DOCSLIB.ORG

L7 Measuring Angular Diameter Distances

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
L7 Measuring Angular Diameter Distances The Astrophysical Journal, 557:L7–L10, 2001 August 10 ൴ ᭧ 2001. The American Astronomical Society. All rights reserved. Printed in U.S.A. MEASURING ANGULAR DIAMETER DISTANCES THROUGH HALO CLUSTERING Asantha Cooray,1,2 Wayne Hu,1 Dragan Huterer,3 and Michael Joffre1 Received 2001 May 7; accepted 2001 July 13; published 2001 July 20 ABSTRACT Current and upcoming wide-field surveys for weak gravitational lensing and the Sunyaev-Zeldovich effect will generate mass-selected catalogs of dark matter halos with internal or follow-up photometric redshift information. Using the shape of the linear power spectrum as a standard ruler that is calibrated by cosmic microwave background 2 14 measurements, we find that a survey of 4000 deg and a mass threshold of 10 M, can be used to determine the comoving angular diameter distance as a function of redshift. In principle, this test also allows an absolute calibration of the distance scale and measurement of the Hubble constant. This test is largely insensitive to the details of halo mass measurements, mass function, and halo bias. Determination of these quantities would further allow a measurement of the linear growth rate of fluctuations. Subject headings: cosmology: theory — large-scale structure of universe On-line material: color figures 1. INTRODUCTION to uncertainties in the mass function and the relationship be- tween the halo masses and the actual observables, e.g., the SZ A number of observational efforts are now underway or temperature decrement or lensing aperture mass. The bias of being planned to image the large-scale structure of the universe the halos is scale-dependent only on small (nonlinear) scales spanning a range of redshifts. These wide-field surveys typi- and can, in principle, be extracted to arbitrary precision from cally cover tens to thousands of square degrees of the sky: the N-body simulations. If and when these quantities are securely ongoing Sloan Digital Sky Survey, the weak gravitational lens- known, one can extract further information from the amplitude ing shear observations with instruments such as the Supernova/ and small-scale behavior of the power spectrum. In particular, Acceleration Probe (SNAP) or the Large Aperture Synoptic the linear growth rate and nonlinear scale provide extra handles Survey Telescope, and surveys of the Sunyaev-Zeldovich (SZ) on the dark energy. For illustrative purposes, we adopt the LCDM cosmology effect (Sunyaev & Zeldovich 1980). p with energy densities (relative to critical) ofQm 0.35 in mat- In addition to their primary science goals, these surveys are p p ter,Qb 0.05 in baryons,QL 0.65 in vacuum energy, the expected to produce catalogs of dark matter halos, which in p the case of lensing and SZ surveys are expected to be essentially dimensionless Hubble constant ofh 0.65 , and a scale- invariant spectrum of primordial fluctuations, normalized to the mass-selected (Wittman et al. 2001; Holder et al. 2000). Lens- p ing and other optical surveys are particularly promising in that present-day galaxy cluster abundance (j8 0.9 ; Viana & Lid- they will provide photometric redshifts on the member galaxies dle 1999). of a given halo (e.g., Hogg et al. 1998); this will render accurate determination of the halo redshift. Halo number counts as a 2. ANGULAR POWER SPECTRUM function of redshift is a well-known and powerful cosmological The angular power spectrum of halos in ith redshift bin is test. Here we consider the additional information supplied by a Limber (1954; Kaiser 1992) projection of the halo number the angular clustering of halos. density power spectrum A feature in an angular power spectrum of known physical scale and originating from a known redshift can be used to H(z) l measure the angular diameter distance between us and this C i p ͵ dz W 2 (z) P ; z ,(1) l ihh2 () redshift; this has most notably been applied to the case of the dAA(z) d cosmic microwave background (CMB) to determine the dis- 3 tance to redshiftz ∼ 10 . The angular power spectrum of halos whereWi(z) is the distribution of halos in a given redshift bin ∫ p provides a similar test based on the standard ruler defined by normalized so thatdz Wi(z) 1 ,H(z) is the Hubble param- its shape. In the adiabatic cold dark matter (CDM) model for eter, anddA is the angular diameter distance in comoving co- structure formation, this standard ruler is essentially the horizon ordinates. Note thatWi(z) comes directly from the observations at matter-radiation equality, and its absolute physical scale can of the number counts as a function of redshift and depends on be directly calibrated with CMB anisotropy data. In principle the mass function and mass sensitivity of the employed ob- then, one can determine the angular diameter distance as a servable. function of redshift and test the properties of the dark energy. If the halos trace the linear density field, As a purely geometric test, this method is largely insensitive p 22lin Phh(k; z) Ab MS (z)D (z)P (k; 0), (2) 1 Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; [email protected], whu@ where ASbM is the mass-averaged halo bias parameter, oddjob.uchicago.edu, [email protected]. lin 2 P (k;0)is the present-day matter power spectrum computed Sherman Fairchild Senior Research Fellow, Department of Physics, Cal- in linear theory, andD(z) is the linear growth function ifornia Institute of Technology, MS 130-33, Pasadena, CA 91125. lin lin 3 Department of Physics, University of Chicago, 5640 South Ellis Avenue, d (k; z) p D(z)d (k;0). A scale-independent halo bias is Chicago, IL 60637; [email protected]. commonly assumed in the so-called halo model (e.g., Seljak L7 L8 MEASURING ANGULAR DIAMETER DISTANCES Vol. 557 2000) and should be valid at least in the linear regime. Equa- tion (1) then becomes l C i p ͵ dz W 2(z)F(z)P lin ;0, (3) l i ()i dA H(z) p 22 F(z) 2 D(z) AbMS (z). (4) dA (z) The underlying linear power spectrum contains two physical scales: the horizon at matter-radiation equality, p ͱ 22ϩ ∝ keq 2Qm H0eq(1 z ) Qm h ,(5) which controls the overall shape of the power spectrum, and the sound horizon at the end of the Compton drag epoch, 22 ksm(Q h ,Q bh ), which controls the small wiggles in the power spectrum. The angular or multipole locations of these features p shift in redshift asleq, s kdeq, sA(z i) . We propose the following i 14 Fig. 1.—Angular power spectrum of halos withM 1 10 M, in a wide- test: measureCl in several redshift bins and, using the fact that ldscales with(z ) , constrain the angular diameter distance field survey in bins ofz p 0.3–0.4 and 1.0–1.2. The binned errors are 1 j eq Ai and assume a survey of 4000 deg2, within reach of upcoming weak lensing as a function of redshift. To be conservative, we ignore the and SZ surveys. The angular power spectrum at high redshifts is shifted toward additional information supplied byls . the right proportional to the increase in the comoving angular diameter distance. In Figure 1, we illustrate the proposed test. The two curves The oscillations are due to baryons, but we ignore the additional information show the halo power spectra in two redshift bins: 0.3 ! z ! they contain. [See the electronic edition of the Journal for a color version of 0.4and 1.0 ! z ! 1.2 . The angular power spectrum correspond- this figure.] ing to the higher redshift bin is shifted to the right in accordance ∼ Assuming Gaussian statistics, we can express the uncertainty to the ratio of angular diameter distances(dl/l ddAA/d ) . Much ≈ in the measurements of the angular power spectrum as of this shift simply reflects the Hubble law,dA z/H0 . Since the physical scale of the two features—the overall shape of the (C iiϩ N ) spectrum and the baryon oscillations—can be calibrated from DC i p ll,(6) l ͱ ϩ the morphology of the CMB peaks, these measurements can, (l 1/2)fsky in principle, be used to determine the Hubble constant inde- p 2 pendently of the distance ladder and distance to last scattering wherefskyVp deg /129,600 is the fraction of the sky covered i surface. by a survey of dimension Vdeg in degrees andNl is the noise In addition to the horizontal shift due to the change in angular power spectrum. We assume that the dominant source of noise i { ¯¯ diameter distance, the power spectra in Figure 1 are shifted is the shot noise so thatNli1/NN , where i is the surface vertically due to the change inF(z) (eq. [4]). By ignoring the density of the halos in the ith redshift bin. We use the PS mass ¯ information contained inF(z) , this purely geometric test is function to predictNi . In Figure 1, the two bins contain roughly robust against uncertainties in the mass selection, mass func- 4 and 6 halos degϪ2 above our minimum mass. In the same tion, and linear bias. Of course, if these uncertainties are pinned figure, we show band power measurement errors following down independently, bothF(z) and the halo abundance in equation (6). Wi(z) will help measure the growth rate of structure. To estimate how well halo clustering can recover cosmo- logical information, we construct the Fisher matrix, 3. PARAMETER ESTIMATION i Nbinsl max (l ϩ 1/2)f ѨC iiѨC Even though the angular diameter distance test is robust p ͸͸ sky ll Fab ii2 ,(7) p p ϩ Ѩ Ѩ against uncertainties in the halo selection function, number i 1 l lmin (CllN ) pabp density, and bias, these quantities enter into the consideration of the signal-to-noise ratio for a realistic survey.
Load more

Recommended publications
  • 2020 July 09 Dr. Paul Hertz Astrophysics Director Science
    2020 July 09 Dr. Paul Hertz Astrophysics Director Science Missions Directorate National Aeronautics and Space administration (NASA) Dear Paul, The NASA Astrophysics Advisory Committee (APAC) had its Summer meeting on 2020 June 23-24. Due to the COVID-19 pandemic and related NASA operational and travel restriction (Stage 4), the entire two-days of the meeting where conducted virtually using WebExtm videoconferencing technology accompanied by dial-in phone lines. The following members of the APAC attended the meeting: Kelly Holley-Bockelman, Laura Brenneman, John Conklin (Vice Chair), Asantha Cooray, Massimiliano Galeazzi, Jessica Gaskin, Hashima Hasan (APAC Executive Secretary), William Jones, Suvrath Mahadevan, Margaret Meixner, Michael Meyer, Leonidas Moustakas, Lucianne Walkowitz, and Chick Woodward (APAC Chair). Public lines were opened, and Dr. Hasan began the meeting by welcoming all the APAC members, and explaining its purpose. Dr. Hasan reminded APAC members who had conflicts of interest with specific topics on the agenda that as conflicted members they were allowed to listen to the presentation but could not participate in the committee’s discussion. Dr. Hasan then reviewed the Federal Advisory Committee Act (FACA) rules. Dr. Woodward then welcomed the members to the meeting, outlined the agenda, and reiterated some of the FACA and conflict of interest rules. APAC members proceeded to introduce themselves. The agenda consisted of the following presentations: • Astrophysics Division Update – Paul Hertz • State of the Profession – Chick Woodward and the APAC Committee • ExoPAG, COPAG, and PhysPAG reports – Michael Meyer, Margaret Meixner, Graca Rocha • SOFIA update – Margaret Meixner, Naseem Rangwala • James Webb update – Eric Smith • ESCAPE update – Kevin France • Athena update – Rob Petre • GUSTO update – Chris Walker • COSI update – John Tomsick • CASE/ARIEL update – Mark Swain • Science Activation update – Kristen Erickson The APAC thanks all the presenters for their time and efforts to provide crisp and informative presentations.
    [Show full text]
  • Gravitational Time Delay Effects on Cosmic Microwave Background Anisotropies
    PHYSICAL REVIEW D, VOLUME 63, 023504 Gravitational time delay effects on cosmic microwave background anisotropies Wayne Hu* Institute for Advanced Study, Princeton, New Jersey 08540 and Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637 Asantha Cooray† Department of Astronomy and Astrophysics, University of Chicago, Chicago, Illinois 60637 ͑Received 2 August 2000; published 18 December 2000͒ We study the effect of gravitational time delay on the power spectra and bispectra of the cosmic microwave background ͑CMB͒ temperature and polarization anisotropies. The time delay effect modulates the spatial surface at recombination on which temperature anisotropies are observed, typically by ϳ1 Mpc. While this is a relatively large shift, its observable effects in the temperature and polarization fields are suppressed by geometric considerations. The leading order effect is from its correlation with the closely related gravitational lensing effect. The change to the temperature-polarization cross power spectrum is of order 0.1% and is hence comparable to the cosmic variance for the power in the multipoles around lϳ1000. While unlikely to be extracted from the data in its own right, its omission in modeling would produce a systematic error comparable to this limiting statistical error and, in principle, is relevant for future high precision experiments. Contributions to the bispectra result mainly from correlations with the Sachs-Wolfe effect and may safely be neglected in a low density universe. DOI: 10.1103/PhysRevD.63.023504 PACS number͑s͒: 98.80.Es, 95.85.Nv I. INTRODUCTION small effects can accumulate along the path. Indeed it is well known that the gravitational lensing of CMB photons has a In order that the full potential of anisotropies in the cos- substantial effect on the power spectrum of the anisotropies mic microwave background ͑CMB͒ temperature and polar- ͓11,12͔.
    [Show full text]
  • Proceedings of Spie
    PROCEEDINGS OF SPIE SPIEDigitalLibrary.org/conference-proceedings-of-spie Overview of the Origins Space telescope: science drivers to observatory requirements Margaret Meixner, Lee Armus, Cara Battersby, James Bauer, Edwin Bergin, et al. Margaret Meixner, Lee Armus, Cara Battersby, James Bauer, Edwin Bergin, Asantha Cooray, Jonathan J. Fortney, Tiffany Kataria, David T. Leisawitz, Stefanie N. Milam, Klaus Pontoppidan, Alexandra Pope, Karin Sandstrom, Johannes G. Staguhn, Kevin B. Stevenson, Kate Y. Su, Charles Matt Bradford, Dominic Benford, Denis Burgarella, Sean Carey, Ruth C. Carter, Elvire De Beck, Michael J. Dipirro, Kimberly Ennico-Smith, Maryvonne Gerin, Frank P. Helmich, Lisa Kaltenegger, Eric. E. Mamajek, Gary Melnick, Samuel Harvey Moseley, Desika Narayanan, Susan G. Neff, Deborah Padgett, Thomas L. Roellig, Itsuki Sakon, Douglas Scott, Kartik Sheth, Joaquin Vieira, Martina Wiedner, Edward Wright, Jonas Zmuidzinas, "Overview of the Origins Space telescope: science drivers to observatory requirements," Proc. SPIE 10698, Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 106980N (24 July 2018); doi: 10.1117/12.2312255 Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 23 Aug 2019 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use Overview of the Origins Space Telescope: Science Drivers to Observatory Requirements Margaret Meixnera,b,c, Lee Armusd, Cara Battersbye, James Bauerf, Edwin Berging, Asantha Coorayh, Jonathan J. Fortneyi, Tiffany Katariaj, David T. Leisawitzc, Stefanie N. Milamc, Klaus Pontoppidana, Alexandra Popek, Karin Sandstroml, Johannes G. Staguhnb,c, Kevin B. Stevensona, Kate Y. Sum, Charles Matt Bradfordj, Dominic Benfordn, Denis Burgarellao, Sean Careyd, Ruth C.
    [Show full text]
  • Travelling Back Through Time COORAYDR ASANTHA
    Travelling back through time DR ASANTHA COORAY With Drs Julie Wardlow and Joseph Smidt from his research group, Professor Asantha Cooray describes the areas of study by which they are seeking to expand knowledge of far distant galaxies and star formation Can you begin by outlining your research goals? Cooray: The fi rst goal for my team is to search for the fi rst galaxies in the distant, early Universe. The fi rst galaxies are expected to be small in size and mass compared to later ones and their distance at almost the edge of the observable Universe makes them hard to see individually with existing observatories. So we look for signals in the sky that suggest their presence through aggregate effects, such as small variations in the total light emitted by them. Such searches for fi rst galaxies are best done at short infrared (like a galaxy), a foreground mass (such as wavelengths in the electromagnetic spectrum. another galaxy, or a cluster of galaxies) and A second research goal is to study the dust- our telescopes on Earth. The light from the enshrouded star formation in distant galaxies. background source has to pass through, or Since optical light is absorbed by dust, such very close to, the foreground mass in order observations are best done at long infrared to reach us. However, as Einstein theorised, wavelengths again from space. Why is there a need to investigate zodiacal the path that light takes is affected by the dust cloud? How does the Zodiacal dust, intervening mass, in much the same way as How will infrared wavelengths further Extragalactic Background and Reionisation light is defl ected by the lens in spectacles.
    [Show full text]
  • Heterodyne Receiver for Origins
    Heterodyne Receiver for Origins a, b c Martina C. Wiedner , * Susanne Aalto, Edward G. Amatucci , d e f g Andrey Baryshev, Cara Battersby , Victor Belitsky, Edwin A. Bergin, h c i j Bruno Borgo, Ruth C. Carter, Emmanuel Caux , Asantha Cooray, c b a f James A. Corsetti, Elvire De Beck , Yan Delorme, Vincent Desmaris, c k l Michael J. DiPirro, Brian Ellison , Anna M. Di Giorgio, m n a Martin Eggens , Juan-Daniel Gallego , Maryvonne Gerin , o p m,q Paul F. Goldsmith , Christophe Goldstein, Frank Helmich , r s t,u Fabrice Herpin , Richard E. Hills , Michiel R. Hogerheijde , v m m a Leslie K. Hunt , Willem Jellema , Geert Keizer, Jean-Michel Krieg, w x p c Gabby Kroes, Philippe Laporte, André Laurens, David T. Leisawitz , a,o c o Dariusz C. Lis , Gregory E. Martins, Imran Mehdi, c,y,z aa c Margaret Meixner, Gary Melnick, Stefanie N. Milam , z h ab David A. Neufeld, Napoléon Nguyen Tuong, René Plume, y r Klaus M. Pontoppidan , Benjamin Quertier-Dagorn, ac,ad c,z aa Christophe Risacher , Johannes G. Staguhn , Edward Tong, ae ac Serena Viti, Friedrich Wyrowski, and † The Origins Space Telescope Mission Concept Study Team aLaboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA), Observatoire de Paris, Université Paris Sciences & Lettres (PSL) Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Paris, France bChalmers University of Technology, Department of Space, Earth and Environment, Onsala Space Observatory, Onsala, Sweden cNASA Goddard Space Flight Center, Greenbelt, Maryland, United
    [Show full text]
  • Astro2020 Science White Paper Probing Feedback in Galaxy Formation with Millimeter-Wave Observations
    Astro2020 Science White Paper Probing Feedback in Galaxy Formation with Millimeter-wave Observations Thematic Areas: Planetary Systems Star and Planet Formation Formation and Evolution of Compact Objects 3 Cosmology and Fundamental Physics Stars and Stellar Evolution Resolved Stellar Populations and their Environments 3 Galaxy Evolution Multi-Messenger Astronomy and Astrophysics Principal Authors: Names: Nicholas Battaglia, J. Colin Hill Institutions: Cornell University, Institute for Advanced Study Emails: [email protected], [email protected] Phones: (607)-255-3735, (509)-220-8589 Co-authors: Stefania Amodeo (Cornell), James G. Bartlett (APC/U. Paris Diderot), Kaustuv Basu (Uni- versity of Bonn), Jens Erler (University of Bonn), Simone Ferraro (Lawrence Berkeley Na- tional Laboratory), Lars Hernquist (Harvard), Mathew Madhavacheril (Princeton), Matthew McQuinn (University of Washington), Tony Mroczkowski (European Southern Observatory), Daisuke Nagai (Yale), Emmanuel Schaan (Lawrence Berkeley National Laboratory), Rachel Somerville (Rutgers/Flatiron Institute), Rashid Sunyaev (MPA), Mark Vogelsberger (MIT), Jessica Werk (University of Washington) Endorsers: James Aguirre (University of Pennsylvania), Zeeshan Ahmed (SLAC), Marcelo Alvarez arXiv:1903.04647v1 [astro-ph.CO] 11 Mar 2019 (UC–Berkeley), Daniel Angles-Alcazar (Flatiron Institute), Chetan Bavdhankar (National Center for Nuclear Physics), Eric Baxter (University of Pennsylvania), Andrew Benson (Carnegie Observatories), Bradford Benson (Fermi National Accelerator Laboratory/ Uni- versity of Chicago), Paolo de Bernardis (Sapienza Università di Roma), Frank Bertoldi (Uni- versity of Bonn), Fredirico Bianchini (University of Melbourne), Colin Bischoff (University of Cincinnati), Lindsey Bleem (Argonne National Laboratory/KICP), J. Richard Bond (Uni- versity of Toronto/ CITA), Greg Bryan (Columbia/Flatiron Institute), Erminia Calabrese (Cardiff), John E. Carlstrom (University of Chicago/Argonne National Laboratory/KICP), Joanne D.
    [Show full text]
  • Implications of a Transition in the Dark Energy Equation of State for the H0 and Σ8 Tensions
    Prepared for submission to JCAP Implications of a transition in the dark energy equation of state for the H0 and σ8 tensions Ryan E. Keeley, a;b;1 Shahab Joudaki,c Manoj Kaplinghat,b David Kirkbyb aKorea Astronomy and Space Science Institute, Yuseong-gu, 776 Daedeok-daero, Daejeon, Korea bCenter for Cosmology, Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA cDepartment of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Ox- ford OX1 3RH, U.K. E-mail: [email protected] Abstract. We explore the implications of a rapid appearance of dark energy between the redshifts (z) of one and two on the expansion rate and growth of perturbations. Using both Gaussian process regression and a parametric model, we show that this is the preferred solu- −1 −1 tion to the current set of low-redshift (z < 3) distance measurements if H0 = 73 km s Mpc to within 1% and the high-redshift expansion history is unchanged from the ΛCDM infer- ence by the Planck satellite. Dark energy was effectively non-existent around z = 2, but its density is close to the ΛCDM model value today, with an equation of state greater than −1 at z < 0:5. If sources of clustering other than matter are negligible, we show that this expansion history leads to slower growth of perturbations at z < 1, compared to ΛCDM, that is measurable by upcoming surveys and can alleviate the σ8 tension between the Planck CMB temperature and low-redshift probes of the large-scale structure. Keywords: dark energy theory, baryon acoustic oscillations, cosmological parameters from CMBR, supernova type Ia - standard candles arXiv:1905.10198v2 [astro-ph.CO] 16 Jan 2020 ArXiv ePrint: 1905.10198 1Corresponding author.
    [Show full text]
  • Highlights and Conclusions of the Chalonge 14Th Paris Cosmology
    HIGHLIGHTS and CONCLUSIONS of the Chalonge 14th Paris Cosmology Colloquium 2010: ‘The Standard Model of the Universe: Theory and Observations’, Ecole Internationale d’Astrophysique Daniel Chalonge Observatoire de Paris in the historic Perrault building, 22-24 July 2010. H. J. de Vega(a,b), M.C. Falvella(c), N. G. Sanchez(b)1 1 a ( ) LPTHE, Universit´ePierre et Marie Curie (Paris VI) et Denis Diderot (Paris VII), Laboratoire Associ´eau CNRS UMR 7589, Tour 24, 5`eme. ´etage, Boite 126, 4, Place Jussieu, 75252 Paris, Cedex 05, France. b ( ) Observatoire de Paris, LERMA. Laboratoire Associ´eau CNRS UMR 8112. 61, Avenue de l’Observatoire, 75014 Paris, France. (c) Italian Space Agency and MIUR, Viale Liegi n.26, 00198 Rome, Italy. (Dated: June 9, 2018) The Chalonge 14th Paris Cosmology Colloquium 2010 was held on 22-24 July in the historic Paris Observatory’s Perrault building, in the Chalonge School spirit combining real cosmologi- cal/astrophysical data and hard theory predictive approach connected to them in the Standard Model of the Universe: News and reviews from WMAP7, BICEP, QUAD, SPT, AMI, ACT, Planck, QUIJOTE, Herschel, SPIRE, ATLAS and HerMES surveys; astrophysics and particle physics dark matter (DM) searches and galactic observations; related theory and simulations, with the aim of synthesis, progress and clarification. Peter Biermann, Daniel Boyanovsky, Asantha Cooray, Clau- dio Destri, Hector de Vega, Gerry Gilmore, Stefan Gottl¨ober, Eiichiro Komatsu, Stacy McGaugh, Anthony Lasenby, Rafael Rebolo, Paolo Salucci, Norma Sanchez and Anton Tikhonov present here their highlights of the Colloquium. Inflection points in several current research lines emerged, partic- ularly on dark matter (DM) where ΛWDM (Warm Dark Matter) emerges impressively over ΛCDM whose ever-increasing galactic scale problems are staggering.
    [Show full text]
  • MOS Participant List
    MOS Participant List Name Affiliation Mohammad Akhshik University Of Connecticut Adebusola Alabi UC, Santa Cruz Anahita Alavi California Institute Of Technology /Ipac Belen Alcalde ESO Leo Alcorn York University Etsegenet Alemu Ethiopia Space Science and Technology Institute James Allison University of Oxford Alba Vega Alonso Tetilla University of Southampton Amirnezam Amiri University of Florence Ricardo Amorín Universidad de La Serena Brett Andrews University of Pittsburgh Behzad Ansarinejad University of Melbourne Karla Z. Arellano-Córdova The University of Texas at Austin Magda Arnaboldi ESO - European Southern Observatory Pablo Arrabal Haro NSF's NOIRLab Anabel Arrieta Universidad Iberoamericana Randa Asa'd American University Of Sharjah Charlotte Avery University of Bath Khuraman Azizova Ege University Neta Bahcall Princeton University William Baker University of Cambridge Michael Balogh University of Waterloo Loreto Barcos-Munoz NRAO/NAASC Amy Barger University Of Wisconsin - Madison Jorge K. Barrera-Ballesteros UNAM Daniela Barrientos Ghent University Nicholas Barth University of Florida Andrew Battisti Australian National University Sirio Belli Center for Astrophysics, Harvard and Smithsonian Sabine Bellstedt International Centre for Radio Astronomy Research Dominic Benford NASA / HQ Minje Beom NMSU (New Mexico State University) Rebecca Bernstein Carnegie Observatories Aliza Beverage University of California, Berkeley Rachel Bezanson University of Pittsburgh Mohit Bhardwaj YYYY Rachana Bhatawdekar European Space Agency (ESA ESTEC)
    [Show full text]
  • Gigantic Gravity 'Lenses' Magnify Galaxies Far, Far Away 19 November 2010, by Holly B
    Gigantic gravity 'Lenses' magnify galaxies far, far away 19 November 2010, by Holly B. Martin looking in a funhouse mirror. But in all cases, the distorted images are magnified, making the background galaxies appear brighter and therefore easier to study. The universe contains billions of galaxies, but getting the chance alignment that produces a gravity lens is something like finding a needle in the haystack. Scientists must sift through large volumes of data to discover only a few possibilities, and then study these further to verify that a lensing event has occurred. "Since about 1978, astronomers probably have found about 200 gravitational lensing events, but This diagram illustrates a cosmic phenomenon known as gravitational lensing, in which a nearby galaxy distorts, that involved a very slow search through lots and but also magnifies a second, more distant galaxy in the lots of data," said Asantha Cooray, Professor of background, making it appear brighter and easier to Physics and Astronomy at University of California in study. Credit: Zina Deretsky, National Science Irvine. He and dozens of other scientists from Foundation around the world collaborated on a recent project to make the process faster. Largest space mirror A chance alignment of galaxies, recently observed by a space observatory, presents the perfect Using data collected by the Herschel Astrophysical opportunity for studying star-forming galaxies Terahertz Large Area Survey (Herschel?ATLAS) billions of light-years away. the team of researchers have demonstrated a way to quickly and easily find strong gravitational For decades, astronomers have used Einstein's lensing events with close to 100 percent efficiency.
    [Show full text]
  • 11 July 2017 Dr. Paul Hertz Astrophysics Director Science
    College of Arts and Sciences Department of Astronomy 4005 McPherson Laboratory 140 West 18th Avenue Columbus, OH 43210-1173 614-292-1912 Phone 614-292-2928 Fax [email protected] 11 July 2017 Dr. Paul Hertz Astrophysics Director Science Mission Directorate National Aeronautics and Space Administration (NASA) Dear Paul, The NASA Astrophysics Advisory Committee (APAC) met at NASA HQ on April 24 and 25, 2017. The following members of the APAC were present: Natalie Batalha (first day only), Marshall (Mark) Bautz (via telecon), James (Jamie) J. Bock, Alan Boss, Patricia Boyd, Asantha Cooray, Neil Cornish, Brenda Dingus, Debra Fischer (via telecon, second day only), Scott Gaudi (APAC Chair), Jason Kalirai, Feryal Ozel, Paul Scowen, Yun Wang, and Beth Willman (via telecon). Hashima Hasan (APAC Executive Secretary) was also in attendance. Dr. Hasan opened the meeting by welcoming the APAC members. She noted that a few APAC members had conflicts of interest with specific topics on the agenda. During those presentations, the conflicted members would be allowed to listen to the presentation, but they could not participate in discussion. Dr. Hasan then reviewed the Federal Advisory Committee Act (FACA) rules. Dr. Gaudi added that offline conversations cannot form the basis for APAC recommendations. Dr. Rachel Somerville recently resigned from the (now defunct) Astrophysics Subcommittee (APS); Dr. Gaudi thanked her for her time and service. Astrophysics Division Update Dr. Paul Hertz (Director, Astrophysics Division (APD)), presented an update APD on activities. He welcomed the APAC members, noting that APS had been rechartered as a Federal advisory (FACA) committee. As they now advise him, their letter with findings and recommendations should be addressed to him, and he then acts on the advice, recommendations, and conclusions of the letter, as appropriate.
    [Show full text]
  • Proceedings of Spie
    PROCEEDINGS OF SPIE SPIEDigitalLibrary.org/conference-proceedings-of-spie Integration and instrument characterization of the cosmic infrared background experiment 2 (CIBER-2) Chi H. Nguyen, Benjamin Stewart, Seung-Cheol Bang, James J. Bock, Asantha Cooray, et al. Chi H. Nguyen, Benjamin Stewart, Seung-Cheol Bang, James J. Bock, Asantha Cooray, Kenta Danbayashi, Ambar DeSantiago, Viktor Hristov, Tomoya Kojima, Phillip Korngut, Kevin Kruse, Alicia Lanz, Dae-Hee Lee, Lunjun Liu, Jared Loewenthal, Peter Mason, Toshio Matsumoto, Shuji Matsuura, Ryo Ohta, Christian Pape, Won-Kee Park, Dorin Patru, James Parkus, Kei Sano, Aoi Takahashi, Mark Peryer, Kohji Takimoto, Kohji Tsumura, Takehiko Wada, Shiang-Yu Wang, Yasuhiro Yamada, Michael Zemcov, "Integration and instrument characterization of the cosmic infrared background experiment 2 (CIBER-2)," Proc. SPIE 10698, Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 106984J (6 July 2018); doi: 10.1117/12.2311595 Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 12/5/2018 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use Integration and Instrument Characterization of the Cosmic Infrared Background ExpeRiment 2 (CIBER-2) Chi H. Nguyena, Benjamin Stewarta, Seung-Cheol Bangi, James J. Bockb,c, Asantha Coorayd, Kenta Danbayashie, Ambar DeSantiagoa, Viktor Hristovb, Tomoya Kojimae, Phillip Korngutb, Kevin Krusea, Alicia Lanzb, Dae-Hee
    [Show full text]