Verschuur G.L.,Arecibo Observatory
Astrophysical Journal | Year: 2015
High-resolution galactic neutral hydrogen (HI) data obtained with the Green Bank Telescope (GBT) over 56 square degrees of sky around l = 132°, b = 25° are compared with small-scale structure in the Cosmic Microwave Background observed by PLANCK, specifically at 143 and 857 GHz, as well as with 100 μm observations from the IRIS survey. The analysis uses data in 13 2° × 2° sub-areas found in the IRSA database at IPAC. The results confirm what has been reported previously; nearby galactic HI features and high-frequency continuum sources believed to be cosmological are in fact clearly associated. While several attempts strongly suggest that the associations are statistically significant, the key to understanding the phenomenon lies in the fact that in any given area HI is associated with cirrus dust at certain HI velocities and with 143 GHz features at different velocities. At the same time, for the 13 sub-areas studied, there is very little overlap between the dust and 143 GHz features. The data do not imply that the HI itself gives rise to the high-frequency continuum emission. Rather, they appear to indicate undiagnosed brightness enhancements indirectly associated with the HI. If low density interstellar electrons concentrated into clumps, or observed in directions where their integrated line-of-sight column densities are greater than the background in a manner similar to the phenomena that give rise to structure in diffuse HI structure, they will profoundly affect attempts to create a foreground electron mask used for processing PLANCK as well as WMAP data. © 2015. The American Astronomical Society. All rights reserved.
Wharton R.S.,Cornell University |
Chatterjee S.,Cornell University |
Cordes J.M.,Cornell University |
Deneva J.S.,Arecibo Observatory |
Lazio T.J.W.,Jet Propulsion Laboratory
Astrophysical Journal | Year: 2012
The detection of radio pulsars within the central few parsecs of the Galaxy would provide a unique probe of the gravitational and magneto-ionic environments in the Galactic center (GC) and, if close enough to SgrA*, precise tests of general relativity in the strong-field regime. While it is difficult to find pulsars at radio wavelengths because of interstellar scattering, the payoff from detailed timing of pulsars in the GC warrants a concerted effort. To motivate pulsar surveys and help define search parameters for them, we constrain the pulsar number and spatial distribution using a wide range of multiwavelength measurements. These include the five known radio pulsars within 15′ of SgrA*, non-detections in high-frequency pulsar surveys of the central parsec, radio and gamma-ray measurements of diffuse emission, a catalog of radio point sources from an imaging survey, infrared observations of massive star populations in the central few parsecs, candidate pulsar wind nebulae in the inner 20pc, and estimates of the core-collapse supernova rate based on X-ray measurements. We find that under current observational constraints, the inner parsec of the Galaxy could harbor as many as 103 active radio pulsars that are beamed toward Earth. Such a large population would distort the low-frequency measurements of both the intrinsic spectrum of SgrA* and the free-free absorption along the line of sight of SgrA*. © 2012. The American Astronomical Society. All rights reserved..
Taylor P.A.,Arecibo Observatory |
Margot J.-L.,University of California at Los Angeles
Icarus | Year: 2014
We derive the locations of the fully synchronous end states of tidal evolution for binary asteroid systems having one spherical component and one oblate- or prolate-spheroid component. Departures from a spherical shape, at levels observed among binary asteroids, can result in the lack of a stable tidal end state for particular combinations of the system mass fraction and angular momentum, in which case the binary must collapse to contact. We illustrate our analytical results with near-Earth Asteroids (8567) 1996 HW1, (66391) 1999 KW4, and 69230 Hermes. © 2013 Elsevier Inc.
News Article | April 7, 2016
New results from NANOGrav -- the North American Nanohertz Observatory for Gravitational Waves -- establish astrophysically significant limits in the search for low-frequency gravitational waves. This result provides insight into how often galaxies merge and how those merging galaxies evolve over time. To obtain this result, scientists required an exquisitely precise, nine-year pulsar-monitoring campaign conducted by two of the most sensitive radio telescopes on Earth, the Green Bank Telescope in West Virginia and the Arecibo Observatory in Puerto Rico.
A Swiss company is set to become the first firm to capture carbon dioxide from the air and sell it on a commercial scale, a stepping stone to larger facilities that could one day help to combat global warming. Around July, Climeworks will start capturing some 75 tonnes of CO per month at its plant near Zurich, then selling the gas to nearby greenhouses to boost crop growth. Another company — Carbon Engineering in Calgary, Canada, which has been capturing CO since October but is yet to bring it to market — hopes to show that it can convert the gas into liquid fuel. Facilities worldwide already capture the gas from power-plant exhausts, but until 2015 only small demonstration projects sucked it up from air. Human trials will get under way for treatments that use DNA-editing technologies. Sangamo Biosciences in Richmond, California, will test the use of enzymes called zinc-finger nucleases to correct a gene defect that causes haemophilia. Working with Biogen of Cambridge, Massachusetts, it will also start a trial to look at whether the technique can boost a functional form of haemo-globin in people with the blood disorder β-thalassaemia. Scientists and ethicists hope to agree on broad safety and ethical guidelines for gene editing in humans in late 2016. And this year could see the birth of the first gene-edited monkeys that show symptoms of the human disorders they are designed to model. Physicists think there is a good chance that they will see the first evidence of gravitational waves — ripples in space-time caused by dense, moving objects such as spiralling neutron stars — thanks to the Advanced Laser Interferometer Gravitational-Wave Observatory (Advanced LIGO). And Japan will launch Astro-H, a next-generation X-ray satellite observatory that, among other things, could confirm or refute the claim that heavy neutrinos give off dark-matter signals known as bulbulons. Hints of a potential new particle from the supercharged Large Hadron Collider (LHC), which has been running at record energies since last June, could become clearer as the machine rapidly accumulates data. Even if the particle is not confirmed, the LHC could still unearth other exotic phenomena, such as glueballs: particles made entirely of the carriers of the strong nuclear force. Scientists will soon hear whether funding for research that makes viruses more dangerous can resume. In October 2014, the US government abruptly suspended financial support for ‘gain-of-function’ studies. These experiments could increase understanding of how certain pathogens evolve and how they can be destroyed, but critics say that the work also boosts the risk of, for example, accidental release of deadly viruses. A risk–benefit analysis was completed in December 2015, and the US National Science Advisory Board for Biosecurity will issue recommendations in the next few months on whether to resume funding — potentially with tightened restrictions on the research. One lucky research group will win a $50-million grant for heart-disease research from Internet giant Google and the American Heart Association. Google’s disease-research portfolio is growing, and neuroscientists are eager to see what Thomas Insel, former director of the US National Institute of Mental Health, will do at the firm, where he has been leading a mental-health effort since November. Private funding could also make its mark in space: the non-profit Planetary Society in Pasadena, California, plans to launch a US$4.5-million mission in April to test its light-driven spacecraft, LightSail. The orbits of Earth and Mars will bring the planets close to each other this year, creating the perfect opportunity for a trip to the red planet. A joint mission between the European Space Agency (ESA) and Roscosmos will capitalize on that chance. Launching in March, ExoMars 2016 will analyse gases in Mars’s atmosphere and test landing technology. Farther afield, NASA’s Juno mission will arrive at Jupiter in July. In September, ESA’s craft Rosetta will make a death dive into the comet it orbits; mourners can console themselves with the launch of NASA’s OSIRIS-REx, a mission to bring back samples from the asteroid Bennu. Hot on the heels of the launch of the US$100-million Dark Matter Particle Explorer (DAMPE) last December, China’s National Space Science Center will launch the second and third space-science probes in its planned series of five. The world’s first quantum communications test satellite will blast off in June, and the Hard X-ray Modulation Telescope — which will scour the sky for energetic sources of radiation, such as black holes and neutron stars — will fly by the end of the year. September will see China complete construction of the 500-meter Aperture Spherical Radio Telescope (FAST), which will supersede Puerto Rico’s Arecibo Observatory as the world’s largest radio telescope. In Hawaii, the team behind the controversial Thirty Meter Telescope, which had its construction permit revoked in December, will try to work out whether and how it can move the project forward. The first results from an ambitious project to analyse the world’s microbial communities are expected this year. The Earth Microbiome Project, which launched in 2010, aims to sequence and characterize at least 200,000 samples of microbial DNA taken from everything from Komodo dragon tongues to soil in the Siberian tundra. The project promises to uncover unprecedented levels of biological diversity. In November, the United States will elect a new president. If a Republican takes the White House, long-debated plans to bury nuclear waste at Yucca Mountain in Nevada may well resurface, and federal funding for climate and social science could face the chop. And if Canada’s Liberal government lives up to its pre-election promises, the country will get a chief science officer, who researchers trust will arrive with a drive to rebuild the depleted ranks of government scientists. Neuroscientists hope to finally identify genes that are crucial to regulating the timing and duration of sleep but have been difficult to tease out, possibly because they also have other functions in the brain. Pinpointing these genes could shed light on sleep disorders and some psychiatric illnesses, which scientists now realize are linked to highly disrupted sleep patterns. The SESAME (Synchrotron-light for Experimental Science and Applications in the Middle East) facility will switch on in Jordan towards the end of 2016. The ring-shaped particle accelerator will generate intense light to probe materials and biological structures down to the atomic level. It is the region’s first major international research facility, and a rare collaboration between governments including Iran, Israel and the Palestinian Authority. Support to build a similar facility in Africa is likely to gather pace. And in June, scientists will get to use bright X-ray beams at the world’s first fourth-generation synchrotron, MAX IV in Lund, Sweden.