Institution
Abastumani Astrophysical Observatory
Facility•Tbilisi, Georgia•
About: Abastumani Astrophysical Observatory is a facility organization based out in Tbilisi, Georgia. It is known for research contribution in the topics: Pulsar & Magnetic field. The organization has 292 authors who have published 698 publications receiving 26659 citations.
Topics: Pulsar, Magnetic field, Magnetohydrodynamics, Blazar, Corona
Papers published on a yearly basis
Papers
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Shadab Alam1, Franco D. Albareti2, Carlos Allende Prieto3, Carlos Allende Prieto4 +360 more•Institutions (102)
TL;DR: The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrogram, and a novel optical interferometer.
Abstract: The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 sq. deg of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-Object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include measured abundances of 15 different elements for each star. In total, SDSS-III added 2350 sq. deg of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 sq. deg; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5,513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra.
2,471 citations
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University of Washington1, Paris Diderot University2, Lawrence Berkeley National Laboratory3, New York University4, University of Utah5, Apache Corporation6, Autonomous University of Madrid7, Yale University8, University of Barcelona9, Harvard University10, Aix-Marseille University11, Princeton University12, Carnegie Mellon University13, Ohio State University14, University of Portsmouth15, University of California, Irvine16, University College London17, University of Valencia18, Max Planck Society19, Leibniz Institute for Astrophysics Potsdam20, Institut d'Astrophysique de Paris21, Spanish National Research Council22, Columbia University23, University of California, Berkeley24, Drexel University25, Korea Institute for Advanced Study26, Institute for the Physics and Mathematics of the Universe27, Abastumani Astrophysical Observatory28, Pennsylvania State University29, University of California, San Diego30, University of Wisconsin-Madison31, Open University32, Case Western Reserve University33
TL;DR: In this paper, the authors present a measurement of the cosmic distance scale from detections of the baryon acoustic oscillations in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III (SDSS-III).
Abstract: We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III (SDSS-III). Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately $8\,500$ square degrees and the redshift range $0.2
2,040 citations
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Kyle S. Dawson1, David J. Schlegel2, Christopher P. Ahn1, Scott F. Anderson3 +181 more•Institutions (51)
TL;DR: The Baryon Oscillation Spectroscopic Survey (BOSS) as discussed by the authors was designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure.
Abstract: The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg2 to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Lyα forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Lyα forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance dA to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Lyα forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate DA (z) and H –1(z) parameters to an accuracy of 1.9% at z ~ 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS.
1,938 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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Boston University1, Saint Petersburg State University2, Isaac Newton Institute3, University of Michigan4, Aalto University5, Spanish National Research Council6, University of Arizona7, Harvard University8, Massachusetts Institute of Technology9, Lowell Observatory10, University of Southampton11, Abastumani Astrophysical Observatory12
TL;DR: In this article, the authors present results from monitoring the multi-waveband flux, linear polarization, and parsec-scale structure of the quasar PKS 1510-089, concentrating on eight major γ-ray flares that occurred during the interval 2009.5.
Abstract: We present results from monitoring the multi-waveband flux, linear polarization, and parsec-scale structure of the quasar PKS 1510 – 089, concentrating on eight major γ-ray flares that occurred during the interval 2009.0-2009.5. The γ-ray peaks were essentially simultaneous with maxima at optical wavelengths, although the flux ratio of the two wave bands varied by an order of magnitude. The optical polarization vector rotated by 720° during a five-day period encompassing six of these flares. This culminated in a very bright, ~1 day, optical and γ-ray flare as a bright knot of emission passed through the highest-intensity, stationary feature (the "core") seen in 43 GHz Very Long Baseline Array images. The knot continued to propagate down the jet at an apparent speed of 22c and emit strongly at γ-ray energies as a months-long X-ray/radio outburst intensified. We interpret these events as the result of the knot following a spiral path through a mainly toroidal magnetic field pattern in the acceleration and collimation zone of the jet, after which it passes through a standing shock in the 43 GHz core and then continues downstream. In this picture, the rapid γ-ray flares result from scattering of infrared seed photons from a relatively slow sheath of the jet as well as from optical synchrotron radiation in the faster spine. The 2006-2009.7 radio and X-ray flux variations are correlated at very high significance; we conclude that the X-rays are mainly from inverse Compton scattering of infrared seed photons by 20-40 MeV electrons.
490 citations
Authors
Showing all 293 results
Name | H-index | Papers | Citations |
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Yurii Maravin | 135 | 1689 | 102870 |
Giulio Tononi | 114 | 511 | 58519 |
Omar M. Kurtanidze | 63 | 157 | 10830 |
Lado Samushia | 52 | 116 | 22580 |
M. G. Nikolashvili | 49 | 97 | 6064 |
Teimuraz V. Zaqarashvili | 42 | 187 | 4912 |
Givi N. Kimeridze | 40 | 73 | 5322 |
Lorand A. Sigua | 39 | 70 | 5812 |
Tina Kahniashvili | 36 | 103 | 3606 |
Michael Gedalin | 32 | 181 | 3162 |
Vasilii V. Gvaramadze | 31 | 147 | 2792 |
Sofia O. Kurtanidze | 30 | 55 | 2725 |
David Tsiklauri | 28 | 132 | 2341 |
George I. Melikidze | 26 | 89 | 1956 |
David Kuridze | 22 | 55 | 1304 |