Supernovae in Deep Hubble Space Telescope Galaxy Cluster Fields: Cluster Rates and Field Counts

We have searched for high-redshift supernova (SN) candidates in multiple deep Hubble Space Telescope (HST) archival images of nine galaxy-cluster fields. We detect six apparent SNe, with I814 between 21.6 and 28.4 mag. There is roughly 1 SN per deep (flux limit I814 > 26 mag), doubly-imaged, WFPC2 cluster field. Two SNe are associated with cluster galaxies (at redshifts z=0.18 and z=0.83), three are probably in galaxies not in the clusters (at z=0.49, z=0.60, and z=0.98), and one is at unknown z. After accounting for observational efficiencies and uncertainties (statistical and systematic) we derive the rate of type-Ia SNe within the projected central 500 kpc of rich clusters: R=0.20(+0.84)(-0.19) SNu in clusters at z=0.18 to 0.37, and R=0.41(+1.23)(-0.39) SNu in clusters at z=0.83 to 1.27 (95 per cent confidence interval; H_0=50; 1 SNu = 1 SN per century per 10^10 L_B_sun). Combining the two redshift bins, the SN rate at a mean redshift of z=0.41 is R(z=0.41) = 0.30(+0.58)(-0.28) SNu. The upper bounds argue against SNe-Ia being the dominant source of the large iron mass observed in the intra-cluster medium. We also compare our observed counts of field SNe (i.e., non-cluster SNe of all types) to recent model predictions. The observed field count is zero or one SN with I814 < 26 mag, and 1 to 3 SNe with I814 < 27 mag. These counts are about two times lower than some of the predictions. Since the counts at these magnitudes are likely dominated by type-II SNe, our observations may suggest obscuration of distant SNe-II, or a SN-II luminosity distribution devoid of a large high-luminosity tail.Comment: MNRAS, in press. Small modifications in final version include redshifts for all five detected SN host galaxies, upward revision of cluster SN-Ia rates, and some changes in field SN count

SFX, Information Needs, the Academic Library, and Its User

Introduction Libraries need an efficient way to manage their diverse electronic resources. At the same time, they need a tool that provides users with easy access to those digital items. Guaranteed simple and reliable access to full text sources (depending on existing subscriptions of course) is one of the main concerns of libraries in the digital age. The tool that supplied the solution to this problem is the OpenURL link resolver. (Ponsford, Stephens & Sewell, 2011). Today, SFX by Ex Libris is the most widely used OpenURL link resolver (Robertson &. Soderdahl, 2004). This article examines whether SFX can be used not only as a link resolver, but also as a tool for assessing user information needs. We shall review SFX\u27s contribution to the assessment of information needs in an academic library and its benefits to the users and to the library. Background Most commonly, link resolvers provide the library patron with the ability to move quickly from a citation in an abstracting and indexing database to the full text itself (Robertson &. Soderdahl, 2004). SFX and other link resolvers seamlessly offer links from one information resource to another. For example, users can jump from a citation in an abstracting and indexing source database to target resources, such as full-text articles, online catalogs, interlibrary loan or other options a library chooses to offer. The whole range of possible options is displayed in one menu, instead of having to perform multiple separate searches to locate what they are looking for. (Wakimoto, Walker & Dabbour, 2006). When integrating SFX software with Google Scholar, which is widely used by academics as one of the main gates to reliable academic sources, it enables users to search the library’s collection for e-journals, and eBooks, all through Google Scholar itself. Clicking on SFX icons in Google Scholar, the user is redirected to the SFX resolver, which displays links to the selected article that is a part of the library\u27s subscriptions elsewhere or displays other services related to the article, such as an interlibrary loan service or other function the library chose to offer. (Xu, 2010; Stowers& Tucker, 2009). SFX was first developed at the University of Ghent by Herbert Van de Sompel and was released as a commercial product by Ex Libris in 2001. SFX is an XML-based product that was not only built on the OpenURL framework, it was the technology for which OpenURL was originally defined and thus was the first OpenURL-based link resolver on the market. (Robertson & Soderdahl, 2004). Since 2001, for ten years now, SFX offers a wealth of features for end users and librarians at over 1800 institutions in more than 50 countries as ExLibris puts it. SFX offers its users four major benefits. First, it allows the retrieval of full text items that are part of the library\u27s subscriptions. Second, it enables users to find full text by its citation details without knowing in which database it is hosted. Third, if there is only a print option of the article available it will direct users to the library catalog for the holding information. In case the library doesn\u27t have the requested item, the interlibrary loan option will be suggested by the software. Last but not least, since 2009, SFX includes a recommender system, bX. By harvesting metadata from the SFX usage log files from all of the subscribing institutions, bX provides recommendations to articles. The bX recommendation service is similar to a commercial web site recommender. When a user searches for a specific article he gets a list of articles other users found interesting. This feature is very useful for users (Ponsford, Stephens, Sewell, 2011; Xu, 2010; Imler, 2011). SFX offers some crucial benefits for libraries, too. It not only helps to manage its electronic resources and provides smooth access to its customers, but also it allows librarians to learn a lot more about user information behavior and needs, using its unique features such as its statistical reports and more. The University of Haifa is located in the northern part of Israel, on Mount Carmel and across the Mediterranean Sea. The university community has about 18,000 students (bacholars, graduates, and PhD students) and over 1,200 faculty members. The Younes & Soraya Nazarian library is a central library which serves the entire university community. Its collection comprises more than 2 million books and electronic resources, among them 45,000 electronic journals. In January 2005, the library integrated the SFX software into its systems. The library experience with SFX and report analysis from the SFX log files will be used to demonstrate the potential advantage of SFX in the area of assessing information needs. How SFX Reveals and Satisfies the Academic User\u27s Information Needs The focus of this article is the contribution of SFX as a tool assisting the library to evaluate user information needs and satisfy some of them. This article will assess information needs by some of the parameters as first suggested by David Nicholas in 2000 and updated to the digital consumer by Nicholas & Herman in 2009 (Nicholas, 2000 ; Nicholas & Herman, 2009). SFX usage & statistical reports, produced at the Younes & Soraya Nazarian library of the University of Haifa, will be the source to the data presented according to these parameters

SFX, Information Needs, the Academic Library, and Its User

Introduction Libraries need an efficient way to manage their diverse electronic resources. At the same time, they need a tool that provides users with easy access to those digital items. Guaranteed simple and reliable access to full text sources (depending on existing subscriptions of course) is one of the main concerns of libraries in the digital age. The tool that supplied the solution to this problem is the OpenURL link resolver. (Ponsford, Stephens & Sewell, 2011). Today, SFX by Ex Libris is the most widely used OpenURL link resolver (Robertson &. Soderdahl, 2004). This article examines whether SFX can be used not only as a link resolver, but also as a tool for assessing user information needs. We shall review SFX\u27s contribution to the assessment of information needs in an academic library and its benefits to the users and to the library. Background Most commonly, link resolvers provide the library patron with the ability to move quickly from a citation in an abstracting and indexing database to the full text itself (Robertson &. Soderdahl, 2004). SFX and other link resolvers seamlessly offer links from one information resource to another. For example, users can jump from a citation in an abstracting and indexing source database to target resources, such as full-text articles, online catalogs, interlibrary loan or other options a library chooses to offer. The whole range of possible options is displayed in one menu, instead of having to perform multiple separate searches to locate what they are looking for. (Wakimoto, Walker & Dabbour, 2006). When integrating SFX software with Google Scholar, which is widely used by academics as one of the main gates to reliable academic sources, it enables users to search the library’s collection for e-journals, and eBooks, all through Google Scholar itself. Clicking on SFX icons in Google Scholar, the user is redirected to the SFX resolver, which displays links to the selected article that is a part of the library\u27s subscriptions elsewhere or displays other services related to the article, such as an interlibrary loan service or other function the library chose to offer. (Xu, 2010; Stowers& Tucker, 2009). SFX was first developed at the University of Ghent by Herbert Van de Sompel and was released as a commercial product by Ex Libris in 2001. SFX is an XML-based product that was not only built on the OpenURL framework, it was the technology for which OpenURL was originally defined and thus was the first OpenURL-based link resolver on the market. (Robertson & Soderdahl, 2004). Since 2001, for ten years now, SFX offers a wealth of features for end users and librarians at over 1800 institutions in more than 50 countries as ExLibris puts it. SFX offers its users four major benefits. First, it allows the retrieval of full text items that are part of the library\u27s subscriptions. Second, it enables users to find full text by its citation details without knowing in which database it is hosted. Third, if there is only a print option of the article available it will direct users to the library catalog for the holding information. In case the library doesn\u27t have the requested item, the interlibrary loan option will be suggested by the software. Last but not least, since 2009, SFX includes a recommender system, bX. By harvesting metadata from the SFX usage log files from all of the subscribing institutions, bX provides recommendations to articles. The bX recommendation service is similar to a commercial web site recommender. When a user searches for a specific article he gets a list of articles other users found interesting. This feature is very useful for users (Ponsford, Stephens, Sewell, 2011; Xu, 2010; Imler, 2011). SFX offers some crucial benefits for libraries, too. It not only helps to manage its electronic resources and provides smooth access to its customers, but also it allows librarians to learn a lot more about user information behavior and needs, using its unique features such as its statistical reports and more. The University of Haifa is located in the northern part of Israel, on Mount Carmel and across the Mediterranean Sea. The university community has about 18,000 students (bacholars, graduates, and PhD students) and over 1,200 faculty members. The Younes & Soraya Nazarian library is a central library which serves the entire university community. Its collection comprises more than 2 million books and electronic resources, among them 45,000 electronic journals. In January 2005, the library integrated the SFX software into its systems. The library experience with SFX and report analysis from the SFX log files will be used to demonstrate the potential advantage of SFX in the area of assessing information needs. How SFX Reveals and Satisfies the Academic User\u27s Information Needs The focus of this article is the contribution of SFX as a tool assisting the library to evaluate user information needs and satisfy some of them. This article will assess information needs by some of the parameters as first suggested by David Nicholas in 2000 and updated to the digital consumer by Nicholas & Herman in 2009 (Nicholas, 2000 ; Nicholas & Herman, 2009). SFX usage & statistical reports, produced at the Younes & Soraya Nazarian library of the University of Haifa, will be the source to the data presented according to these parameters

A Magnified View of the Kinematics and Morphology of RCSGA 032727-132609: Zooming in on a Merger at z=1.7

We present a detailed analysis of multi-wavelength HST/WFC3 imaging and Keck/OSIRIS near-IR AO-assisted integral field spectroscopy for a highly magnified lensed galaxy at z=1.70. This young starburst is representative of UV-selected star-forming galaxies (SFG) at z~2 and contains multiple individual star-forming regions. Due to the lensing magnification, we can resolve spatial scales down to 100pc in the source plane of the galaxy. The velocity field shows disturbed kinematics suggestive of an ongoing interaction, and there is a clear signature of a tidal tail. We constrain the age, reddening, SFR and stellar mass of the star-forming clumps from SED modelling of the WFC3 photometry and measure their H-alpha luminosity, metallicity and outflow properties from the OSIRIS data. With strong star formation driven outflows in four clumps, RCSGA0327 is the first high redshift SFG at stellar mass <10^10 M_sun with spatially resolved stellar winds. We compare the H-alpha luminosities, sizes and dispersions of the star-forming regions to other high-z clumps as well as local giant HII regions and find no evidence for increased clump star formation surface densities in interacting systems, unlike in the local Universe. Spatially resolved SED modelling unveils an established stellar population at the location of the largest clump and a second mass concentration near the edge of the system which is not detected in H-alpha emission. This suggests a picture of an equal-mass mixed major merger, which has not triggered a new burst of star formation or caused a tidal tail in the gas-poor component.Comment: 22 pages, 16 figures, accepted to Ap

An iterative joint codebook and classifier improvement algorithm for finite-state vector quantization

A finite-state vector quantizer (FSVQ) is a multicodebook system in, which the current state (or codebook) is chosen as a function of the previously quantized vectors. The authors introduce a novel iterative algorithm for joint codebook and next state function design of full search finite-state vector quantizers. They consider the fixed-rate case, for which no optimal design strategy is known. A locally optimal set of codebooks is designed for the training data and then predecessors to the training vectors associated with each codebook are appropriately labelled and used in designing the classifier. The algorithm iterates between next state function and state codebook design until it arrives at a suitable solution. The proposed design consistently yields better performance than the traditional FSVQ design method (under identical state space and codebook constraints)

Probing Individual Star Forming Regions Within Strongly Lensed Galaxies at z > 1

Star formation occurs on physical scales corresponding to individual star forming regions, typically of order ~100 parsecs in size, but current observational facilities cannot resolve these scales within field galaxies beyond the local universe. However, the magnification from strong gravitational lensing allows us to measure the properties of these discrete star forming regions within galaxies in the distant universe. New results from multi-wavelength spectroscopic studies of a sample of extremely bright, highly magnified lensed galaxies are revealing the complexity of star formation on sub-galaxy scales during the era of peak star formation in the universe. We find a wide range of properties in the rest-frame UV spectra of individual galaxies, as well as in spectra that originate from different star forming regions within the same galaxy. Large variations in the strengths and velocity structure of Lyman-alpha and strong P Cygni lines such as C IV, and MgII provide new insights into the astrophysical relationships between extremely massive stars, the elemental abundances and physical properties of the nebular gas those stars ionize, and the galactic-scale outflows they power.Comment: 4 pages, 3 figures. To be published in the Proceedings of IAU Symposium 309. For more details and closely related work see also arXiv:1310.6695 and arXiv:1406.335