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pacome delva

Milky Way Grew by Swallowing Other Galaxies - 0 views

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    Globular clusters in our galaxy would be the remnants of dwarf galaxies eaten by our galaxy the milky way ! This assumption is quite revolutionary and would support an accretion model of the universe rather than the formation of huge galaxies. So what about the formation of giant black holes in the center of galaxies...?
Alexander Wittig

Scientists discover hidden galaxies behind the Milky Way - 1 views

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    Hundreds of hidden nearby galaxies have been studied for the first time, shedding light on a mysterious gravitational anomaly dubbed the Great Attractor. Despite being just 250 million light years from Earth-very close in astronomical terms-the new galaxies had been hidden from view until now by our own galaxy, the Milky Way. Using CSIRO's Parkes radio telescope equipped with an innovative receiver, an international team of scientists were able to see through the stars and dust of the Milky Way, into a previously unexplored region of space. The discovery may help to explain the Great Attractor region, which appears to be drawing the Milky Way and hundreds of thousands of other galaxies towards it with a gravitational force equivalent to a million billion Suns. Lead author Professor Lister Staveley-Smith, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said the team found 883 galaxies, a third of which had never been seen before. "The Milky Way is very beautiful of course and it's very interesting to study our own galaxy but it completely blocks out the view of the more distant galaxies behind it," he said. Professor Staveley-Smith said scientists have been trying to get to the bottom of the mysterious Great Attractor since major deviations from universal expansion were first discovered in the 1970s and 1980s. "We don't actually understand what's causing this gravitational acceleration on the Milky Way or where it's coming from," he said. "We know that in this region there are a few very large collections of galaxies we call clusters or superclusters, and our whole Milky Way is moving towards them at more than two million kilometres per hour." The research identified several new structures that could help to explain the movement of the Milky Way, including three galaxy concentrations (named NW1, NW2 and NW3) and two new clusters (named CW1 and CW2).
Marion Nachon

Galaxy collisions not the only source of monster black hole activity | Space | EarthSky - 1 views

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    In a surprise announcement earlier today (July 13), the European Southern Observatory said that monster black holes - those giants of millions or billions of solar masses, thought to lurk at the hearts of most galaxies - have a mechanism to become active other than galaxy collisions.
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    "A new study combining data from ESO's Very Large Telescope and ESA's XMM-Newton X-ray space observatory has turned up a surprise. Most of the huge black holes in the centers of galaxies in the past 11 billion years were not turned on by mergers between galaxies, as had been previously thought." and "The process that activates a sleeping black hole - turning its galaxy from quiet to active - has been a mystery in astronomy. What triggers the violent outbursts at a galaxy's center, which then becomes an active galactic nucleus? Up to now, many astronomers thought that most of these active nuclei were turned on when two galaxies merged, or when they passed close to each other and the disrupted material became fuel for the central black hole. Results of the new study indicate this idea may be wrong for many active galaxies." very interesting indeed
jaihobah

The Network Behind the Cosmic Web - 1 views

shared by jaihobah on 18 Apr 16 - No Cached
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    "The concept of the cosmic web-viewing the universe as a set of discrete galaxies held together by gravity-is deeply ingrained in cosmology. Yet, little is known about architecture of this network or its characteristics. Our research used data from 24,000 galaxies to construct multiple models of the cosmic web, offering complex blueprints for how galaxies fit together. These three interactive visualizations help us imagine the cosmic web, show us differences between the models, and give us insight into the fundamental structure of the universe."
pacome delva

The Quasar That Built a Galaxy - 0 views

  • One of the quasar's jets is aimed directly at the galaxy, and the team thinks it's likely that the jet is driving the star-making process by blasting matter into the galaxy.
  • The discovery creates a new picture of galaxy formation
pacome delva

Galaxy study backs general relativity - 1 views

  • The observed ratio, dubbed EG, has a value of 0.39 ± 0.06. This agrees with general relativity, which predicts a value of 0.4. Crucially, the measurement rules out the tensor, vector scalar (TeVeS) model of modified gravity, which has an EG of 0.22 and does not need dark matter. The result does not, however, preclude the f(R) theory – which is more similar to general relativity and has EG values in the 0.328–0.365 range.
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    mmm, i wonder if this study takes into account the non linearities studied in the Ariadna on galaxies...
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    Luzi: any comment?
pacome delva

Galaxy Zoo 2 : The Story So Far - 3 views

  • The original Galaxy Zoo was launched in July 2007, with a data set made up of a million galaxies imaged with the robotic telescope of the Sloan Digital Sky Survey. With so many galaxies, the team thought that it might take at least two years for visitors to the site to work through them all. Within 24 hours of launch, the site was receiving 70,000 classifications an hour, and more than 50 million classifications were received by the project during its first year, from almost 150,000 people.
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    this is what I call a nice example of crowdsourcing or citizen scientists .... (remember my idea in the ideastorm ?? :-)
Thijs Versloot

Properties of galaxies reproduced by hydrodynamic simulation (VIDEO) - 3 views

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    Scientists at MIT have traced 13 billion years of galaxy evolution, from shortly after the Big Bang to the present day. Their simulation, named Illustris, captures both the massive scale of the Universe and the intriguing variety of galaxies - something previous modelers have struggled to do. It produces a Universe that looks remarkably similar to what we see through our telescopes, giving us greater confidence in our understanding of the Universe, from the laws of physics to our theories about galaxy formation. "Simulation is the future of innovation"
Luís F. Simões

The Amazing Trajectories of Life-Bearing Meteorites from Earth - Technology Review - 0 views

  • That raises another interesting question: how quickly could life-bearing ejecta from Earth (or anywhere else) seed the entire galaxy? Hara and co calculate that it would take some 10^12 years for ejecta to spread through a volume of space the size of the Milky Way. But since our galaxy is only 10^10 years old, a single ejection event could not have done the trick. However, they say that if life evolved at 25 different sites in the galaxy 10^10 years ago, then the combined ejecta from these places would now fill the Milky Way.
  • Ref: arxiv.org/abs/1204.1719: Transfer of Life-Bearing Meteorites from Earth to Other Planets
Juxi Leitner

Artificial Astronomer Analyzes Galaxies Almost As Well As We Do | Singularity Hub - 1 views

  • program to agree with human analysis at an impressive rate of more than 90%
ESA ACT

Home | Galaxy Zoo - 0 views

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    An alternative to curiosity cloning: Let millions of people have a look at the pictures...
jaihobah

A precise extragalactic test of General Relativity - 0 views

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    Einstein's theory of gravity, General Relativity (GR), has been tested precisely within the Solar System. However, it has been difficult to test GR on the scale of an individual galaxy. Collett et al. exploited a nearby gravitational lens system, in which light from a distant galaxy (the source) is bent by a foreground galaxy (the lens). Mass distribution in the lens was compared with the curvature of space-time around the lens, independently determined from the distorted image of the source. The result supports GR and eliminates some alternative theories of gravity.
jaihobah

Debate Intensifies Over Dark Disk Theory | Quanta Magazine - 0 views

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    An alternative idea to the standard WIMP halo picture for the DM distribution in the galaxy
santecarloni

Astronomers Discover Rectangular Galaxy - Technology Review - 0 views

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    ...they came in all shapes...
pacome delva

A New Way to Map the Universe - 0 views

  • A new technique might soon enable cosmologists to map the universe even when they can't pick out individual galaxies. If it works, researchers would be able to probe the structure of 500 times as much of the universe as they have studied so far.
  • With a purpose-built radio telescope, the approach could map as much as 50% of the observable universe far faster and cheaper than galaxy surveys can, Loeb says.
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    impressive
Joris _

Public asked to define a galaxy - 1 views

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    "collective wisdom" to define what a "galaxy" is. Is it really a good approach ? It does not seem any sociologist is involved in the process. http://arxiv.org/PS_cache/arxiv/pdf/1101/1101.3309v1.pdf
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    How about "collective wisdom" on what "stupid research" is?
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