May 23, 2017

Review: The Cosmic Cocktail by Katherine Freese

A stellar recipe!

It’s the hottest topic in modern astrophysics. What exactly is dark matter and dark energy? It is kind of amazing to think that astrophysicists do not yet completely understand just what most of the universe is made of. [Read more...]

19.04.11: AMS-02: A Preview.

AMS-02…Good to Go! (Credit: NASA.gov). 

A very special payload will be aboard the final flight of Space Shuttle Endeavour, one that had a long hard road to launch. The Alpha Magnetic Spectrometer (AMS) is destined for installation early next month on the S3 Upper Inboard Payload Attach Site on the International Space Station. Once aboard the ISS, the AMS will begin doing real science almost immediately, utilizing a large permanent magnet and no less than five detectors to perform astrophysical experiments. [Read more...]

29.05.10: CERN Moves into New Sub-Atomic Territory.

The LHC tunnel. (Credit: CERN/LHC/Maximilien Brice).

The LHC tunnel. (Credit: CERN/LHC/Maximilien Brice).

 

    The Large Hadron Collider (LHC) is starting to show its stuff. Earlier this year, scientists at the CERN institute on the Swiss-French border powered LHC into uncharted territory, conducting proton collisions in the 7 trillion electron volt (TeV) range.  This is a first for particle physics. One again, the world didn’t end in a dark matter strangelet, a super-massive black hole did not emerge and burrow to the center of our planet, and time travelers from the future did not emerge to sabotage the collider.

    The plan now is to run the LHC at the 7 TeV range for a period of 18 months to 2 years to gain data over known particles and check their agreement with standard particle physics, so that the search for the unknown can begin. Top of the most-wanted list is the Higgs-Boson, an undiscovered particle predicted by super-symmetry. There is a chance that the LHC will nab the Higgs-Boson in its first run if it inhabits the mass range of 160 giga-electron volts (GeV). This is doubtful, but not out of the realm of possibility, since current capabilities go down to 400 GeV. When at full power, the LHC will push those sensitivities down to 800 GeV. The sensitivity of the data measured is expected to be of the level of one inverse femtobarn. This is equal to 1 x 10-43 of a meter, or one trillionth of the diameter of a uranium nucleus. Eventual LHC runs envision detection of exotic particles all the way up into the 2 TeV range.

After the current 7TeV run is completed, a one year shut down will occur for maintenance and upgrades. The subsequent run will see the LHC operating in the 14TeV range for 8 month periods, with 4 month maintenance cycle. The LHC promises to solve the mysteries of super symmetry as well as the questions of dark matter and baryonic matter formation in the early universe. And let’s not forget the concept of string theory that is currently badly in need of observational proof. Along with the LHC, the Alpha Magnetic Spectrometer to be placed on the International Space Station later this year on the final shuttle flight promises to answer some key questions in particle physics. Could we have a Grand Unified “Theory of Everything” that you could fit onto a t-shirt in the next few years? Stay tuned!

23.05.10-Are Black Holes the Key to Dark Matter?

Artist's impression of a torus surrounding a massive black hole. (Credit V. Beckmann.NASA).

An artist’s conception of a gas torus surrounding a super-massive black hole. (Credit: V.Beckmann/NASA).

   For the past few decades, astronomers have been hot on the trail of the “missing” part of our universe. About 23 percent of our universe appears to be comprised of dark matter, non-luminous material that gives itself away only via gravitational interaction. Pinning down dark matter has been the name of the cosmological game, and researchers have looked at everything from MACHOs (Massive Compact Halo Objects) to WIMPs (Weakly Interacting Massive Particles) to everything conceivable, however bizarre or mundane, in between. Now, researchers at the National Autonomous University of Mexico may have gained a key insight into the nature of dark matter, as well as the evolution of galaxies and how the super-massive black holes at their heart are formed. Researchers William Lee and Xavier Hernandez studied the absorption rates of these massive beasts, noting how simulations stacked up with what we observe in the universe we see today. Their findings suggest that dark matter at the cores of galaxies should be fairly homogonous; at a critical mass larger than seven solar masses per cubic light year, a runaway effect occurs, twisting and altering galaxies from the stately whirlpool we see today. Of course, with this mass limit constraint, one could easily ask the question; how did these black holes reach multi-million solar mass status in the first place?  Further studies and data gathered by platforms such as the James Webb Space Telescope will no doubt shed “new light” (bad pun intended) on dark matter as well as tweak standard models and refine the nature of its role in the evolution of the cosmos.

30.03.10- Fermi: On the Hunt for Dark Matter.

A one year portrait of our galaxy in gamma-rays as seen by Fermi. (Credit: NASA).

A one year portrait of our galaxy in gamma-rays as seen by Fermi. (Credit: NASA).

 

   One of the major astrophysical mysteries of our time may be on the verge of being solved. Namely, where is 85% of our universe? That’s the amount that is predicted to be composed of enigmatic dark matter. Now, scientists using NASA’s Fermi Gamma-ray Space Telescope (formerly known as GLAST) have found tantalizing clues at the core of or galaxy; an electron haze thought to be the signature of dark matter annihilations. Fermi passed a milestone of 100 billion detection events with its Large Area Telescope (LAT) last month; such unprecedented sensitivity is giving scientists a new window on the gamma-ray universe. The key is to isolate dark matter sources from other, more “mundane” cosmic events. The tale started back in 2004, when the Wilkinson Microwave Anisotropy Probe (WMAP) began detecting a microwave “haze” centered on the center of our galaxy. Then, just over a year ago, Europe’s Payload for Antimatter Matter Exploration & Light-nuclei Astrophysics (PAMELA) and NASA’s balloon based Advanced Thin Ionization Calorimeter (ATIC) both independently detected high energy positrons and electrons that seemed to emanate from the vicinity of our solar system. This could be explained either by dark matter annihilation or a hidden local dark body source, either conclusion equally bizarre. A good candidate for the Fermi emissions are the annihilation of dark matter neutralinos, which serve as their own anti-particle. The predicted number of neutralino events, however, do not match the quantity of gamma-ray emissions that Fermi sees. Other Earth-bound dark matter detectors are entering the fray, such as the XENON100, and Large Underground Xenon (LUX) dark matter experiment.  Could the puzzle of dark matter be on the verge of an answer soon? Stay tuned…

25.10.09: In Search of a Mirror Universe.

The AMS mission patch to be flown on STS-134 Endevor as the final Space Shuttle flight! (Credit:NASA).

The AMS mission patch to be flown on STS-134 Endeavor on THE final Space Shuttle flight! (Credit:NASA).

There is one enduring mystery in cosmology that just won’t budge; namely, just what happened to all that pesky anti-matter that was presumably created during the Big Bang? Was it annihilated, only to leave the infinitesimally small faction of pedestrian “normal” baryonic matter that comprises the universe that we know and love, or are there still areas that antimatter predominates? Now, cosmologists are getting their wish in the form of the Alpha Magnetic Spectrometer (AMS), due to launch aboard the last shuttle flight and bound for the International Space Station late next year. Once installed, AMS will search the entire sky with an unprecedented accuracy looking for ultra-high energy cosmic rays in the form of anti-helium nuclei. Antimatter looks and behaves just like normal matter…except when it meets up with its mirror cousin. If you meet your anti-matter twin on the road, don’t shake hands with him or her, our you’ll both vanish in a flash of pure energy conversion Ala E=mc^2! The AMS will also look for such exotica as dark matter, micro-quasars, and strangelets, a proposed new form of matter. And that’s just the stuff we know about! I smell a possible Nobel in the works…are you reading this, CERN? The AMS has been an on-again, off-again payload that Congress just green-lighted last year. The AMS promises to reveal a big old, bizarre universe out there. With a sensitivity 200 times anything that’s flown previous, AMS should conclusively prove or disprove the potential existence of any lurking antimatter galaxies out to a radius of 100 mega-parsecs. Like CERN, AMS will also generate terabytes of data to keep astrophysicists awake nights, and will be a fitting end to the shuttle fleets’ career!

August 2009:News & Notes

 

 

You can almost see Neil's foot print! (Credit: NASA/LRO).

You can almost see Neil's foot print! (Credit: NASA/LRO).

 

- The LRO Photographs the Apollo landing sites: Fans of this space may have noticed the racy lunar pics we ran a week back as part of our From Earth to the Moon review. The Lunar Reconnaissance Orbiter did indeed snap pics of the famous Apollo landing sites last month. These clearly show the hardware left at multiple sites, as well as the base(s) of the Lunar Lander ascent stages, complete with shadow. You can even see the astronaut’s foot trails in the lunar dust! And the LRO hasn’t even entered its cruising orbit yet… expect more great pics to come! [Read more...]