A Cold Cosmic Mystery Solved: Astronomers discover what might be the largest known structure in the universe that leaves its imprint on cosmic microwave background radiation

The Cold Spot area resides in the constellation Eridanus in the southern galactic hemisphere. The insets show the environment of this anomalous patch of the sky as mapped by Szapudi’s team using PS1 and WISE data and as observed in the cosmic microwave background temperature data taken by the Planck satellite. The angular diameter of the vast supervoid aligned with the Cold Spot, which exceeds 30 degrees, is marked by the white circles. Graphics by Gergő Kránicz. Image credit: ESA Planck Collaboration. High-resolution version (6.6 Mb)

Synopsis: A very large cold spot that has been a mystery for over a decade can now be explained

In 2004, astronomers examining a map of the radiation leftover from the Big Bang (the cosmic microwave background, or CMB) discovered the Cold Spot, a larger-than-expected unusually cold area of the sky. The physics surrounding the Big Bang theory predicts warmer and cooler spots of various sizes in the infant universe, but a spot this large and this cold was unexpected.

Now, a team of astronomers led by Dr. István Szapudi of the Institute for Astronomy at the University of Hawaii at Manoa may have found an explanation for the existence of the Cold Spot, which Szapudi says may be “the largest individual structure ever identified by humanity.” 

If the Cold Spot originated from the Big Bang itself, it could be a rare sign of exotic physics that the standard cosmology (basically, the Big Bang theory and related physics) does not explain. If, however, it is caused by a foreground structure between us and the CMB, it would be a sign that there is an extremely rare large-scale structure in the mass distribution of the universe. 

Using data from Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA’s Wide Field Survey Explorer (WISE) satellite, Szapudi’s team discovered a large supervoid, a vast region 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known universe. This void was found by combining observations taken by PS1 at optical wavelengths with observations taken by WISE at infrared wavelengths to estimate the distance to and position of each galaxy in that part of the sky.

Earlier studies, also done in Hawaii, observed a much smaller area in the direction of the Cold Spot, but they could establish only that no very distant structure is in that part of the sky. Paradoxically, identifying nearby large structures is harder than finding distant ones, since we must map larger portions of the sky to see the closer structures. The large three-dimensional sky maps created from PS1 and WISE by Dr. András Kovács (Eötvös Loránd University, Budapest, Hungary) were thus essential for this study. The supervoid is only about 3 billion light-years away from us, a relatively short distance in the cosmic scheme of things.

Imagine there is a huge void with very little matter between you (the observer) and the CMB. Now think of the void as a hill. As the light enters the void, it must climb this hill. If the universe were not undergoing accelerating expansion, then the void would not evolve significantly, and light would descend the hill and regain the energy it lost as it exits the void. But with the accelerating expansion, the hill is measurably stretched as the light is traveling over it. By the time the light descends the hill, the hill has gotten flatter than when the light entered, so the light cannot pick up all the energy it lost upon entering the void. The light exits the void with less energy, and therefore at a longer wavelength, which corresponds to a colder temperature.

Getting through a supervoid can take millions of years, even at the speed of light, so this measurable effect, known as the Integrated Sachs-Wolfe (ISW) effect, might provide the first explanation one of the most significant anomalies found to date in the CMB, first by a NASA satellite called the Wilkinson Microwave Anisotropy Probe (WMAP), and more recently, by Planck, a satellite launched by the European Space Agency.

While the existence of the supervoid and its expected effect on the CMB do not fully explain the Cold Spot, it is very unlikely that the supervoid and the Cold Spot at the same location are a coincidence. The team will continue its work using improved data from PS1 and from the Dark Energy Survey being conducted with a telescope in Chile to study the Cold Spot and supervoid, as well as another large void located near the constellation Draco. 

The study is being published online on April 20 in Monthly Notices of the Royal Astronomical Society by the Oxford University Press. In addition to Szapudi and Kovács, researchers who contributed to this study include UH Manoa alumnus Benjamin Granett (now at the National Institute for Astrophysics, Italy), Zsolt Frei (Eötvös Loránd), and Joseph Silk (Johns Hopkins).

Contacts:

Dr. István Szapudi
+1 808 956-6196
szapudi@ifa.hawaii.edu
 
Dr. András Kovács
+34 93 176 3966
akovacs@ifae.es

Dr. Roy Gal
+1 808-956-6235
cell: +1 301-728-8637
rgal@ifa.hawaii.edu

Ms. Louise Good
Media Contact
+1 808-381-2939
good@ifa.hawaii.edu

 Source:  Institute for Astronomy - University of Hawaii 

Note:

Founded in 1967, the Institute for Astronomy at the University of Hawaii at Manoa conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Maunakea. The Institute operates facilities on the islands of Oahu, Maui, and Hawaii.

The Pan-STARRS1 Surveys (PS1) have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, and the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eötvös Loránd University (ELTE), and the Los Alamos National Laboratory.

A Strange Lonely Planet without a Star

Multicolor image from the Pan-STARRS1 telescope of the free-floating planet PSO J318.5-22, in the constellation of Capricornus. The planet is extremely cold and faint, about 100 billion times fainter in optical light than the planet Venus. Most of its energy is emitted at infrared wavelengths. The image is 125 arcseconds on a side. Credit: N. Metcalfe & Pan-STARRS 1 Science Consortium

WIRCam stacked image of the newly discovered planet. Credits: Dr. Trent Dupuy, Harvard-Smithsonian Center for Astrophysics.

An international team of astronomers has discovered an exotic young planet that is not orbiting a star. This free-floating planet is just 80 light-years away from Earth and has a mass only six times that of Jupiter. The planet formed a mere 12 million years ago—a newborn in terms of planetary lifetimes.

During the past decade, extrasolar planets have been discovered at an incredible pace, with about a thousand found by indirect methods such as wobbling or dimming of their host stars induced by the planet. However, only a handful of planets have been directly imaged, all of which are around young stars, less than 200 million years old. These planets are hard to study because they are right next to their bright host star. In order to understand the physical properties of these planets, astronomers compare them to cold and low mass brown dwarfs that are isolated thus much easier to study. The idea is that the smallest and coldest dwarf stars will have similar properties than those of the giant planets. However, efforts to link these two classes of objects together have so far been unsuccessful. These planets are truly unique objects. 

Using the Pan-STARRS1 (PS1) wide-field survey telescope on Haleakala, Maui, an international team of astronomers identified an object with a faint and unique heat signature. Follow-up observations using IRTF, Gemini, UKIRT and CFHT on Mauna Kea show that it has properties similar to those of gas-giant planets found orbiting around young stars. This free-floating planet, dubbed PSO J318.5-22, is just 80 light-years away from Earth and has a mass only six times that of Jupiter. PSO J318.5-22 is one of the lowest-mass free-floating objects known, perhaps the very lowest. But its most unique aspect is its similar mass, color, and energy output to directly imaged planets. 

 The team did astrometric monitoring of PSO J318.5-22 obtaining 9 epoch over two years using WIRCam on CFHT. The resulting median astrometric precision per epoch is 4.0 milliarcseconds, a stunningly precise measurement for such a faint, cool object. This allowed the direct determination of the distance to PSO J318.5-22 and it's absolute J band magnitude, important parameters for this type of study. Also, using the high precision astrometry provided by WIRCam, the team was able to conclude that PSO J318.5-22 belongs to a collection of young stars called the Beta Pictoris moving group that formed about 12 million years ago thus determining the age of PSO J318.5-22. 

The discovery paper of PSO J318.5-22 is being published by Astrophysical Journal Letters and is available from the arXiv. The key authors of the paper are the lead author, Dr. Michael Liu (Institute for Astronomy at the University of Hawaii at Manoa), Dr. Niall Deacon (Max Planck Institute for Astronomy, Germany), Dr. Katelyn Allers (Bucknell University), Dr. Trent Dupuy (Harvard-Smithsonian Center for Astrophysics), and Michael Kotson and Kimberly Aller (University of Hawaii at Manoa). 

For more Information, please see the official press release.

Canada-France-Hawaii Telescope 

Contacts:

Dr. Michael Liu
mliu@ifa.hawaii.edu
+1-808-956-6666

Dr. Eugene Magnier
eugene@ifa.hawaii.edu
+1-808-232-8440

Louise Good
Media contact
good@ira.hawaii.edu
+1-808-956-9403 

 Source:  Canada-France-Hawaii Telescope 

Ten Thousandth Near-Earth Object Unearthed in Space

Asteroid 2013 MZ5 as seen by the University of Hawaii's PanSTARR-1 telescope. In this animated gif, the asteroid moves relative to a fixed background of stars. Asteroid 2013 MZ5 is in the right of the first image, towards the top, moving diagonally left/down. Image credit: PS-1/UH.  › Larger view | Unannotated version

More than 10,000 asteroids and comets that can pass near Earth have now been discovered. The 10,000th near-Earth object, asteroid 2013 MZ5, was first detected on the night of June 18, 2013, by the Pan-STARRS-1 telescope, located on the 10,000-foot (convert) summit of the Haleakala crater on Maui. Managed by the University of Hawaii, the PanSTARRS survey receives NASA funding.

Ninety-eight percent of all near-Earth objects discovered were first detected by NASA-supported surveys.

"Finding 10,000 near-Earth objects is a significant milestone," said Lindley Johnson, program executive for NASA's Near-Earth Object Observations Program at NASA Headquarters, Washington. "But there are at least 10 times that many more to be found before we can be assured we will have found any and all that could impact and do significant harm to the citizens of Earth." During Johnson's decade-long tenure, 76 percent of the NEO discoveries have been made.

Near-Earth objects (NEOs) are asteroids and comets that can approach the Earth's orbital distance to within about 28 million miles (45 million kilometers). They range in size from as small as a few feet to as large as 25 miles (41 kilometers) for the largest near-Earth asteroid, 1036 Ganymed.

Asteroid 2013 MZ5 is approximately 1,000 feet (300 meters) across. Its orbit is well understood and will not approach close enough to Earth to be considered potentially hazardous.

"The first near-Earth object was discovered in 1898," said Don Yeomans, long-time manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "Over the next hundred years, only about 500 had been found. But then, with the advent of NASA's NEO Observations program in 1998, we've been racking them up ever since. And with new, more capable systems coming on line, we are learning even more about where the NEOs are currently in our solar system, and where they will be in the future."

Of the 10,000 discoveries, roughly 10 percent are larger than six tenths of a mile (one kilometer) in size - roughly the size that could produce global consequences should one impact the Earth. However, the NASA NEOO program has found that none of these larger NEOs currently pose an impact threat and probably only a few dozen more of these large NEOs remain undiscovered.

The vast majority of NEOs are smaller than one kilometer, with the number of objects of a particular size increasing as their sizes decrease. For example, there are expected to be about 15,000 NEOs that are about one-and-half football fields in size (460 feet, or 140 meters), and more than a million that are about one-third a football field in size (100 feet, or 30 meters). A NEO hitting Earth would need to be about 100 feet (30 meters) or larger to cause significant devastation in populated areas. Almost 30 percent of the 460-foot-sized (140-meter-sized) NEOs have been found, but less than 1 percent of the 100-foot-sized NEOs have been detected.

When it originated, the NASA-instituted Near-Earth Object Observations Program provided support to search programs run by the Massachusetts Institute of Technology's Lincoln Laboratory (LINEAR); the Jet Propulsion Laboratory (NEAT); the University of Arizona (Spacewatch, and later Catalina Sky Survey) and the Lowell Observatory (LONEOS). All these search teams report their observations to the Minor Planet Center, the central node where all observations from observatories worldwide are correlated with objects, and they are given unique designations and their orbits are calculated.

"When I began surveying for asteroids and comets in 1992, a near-Earth object discovery was a rare event," said Tim Spahr, director of the Minor Planet Center. "These days we average three NEO discoveries a day, and each month the Minor Planet Center receives hundreds of thousands of observations on asteroids, including those in the main-belt. The work done by the NASA surveys, and the other international professional and amateur astronomers, to discover and track NEOs is really remarkable."

Within a dozen years, the program achieved its goal of discovering 90 percent of near-Earth objects larger than 3,300 feet (1 kilometer) in size. In December 2005, NASA was directed by Congress to extend the search to find and catalog 90 percent of the NEOs larger than 500 feet (140 meters) in size. When this goal is achieved, the risk of an unwarned future Earth impact will be reduced to a level of only one percent when compared to pre-survey risk levels. This reduces the risk to human populations, because once an NEO threat is known well in advance, the object could be deflected with current space technologies.

Currently, the major NEO discovery teams are the Catalina Sky Survey, the University of Hawaii's Pan-STARRS survey and the LINEAR survey. The current discovery rate of NEOs is about 1,000 per year.

NASA's Near-Earth Object Observations Program manages and funds the search for, study of and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. The Minor Planet Center is funded by NASA and hosted by the Smithsonian Astrophysical Observatory in Cambridge, MA. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena. More information about asteroids and near-Earth objects is available at: http://neo.jpl.nasa.gov/, http://www.jpl.nasa.gov/asteroidwatch and via Twitter at http://www.twitter.com/asteroidwatch .

DC Agle
Jet Propulsion Lab., Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov