[9] arXiv:0801.3870 [ps, pdf, other] Title: The case for OH suppression at near-infrared wavelengths Authors: S.C. Ellis (AAO), J. Bland-Hawthorn (University of Sydney) Comments: Accepted for publication in MNRAS Subjects: Astrophysics (astro-ph) We calculate the advances in near-infrared astronomy made possible through the use of fibre Bragg gratings to selectively remove hydroxyl emission lines from the night sky spectrum. Fibre Bragg gratings should remove OH lines at high resolution (R=10,000), with high suppression (30dB) whilst maintaining high throughput (~90 per cent) between the lines. Devices currently under construction should remove 150 lines in each of the J and H bands, effectively making the night sky surface brightness ~4 magnitudes fainter. This background reduction is greater than the improvement adapative optics makes over natural seeing; photonic OH suppression is at least as important as adaptive optics for the future of cosmology. We present a model of the NIR sky spectrum, and show that the interline continuum is very faint (~80 ph/s/m^s/arcsec/micron on the ecliptic plane). We show that OH suppression by high dispersion, i.e. `resolving out' the skylines, cannot obtain the required level of sensitivity to reach the interline continuum due to scattering of light. The OH lines must be suppressed prior to dispersion. We have simulated observations employing fibre Bragg gratings of first light objects, high redshift galaxies and cool, low-mass stars. The simulations are of complete end-to-end systems from object to detector. The results demonstrate that fibre Bragg grating OH suppression will significantly advance our knowledge in many areas of astrophysics, and in particular will enable rest-frame ultra-violet observations of the Universe at the time of first light and reionisation. 15] arXiv:0801.3905 [ps, pdf, other] Title: Average Properties of a Large Sample of z_abs ~ z_em associated Mg II Absorption Line Systems Authors: D.Vanden Berk, P.Khare, D.G.York, G.T.Richards, B.Lundgren, Y.Alsayyad, V.P.Kulkarni, M.SubbaRao, D.P.Schneider, T. Heckman, S.Anderson, A.P.S.Crotts, J. Frieman, C. Stoughton, J.T.Lauroesch, P.B.Hall, A.Meiksin, M. Steffing, J.Vanlandingham Comments: Accepted for publication in ApJ Subjects: Astrophysics (astro-ph) We have studied a sample of 415 associated (z_ab z_em; relative velocity with respect to QSO <3000km/s) Mg II absorption systems with 1.0<=z_ab<=1.86, in the spectra of SDSS DR3 QSOs, to determine the dust content and ionization state in the absorbers. We studied the dependence of these properties on the properties of the QSOs and also, compared the properties with those of a similarly selected sample of 809 intervening systems (apparent relative velocity with respect to the QSO of >3000km/s), so as to understand their origin. From the analysis of the composite spectra, as well as from the comparison of measured equivalent widths in individual spectra, we conclude that the associated Mg II absorbers have higher apparent ionization, measured by the strength of the C IV absorption lines compared to the Mg II absorption lines, than the intervening absorbers. The ionization so measured appears to be related to apparent ejection velocity, being lower as the apparent ejection velocity is more and more positive. There is clear evidence, from the composite spectra, for SMC like dust attenuation in these systems; the 2175AA absorption feature is not present. The extinction is almost twice that observed in the similarly selected sample of intervening systems. We reconfirm that QSOs with non-zero FIRST radio flux are intrinsically redder than the QSOs with no detection in the FIRST survey. The incidence of associated Mg II systems in QSOs with non-zero FIRST radio flux is 1.7 times that in the QSOs with no detection in the FIRST survey. The associated absorbers in radio-detected QSOs which comprise about 12% of our sample, cause 3 times more reddening than the associated absorbers in radio-undetected QSOs. This excess reddening possibly suggests an intrinsic nature for the associated absorbers in radio-detected QSOs. arXiv:0801.4010 [ps, pdf, other] Title: Symposium Summary Authors: Claus Leitherer (STScI) Comments: 10 pages. Summary talk of IAU Symp. 250, Massive Stars as Cosmic Engines, Kauai (HI), 12/2007, ed. F. Bresolin, P. Crowther, & J. Puls Subjects: Astrophysics (astro-ph) I summarize the highlights of the conference. First I provide a brief history of the beach symposia series our massive star community has been organizing. Then I use most of my allocated space discussing what I believe are the main answered and open questions in the field. Finally I conclude with a perspective of the future of massive star research. [29] arXiv:0801.4017 [ps, pdf, other] Title: The Subaru/XMM-Newton Deep Survey (SXDS) - II. Optical Imaging and Photometric Catalogs Authors: H. Furusawa, G. Kosugi, M. Akiyama, T. Takata, K. Sekiguchi, I. Tanaka, I. Iwata, M. Kajisawa, N. Yasuda, M. Doi, M. Ouchi, C. Simpson, K. Shimasaku, T. Yamada, J. Furusawa, T. Morokuma, C. M. Ishida, K. Aoki, T. Fuse, M. Imanishi, M. Iye, H. Karoji, N. Kobayashi, T. Kodama, Y. Komiyama, Y. Maeda, S. Miyazaki, Y. Mizumoto, F. Nakata, J. Noumaru, R. Ogasawara, S. Okamura, T. Saito, T. Sasaki, Y. Ueda, M. Yoshida Comments: 55 pages, 22 figures, 9 tables, accepted by ApJS, a higher-resolution version is available at this http URL Subjects: Astrophysics (astro-ph) We present multi-waveband optical imaging data obtained from observations of the Subaru/XMM-Newton Deep Survey (SXDS). The survey field, centered at R.A.=02:18:00, decl.=-05:00:00, has been the focus of a wide range of multi-wavelength observing programs spanning from X-ray to radio wavelengths. A large part of the optical imaging observations are carried out with Suprime-Cam on Subaru Telescope at Mauna Kea in the course of Subaru Telescope Observatory Projects. This paper describes our optical observations, data reduction and analysis procedures employed, and the characteristics of the data products. A total area of 1.22 sqdeg is covered in five contiguous sub-fields, each of which corresponds to a single Suprime-Cam field of view (34'x27'), in five broad-band filters B, V, Rc, i', z' to the depths of B=28.4, V=27.8, Rc=27.7, i'=27.7 and z'=26.6 (AB, 3-sigma, 2-arcsec aperture). The data are reduced and compiled into five multi-waveband photometric catalogs, separately for each Suprime-Cam pointing. The i'-band catalogs contain about 900,000 objects, making the SXDS catalogs one of the largest multi-waveband catalogs in corresponding depth and area coverage. The SXDS catalogs can be used for an extensive range of astronomical applications such as the number density of the Galactic halo stars to the large scale structures at the distant universe. The number counts of galaxies are derived and compared with those of existing deep extragalactic surveys. The optical data, the source catalogs, and configuration files used to create the catalogs are publicly available via the SXDS web page (this http URL) [39] arXiv:0801.4255 [ps, pdf, other] Title: A generalisation of the mass-sheet degeneracy producing ring-like artefacts in the lens mass distribution Authors: J. Liesenborgs, S. De Rijcke, H. Dejonghe, P. Bekaert Comments: 6 pages, accepted for publication by MNRAS Subjects: Astrophysics (astro-ph) The inversion of a gravitational lens system is, as is well known, plagued by the so-called mass-sheet degeneracy: one can always rescale the density distribution of the lens and add a constant-density mass-sheet such that the, also properly rescaled, source plane is projected onto the same observed images. For strong lensing systems, it is often claimed that this degeneracy is broken as soon as two or more sources at different redshifts are available. This is definitely true in the strict sense that it is then impossible to add a constant-density mass-sheet to the rescaled density of the lens without affecting the resulting images. However, often one can easily construct a more general mass distribution -- instead of a constant-density sheet of mass -- which gives rise to the same effect: a uniform scaling of the sources involved without affecting the observed images. We show that this can be achieved by adding one or more circularly symmetric mass distributions, each with its own center of symmetry, to the rescaled mass distribution of the original lens. As it uses circularly symmetric distributions, this procedure can lead to the introduction of ring shaped features in the mass distribution of the lens. In this paper, we show explicitly how degenerate inversions for a given strong lensing system can be constructed. It then becomes clear that many constraints are needed to effectively break this degeneracy. [1] arXiv:0801.4559 [ps, pdf, other] Title: A Limit on the Number Density of Bright z~7 Galaxies Authors: Elizabeth R. Stanway (Bristol), Malcolm N. Bremer (Bristol), Valentina Squitieri (Bristol), Laura S. Douglas (Bristol, Paris), Matthew D. Lehnert (Paris) Comments: 8 pages, accepted for publication in MNRAS Subjects: Astrophysics (astro-ph) We present a survey of bright optical dropout sources in two deep, multiwavelength surveys comprising eleven widely-separated fields, aimed at constraining the galaxy luminosity function at z~7 for sources at 5-10L*(z=6). Our combined survey area is 225 arcmin^2 to a depth of J=24.2 (AB, 3 sigma) and 135 arcmin^2 to J=25.3 (AB, 4 sigma). We find that infrared data longwards of 2 microns is essential for classifying optical dropout sources, and in particular for identifying cool Galactic star contaminants. Our limits on the number density of high redshift sources are consistent with current estimates of the Lyman break galaxy luminosity function at z=6. [29] arXiv:0801.4674 [ps, pdf, other] Title: Was the Universe neutral beyond redshift six? Authors: S. Gallerani, A. Ferrara, X. Fan, Choudhury T. Roy, R. Salvaterra Comments: 6 pages, 3 figures; to appear in the Proceedings `A Century of Cosmology', San Servolo (Venezia, Italy), August 2007, to be published in `Il Nuovo Cimento' Subjects: Astrophysics (astro-ph) We provide measurements of the neutral hydrogen fraction xHI at z~6, by comparing semi-analytical models of the Lyalpha forest with observations of high-z quasars and Gamma Ray Bursts absorption spectra. We analyze the transmitted flux in a sample of 17 QSOs spectra at 5.74