European Southern Observatory

About: European Southern Observatory is a facility organization based out in Garching bei München, Germany. It is known for research contribution in the topics: Galaxy & Stars. The organization has 3594 authors who have published 16157 publications receiving 823095 citations. The organization is also known as: The European Southern Observatory，ESO & ESO.

Measurements of the temperature and E-mode polarization of the CMB from 500 square degrees of SPTpol data

Abstract: Author(s): Henning, JW; Sayre, JT; Reichardt, CL; Ade, PAR; Anderson, AJ; Austermann, JE; Beall, JA; Bender, AN; Benson, BA; Bleem, LE; Carlstrom, JE; Chang, CL; Chiang, HC; Cho, HM; Citron, R; Moran, CC; Crawford, TM; Crites, AT; Haan, TD; Dobbs, MA; Everett, W; Gallicchio, J; George, EM; Gilbert, A; Halverson, NW; Harrington, N; Hilton, GC; Holder, GP; Holzapfel, WL; Hoover, S; Hou, Z; Hrubes, JD; Huang, N; Hubmayr, J; Irwin, KD; Keisler, R; Knox, L; Lee, AT; Leitch, EM; Li, D; Lowitz, A; Manzotti, A; McMahon, JJ; Meyer, SS; Mocanu, L; Montgomery, J; Nadolski, A; Natoli, T; Nibarger, JP; Novosad, V; Padin, S; Pryke, C; Ruhl, JE; Saliwanchik, BR; Schaffer, KK; Sievers, C; Smecher, G; Stark, AA; Story, KT; Tucker, C; Vanderlinde, K; Veach, T; Vieira, JD; Wang, G; Whitehorn, N; Wu, WLK; Yefremenko, V | Abstract: We present measurements of the E-mode polarization angular auto-power spectrum (EE) and temperature-E-mode cross-power spectrum (TE) of the cosmic microwave background (CMB) using 150 GHz data from three seasons of SPTpol observations. We report the power spectra over the spherical harmonic multipole range 50 l l ≤ 8000 and detect nine acoustic peaks in the EE spectrum with high signal-to-noise ratio. These measurements are the most sensitive to date of the EE and TE power spectra at l g 1050 and l g 1475, respectively. The observations cover 500 , a fivefold increase in area compared to previous SPTpol analyses, which increases our sensitivity to the photon diffusion damping tail of the CMB power spectra enabling tighter constraints on ΛCDM model extensions. After masking all sources with unpolarized flux mJy, we place a 95% confidence upper limit on residual polarized point-source power of at Dl = l(l+1)ll/2π l 0.107 μK2 at l = 3000, suggesting that the EE damping tail dominates foregrounds to at least l= 4050 with modest source masking. We find that the SPTpol data set is in mild tension with the ΛCDM model (2.1 δ), and different data splits prefer parameter values that differ at the ∼ 1 δ level. When fitting SPTpol data at l l 1000, we find cosmological parameter constraints consistent with those for Planck temperature. Including SPTpol data at lg 1000 results in a preference for a higher value of the expansion rate (H071.3 ± 2.1 Km s-1 Mpc-1) and a lower value for present-day density fluctuations (δ8 =0.77 ±0.02).

150 W highly-efficient Raman fiber laser

Abstract: We report a more than 150 W spectrally-clean continuous wave Raman fiber laser at 1120 nm with an optical efficiency of 85%. A ~30 m standard single mode silica fiber is used as Raman gain fiber to avoid second Stokes emission. A spectrally asymmetric resonator (in the sense of mirror reflection bandwidth) with usual fiber Bragg gratings is designed to minimize the laser power lost into the unwanted direction, even when the effective reflectivity of the rear fiber Bragg grating becomes as low as 81.5%.

On the Lyalpha emission from gamma-ray burst host galaxies: Evidence for low metallicities

Abstract: We report on the results of a search for Ly emission from the host galaxy of the z= 2:140 GRB 011211 and other galaxies in its surrounding field. We detect Ly emission from the host as well as from six other galaxies in the field. The restframe equivalent width of the Ly line from the GRB 011211 host is about 21 A. This is the fifth detection of Ly emission out of five possible detections from GRB host galaxies, strongly indicating that GRB hosts, at least at high redshifts, are Ly emitters. This is intriguing as only 25% of the Lyman-Break selected galaxies at similar redshifts have Ly emission lines with restframe equivalent width larger than 20 A. Possible explanations are i) a preference for GRB progenitors to be metal-poor as expected in the collapsar model, ii) an optical afterglow selection bias against dusty hosts, and iii) a higher fraction of Ly emitters at the faint end of the luminosity function for high- z galaxies. Of these, the current evidence seems to favour i).

Hubble Space Telescope hot Jupiter transmission spectral survey: a detection of Na and strong optical absorption in HAT-P-1b

Abstract: We present an optical to near-infrared transmission spectrum of the hot Jupiter HAT-P-1b, based on Hubble Space Telescope observations, covering the spectral regime from 0.29 to 1.027 μm with Space Telescope Imaging Spectrograph (STIS), which is coupled with a recent Wide Field Camera 3 (WFC3) transit (1.087 to 1.687 μm). We derive refined physical parameters of the HAT-P-1 system, including an improved orbital ephemeris. The transmission spectrum shows a strong absorption signature shortward of 0.55 μm, with a strong blueward slope into the near-ultraviolet. We detect atmospheric sodium absorption at a 3.3σ significance level, but find no evidence for the potassium feature. The red data imply a marginally flat spectrum with a tentative absorption enhancement at wavelength longer than ∼0.85 μm. The STIS and WFC3 spectra differ significantly in absolute radius level (4.3 ± 1.6 pressure scaleheights), implying strong optical absorption in the atmosphere of HAT-P-1b. The optical to near-infrared difference cannot be explained by stellar activity, as simultaneous stellar activity monitoring of the G0V HAT-P-1b host star and its identical companion show no significant activity that could explain the result. We compare the complete STIS and WFC3 transmission spectrum with theoretical atmospheric models which include haze, sodium and an extra optical absorber. We find that both an optical absorber and a supersolar sodium to water abundance ratio might be a scenario explaining the HAT-P-1b observations. Our results suggest that strong optical absorbers may be a dominant atmospheric feature in some hot Jupiter exoplanets.

Luminous blue variables as the progenitors of supernovae with quasi-periodic radio modulations

Abstract: The interaction between supernova ejecta and circumstellar matter, arising from previous episodes of mass loss, provides us with a means of constraining the progenitors of supernovae. Radio observations of a number of supernovae show quasi-periodic deviations from a strict power-law decline at late times. Although several possibilities have been put forward to explain these modulations, no single explanation has proven to be entirely satisfactory. Here we suggest that Luminous blue variables undergoing S-Doradus type variations give rise to enhanced phases of mass loss that are imprinted on the immediate environment of the exploding star as a series of density enhancements. The variations in mass loss arise from changes in the ionization balance of Fe, the dominant ion that drives the wind. With this idea, we find that both the recurrence timescale of the variability and the amplitude of the modulations are in line with the observations. Our scenario thus provides a natural, single-star explanation for the observed behaviour that is, in fact, expected on theoretical grounds.