Institution
Institute of Cosmology and Gravitation, University of Portsmouth
About: Institute of Cosmology and Gravitation, University of Portsmouth is a based out in . It is known for research contribution in the topics: Galaxy & Redshift. The organization has 297 authors who have published 1207 publications receiving 76919 citations.
Topics: Galaxy, Redshift, Dark energy, Dark matter, Cosmic microwave background
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the authors used the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to determine the Hubble constant from optical and infrared observations of over 600 Cepheid variables in the host galaxies of eight recent Type Ia supernovae (SNe Ia), providing the calibration for a magnitude-redshift relation based on 253 SNeIa.
Abstract: We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to determine the Hubble constant from optical and infrared observations of over 600 Cepheid variables in the host galaxies of eight recent Type Ia supernovae (SNe Ia), providing the calibration for a magnitude-redshift relation based on 253 SNe Ia. Increased precision over past measurements of the Hubble constant comes from five improvements: (1) more than doubling the number of infrared observations of Cepheids in the nearby SN hosts; (2) increasing the sample size of ideal SN Ia calibrators from six to eight; (3) increasing by 20% the number of Cepheids with infrared observations in the megamaser host NGC 4258; (4) reducing the difference in the mean metallicity of the Cepheid comparison samples between NGC 4258 and the SN hosts from Δlog [O/H] = 0.08 to 0.05; and (5) calibrating all optical Cepheid colors with a single camera, WFC3, to remove cross-instrument zero-point errors. The result is a reduction in the uncertainty in H 0 due to steps beyond the first rung of the distance ladder from 3.5% to 2.3%. The measurement of H 0 via the geometric distance to NGC 4258 is 74.8 ± 3.1 km s–1 Mpc–1, a 4.1% measurement including systematic uncertainties. Better precision independent of the distance to NGC 4258 comes from the use of two alternative Cepheid absolute calibrations: (1) 13 Milky Way Cepheids with trigonometric parallaxes measured with HST/fine guidance sensor and Hipparcos and (2) 92 Cepheids in the Large Magellanic Cloud for which multiple accurate and precise eclipsing binary distances are available, yielding 74.4 ± 2.5 km s–1 Mpc–1, a 3.4% uncertainty including systematics. Our best estimate uses all three calibrations but a larger uncertainty afforded from any two: H 0 = 73.8 ± 2.4 km s–1 Mpc–1 including systematic errors, corresponding to a 3.3% uncertainty. The improved measurement of H 0, when combined with the Wilkinson Microwave Anisotropy Probe (WMAP) 7 year data, results in a tighter constraint on the equation-of-state parameter of dark energy of w = –1.08 ± 0.10. It also rules out the best-fitting gigaparsec-scale void models, posited as an alternative to dark energy. The combined H 0 + WMAP results yield N eff = 4.2 ± 0.7 for the number of relativistic particle species in the early universe, a low-significance excess for the value expected from the three known neutrino flavors.
1,680 citations
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TL;DR: In this article, a sample of spectroscopically identified galaxies with z < 0.2 from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7), covering 6813 deg(2).
Abstract: We create a sample of spectroscopically identified galaxies with z < 0.2 from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7), covering 6813 deg(2). Galaxies are chosen to sample the highest mass haloes, with an effective bias of 1.5, allowing us to construct 1000 mock galaxy catalogues (described in Paper II), which we use to estimate statistical errors and test our methods. We use an estimate of the gravitational potential to 'reconstruct' the linear density fluctuations, enhancing the baryon acoustic oscillation (BAO) signal in the measured correlation function and power spectrum. Fitting to these measurements, we determine D-V(z(eff) = 0.15) = (664 +/- 25)(r(d)/r(d, fid)) Mpc; this is a better than 4 per cent distance measurement. This 'fills the gap' in BAO distance ladder between previously measured local and higher redshift measurements, and affords significant improvement in constraining the properties of dark energy. Combining our measurement with other BAO measurements from Baryon Oscillation Spectroscopic Survey and 6-degree Field Galaxy Redshift Survey galaxy samples provides a 15 per cent improvement in the determination of the equation of state of dark energy and the value of the Hubble parameter at z = 0 (H-0). Our measurement is fully consistent with the Planck results and the Lambda cold dark matter concordance cosmology, but increases the tension between Planck+BAO H-0 determinations and direct H-0 measurements.
1,566 citations
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TL;DR: Galaxy Zoo as mentioned in this paper provides visual morphological classifications for nearly one million galaxies, extracted from the Sloan Digital Sky Survey (SDSS), which was made possible by inviting the general public to visually inspect and classify these galaxies via the internet.
Abstract: In order to understand the formation and subsequent evolution of galaxies one must first distinguish between the two main morphological classes of massive systems: spirals and early-type systems. This paper introduces a project, Galaxy Zoo, which provides visual morphological classifications for nearly one million galaxies, extracted from the Sloan Digital Sky Survey (SDSS). This achievement was made possible by inviting the general public to visually inspect and classify these galaxies via the internet. The project has obtained more than 4 × 107 individual classifications made by ∼105 participants. We discuss the motivation and strategy for this project, and detail how the classifications were performed and processed. We find that Galaxy Zoo results are consistent with those for subsets of SDSS galaxies classified by professional astronomers, thus demonstrating that our data provide a robust morphological catalogue. Obtaining morphologies by direct visual inspection avoids introducing biases associated with proxies for morphology such as colour, concentration or structural parameters. In addition, this catalogue can be used to directly compare SDSS morphologies with older data sets. The colour–magnitude diagrams for each morphological class are shown, and we illustrate how these distributions differ from those inferred using colour alone as a proxy for morphology.
1,380 citations
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Heidelberg University1, Korea Institute for Advanced Study2, University of Nottingham3, Institute of Cosmology and Gravitation, University of Portsmouth4, University of Oxford5, University of Bologna6, Istituto Nazionale di Fisica Nucleare7, INAF8, University of Padua9, University of Toulouse10, University of Geneva11, University of Trieste12, Roma Tre University13, University of Milan14, University of Oslo15, Federal University of Rio Grande do Norte16, University College London17, Imperial College London18, Ludwig Maximilian University of Munich19, Autonomous University of Madrid20, ETH Zurich21, University of Edinburgh22, Leiden University23, Sun Yat-sen University24, Max Planck Society25, Royal Institute of Technology26, University of Milano-Bicocca27, University of California, Berkeley28, University of Pennsylvania29, Universidade Federal do Espírito Santo30, University of Porto31, University of Portsmouth32, King's College London33, Durham University34, Institut d'Astrophysique de Paris35, Helsinki Institute of Physics36, University of Lisbon37, Université Paris-Saclay38, Paris Diderot University39, University of Surrey40, University of Trento41, University of Chile42, Academy of Sciences of the Czech Republic43, University of Cyprus44, University of Barcelona45, California Institute of Technology46, Perimeter Institute for Theoretical Physics47
TL;DR: Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015-2025 program as discussed by the authors, which will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shift of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky.
Abstract: Euclid is a European Space Agency medium-class mission selected for launch in 2020 within the cosmic vision 2015–2025 program. The main goal of Euclid is to understand the origin of the accelerated expansion of the universe. Euclid will explore the expansion history of the universe and the evolution of cosmic structures by measuring shapes and red-shifts of galaxies as well as the distribution of clusters of galaxies over a large fraction of the sky. Although the main driver for Euclid is the nature of dark energy, Euclid science covers a vast range of topics, from cosmology to galaxy evolution to planetary research. In this review we focus on cosmology and fundamental physics, with a strong emphasis on science beyond the current standard models. We discuss five broad topics: dark energy and modified gravity, dark matter, initial conditions, basic assumptions and questions of methodology in the data analysis. This review has been planned and carried out within Euclid’s Theory Working Group and is meant to provide a guide to the scientific themes that will underlie the activity of the group during the preparation of the Euclid mission.
1,211 citations
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Michael R. Blanton1, Matthew A. Bershady2, Bela Abolfathi3, Franco D. Albareti4 +412 more•Institutions (91)
TL;DR: SDSS-IV as mentioned in this paper is a project encompassing three major spectroscopic programs: the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and the Time Domain Spectroscopy Survey (TDSS).
Abstract: We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median $z\sim 0.03$). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between $z\sim 0.6$ and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
1,200 citations
Authors
Showing all 297 results
Name | H-index | Papers | Citations |
---|---|---|---|
Robert C. Nichol | 187 | 851 | 162994 |
Daniel Thomas | 134 | 846 | 84224 |
Will J. Percival | 129 | 473 | 87752 |
Tommaso Treu | 126 | 715 | 49090 |
Claudia Maraston | 103 | 362 | 59178 |
Marco Cavaglia | 93 | 372 | 60157 |
Ashley J. Ross | 90 | 248 | 46395 |
David A. Wake | 89 | 214 | 46124 |
László Á. Gergely | 89 | 426 | 60674 |
L. K. Nuttall | 89 | 253 | 54834 |
Rita Tojeiro | 87 | 229 | 43140 |
Roy Maartens | 86 | 432 | 23747 |
David Keitel | 85 | 253 | 56849 |
Davide Pietrobon | 83 | 152 | 62010 |
Gong-Bo Zhao | 81 | 287 | 35540 |