DOCSLIB.ORG

Formation and Growth of the First Supermassive Black Holes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Formation and Growth of the First Supermassive Black Holes Formation and Growth of the First Supermassive Black Holes Ph.D. Thesis by Tilman Hartwig UNIVERSITÉ PIERRE ET MARIE CURIE École Doctorale d’Astronomie et Astrophysique d’Île-de-France Ph.D. Thesis to obtain the title of Doctor in Astrophysics of the University Pierre et Marie Curie Presented by Tilman Hartwig Formation and Growth of the First Supermassive Black Holes Thesis Advisor: Dr. Marta Volonteri prepared at the Institut d’Astrophysique de Paris, CNRS (UMR 7095), Université Pierre et Marie Curie (Paris VI) with financial support from the European Research Council grant ‘BLACK’ Presented and publicly defended on the 22nd of September, 2017 to a jury consisting of Reviewers: Michela Mapelli - INAF, Padova, Italy Jarrett Johnson - LANL, Los Alamos, USA Advisor: Marta Volonteri - IAP, Paris, France President: Frédéric Daigne - IAP, Paris, France Examiner: Ralf Klessen - ZAH, Heidelberg, Germany Formation and Growth of the First Supermassive Black Holes Supermassive black holes reside in the centres of most massive galaxies and we observe correlations between their mass and properties of the host galaxies, such as bulge mass or stellar velocity dispersion. Besides this correlation between a galaxy and its central black hole (BH), we see BHs more massive than one billion solar masses already a few hundred million years after the Big Bang. These supermassive BHs at high redshift are just the tip of the iceberg of the entire BH population, but they challenge our understanding of the formation and growth of the first BHs. With this thesis, I contribute to a better understanding of the formation and growth of the first supermassive BHs with theoretical models and comparisons to recent observations. I improve radiative transfer in 3D hydrodynamical simulations to study the formation of massive BH seeds and analyse the feedback of accreting BHs in their typical host galaxies with a novel 2D analytical approach. Moreover, I model observations of the Lyman-α emitter CR7 and of the first detection of gravitational waves with a semi-analytical model of early star formation. Our improved method to calculate H2 self-shielding in simulations of supermassive star and BH seed formation (‘direct collapse’) yields probabilities to form massive seed BHs that are more than one order of magnitude higher than previously expected. We find that CR7 might be the first candidate to host such a direct collapse BH and we disprove the initially claimed existence of a massive metal-free stellar population in CR7. To better constrain a different seeding scenario for the first BHs, we calculate the merger rate density of binary BHs from the first stars and their detection rates with aLIGO. Our model demonstrates that upcoming detections of gravitational waves in the next decades will allow to put tighter constraints on the properties of the first stars and therefore on formation scenarios of the first BHs. To follow the subsequent accretion of the seed BHs, we develop a 2D analytical model of active galactic nuclei-driven outflows to demonstrate that a more realistic disc profile reduces the amount of gas that is ejected out of the halo, compared to existing 1D models. The outflow prevents gas accretion on to the central BH for only about ∼ 1 Myr, which permits almost continuous gas inflow in the disc plane. 4:8 Our model yields a correlation of MBH / σ between the BH mass and the host’s velocity dispersion, close to observations. In the last chapter, we conclude by summarising our results and presenting future research perspectives. Formation et Croissance des Premiers Trous Noirs Supermassifs Les trous noirs supermassifs résident dans les centres de la plupart des galaxies massives et on observe des corrélations entre leurs masses et les propriétés de leurs galaxies hôtes, comme la masse du bulbe ou la dispersion des vitesses stellaires. De plus, on observe des trous noirs de plus d’un milliard de masses solaires quelques centaines de millions d’années seulement après le Big Bang. Ces trous noirs supermassifs présents dans l’univers jeune ne sont que le sommet de l’iceberg de l’ensemble de la population de trous noirs, mais ils mettent en question notre compréhension de la formation et de la croissance des premiers trous noirs. Avec cette thèse, je contribue à une meilleure compréhension de la formation et la croissance des pre- miers trous noirs supermassifs grâce à des modèles théoriques et des comparaisons avec des observations récentes. J’améliore le transfert radiatif dans les simulations hydrodynamiques pour étudier la formation des graines massives de trous noirs et j’analyse la rétroaction des trous noirs accretant dans leurs galaxies hôtes avec une nouvelle approche analytique en 2D. De plus, je modélise les observations de l’émetteur de Lyman-α CR7 et de la première détection d’ondes gravitationnelles avec un modèle semi-analytique de formation des premières étoiles. Notre nouvelle méthode améliorant le calcul de la densité de colonne de H2 dans les simulations de la formation d’étoiles supermassives et de graines de trous noirs («effondrement direct») donne des probabilités pour former des graines massives de trous noirs qui sont plus d’un ordre de grandeur plus élevées que prédit précédemment. Nous trouvons que CR7 pourrait être le premier candidat à héberger un tel trou noir formé par effondrement direct et nous démentons l’existence initialement revendiquée d’une population stellaire massive primordial dans CR7. Nous calculons la densité des taux de fusion des trous noirs binaires des premières étoiles et leurs taux de détection avec aLIGO. Notre modèle démontre que les détections des ondes gravitationnelles à venir au cours des prochaines décennies permettront d’imposer des contraintes plus strictes sur les propriétés des premières étoiles et donc sur les scénarios de formation des premiers trous noirs. Nous développons un modèle analytique en 2D de la rétroaction des noyaux actifs de galaxie pour démontrer qu’un profil de disque plus réaliste réduit la quantité de gaz qui est éjectée du halo par rapport aux modèles 1D existants. La rétroaction empêche l’accretion de gaz sur le trou noir central pendant seulement ∼ 1 million d’année environ, ce qui permet une accretion de 4:8 gaz presque continue dans le plan du disque. Notre modèle donne une corrélation de MBH / σ entre la masse du trou noir et la dispersion des vitesses stellaires de la galaxie hôte, en concordance avec les observations. Dans le dernier chapitre, nous concluons en résumant nos résultats et en présentant les perspectives de recherche futures. Contents 1 Introduction 10 1.1 Motivation............................................ 10 1.2 Cosmological structure formation................................ 11 1.2.1 Cosmological framework................................. 11 1.2.2 Thermal and chemical evolution............................ 13 1.2.3 Jeans analysis....................................... 14 1.2.4 Non-linear structure formation............................. 16 1.3 Formation of the first stars................................... 17 1.3.1 Primordial chemistry................................... 19 1.3.2 Collapse of a primordial cloud.............................. 20 1.3.3 Fragmentation...................................... 21 1.3.4 Evolution of protostars................................. 23 1.3.5 Observational signatures of the first stars....................... 25 1.4 Formation of the first supermassive black holes........................ 26 1.4.1 Observations....................................... 26 1.4.2 Seed formation scenarios................................. 28 1.4.3 Mass accretion and AGN feedback........................... 30 2 Improving H2 Self-Shielding 33 2.1 Motivation............................................ 33 2.2 Methodology........................................... 33 2.2.1 Moving-mesh code AREPO............................... 34 2.2.2 Initial conditions..................................... 35 2.2.3 Chemistry......................................... 36 2.2.4 H2 self-shielding..................................... 37 2.3 Results............................................... 40 2.3.1 Determination of Jcrit .................................. 41 2.3.2 Differences in the H2 self-shielding........................... 43 2.3.3 Impossibility of a simple correction factor....................... 46 2.3.4 Effect of damping wings................................. 47 2.3.5 Mass infall rate...................................... 49 2.4 Caveats.............................................. 51 2.4.1 Stellar spectrum..................................... 51 2.4.2 Resolution......................................... 52 2.4.3 Photochemistry...................................... 52 2.5 Conclusions............................................ 53 7 Contents 3 Gravitational waves from the remnants of the first stars 54 3.1 Introduction............................................ 54 3.2 Methodology........................................... 56 3.2.1 Self-consistent Pop III star formation......................... 56 3.2.2 Binary sampling and evolution............................. 57 3.2.3 Detectability....................................... 60 3.3 Results............................................... 61 3.4 Discussion............................................. 64 4 Exploring the nature of the Lyman-α emitter CR7 66 4.1 Introduction............................................ 66 4.2 Observational constraints.................................... 67 4.3 Methodology..........................................
Load more

Recommended publications
  • Kepler-452B Is Not a New Earth a Twin of the Sun-Jupiter System
    cover EN:l'astrofilo 28/08/15 10:12 Page 1 THE FREE MULTIMEDIA MAGAZINE THAT KEEPS YOU UPDATED ON WHAT IS HAPPENING IN SPACE Bi-monthly magazine of scientific and technical information ✶ September-October 2015 issue astonishing PLUTO Kepler-452b is not a new Earth A twinofthe Sun-Jupiter system www.astropublishing.com ✶ ita.astropublishing.com ✶ [email protected] colophon EN:l'astrofilo 28/08/15 10:17 Page 3 SUMMARY BI-MONTHLY MAGAZINE OF SCIENTIFIC AND TECHNICAL INFORMATION Astonishing Pluto FREELY AVAILABLE THROUGH A faultless mission, that of New Horizons: after a journey of nine and a half years it finally made its THE INTERNET rendezvous with Pluto one minute earlier than predicted and performed its task in the best of ways, 4 revealing a world remarkably more lively and varied than we could have imagined. In these pages... September-October 2015 Kepler-452b is not a new Earth Discovering a planet very similar to ours, at just the right distance from a star identical to the Sun, would be an important step forward in the search for extraterrestrial life. The rush to reach this goal 18 could, however, make us overly optimistic and lead us to define the same as Earth a planet that in... First detection of lithium from an exploding star The light chemical element lithium is one of the few elements that is predicted to have been created by the Big Bang, 13.8 billion years ago. But understanding the amounts of lithium observed in stars around 26 us today in the Universe has given astronomers headaches.
    [Show full text]
  • Mark Dijkstra
    M. Dijkstra (UiO) Aspen, 2016 Mark Dijkstra with: Shiv Sethi (RRI), Abraham Loeb (CfA), Max Gronke (UiO) & David Sobral (Lancaster) arXiv:1601.04712 (ApJ accepted), Dijkstra, Sethi & Loeb arXiv:1602.07695 (resubmitted to ApJ), Dijkstra, Gronke & Sobral M. Dijkstra (UiO) Aspen, 2016 The Direct Collapse Black Hole Scenario `….as long as H2 formation is suppressed, these massive clumps do not fragment but rather cool and continue to collapse isothermally at a temperature of ~104 K.… ‘ from Bromm & Loeb 2003 Credit: John Wise M. Dijkstra (UiO) Aspen, 2016 The Direct Collapse Black Hole Scenario Extremely interesting from a [Lyα] radiative transfer (RT) point of view: 1. Pristine environment 2. Suppressed fragmentation 3. Suppressed H2 content. 4. No star formation & stellar feedback, dust. Ordinary challenges one faces when modelling interstellar Lyα RT are absent. Lyα `survival probability’ is maximised. M. Dijkstra (UiO) Aspen, 2016 Observational Signature of DCBHs I: Lyα Study Lyα RT through simplified models of DCBH formation. M. Dijkstra (UiO) Aspen, 2016 Observational Signature of DCBHs I: Lyα Study Lyα RT through simplified models of DCBH formation. M. Dijkstra (UiO) Aspen, 2016 Observational Signature of DCBHs I: Lyα Study Lyα RT through simplified models of DCBH formation. M. Dijkstra (UiO) Aspen, 2016 Results I: Lyα Luminosity Lyα luminosity as function of mean cloud density for cloud photoionized by central ionising source (powered by in place DCBH of mass MBH) fully ionised (density bound) cloud: recombination luminosity ~ n2 M. Dijkstra (UiO) Aspen, 2016 Results I: Lyα Luminosity Lyα luminosity as function of mean cloud density for cloud photoionized by central ionising source (powered by in place DCBH of mass MBH) Maximum luminosity set by black hole mass at ~ erg/s Independent of geometry! fesc —> 0 For predictions of emerging spectra, see Dijkstra, Gronke & Sobral 2016 M.
    [Show full text]
  • 8 October Version
    A F irst T ransients Survey with JWST: the FLARE project Lifan Wang et al 8 October version Received ; accepted –2– ABSTRACT JWST was conceived and built to answer one of the most fundamental ques- tions that humans can address empirically: “How did the Universe make its first stars?”. This can be attempted in classical stare mode and by still photography - with all the pitfalls of crowding and multi-band redshifts of objects of which a spectrum was never obtained. Our First Lights At REionization (FLARE) project transforms the quest for the epoch of reionization from the static to the time domain. It targets the complementary question: “What happened to those first stars?”. It will be answered by observations of the most luminous events: supernovae and accretion on to black holes formed by direct collapse from the primordial gas clouds. These transients provide direct constraints on star-formation rates (SFRs) and the truly initial Initial Mass Function (IMF), and they may identify possible stellar seeds of supermassive black holes (SMBHs). Furthermore, our knowledge of the physics of these events at ultra-low metallic- ity will be much expanded. JWST’s unique capabilities will detect these most luminous and earliest cosmic messengers easily in fairly shallow observations. However, these events are very rare at the dawn of cosmic structure formation and so require large area coverage. Time domain astronomy can be advanced to an unprecedented depth by means of a shallow field of JWST reaching 27 mag AB in 2 µm and 4.4 µm over a field as large as 0.1 square degree visited multiple times each year.
    [Show full text]
  • Baseline Metal Enrichment from Population III Star Formation in Cosmological Volume Simulations
    MNRAS 000,1{ ?? (2017) Preprint 19 January 2018 Compiled using MNRAS LATEX style file v3.0 Baseline Metal Enrichment from Population III Star Formation in Cosmological Volume Simulations Jason Jaacks1?, Robert Thompson2;3, Steven L. Finkelstein1 and Volker Bromm1 1 Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 2 Portalarium Inc., Austin, TX 78731 3 National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Champaign, IL 61801 Accepted XXX. Received YYY; in original form ZZZ ABSTRACT We utilize the hydrodynamic and N-body code GIZMO coupled with our newly devel- oped sub-grid Population III (Pop III) Legacy model, designed specifically for cosmo- logical volume simulations, to study the baseline metal enrichment from Pop III star formation at z > 7. In this idealized numerical experiment, we only consider Pop III star formation. We find that our model Pop III star formation rate density (SFRD), −3 −1 −1 which peaks at ∼ 10 M yr Mpc near z ∼ 10, agrees well with previous numerical studies and is consistent with the observed estimates for Pop II SFRDs. The mean Pop III metallicity rises smoothly from z = 25 − 7, but does not reach the critical −4 metallicity value, Zcrit = 10 Z , required for the Pop III to Pop II transition in star formation mode until z ' 7. This suggests that, while individual halos can suppress in-situ Pop III star formation, the external enrichment is insufficient to globally ter- minate Pop III star formation. The maximum enrichment from Pop III star formation −2 in star forming dark matter halos is Z ∼ 10 Z , whereas the minimum found in −7 externally enriched haloes is Z & 10 Z .
    [Show full text]
  • Exploring the Nature of the Lyman-Α Emitter
    Mon. Not. R. Astron. Soc. 000, 1–21 (2016) Printed 22 August 2018 (MN LATEX style file v2.2) Exploring the nature of the Lyman-α emitter CR7 Tilman Hartwig1,2⋆, Muhammad A. Latif1,2, Mattis Magg3, Volker Bromm4, Ralf S. Klessen3,5, Simon C. O. Glover3, Daniel J. Whalen3,6, Eric W. Pellegrini3, and Marta Volonteri1,2 1Sorbonne Universit´es, UPMC Univ Paris 06, UMR 7095, Institut d’Astrophysique de Paris, F-75014 Paris, France 2CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France 3Universit¨at Heidelberg, Zentrum f¨ur Astronomie, Institut f¨ur Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg, Germany 4Department of Astronomy, University of Texas, Austin, Texas 78712, USA 5Universit¨at Heidelberg, Interdisziplin¨ares Zentrum f¨ur wissenschaftliches Rechnen 6Institute of Cosmology and Gravitation, University of Portsmouth,Portsmouth PO1 3FX, UK 22 August 2018 ABSTRACT CR7 is the brightest Lyman-α emitter observed at z > 6, which shows very strong Lyman-α and Heii 1640 A˚ line luminosities, but no metal line emission. Previous stud- ies suggest that CR7 hosts either young primordial stars with a total stellar mass of 7 6 ∼ 10 M⊙ or a black hole of & 10 M⊙. Here, we explore different formation scenarios for CR7 with a semianalytical model, based on the random sampling of dark matter merger trees. We are unable to reproduce the observational constraints with a primor- dial stellar source, given our model assumptions, due to the short stellar lifetimes and the early metal enrichment. Black holes that are the remnants of the first stars are either not massive enough, or reside in metal-polluted haloes, ruling out this possible explanation of CR7.
    [Show full text]
  • On the Nature and Physical Conditions of the Luminous Lyα Emitter CR7
    MNRAS 000,1{18 (2017) Preprint 25 October 2017 Compiled using MNRAS LATEX style file v3.0 On the nature of the luminous Lyα emitter CR7 and its UV components: physical conditions and JWST predictions? David Sobral1;2 , Jorryt Matthee2, Gabriel Brammer3, Andrea Ferrara4;5, Lara Alegre6 y Huub R¨ottgering2, Daniel Schaerer7;8, Bahram Mobasher9, Behnam Darvish10 1 Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK 2 Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands 3 Space Telescope Science Institute, 3700 San Martin Dr, Baltimore MD 21211, USA 4 Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy 5 Kavli IPMU, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8583, Japan 6 Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK 7 Observatoire de Gen`eve, UniversitO} de GenRve,´ 51 Ch. des Maillettes, 1290 Versoix, Switzerland 8 CNRS, IRAP, 14 Avenue E. Belin, 31400 Toulouse, France 9 Department of Physics and Astronomy, University of California, 900 University Ave., Riverside, CA 92521, USA 10 Cahill Center for Astrophysics, California Institute of Technology, 1216 East California Boulevard, Pasadena, CA 91125, USA 25 October 2017 ABSTRACT We present new HST/WFC3 grism observations and re-analyse VLT data to unveil the continuum, variability and rest-frame UV lines of the three UV components of the most luminous Lyα emitter at z = 6:6, COSMOS Redshift 7 (CR7; Sobral et al. 2015). Our re-reduced, flux calibrated X-SHOOTER spectra of CR7 reveal a tentative detection of 17 1 2 Heii with FHeII = (1:8 0:7) 10− erg s− cm− and we identify the signal ( 2:6 σ) as coming only from observations± × obtained along the major axis of Lyα emission.∼ There is a change of +0.2-0.5 mag in UltraVISTA J band data for CR7 from DR2 to DR3, which virtually eliminates the strong J-band excess previously interpreted as being caused by Heii.
    [Show full text]
  • Emission from Black Holes and Supernovae in the Early Universe Brandon Kerry Wiggins Brigham Young University
    Brigham Young University BYU ScholarsArchive All Theses and Dissertations 2016-07-01 Emission from Black Holes and Supernovae in the Early Universe Brandon Kerry Wiggins Brigham Young University Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Astrophysics and Astronomy Commons BYU ScholarsArchive Citation Wiggins, Brandon Kerry, "Emission from Black Holes and Supernovae in the Early Universe" (2016). All Theses and Dissertations. 6432. https://scholarsarchive.byu.edu/etd/6432 This Dissertation is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in All Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Emission from Black Holes and Supernovae in the Early Universe Brandon Kerry Wiggins A dissertation submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Doctor of Philosophy David Neilsen, Chair Wesley Even Denise Stephens Eric Hirschmann J. Ward Moody Michael Joner Department of Physics and Astronomy Brigham Young University July 2016 Copyright © 2016 Brandon Kerry Wiggins All Rights Reserved ABSTRACT Emission from Black Holes and Supernovae in the Early Universe Brandon Kerry Wiggins Department of Physics and Astronomy, BYU Doctor of Philosophy To constrain the era when the first galaxies and stars appeared upcoming instruments will rely on the brightest events in the universe: supernovae and brilliant emission from massive black holes. In this dissertation, we investigate the observability of certain types of supernovae of the very first stars (Population III stars) and find that while these events are sufficiently luminous to be observed with deep-sky instruments such as the James Webb Space Telescope (JWST), they may not observe these particular types of events in their lifetimes.
    [Show full text]
  • April 2018 BRAS Newsletter
    Monthly Meeting Monday, April 9th at 7PM at HRPO (Monthly meetings are on 2nd Mondays, Highland Road Park Observatory). Presentation: Webinar with Tom Fields, contributing editor to Sky and Telescope, discussing his starlight spectrum analysis software. What's In This Issue? President’s Message Secretary's Summary Outreach Report Light Pollution Committee Report Recent Forum Entries 20/20 Vision Campaign Messages from the HRPO Friday Night Lecture Series NASA Events Globe at Night International Astronomy Day Observing Notes – Sextans & Mythology Like this newsletter? See PAST ISSUES online back to 2009 Visit us on Facebook – Baton Rouge Astronomical Society Newsletter of the Baton Rouge Astronomical Society April 2018 © 2018 President’s Message To recap last month and highlight upcoming events, BRAS got written up in the 225 Magazine, March (photos on Pages 2 and 3). We had a delightful monthly meeting, and I would like to thank John Martinez of the Pontchartrain Astronomy Society for his informative talk on Trappist-1 and the search for Alien Planets In March we planned to have a BRAS Night at Observatory on Saturday, March 17, however it was canceled due to our "fair weather friend" a forecast of less than ideal weather. We expect to have another very soon so let us know if you are willing to come. We said farewell to the long night of winter. Then there is April 9 at HRPO, to which I would like to invite you, your family and friends. The 2018 Annual DSSG Spring Scrimmage will be held from April 12 to April 15 at Feliciana Retreat Center.
    [Show full text]
  • 2008.01731 V1
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Lancaster E-Prints MNRAS 000,1{18 (2020) Preprint 6 August 2020 Compiled using MNRAS LATEX style file v3.0 The nature of CR7 revealed with MUSE: a young starburst powering extended Lyman-α emission at z=6.6 Jorryt Matthee1?, Gabriele Pezzulli1, Ruari Mackenzie1, Sebastiano Cantalupo1, Haruka Kusakabe2, Floriane Leclercq2, David Sobral3, Johan Richard4, Lutz Wisotzki5, Simon Lilly1, Leindert Boogaard6, Raffaella Marino1, Michael Maseda6, Themiya Nanayakkara6;7 1 Department of Physics, ETH Zurich,¨ Wolfgang-Pauli-Strasse 27, 8093 Zurich,¨ Switzerland 2 Observatoire de Gen`eve, Universit´ede Gen`eve, 51 chemin de P´egase, 1290 Versoix, Switzerland 3 Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK 4 Univ. Lyon, Univ. Lyon1, Ens de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, F-69230, Saint-Genis-Laval, France 5 Leibniz-Institut fur¨ Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany 6 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands 7 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122, Australia 6 August 2020 ABSTRACT CR7 is among the most luminous Lyman-α emitters (LAEs) known at z = 6:6 and con- sists of at least three UV components that are surrounded by Lyman-α (Lyα) emission. Previous studies have suggested that it may host an extreme ionising source. Here, we present deep integral field spectroscopy of CR7 with VLT/MUSE. We measure extended emission with a similar halo scale length as typical LAEs at z 5.
    [Show full text]
  • Insights Mock Test Series 2015: Test – 28 Solutions
    INSIGHTS MOCK TEST SERIES 2015: TEST – 28 SOLUTIONS 1. Solution: d) This recent article is The Hindu is the most comprehensive article written on INO by Kalam and Srijan Pal Singh. It will address all aspects of Neutrino related studies too. Its an important topic for this year Prelims. http://www.thehindu.com/opinion/lead/going-all-out-for-neutrino-research/article7322627.ece 2. Solution: c) Neutrinos are the information bearers of the universe — which are almost never lost in their path. India’s effort in studying neutrinos at INO may help us unravel the deepest mystery of the universe — why there is more matter than antimatter in the universe. Neutrinos are the least harmful of all elementary particles, as they almost never react with solid bodies. The mean free path for iron, or the average distance a neutrino will travel in say an iron rod, before interacting with an atom, is about 1 light year. Needless to say, with the human body being less than 2 metres in height, any harmful effect of neutrino is near impossible. Also, people tend to confuse the “neutrino” for the “neutron”. This has also led to the confusion that neutrinos can be weaponised, which is far from the truth. The neutron bomb, which many discuss, is dangerous but has nothing to do with harmless neutrinos and is made based on a technology around the neutrons, particles which are much heavier. 3. Solution: a) The h-index is an index that attempts to measure both the productivity and citation impact of the published body of work of a scientist or scholar.
    [Show full text]
  • You Can Download That Here
    IMPORTANT INFORMATION ARTery: The ARTery is the heART of all THE DEPOT: The Depot is our icey MEDIA: We continue to get a lot of publicity things art on the Paddock and open 24/7. information hub. Wanna buy some ice? Depot. thanks to our Media Team so we may have It’s a public space where all are welcome, Sign up for a volunteer shift? Depot. Advertise some media personnel on site. They will be near the Depot. Come hang out in the shade, a new event? Depot. Lost wallet, keys or easily identifiable; wearing a Media Pass, and create collaboratively or by yourself in the phone? Depot. Need to contact the Site walking around with a Kiwiburn Liaison. company of others. Learn how you can get Manager? Depot. General questions? Depot. an Art Grant to bring your epic idea to the Forgot your tampons/condoms/toothbrush/ MOOP (Matter-Out-Of-Place): Our Paddock next year! View designs and images mind? Depot. Need a ride home? Depot. Come community respects the environment. We of Kiwiburn’s Temples and Effigies. Check out have a yarn, find your marbles, and enjoy are committed to leaving no physical trace the Event Guide for information on artist talks some misinformation in our front yard. Open of our activities wherever we gather. If you and art tours! 10am–5pm daily. see MOOP, pick it up. You are responsible for ensuring your campsite is clean before you BE RESPECTFUL: Kiwiburn is held on FIRE BAN: There are to be NO open fires leave. Please do not leave food scraps.
    [Show full text]
  • Observing Galaxy Mergers at the Epoch of Reionization
    DRAFT VERSION AUGUST 11, 2018 Typeset using LATEX twocolumn style in AASTeX61 OBSERVING GALAXY MERGERS AT THE EPOCH OF REIONIZATION EVGENII A. CHAIKIN,1 NADEZDA V. TYULNEVA,1 AND ALEXANDER A. KAUROV2 1Peter the Great St. Petersburg Polytechnic University, Politechnicheskaya 29, 194021, St. Petersburg, Russia 2Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540, USA ABSTRACT The galaxies with photometric redshifts observed in a close angular proximity might be either projection coincidences, strongly lensed images of the same galaxy, or separate galaxies that are in a stage of merging. We search for the groups of galaxies in the Hubble Ultra Deep Field (HUDF09) in z ∼ 7 and z ∼ 8 drop-out samples. We find no close pairs among 50 galaxies in the z ∼ 7 sample, while in the z ∼ 8 sample we find that 6 out of 22 galaxies have a companion within ∼ 100 (3 pairs). Adopting a numerical simulation and performing forward modeling we show that even though mergers are unlikely to have such a high fraction, the projection coincidences and the strong lensing are even less likely mechanisms to account for all of three pairs. Alternatively, there is a possibility of the contamination in the drop-out catalog from lower redshifts, which potentially can account for all of the groups. Finally, we make projection on the sensitivity to mergers of the James Webb Space Telescope, and discuss the possible applications of the high-redshift merging galaxies for decreasing cosmic variance effect on the luminosity function and for improving the accuracy of photometric redshifts in general. Keywords: galaxies: high-redshift — galaxies: photometry arXiv:1712.04110v1 [astro-ph.GA] 12 Dec 2017 Corresponding author: Alexander A.
    [Show full text]