The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type Ia supernovae (SNe Ia) using ...repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5° wide centered on the celestial equator in the Southern Galactic Cap that has been imaged numerous times in earlier years, enabling construction of a deep reference image for the discovery of new objects. Supernova imaging observations are being acquired between September 1 and November 30 of 2005-7. During the first two seasons, each region was imaged on average every five nights. Spectroscopic follow-up observations to determine supernova type and redshift are carried out on a large number of telescopes. In its first two three-month seasons, the survey has discovered and measured light curves for 327 spectroscopically confirmed SNe Ia, 30 probable SNe Ia, 14 confirmed SNe Ib/c, 32 confirmed SNe II, plus a large number of photometrically identified SNe Ia, 94 of which have host-galaxy spectra taken so far. This paper provides an overview of the project and briefly describes the observations completed during the first two seasons of operation.
The Sloan Digital Sky Survey-II Supernova Survey has identified a large number of new transient sources in a 300 deg{sup 2} region along the celestial equator during its first two seasons of a ...three-season campaign. Multi-band (ugriz) light curves were measured for most of the sources, which include solar system objects, galactic variable stars, active galactic nuclei, supernovae (SNe), and other astronomical transients. The imaging survey is augmented by an extensive spectroscopic follow-up program to identify SNe, measure their redshifts, and study the physical conditions of the explosions and their environment through spectroscopic diagnostics. During the survey, light curves are rapidly evaluated to provide an initial photometric type of the SNe, and a selected sample of sources are targeted for spectroscopic observations. In the first two seasons, 476 sources were selected for spectroscopic observations, of which 403 were identified as SNe. For the type Ia SNe, the main driver for the survey, our photometric typing and targeting efficiency is 90%. Only 6% of the photometric SN Ia candidates were spectroscopically classified as non-SN Ia instead, and the remaining 4% resulted in low signal-to-noise, unclassified spectra. This paper describes the search algorithm and the software, and the real-time processing of the SDSS imaging data. We also present the details of the supernova candidate selection procedures and strategies for follow-up spectroscopic and imaging observations of the discovered sources.
We present a measurement of the rate of Type Ia supernovae (SNe Ia) from the first of three seasons of data from the SDSS-II Supernova Survey. For this measurement, we include 17 SNe Ia at redshift ...image. Assuming a flat cosmology with image, we find a volumetric SN Ia rate of image, at a volume-weighted mean redshift of 0.09. This result is consistent with previous measurements of the SN Ia rate in a similar redshift range. The systematic errors are well controlled, resulting in the most precise measurement of the SN Ia rate in this redshift range. We use a maximum likelihood method to fit SN rate models to the SDSS-II Supernova Survey data in combination with other rate measurements, thereby constraining models for the redshift evolution of the SN Ia rate. Fitting the combined data to a simple power-law evolution of the volumetric SN Ia rate, image, we obtain a value of image, i.e., the SN Ia rate is determined to be an increasing function of redshift at the image2.5 capital sigma level. Fitting the results to a model in which the volumetric SN rate is image, where image is the stellar mass density and image is the star formation rate, we find image.
This paper presents spectroscopy of supernovae (SNe) discovered in the first season of the Sloan Digital Sky Survey-II SN Survey. This program searches for and measures multi-band light curves of SNe ...in the redshift range z = 0.05-0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the SN population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our SN spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the SN and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host-galaxy contamination existing in the majority of our SN spectra.
This article examines the quality and rigor of the academic literature on radicalization. Drawing on a sample of 260 publications that make claims for empirical research and were published between ...1980 and 2010, it shows that qualitative approaches dominate, and that a significant number of publications relies on secondary sources-not primary research-to support their conclusions. Methodologies tend to be stronger and more rigorous in the social sciences than the humanities. Overall, it finds that research on radicalization contains clusters of excellence that meet the highest scholarly standards, but that it also suffers from some of the same problems that afflict the wider field of terrorism studies: 34 percent of the items in our sample were either methodologically or empirically poor, whereas 11 percent were both. The article argues that this situation may have resulted from an overreliance on (poorly controlled) government money, the nature of the subject itself, and the absence of a unified academic "field" through which tougher academic standards could be enforced.
What Everyone Says Liu, Alan; Droge, Abigail; Kleinman, Scott ...
Daedalus,
08/2022, Letnik:
151, Številka:
3
Journal Article
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Using computational means to understand patterns in how the humanities are mentioned in U.S. journalism, the WhatEvery1Says project brings into focus challenging problems in the perception of the ...humanities. This essay reports on the project’s findings and some of the further questions that emerged from them. For example, how does the “humanities crisis” appear among the many crises of our time? Why do the humanities figure so often in connection with concrete, ordinary life yet also seem abstract in value? How can more of the substance of humanistic research be communicated as opposed to appearing as just academic business? And why is there so little focus in the media on how underrepresented populations are positioned in relation to the humanities by comparison to science and social, political, or economic issues? The essay concludes by recommending that the humanities reframe their crisis as part of larger human crises requiring multidisciplinary “grand challenge” approaches.
Using effective temperature and metallicity derived from SDSS spectra for image60,000 F- and G-type main-sequence stars, we develop polynomial models for estimating these parameters from the SDSS ...image and image colors. These photometric estimates have similar error properties as those determined from SDSS spectra. We apply this method to SDSS photometric data for over 2 million F/G stars and measure the unbiased metallicity distribution for a complete volume-limited sample of stars at distances between 500 pc and 8 kpc. The metallicity distribution can be exquisitely modeled using two components with a spatially varying number ratio, which correspond to disk and halo. The two components also possess the kinematics expected for disk and halo stars. The metallicity of the halo component is spatially invariant, while the median disk metallicity smoothly decreases with distance from the Galactic plane from -0.6 at 500 pc to -0.8 beyond several kiloparsecs. The absence of a correlation between metallicity and kinematics for disk stars is in a conflict with the traditional decomposition in terms of thin and thick disks. We detect coherent substructures in the kinematics-metallicity space, such as the Monoceros stream, which rotates faster than the LSR, and has a median metallicity of image, with an rms scatter of only image0.15 dex. We extrapolate our results to the performance expected from the Large Synoptic Survey Telescope (LSST) and estimate that LSST will obtain metallicity measurements accurate to 0.2 dex or better, with proper-motion measurements accurate to image0.5 mas yr super(-1), for about 200 million F/G dwarf stars within a distance limit of image100 kpc.
Kleinman traces the historical sources of the story of "Havelok the Dane," which is very well known in eastern England from the 12th century until the end of the Middle Ages. The earliest ...Anglo-Norman version was presented in Geofrey Gaimar's "Estoire des Engleis." Later, a number of shorter versions of the story came from the 14th century Middle Ages such as the English poem "Havelok the Dane," which differs from Gaimar's account in the names of its characters and many details of the plot.
Kleinman demonstrates that Anglo-Saxon legal discourse continued to function as a vehicle for exploration of current legal disputes, specifically the status of the royal forest. More generally, he ...wishes to demonstrate that vernacular writers in post-Conquest England turned repeatedly to the image of the forest as a means of examining the importance of historical continuity to the legitimacy of legal principles and practices. In the first part of Kleinman's discussion, he shows how the creation of this new jurisdictional region, not strictly defined by older boundaries, challenged established notions about the "immemoriality" of the law and its relation to kingship. He next discusses the use of fri∂ in Anglo-Saxon legal language and argue that its adoption as a term for the royal forest prompts reflection about the legal basis for social freedoms and prerogatives. Looking especially at La ... amon's Brut, he will suggest that the forest was a disputable territory in which rival native or local claims vied with colonial or royal ones. Among the competing forensic traditions, the king's jurisdiction over the forest is the means by which La ... amon recognizes that royal authority serves at once as a medium for legal change and for the naturalization of foreign legal practices. In the final section of this essay, he explores the use of fri∂ by two of La ... amon's later readers, the Otho reviser of the Brut and the poet of the Alliterative Morte Arthure.(ProQuest: ... denotes non-US-ASCII text omitted.)
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