540 research outputs found

    PRM48 Diagnostic Tools for the Assessment of the Underlying Model Assumptions in the Study of Health Care Costs

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    The WiFeS S7 AGN survey: Current status and recent results on NGC 6300

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    The Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) is a targeted survey probing the narrow-line regions (NLRs) of a representative sample of ~140 nearby (z<0.02) Seyfert galaxies by means of optical integral field spectroscopy. The survey is based on a homogeneous data set observed using the Wide Field Spectrograph WiFeS. The data provide a 25x38 arcsec2^2 field-of-view around the galaxy centre at typically ~1.5 arcsec spatial resolution and cover a wavelength range between ~3400 - 7100 A˚\AA at spectral resolutions of ~100 km s1^{-1} and ~50 km s1^{-1} in the blue and red parts, respectively. The survey is primarily designed to study gas excitation and star formation around AGN, with a special focus on the shape of the AGN ionising continuum, the interaction between radio jets and the NLR gas, and the nature of nuclear LINER emission. We provide an overview of the current status of S7-based results and present new results for NGC 6300.Comment: 5 pages, 1 figure, Refereed Proceeding of the "The Universe of Digital Sky Surveys" conference held at the INAF - Observatory of Capodimonte, Naples, on 25th-28th november 2014, to be published on Astrophysics and Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodic

    Dual axis operation of a micromachined rate gyroscope,

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    SUMMARY Since micromachining technology has raised the prospect of fabricating high performance sensors without the associated high cost and large size, many researchers [i,2,3,4] have investigated micromachined rate gyroscopes. The vast majority of research has focused on single input axis rate gyroscopes, but this paper presents work on a dual input axis micromachined rate gyroscope. The key to successful simultaneous dual axis operation is the quad symmetry of the circular oscillating rotor design. Untuned gyroscopes with mismatched modes yielded random walk as low as 10 &quot;/dhour with cross sensitivity ranging from 6% to 16%. Mode frequency matching via electrostatic tuning allowed pefiormance better than 2 Vdhour, but at the expense of excessive cross sensitivity

    Testing Diagnostics of Nuclear Activity and Star Formation in Galaxies at z>1

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    We present some of the first science data with the new Keck/MOSFIRE instrument to test the effectiveness of different AGN/SF diagnostics at z~1.5. MOSFIRE spectra were obtained in three H-band multi-slit masks in the GOODS-S field, resulting in two hour exposures of 36 emission-line galaxies. We compare X-ray data with the traditional emission-line ratio diagnostics and the alternative mass-excitation and color-excitation diagrams, combining new MOSFIRE infrared data with previous HST/WFC3 infrared spectra (from the 3D-HST survey) and multiwavelength photometry. We demonstrate that a high [OIII]/Hb ratio is insufficient as an AGN indicator at z>1. For the four X-ray detected galaxies, the classic diagnostics ([OIII]/Hb vs. [NII]/Ha and [SII]/Ha) remain consistent with X-ray AGN/SF classification. The X-ray data also suggest that "composite" galaxies (with intermediate AGN/SF classification) host bona-fide AGNs. Nearly 2/3 of the z~1.5 emission-line galaxies have nuclear activity detected by either X-rays or the classic diagnostics. Compared to the X-ray and line ratio classifications, the mass-excitation method remains effective at z>1, but we show that the color-excitation method requires a new calibration to successfully identify AGNs at these redshifts.Comment: 7 pages, 4 figures. Accepted to ApJ Letter

    GOODS-HerschelHerschel: identification of the individual galaxies responsible for the 80-290μ\mum cosmic infrared background

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    We propose a new method of pushing HerschelHerschel to its faintest detection limits using universal trends in the redshift evolution of the far infrared over 24μ\mum colours in the well-sampled GOODS-North field. An extension to other fields with less multi-wavelength information is presented. This method is applied here to raise the contribution of individually detected HerschelHerschel sources to the cosmic infrared background (CIRB) by a factor 5 close to its peak at 250μ\mum and more than 3 in the 350μ\mum and 500μ\mum bands. We produce realistic mock HerschelHerschel images of the deep PACS and SPIRE images of the GOODS-North field from the GOODS-HerschelHerschel Key Program and use them to quantify the confusion noise at the position of individual sources, i.e., estimate a "local confusion noise". Two methods are used to identify sources with reliable photometric accuracy extracted using 24μ\mum prior positions. The clean index (CI), previously defined but validated here with simulations, which measures the presence of bright 24μ\mum neighbours and the photometric accuracy index (PAI) directly extracted from the mock HerschelHerschel images. After correction for completeness, thanks to our mock HerschelHerschel images, individually detected sources make up as much as 54% and 60% of the CIRB in the PACS bands down to 1.1 mJy at 100μ\mum and 2.2 mJy at 160μ\mum and 55, 33, and 13% of the CIRB in the SPIRE bands down to 2.5, 5, and 9 mJy at 250μ\mum, 350μ\mum, and 500μ\mum, respectively. The latter depths improve the detection limits of HerschelHerschel by factors of 5 at 250μ\mum, and 3 at 350μ\mum and 500μ\mum as compared to the standard confusion limit. Interestingly, the dominant contributors to the CIRB in all HerschelHerschel bands appear to be distant siblings of the Milky Way (zz\sim0.96 for λ\lambda<<300μ\mum) with a stellar mass of MM_{\star}\sim9×\times1010^{10}M_{\odot}.Comment: 22 pages, 16 figures. Accepted for publication by Astronomy and Astrophysic

    Cosmic Star Formation History and its Dependence on Galaxy Stellar Mass

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    We examine the cosmic star formation rate (SFR) and its dependence on galaxy stellar mass over the redshift range 0.8 < z < 2 using data from the Gemini Deep Deep Survey (GDDS). The SFR in the most massive galaxies (M > 10^{10.8} M_sun) was six times higher at z = 2 than it is today. It drops steeply from z = 2, reaching the present day value at z ~ 1. In contrast, the SFR density of intermediate mass galaxies (10^{10.2} < M < 10^{10.8} M_sun) declines more slowly and may peak or plateau at z ~ 1.5. We use the characteristic growth time t_SFR = rho_M / rho_SFR to provide evidence of an associated transition in massive galaxies from a burst to a quiescent star formation mode at z ~ 2. Intermediate mass systems transit from burst to quiescent mode at z ~ 1, while the lowest mass objects undergo bursts throughout our redshift range. Our results show unambiguously that the formation era for galaxies was extended and proceeded from high to low mass systems. The most massive galaxies formed most of their stars in the first ~3 Gyr of cosmic history. Intermediate mass objects continued to form their dominant stellar mass for an additional ~2 Gyr, while the lowest mass systems have been forming over the whole cosmic epoch spanned by the GDDS. This view of galaxy formation clearly supports `downsizing' in the SFR where the most massive galaxies form first and galaxy formation proceeds from larger to smaller mass scales.Comment: Accepted for publication in ApJ
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