Little Galaxies Are Big on Dark Matter
The stellar stream in the halo of the nearby dwarf starburst galaxy NGC 4449 is resolved into its individual starry constituents in this exquisite image taken with the 8.2-meter Subaru Telescope and Suprime-Cam. Image credit: R. Jay GaBany and Aaron J. Romanowsky (UCSC) in collaboration with David Martinez-Delgado (MPIA) and NAOJ. Image processed by R. Jay GaBany
Dark matter… It came into existence at the moment of the Big Bang. Within its confines, galaxies formed and evolved. If you add up all the parts contained within any given galaxy you derive its mass, yet its gravitational effects can only be explained by the presence of this mysterious subatomic particle. It would be easy to believe that the larger the galaxy, the larger the amount of dark matter should be present, but new research shows that isn’t so. Dwarf galaxies have even higher proportions of dark matter than their larger counterparts. Although the dwarfs are the most common of all, we know very little about them – even when they consume each other. Enter the star stream… (…)
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New Submillimetre Camera Sheds Light on the Dark Regions of the Universe
A composite image of the Whirlpool Galaxy (also known as M51). The green image is from the Hubble Space Telescope and shows the optical wavelength. The submillimetre light detected by SCUBA-2 is shown in red (850 microns) and blue (450 microns). The Whirlpool Galaxy lies at an estimated distance of 31 million light years from Earth in the constellation Canes Venatici Credit: JAC / UBC / Nasa
The stars and faint galaxies you see when you look up at the night sky are all emitting light within the visible light spectrum — the portion of the electromagnetic spectrum we can see with our unaided eyes or through optical telescopes. But our galaxy, and many others, contain huge amounts of cold dust that absorbs visible light. This accounts for the dark regions.
A new camera recently unveiled at the James Clerk Maxwell Telescope (JCMT) in Hawaii promises to figuratively shed light on this dark part of the universe. The SCUBA-2 submillimetre camera (SCUBA in this case is an acronym for Submillimetre Common-User Bolometer Array) can detect light at lower energy levels, allowing astronomers to gather data on these dark areas and ultimately learn more about our universe and its formation. (…)
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Astronomy Without A Telescope – Could Dark Matter Not Matter?
Rotation curves of the Andromeda Galaxy. Actual rotational velocities of the outer stars are the white line, while velocities that would be expected from the estimated mass of the visible matter in the galaxy are the red line. Hence, we conclude that over 80% of the galaxy’s mass must be dark matter. (Credit Queens Uni.).
You probably want to put on your skeptical goggles and set them to maximum for this one. An Italian mathematician has come up with some complex formulae that can, with remarkable similarity, mimic the rotation curves of spiral galaxies without the need for dark matter.
Currently, these galactic rotation curves represent key evidence for the existence of dark matter – since the outer stars of spinning galaxies often move around a galactic disk so fast that they should fly off into intergalactic space – unless there is an additional ‘invisible’ mass present in the galaxy to gravitationally hold them in their orbits.(…)
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One promising puzzle piece for confirming dark matter now seems unlikely fit
Astronomy Magazine News Article – Released:11/29/2011
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Positron Signaling For Dark Matter Inconclusive
The Fermi Gamma-ray Space Telescope (formerly called GLAST). Credit: NASA
A couple of years ago, the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics, PAMELA, sent us back some curious information… an overload of anti-matter in the Milky Way. Why does this member of the cosmic ray spectrum have interesting implications to the scientific community? It could mean the proof needed to confirm the existence of dark matter. (…)
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Newly found dwarf galaxies could help reveal the nature of dark matter
Astronomy Magazine News Article – Released:11/7/2011
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Dark matter mystery deepens
Astronomy Magazine News Article – Released:10/18/2011
Astronomy.com News – Presented by Astronomy Magazine
Dark and bright: The European Space Agency chooses next two science missions
Astronomy Magazine News Article – Released:10/17/2011
Astronomy.com News – Presented by Astronomy Magazine
Hubble survey carries out a dark matter census
Astronomy Magazine News Article – Released:10/13/2011
Astronomy.com News – Presented by Astronomy Magazine
Dark Matter Movie from the Bolshoi Simulation
What if you could fly through the universe and see dark matter?
Black hole, star collisions may illuminate universe’s dark side
Astronomy Magazine News Article – Released:9/22/2011
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Gamma-ray bursts shed light on the nature of dark energy
Astronomy Magazine News Article – Released:9/20/2011
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Alone In The Dark?
This is the portion of sky in which astronomers found the Segue 1 dwarf galaxy. Can you see it? Credit: Marla Geha
Two years ago, Marla Geha, a Yale University astronomer, Joshua Simon from the Carnegie Institution of Washington, and their colleagues discovered something unusual while studying with the Keck II telescope and information for the Sloan Digital Sky Survey. Their observations turned up a contrasting group of stars which all appeared to be moving in unison – not just a moving cluster of similar stars which could have been torn away from the nearby Sagittarius dwarf galaxy. The team knew they were on to something, but a competing group of astronomers at Cambridge University was skeptical. Too bad… there was a dark treasure right there before their eyes. (…)
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Post tags: Dark Galaxy, Dark Matter, Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS), Keck II, Moving Stellar Groups, Segue 1
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“Zombie” stars key to measuring dark energy
Astronomy Magazine News Article – Released:7/5/2011
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Model Lighting Ordinance Means Preservation Of Future Dark Skies
Image Courtesy of IDA
For every astronomer everywhere – and even naturalists – the need to preserve dark skies has been an issue tackled by the International Dark Skies Association for over two decades. It’s more than just asking your neighbor to turn off their porch light while you’re observing. It’s about light pollution as a whole – from government to community lighting. In the past the IDA has relied on education, but now things could be getting a whole lot better. (…)
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Astronomy Without A Telescope – Holographic Dark Information Energy
The bubble nebula NGC 7635 – it doesn't have a lot to do with Holographic Dark Information Energy, but you have to start these articles with an image. Credit: Croman/an APOD for November 7 2005.
Holographic Dark Information Energy gets my vote for the best mix of arcane theoretical concepts expressed in the shortest number of words – and just to keep it interesting, it’s mostly about entropy.(…)
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GALEX Confirms Nature of Dark Energy
New results from NASA's Galaxy Evolution Explorer and the Anglo-Australian Telescope atop Siding Spring Mountain in Australia confirm that dark energy (represented by purple grid) is a smooth, uniform force that now dominates over the effects of gravity (green grid). The observations follow from careful measurements of the separations between pairs of galaxies (examples of such pairs are illustrated here).Image credit: NASA/JPL-Caltech
From a JPL press release:
A five-year survey of 200,000 galaxies, stretching back seven billion years in cosmic time, has led to one of the best independent confirmations that dark energy is driving our universe apart at accelerating speeds. The survey used data from NASA’s space-based Galaxy Evolution Explorer and the Anglo-Australian Telescope on Siding Spring Mountain in Australia.
(…)
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IceCube After Dark
My colleague Liz Kruesi did a great job covering some of last week’s highlights at the Antarctic Science Symposium and IceCube and particle physics symposium, but unfortunately she couldn’t stay for the final event. That’s too bad, because it was mostly just a celebratory conclusion, complete with free food and beer. But since the conference took place in Madison, Wisconsin, where I live (while Liz had to drive more than an hour home afterward to rescue her dog), I graciously volunteered to cover the party. Anyone familiar with our video series shouldn’t be surprised.
Antarctica is home to countless scientists who can get down and party just as hard (practically) as your typical college student. // Photo by NASATo put things in perspective, I’ll remind you that Madison is a college town, home to, not surprisingly, the University of Wisconsin-Madison. It might have been nice if someone had reminded the symposium’s planners that this past weekend was also the date of one of the city’s two biggest parties of the year. I’m sure poor Liz wasn’t the only one befuddled by hordes of drunk college students, a lack of parking, and the general debauchery in the air she witnessed before she departed Saturday afternoon.
Perhaps it was all part of the planners’ … plans. This final event, called IceCube After Dark, took place at The Majestic, a somewhat raucous theater that occasionally puts on performances of The Rocky Horror Picture Show. The free beer and hors d’oeuvres made the concluding event feel like the scientific equivalent of the partying a few blocks away.
After about a half-hour of mingling and jazzy standards playing in the background, the main presentation began. Mark Krasberg of UW-Madison gave a PowerPoint talk broadly outlining the IceCube experiment and what it is trying to do. Unfortunately, either the attendees’ familiarity with the subject or their alcohol consumption often forced Krasberg to wait for the chatter to die down, frequently lamenting how it impaired his concentration. I didn’t blame him, and vowed to speak more quietly.
When Krasberg moved from the science and schematics to pictures of penguins, the crowd instantly hushed. Sea lions, whales, various penguins, the auroa australis, and Antarctica’s frozen beauty kept the audience rapt for the remainder of the talk, which ended with standing ovations and cheers.
Next up were selections from the 2005 South Pole International Film Festival (SPIFF), which were variously hilarious, musical, and hard to understand (the Norwegian film).
SPIFF marked the night’s official end, but the symposium’s planners had one final surprise. The Majestic’s famed “80S VS 90S” night would supposedly feature a heavy dose of notoriously scientific rapper Ice Cube. I left before I could verify this, however. If I’m going to dance to rap music slightly buzzed, I might as well do it with 20,000 others outside.
We missed you, Liz!
Astronomy Without A Telescope – Dark Statistics
The dark flow hypothesis. A region of the observable universe is being influenced by a mysterious something outside the observable universe (which we can’t observe). Source: universe-review.ca
The hypothetical dark flow seen in the movement of galaxy clusters requires that we can reliably identify a clear statistical correlation in the motion of distant objects which are, in any case, flowing outwards with the expansion of the universe and may also have their own individual (or peculiar) motion arising from gravitational interactions. (…)
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Hubble rules out one alternative to dark energy
Astronomy Magazine News Article – Released:3/22/2011
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Herschel measures dark matter required for star-forming galaxies
Astronomy Magazine News Article – Released:2/17/2011
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Hunt for Dark Matter Closes in at the LHC
The Large Hadron Collider’s Compact Muon Solenoid (CMS) detector. Credit: CMS Collaboration/CERN
From an Imperial College London press release:
Physicists say they are closer than ever to finding the source of the Universe’s mysterious dark matter, following a better than expected year of research at the Compact Muon Solenoid (CMS) particle detector, part of the Large Hadron Collider (LHC) at CERN in Geneva.
(…)
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No direct link between black holes and dark matter
Astronomy Magazine News Article – Released:1/20/2011
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Measuring dark energy just got better
Astronomy Magazine News Article – Released:1/13/2011
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Shedding New Light on the Cosmic Dark Ages
Representation of the timeline of the universe over 13.7 billion years, from the Big Bang, through the cosmic dark ages and formation of the first stars, to the expansion in the universe that followed. Credit: NASA/WMAP Science Team.
From a University of Cambridge press release:
Remnants of the first stars have helped astronomers get closer to unlocking the “dark ages” of the cosmos. A team of researchers from the University of Cambridge and California Institute of Technology are using light emitted from massive black holes called quasars to “light up” gases released by the early stars, which exploded billions of years ago. As a result, they have found what they refer to as the missing link in the evolution of the chemical universe.
(…)
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Shining starlight on the dark cocoons of star birth
Astronomy Magazine News Article – Released:9/27/2010
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Solving the Mystery of Dark Gamma Ray Bursts
Artists impression of a dark gamma-ray burst. Credit: ESO
Unraveling the mystery of Gamma Ray Bursts (GRBs) is a story filled with international intrigue, fantastic claims, serious back-tracking, and incremental improvements in our understanding of the true nature and implications of the most energetic, destructive forces in the Universe. New results from a team of scientists studying so-called “dark gamma-ray bursts” have firmly snapped a new piece into the GRB puzzle. This research is presented in a paper to appear in the journal Astronomy & Astrophysics on December 16, 2010.
(…)
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Light dawns on dark gamma-ray bursts
Astronomy Magazine News Article – Released:12/16/2010
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Dark Belt Reappearing on Jupiter
Why are planet-circling clouds disappearing and reappearing on Jupiter?
The National Science Foundation gives multi-university project $8 million to study dark energy
Astronomy Magazine News Article – Released:10/21/2010
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Detailed dark matter map yields clues to galaxy cluster growth
Astronomy Magazine News Article – Released:11/12/2010
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Hubble Provides Most Detailed Dark Matter Map Yet
This NASA Hubble Space Telescope image shows the distribution of dark matter in the center of the giant galaxy cluster Abell 1689, containing about 1,000 galaxies and trillions of stars. Credit: NASA, ESA, D. Coe (NASA Jet Propulsion Laboratory/California Institute of Technology, and Space Telescope Science Institute), N. Benitez (Institute of Astrophysics of Andalusia, Spain), T. Broadhurst (University of the Basque Country, Spain), and H. Ford (Johns Hopkins University)
Using Hubble’s Advanced Camera for Surveys, astronomers have been able to chart invisible dark matter in a distant galaxy, which enabled them to create one of the sharpest and most detailed maps of dark matter in the universe. Looking for invisible and indeterminate matter is a difficult job, but one that astronomers have been trying to do for over a decade. This new map also might provide clues on that other mysterious stuff in the universe — dark energy – and what role it played in the universe’s early formative years.
(…)
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Why is this planet so dark?
What is causing these dark streaks on Mars?
In silhouette against a crowded star field
Was this image taken with a telescope or a microscope?