601,304 research outputs found
Herschel-ATLAS: Blazars in the science demonstration phase field
To investigate the poorly constrained sub-mm counts and spectral properties of blazars we searched for these in the Herschel-ATLAS (H-ATLAS) science demonstration phase (SDP) survey catalog.
We cross-matched 500 μm sources brighter than 50 mJy with the FIRST radio catalogue. We found two blazars, both previously known. Our study is among the first blind blazar searches at sub-mm wavelengths, i.e., in the spectral regime where little is still known about the blazar SEDs, but where the synchrotron peak of the most luminous blazars is expected to occur. Our early results are consistent with educated extrapolations of lower frequency counts and question indications of substantial spectral curvature downwards and of spectral upturns at mm wavelengths. One of the two blazars is identified with a Fermi/LAT γ-ray source and a WMAP source. The physical parameters of the two blazars are briefly discussed. These observations demonstrate that the H-ATLAS survey will provide key information about the physics of blazars and their contribution to sub-mm counts
Demonstrations for Children of All Age- The Cork Canon
Demonstrations are one of the most useful techniques for teaching science to anyone, regardless of age. Demonstrations attract attention and normally make the observer want to learn more about what is happening. This paper reports on The Cork Cannon, one of the favorite demonstrations done in the demonstration road show, Phun Physics, that travels to schools within about 60 miles of Charlottesville. The Department of Physics and the Center for Science, Mathematics, and Engineering Education sponsor this demonstration show, which was seen by about 8000 persons during the last school year. Although quite simple, the Cork Cannon demonstration is rich in pedagogy and can be used to illuminate several ideas, including temperature, pressure, phase change, heat conduction, water vapor, humidity, projectile motion, air resistance, atmosphere, and kinetic theory
HerMES: SPIRE Science Demonstration Phase maps
We describe the production and verification of sky maps of the five Spectral and Photometric Imaging Receiver (SPIRE) fields observed as part of the Herschel Multi-tiered Extragalactic Survey (HerMES) during the Science Demonstration Phase (SDP) of the Herschel mission. We have implemented an iterative map-making algorithm [The SPIRE-HerMES Iterative Mapper (SHIM)] to produce high fidelity maps that preserve extended diffuse emission on the sky while exploiting the repeated observations of the same region of the sky with many detectors in multiple scan directions to minimize residual instrument noise. We specify here the SHIM algorithm and outline the various tests that were performed to determine and characterize the quality of the maps and verify that the astrometry, point source flux and power on all relevant angular scales meet the needs of the HerMES science goals. These include multiple jackknife tests, determination of the map transfer function and detailed examination of the power spectra of both sky and jackknife maps. The map transfer function is approximately unity on scales from 1 arcmin to 1°. Final maps (v1.0), including multiple jackknives, as well as the SHIM pipeline, have been used by the HerMES team for the production of SDP papers
HerMES: SPIRE Science Demonstration Phase maps
We describe the production and verification of sky maps of the five Spectral and Photometric Imaging Receiver (SPIRE) fields observed as part of the Herschel Multi-tiered Extragalactic Survey (HerMES) during the Science Demonstration Phase (SDP) of the Herschel mission. We have implemented an iterative map-making algorithm [The SPIRE-HerMES Iterative Mapper (SHIM)] to produce high fidelity maps that preserve extended diffuse emission on the sky while exploiting the repeated observations of the same region of the sky with many detectors in multiple scan directions to minimize residual instrument noise. We specify here the SHIM algorithm and outline the various tests that were performed to determine and characterize the quality of the maps and verify that the astrometry, point source flux and power on all relevant angular scales meet the needs of the HerMES science goals. These include multiple jackknife tests, determination of the map transfer function and detailed examination of the power spectra of both sky and jackknife maps. The map transfer function is approximately unity on scales from 1 arcmin to 1°. Final maps (v1.0), including multiple jackknives, as well as the SHIM pipeline, have been used by the HerMES team for the production of SDP papers
The Herschel Virgo Cluster Survey: I. Luminosity functions
We describe the Herschel Virgo Cluster Survey (HeViCS) and the first data
obtained as part of the Science Demonstration Phase (SDP). The data cover a
central 4x4 sq deg region of the cluster. We use SPIRE and PACS photometry data
to produce 100, 160, 250, 350 and 500 micron luminosity functions (LFs) for
optically bright galaxies that are selected at 500 micron and detected in all
bands. We compare these LFs with those previously derived using IRAS, BLAST and
Herschel-ATLAS data. The Virgo Cluster LFs do not have the large numbers of
faint galaxies or examples of very luminous galaxies seen previously in surveys
covering less dense environments.Comment: Letter accepted for publication in A&A (Herschel special issue
Space Station Furnace Facility. Volume 2: Requirements definition and conceptual design study
The Space Station Freedom Furnace (SSFF) Project is divided into two phases: phase 1, a definition study phase, and phase 2, a design and development phase. TBE was awarded a research study entitled, 'Space Station Furnace Facility Requirements Definition and Conceptual Design Study' on June 2, 1989. This report addresses the definition study phase only. Phase 2 is to be complete after completion of phase 1. The contract encompassed a requirements definition study and culminated in hardware/facility conceptual designs and hardware demonstration development models to test these conceptual designs. The study was divided into two parts. Part 1 (the basic part of the effort) encompassed preliminary requirements definition and assessment; conceptional design of the SSFF Core; fabrication of mockups; and preparation for the support of a conceptional design review (CoDR). Part 2 (the optional part of the effort) included detailed definition of the engineering and design requirements, as derived from the science requirements; refinement of the conceptual design of the SSFF Core; fabrication and testing of the 'breadboards' or development models; and preparation for and support of a requirements definition review
Nonlinear pi phase shift for single fiber-guided photons interacting with a single atom
Realizing a strong interaction between individual optical photons is an
important objective of research in quantum science and technology. Since
photons do not interact directly, this goal requires, e.g., an optical medium
in which the light experiences a phase shift that depends nonlinearly on the
photon number. Once the additional phase shift for two photons reaches pi, such
an ultra-strong nonlinearity could even enable the direct implementation of
high-fidelity quantum logic operations. However, the nonlinear response of
standard optical media is many orders of magnitude too weak for this task.
Here, we demonstrate the realization of an optical fiber-based nonlinearity
that leads to an additional two-photon phase shift close to the ideal value of
pi. Our scheme employs a whispering-gallery-mode resonator, interfaced by an
optical nanofiber, where the presence of a single rubidium atom in the
resonator results in a strongly nonlinear response. We experimentally show that
this results in entanglement of initially independent incident photons. The
demonstration of this ultra-strong nonlinearity in a fiber-integrated system is
a decisive step towards scalable quantum logics with optical photons.Comment: 22 pages, 6 figure
Demonstration of Entanglement-Enhanced Phase Estimation in Solid
Precise parameter estimation plays a central role in science and technology.
The statistical error in estimation can be decreased by repeating measurement,
leading to that the resultant uncertainty of the estimated parameter is
proportional to the square root of the number of repetitions in accordance with
the central limit theorem. Quantum parameter estimation, an emerging field of
quantum technology, aims to use quantum resources to yield higher statistical
precision than classical approaches. Here, we report the first room-temperature
implementation of entanglement-enhanced phase estimation in a solid-state
system: the nitrogen-vacancy centre in pure diamond. We demonstrate a
super-resolving phase measurement with two entangled qubits of different
physical realizations: an nitrogen-vacancy centre electron spin and a proximal
C nuclear spin. The experimental data shows clearly the uncertainty
reduction when entanglement resource is used, confirming the theoretical
expectation. Our results represent an elemental demonstration of enhancement of
quantum metrology against classical procedure.Comment: 9 pages including the supplementary material, 6 figures in main text
plus 3 figures in supplementary materia
The Herschel Virgo Cluster Survey - V. Star-forming dwarf galaxies – dust in metal-poor environments
We present the dust properties of a small sample of Virgo cluster dwarf galaxies drawn from the science demonstration phase data set of the Herschel Virgo Cluster Survey. These galaxies have low metallicities (7.8 < 12 + log(O/H) < 8.3) and star-formation rates ≲10^(-1) M_☉ yr^(-1). We measure the spectral energy distribution (SED) from 100 to 500 μm and derive dust temperatures and dust masses. The SEDs are fitted by a cool component of temperature T ≲ 20 K, implying dust masses around 10^5 M_☉ and dust-to-gas ratios within the range 10^(-3)–10^(-2). The completion of the full survey will yield a larger set of galaxies, which will provide more stringent constraints on the dust content of star-forming dwarf galaxies
The Herschel Virgo Cluster Survey. VI. The far-infrared view of M87
The origin of the far-infrared emission from the nearby radio galaxy M87 remains a matter of debate. Some studies find evidence of a far-infrared excess due to thermal dust emission, whereas others propose that the far-infrared emission can be explained by synchrotron emission without
the need for an additional dust emission component. We present Herschel PACS and SPIRE observations of M87, taken as part of the science demonstration phase observations of the Herschel Virgo Cluster Survey. We compare these data with a synchrotron model based on mid-infrared, far-infrared, submm and radio data from the literature to investigate the origin of the far-infrared emission. Both the integrated SED and the Herschel surface brightness maps are adequately explained by synchrotron emission. At odds with previous claims, we find no evidence of a diffuse dust component in M87, which is not unexpected in the harsh X-ray environment of this radio galaxy sitting at the core of the Virgo cluster
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