accident,” he says.

Physics requires a one in 4 million chance for results to be considered truth. More observations will need to be made.

Macri says he and other researchers will know more soon, especially if they get to use the James Webb Space Telescope, which will replace Hubble in the year 2018.

The James Webb will be able to look much deeper into space than Hubble and can refine the Hubble constant estimate further.

A modest amount of time with James Webb will allow us to make a very significant improvement on our measurement,” Macri says.

Overall, he says, it’s important to know the exact rate of universal expansion because it will yield a more accurate age of the universe.

To get the age of the universe you need to have the Hubble constant,” he says. Right now the uncertainty of their estimate is 2.4 percent, which is the best yet. But not good enough.

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Dwarf Galaxies Loom Large in Quest for Dark Matter

In its inaugural year of observations, the Dark Energy Survey has already turned up at least eight objects that look to be new satellite dwarf galaxies of the Milky Way.

These miniature galaxies — the first discovered in a decade — shine with a mere billionth of our galaxy’s brightness and each contain a million times less mass.

Astronomers believe the vast majority of material in dwarf galaxies is dark matter, a mysterious substance composing 80 percent of all matter in the universe.

Dwarf galaxies have therefore emerged as prime targets for gathering potential clues about dark matter’s composition.




Some theories suggest dark matter particles and antiparticles should produce telltale gamma rays when they collide with each other.

Accordingly, scientists used the Fermi Gamma-Ray Space Telescope to study the newfound dwarf galaxy candidates, as well as a group of dwarf galaxies already on the books.

The telescope detected no significant gamma-ray signals from either set of dwarf galaxies, however, leaving scientists still in the hunt for dark matter.

On May 15, 2015, The Kavli Foundation spoke with three astrophysicists about the continuing search for dark matter data in space and how dwarf galaxies can help us understand the evolution of our universe.

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