Massive galaxy cluster found ‘hiding’ behind the Milky Way

You would think that it would be easy to spot a cosmic structure as enormous as a supercluster holding legions of galaxies, but not so — the Milky Way can hide all kinds of objects, usually due to dust and stars obscuring the view. If you need proof, you just need to ask the astronomers who have discovered the Vela supercluster, a giant collection of galaxies about 800 million light years away (shown as “VSC” above). They only detected it by making “thousands” of spectroscopic studies of partially obscured galaxies — it was hidden on the far side of the Milky Way.

The actual details of the supercluster, such as its full size, mass and gravitational pull, are still forthcoming. Researchers will need to use radio astronomy (such as the new MeerKAT facility) and other techniques to measure an area that remains a relative mystery. Once that happens, however, humanity could learn a lot about the movement of both the Milky Way and other galaxies in the Local Group. Superclusters have enough gravitational influence to pull galaxies along in neighboring clusters, and Vela’s existence could help explain the movement of our celestial home.

Via: ScienceNews

Source: Max Planck Institute, Oxford Journals

Humanity’s corner of the Milky Way may be larger than expected

If you accept conventional views of the Milky Way, humans live in a sort of cosmic cul-de-sac: our star is in the Orion Arm (aka Local Arm), a small spur sitting in between the much larger Sagittarius and Perseus arms. A team of international researchers might just shake up that sense of place, however. They’ve published a study indicating that our arm is much, much larger than once thought. Instead, it incorporates a large arm that extends almost all the way to the Perseus Arm, and another long spur that branches between the Orion and Sagittarius arms. It’s now believed to be about 25,000 light years long, or several times longer than expected.

The findings come after discovering several Orion Arm masers, or bright spots of radio emissions frequently caused by gas. Compare them to a readily available source of light on Earth (here, the light from a handheld red laser) and you can gauge their relative distance and speed.

It won’t surprise you to hear that verifying this data could be difficult. The study relied on the northern hemisphere’s Very Long Baseline Array of telescopes, and you’d need info from the southern hemisphere to form a more complete view. It’s not as if you can fly above the galaxy to get a better look, either. Even so, what’s here is enough to suggest that our segment of the Milky Way isn’t just a tiny offshoot, and that we don’t know as much about our galactic home as we think we do.

Via: Space.com

Source: Science Advances

Scientists map the Milky Way Galaxy in exceptional detail

There have been detailed maps of the Milky Way before, but none quite so ornate as this. Researchers in the HI4PI sky survey have created a fine-grained map of our home galaxy using its most common material: neutral atomic hydrogen. Such studies have taken place before, as you might guess. However, the use of 10 billion data points from large radio telescopes (the Parkes Observatory and Effelsberg 100m) and noise-filtering algorithms have produced an image with twice the sensitivity as the previous best, and four times the angular resolution. The result? A view of the Milky Way so comprehensive that you can finally see the finer details of cloud structures in between stars — they were too blurry before.

The info isn’t just useful for visualizing humanity’s cosmic neighborhood, of course. Those structures likely helped form stars in the Milky Way for billions of years, so they could offer insight into the galaxy’s development. It could help us understand the rest of the universe, as well. As everything we can observe passes through that hydrogen, knowing its concentrations will help scientists correct their findings. It’s like cleaning a window, the study’s Dr. Benjamin Winkel says. The map and its data will be freely available to researchers around the world, so you could see a wave of discoveries that were previously held back by limited maps.

Via: CNN

Source: ICRAR

Universe may hold 10 times more galaxies than once thought

The observable universe was already incomprehensibly big, but it now looks to be even bigger. Astronomers have determined that are likely about 10 times more galaxies than previously thought, or between 1 trillion to 2 trillion. We just don’t have the technology (or physical proximity) to detect them all, according to the researchers. They reached the conclusion after converting Hubble Deep Field images into 3D to study the number of galaxies at a given point in the universe’s history, and using mathematical models to infer the possibility of galaxies that we haven’t spotted. Simply speaking, the volume of galaxies seen over time doesn’t make sense unless there are many we aren’t aware of.

Why don’t we see them? It may be a combination of our limited technology with the evolution of the universe itself. We can only do so much to account for redshifting (the light effect as objects move further away) and interference like cosmic gas, and that’s before accounting for the ever-changing nature of the cosmos. At least the data may help answer a key riddle. The shrinking number of galaxies supports the theory that galactic mergers are shaping the universe, radically reducing the overall galaxy count as more and more collisions take place.

It could be a long while before it’s possible to directly verify these calculations. There may need to be a dramatic improvement in telescope technology. And remember, even the 2 trillion figure likely doesn’t represent the whole universe. The very nature of light limits our ability to see the whole of existence — it’s possible that there are many, many more galaxies lurking out of range.

Via: Washington Post

Source: Hubble Space Telescope

Hubble study helps explain the heyday of galaxy formation

The Hubble Space Telescope still isn’t done giving up secrets of the early universe. Researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that a patch of 10 billion-year-old galaxies in Hubble’s Ultra Deep Field view holds gas that helps explain the “Golden Age” of galaxy and star formation. This first completely “blind” (that is, not expecting anything) 3D millimeter wavelength search of the old universe turned up galaxies with an abundance of carbon monoxide, a hint that they were rich in the molecular gas key to creating stars.

Combined with Hubble’s visible and infrared light data, the ALMA search forms a much more complete picture of galaxy formation. Astronomers could even create a 3D map of the universe’s star-forming potential, transitioning from a young period (where those gas-laden galaxies were common) to today. There’s a promise of more, too. The Ultra Deep Field study covered a slice of sky for 50 hours, but a future initiative, the ALMA Spectroscopic Survey in the Hubble UDF, should cover a larger area over 150 hours. You may hear much more about the history of the cosmos in the near future.

Source: ALMA, NRAO Outreach (Vimeo)

Strange galaxy is made almost entirely of dark matter

A galaxy isn’t big just because it has many stars in it. A worldwide research group has discovered that a galaxy in the Coma cluster, Dragonfly 44, consists of 99.99 percent dark matter. It has about as much mass as our own Milky Way galaxy, but far fewer stars. The team determined the presence of the invisible, mysterious substance based on the motions of the stars themselves — there were too few of them to be moving so quickly. If there weren’t a gravitational force like dark matter to hold them together, those stars would simply fly away.

Dragonfly 44 raises more questions than it solves right now. The team’s Roberto Abraham tells Wired that it’s unclear as to how a dark matter galaxy on this scale could form. Previous examples were much smaller. It’s possible that the formations of the stars (very dense clusters) are a clue, but that’s as far as astronomers can go right now. The hope is that someone will find a similar galaxy closer to home, increasing the chances of finding a dark matter particle and making some sense out a baffling (but virtually ubiquitous) aspect of the universe.

Via: Wired

Source: Astrophysical Journal Letters