On the Evolution of Large-Scale Structure in a Cosmic Void
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An Overview of Nonstandard Signals in Cosmological Data †
Proceeding Paper An Overview of Nonstandard Signals in Cosmological Data † George Alestas ‡,* , George V. Kraniotis ‡ and Leandros Perivolaropoulos ‡ Division of Theoretical Physics, University of Ioannina, 45110 Ioannina, Greece; [email protected] (G.V.K.); [email protected] (L.P.) * Correspondence: [email protected] † Presented at the 1st Electronic Conference on Universe, 22–28 February 2021; Available online: https://ecu2021.sciforum.net/. ‡ Current address: Department of Physics, University of Ioannina, 45110 Ioannina, Greece. Abstract: We discuss in a unified manner many existing signals in cosmological and astrophysical data that appear to be in some tension (2s or larger) with the standard LCDM as defined by the Planck18 parameter values. The well known tensions of LCDM include the H0 tension the S8 tension and the lensing (Alens) CMB anomaly. There is however, a wide range of other, less standard signals towards new physics. Such signals include, hints for a closed universe in the CMB, the cold spot anomaly indicating non-Gaussian fluctuations in the CMB, the hemispherical temperature variance assymetry and other CMB anomalies, cosmic dipoles challenging the cosmological principle, the Lyman-a forest Baryon Accoustic Oscillation anomaly, the cosmic birefringence in the CMB, the Lithium problem, oscillating force signals in short range gravity experiments etc. In this contribution present the current status of many such signals emphasizing their level of significance and referring to recent resources where more details can be found for each signal. We also briefly mention some possible generic theoretical approaches that can collectively explain the non-standard nature of these signals. In many cases, the signals presented are controversial and there is currently debate in the literature on the possible systematic origin of some of these signals. -
Finite Cosmology and a CMB Cold Spot
SLAC-PUB-11778 gr-qc/0602102 Finite cosmology and a CMB cold spot Ronald J. Adler,∗ James D. Bjorken† and James M. Overduin∗ ∗Gravity Probe B, Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, U.S.A. †Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309, U.S.A. The standard cosmological model posits a spatially flat universe of infinite extent. However, no observation, even in principle, could verify that the matter extends to infinity. In this work we model the universe as a finite spherical ball of dust and dark energy, and obtain a lower limit estimate of its mass and present size: the mass 23 is at least 5 10 M⊙ and the present radius is at least 50 Gly. If we are not too far × from the dust-ball edge we might expect to see a cold spot in the cosmic microwave background, and there might be suppression of the low multipoles in the angular power spectrum. Thus the model may be testable, at least in principle. We also obtain and discuss the geometry exterior to the dust ball; it is Schwarzschild-de Sitter with a naked singularity, and provides an interesting picture of cosmogenesis. Finally we briefly sketch how radiation and inflation eras may be incorporated into the model. 1 Introduction The standard or “concordance” model of the present universe has been very successful in that it is consistent with a wide and diverse array of cosmological data. The model posits a spatially flat (k = 0) Friedmann-Robertson-Walker (FRW) universe of infinite extent, filled with dark energy, well described by a cosmological constant, and pressureless cold dark matter or “dust.” Despite the phenomenological success of the model, our present ignorance of the physical nature of both the dark energy and dark matter should prevent us from being complacent. -
What's in This Issue?
A JPL Image of surface of Mars, and JPL Ingenuity Helicioptor illustration. July 11th at 4:00 PM, a family barbeque at HRPO!!! This is in lieu of our regular monthly meeting.) (Monthly meetings are on 2nd Mondays at Highland Road Park Observatory) This is a pot-luck. Club will provide briskett and beverages, others will contribute as the spirit moves. What's In This Issue? President’s Message Member Meeting Minutes Business Meeting Minutes Outreach Report Asteroid and Comet News Light Pollution Committee Report Globe at Night SubReddit and Discord BRAS Member Astrophotos ARTICLE: Astrophotography with your Smart Phone Observing Notes: Canes Venatici – The Hunting Dogs Like this newsletter? See PAST ISSUES online back to 2009 Visit us on Facebook – Baton Rouge Astronomical Society BRAS YouTube Channel Baton Rouge Astronomical Society Newsletter, Night Visions Page 2 of 23 July 2021 President’s Message Hey everybody, happy fourth of July. I hope ya’ll’ve remembered your favorite coping mechanism for dealing with the long hot summers we have down here in the bayou state, or, at the very least, are making peace with the short nights that keep us from enjoying both a good night’s sleep and a productive observing/imaging session (as if we ever could get a long enough break from the rain for that to happen anyway). At any rate, we figured now would be as good a time as any to get the gang back together for a good old fashioned potluck style barbecue: to that end, we’ve moved the July meeting to the Sunday, 11 July at 4PM at HRPO. -
The Triggering of Starbursts in Low-Mass Galaxies
Mon. Not. R. Astron. Soc. 000, 000{000 (0000) Printed 28 September 2018 (MN LATEX style file v2.2) The triggering of starbursts in low-mass galaxies Federico Lelli1;2 ?, Marc Verheijen2, Filippo Fraternali3;1 1Department of Astronomy, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA 2Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV, Groningen, The Netherlands 3Department of Physics and Astronomy, University of Bologna, via Berti Pichat 6/2, 40127, Bologna, Italy ABSTRACT Strong bursts of star formation in galaxies may be triggered either by internal or ex- ternal mechanisms. We study the distribution and kinematics of the H I gas in the outer regions of 18 nearby starburst dwarf galaxies, that have accurate star-formation histories from HST observations of resolved stellar populations. We find that star- burst dwarfs show a variety of H I morphologies, ranging from heavily disturbed H I distributions with major asymmetries, long filaments, and/or H I-stellar offsets, to lop- sided H I distributions with minor asymmetries. We quantify the outer H I asymmetry for both our sample and a control sample of typical dwarf irregulars. Starburst dwarfs have more asymmetric outer H I morphologies than typical irregulars, suggesting that some external mechanism triggered the starburst. Moreover, galaxies hosting an old burst (&100 Myr) have more symmetric H I morphologies than galaxies hosting a young one (.100 Myr), indicating that the former ones probably had enough time to regularize their outer H I distribution since the onset of the burst. We also investigate the nearby environment of these starburst dwarfs and find that most of them (∼80%) have at least one potential perturber at a projected distance .200 kpc. -
Arxiv:1807.06205V1 [Astro-Ph.CO] 17 Jul 2018 1 Introduction2 3 the ΛCDM Model 18 2 the Sky According to Planck 3 3.1 Assumptions Underlying ΛCDM
Astronomy & Astrophysics manuscript no. ms c ESO 2018 July 18, 2018 Planck 2018 results. I. Overview, and the cosmological legacy of Planck Planck Collaboration: Y. Akrami59;61, F. Arroja63, M. Ashdown69;5, J. Aumont99, C. Baccigalupi81, M. Ballardini22;42, A. J. Banday99;8, R. B. Barreiro64, N. Bartolo31;65, S. Basak88, R. Battye67, K. Benabed57;97, J.-P. Bernard99;8, M. Bersanelli34;46, P. Bielewicz80;8;81, J. J. Bock66;10, 7 12;95 57;92 71;56;57 2;6 45;32;48 42 85 J. R. Bond , J. Borrill , F. R. Bouchet ∗, F. Boulanger , M. Bucher , C. Burigana , R. C. Butler , E. Calabrese , J.-F. Cardoso57, J. Carron24, B. Casaponsa64, A. Challinor60;69;11, H. C. Chiang26;6, L. P. L. Colombo34, C. Combet73, D. Contreras21, B. P. Crill66;10, F. Cuttaia42, P. de Bernardis33, G. de Zotti43;81, J. Delabrouille2, J.-M. Delouis57;97, F.-X. Desert´ 98, E. Di Valentino67, C. Dickinson67, J. M. Diego64, S. Donzelli46;34, O. Dore´66;10, M. Douspis56, A. Ducout57;54, X. Dupac37, G. Efstathiou69;60, F. Elsner77, T. A. Enßlin77, H. K. Eriksen61, E. Falgarone70, Y. Fantaye3;20, J. Fergusson11, R. Fernandez-Cobos64, F. Finelli42;48, F. Forastieri32;49, M. Frailis44, E. Franceschi42, A. Frolov90, S. Galeotta44, S. Galli68, K. Ganga2, R. T. Genova-Santos´ 62;15, M. Gerbino96, T. Ghosh84;9, J. Gonzalez-Nuevo´ 16, K. M. Gorski´ 66;101, S. Gratton69;60, A. Gruppuso42;48, J. E. Gudmundsson96;26, J. Hamann89, W. Handley69;5, F. K. Hansen61, G. Helou10, D. Herranz64, E. Hivon57;97, Z. Huang86, A. -
Does Dark Energy Really Exist?
COSMOLOGY Does DARK ENERGY Maybe not. Really Exist? The observations that led astronomers to deduce its existence could have another explanation: that our galaxy lies at the center of a giant cosmic void By Timothy Clifton and Pedro G. Ferreira n science, the grandest revolutions are often of a universe populated by billions of galaxies triggered by the smallest discrepancies. In the that stretch out to our cosmic horizon, we are led I16th century, based on what struck many of to believe that there is nothing special or unique his contemporaries as the esoteric minutiae of ce- about our location. But what is the evidence for KEY CONCEPTS lestial motions, Copernicus suggested that Earth this cosmic humility? And how would we be able ■ The universe appears to be was not, in fact, at the center of the universe. In to tell if we were in a special place? Astronomers expanding at an accelerat- our own era, another revolution began to unfold typically gloss over these questions, assuming ing rate, implying the exis- 11 years ago with the discovery of the accelerat- our own typicality sufficiently obvious to war- tence of a strange new ing universe. A tiny deviation in the brightness of rant no further discussion. To entertain the no- form of energy—dark ener- exploding stars led astronomers to conclude that tion that we may, in fact, have a special location gy. The problem: no one is they had no idea what 70 percent of the cosmos in the universe is, for many, unthinkable. Never- sure what dark energy is. -
Arxiv:Astro-Ph/0401239V1 13 Jan 2004
Paper status: Accepted to the ApJ Missing Massive Stars in Starbursts: Stellar Temperature Diagnostics and the IMF J. R. Rigby and G. H. Rieke Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 [email protected], [email protected] ABSTRACT Determining the properties of starbursts requires spectral diagnostics of their ultraviolet ra- diation fields, to test whether very massive stars are present. We test several such diagnostics, using new models of line ratio behavior combining Cloudy, Starburst99 and up-to-date spectral atlases (Pauldrach et al. 2001; Hillier & Miller 1998). For six galaxies we obtain new measure- ments of Hei 1.7 µm/Br10, a difficult to measure but physically simple (and therefore reliable) diagnostic. We obtain new measurements of Hei 2.06 µm/Brγ in five galaxies. We find that Hei 2.06 µm/Brγ and [Oiii]/Hβ are generally unreliable diagnostics in starbursts. The het- eronuclear and homonuclear mid–infrared line ratios (notably [Neiii] 15.6 µm / [Neii] 12.8 µm) consistently agree with each other and with Hei 1.7 µm/Br10; this argues that the mid–infrared line ratios are reliable diagnostics of spectral hardness. In a sample of 27 starbursts, [Neiii]/[Neii] is significantly lower than model predictions for a Salpeter IMF extending to 100 M⊙. Plausi- ble model alterations strengthen this conclusion. By contrast, the low–mass and low–metallicity galaxies II Zw 40 and NGC 5253 show relatively high neon line ratios, compatible with a Salpeter slope extending to at least ∼ 40–60 M⊙. One solution for the low neon line ratios in the high– metallicity starbursts would be that they are deficient in & 40 M⊙ stars compared to a Salpeter IMF. -
The Cosmic Microwave Background Radiation at Large Scales and the Peak Theory
UNIVERSIDAD DE CANTABRIA La radiaci´ondel fondo c´osmicode microondas a gran escala y la teor´ıade picos por Airam Marcos Caballero Memoria presentada para optar al t´ıtulode Doctor en Ciencias F´ısicas en el Instituto de F´ısicade Cantabria Abril 2017 Declaraci´onde Autor´ıa Enrique Mart´ınezGonz´alez, doctor en ciencias f´ısicasy profesor de investigaci´ondel Consejo Superior de Investigaciones Cient´ıficas, y Patricio Vielva Mart´ınez, doctor en ciencias f´ısicasy profesor contratado doctor de la Universidad de Cantabria, CERTIFICAN que la presente memoria, La radiaci´ondel fondo c´osmicode microondas a gran scala y la teor´ıade picos ha sido realizada por Airam Marcos Caballero bajo nuestra direcci´onen el Instituto de F´ısicade Cantabr´ıa,para optar al t´ıtulode Doctor por la Universidad de Cantabria. Consideramos que esta memoria contiene aportaciones cient´ıficassuficientes para cons- tituir la Tesis Doctoral del interesado. En Santander, a 7 de abril de 2017, Enrique Mart´ınezGonz´alez Patricio Vielva Mart´ınez iii Agradecimientos Ciertamente, esta tesis no podr´ıahaber sido posible sin la ayuda, apoyo, trabajo y con- sejos de mis dos directores, Enrique y Patricio. Gracias a ellos he podido adentrarme en el mundo de la cosmolog´ıa,incluso en regiones que van mucho m´asall´ade lo presentado en esta tesis. Muchas gracias por todo este tiempo en el que no he dejado de aprender. No ser´ıajusto empezar estos agradecimientos sin mencionar tambi´ena los organismos que me han dado cobijo y apoyo econ´omico: el Instituto de F´ısica de Cantabria, la Universidad de Cantabria, el Consejo Superior de Investigaciones Cient´ıficasy el Minis- terio de Econom´ıay Competitividad. -
Arxiv:1310.7574V2 [Astro-Ph.CO] 13 Mar 2015 Ground Radiation—Large-Scale Structure of Universe
A Simple Gravitational Lens Model For Cosmic Voids Bin Chen1;2, Ronald Kantowski1, Xinyu Dai1 ABSTRACT We present a simple gravitational lens model to illustrate the ease of using the embedded lensing theory when studying cosmic voids. It confirms the previously used repulsive lensing models for deep voids. We start by estimating magnitude fluctuations and weak lensing shears of background sources lensed by large voids. We find that sources behind large (∼90 Mpc) and deep voids (density contrast about −0:9) can be magnified or demagnified with magnitude fluctuations of up to ∼0:05 mag and that the weak-lensing shear can be up to the ∼10−2 level in the outer regions of large voids. Smaller or shallower voids produce proportionally smaller effects. We investigate the \wiggling" of the primary cosmic microwave background (CMB) temperature anisotropies caused by intervening cosmic voids. The void-wiggling of primary CMB temperature gradients is of the opposite sign to that caused by galaxy clusters. Only extremely large and deep voids can produce wiggling amplitudes similar to galaxy clusters, ∼15 µK by a large void of radius ∼4◦ and central density contrast −0:9 at redshift 0.5 assuming a CMB background gradient of ∼10 µK arcmin−1. The dipole signal is spread over the entire void area, and not concentrated at the lens' center as it is for clusters. Finally we use our model to simulate CMB sky maps lensed by large cosmic voids. Our embedded theory can easily be applied to more complicated void models and used to study gravitational lensing of the CMB, to probe dark-matter profiles, to reduce the lensing-induced systematics in supernova Hubble diagrams, as well as study the integrated Sachs-Wolfe effect. -
Search for Streaming Motion of Galaxy Clusters Around the Giant Void?
A&A 382, 389–396 (2002) Astronomy DOI: 10.1051/0004-6361:20011500 & c ESO 2002 Astrophysics Search for streaming motion of galaxy clusters around the Giant Void? A. I. Kopylov1,2 andF.G.Kopylova1 1 Special Astrophysical Observatory of RAS, Nizhnij Arkhyz, Karachaevo-Cherkesia 369167, Russia 2 Isaac Newton Institute, Chile, SAO Branch, Russia Received 27 June 2001 / Accepted 27 September 2001 Abstract. We present the results of a study of streaming motion of galaxy clusters around the Giant Void (α ≈ 13h,δ ≈ 40◦,z ≈ 0.11 and a diameter of 300 Mpc) in the distribution of rich Abell clusters. We used the Kormendy relation as a distance indicator taking into account galaxy luminosities. Observations were carried out in Kron– Cousins Rc system on the 6 m and 1 m telescopes of SAO RAS. For 17 clusters in a spherical shell of 50 Mpc in thickness centered on the void no significant diverging motion (expected to be generated by the mass deficit in the void) has been detected. This implies that cosmological models with low Ωm are preferred. To explain small mass underdensity inside the Giant Void, a mechanism of void formation with strong biasing is required. Key words. galaxies: clusters – galaxies: elliptical and lenticular, cD – galaxies: fundamental parameters – galaxies: photometry – galaxies: distances and redshifts – cosmology: large-scale structure of Universe 1. Introduction constant (within the underdense region) relative to the global value of the Hubble constant (Wu et al. 1996). The To understand the origin and evolution of large scale struc- maximal peculiar velocity within the void is a rather sen- ture in the universe it is important to study inhomo- sitive function of Ωm and the density contrast in the void geneities of the largest size (mass) – superclusters and (Hoffman & Shaham 1982; Wu et al. -
The Evolution of Galaxies in Groups
THE EVOLUTION OF GALAXIES IN GROUPS: HOW GALAXY PROPERTIES ARE AFFECTED BY THEIR GROUP PROPERTIES by Melissa Gillone A thesis submitted to the University of Birmingham for the degree of Doctor of Philosophy Astrophysics and Space Research Group School of Physics and Astronomy University of Birmingham September 2015 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. Abstract It has been long known that galaxy properties are strongly connected to their envi- ronment; however, a complete picture is still missing. This work's aim is to better understand the role of environment in shaping the galaxy properties, using a sample of 25 redshift-selected galaxy groups at 0.060 < z < 0.063, for which 30 multi-wavelength parameters are available. Given the wide variety of group dynamical states, it was fundamental to try and identify different classes of groups performing a statistical clustering analysis using all the available parameters independently of their physical meaning, which resulted in two classes distinct by their mass. To move beyond mass- driven correlations, a new clustering analysis was performed removing the mass depen- dent properties, this approach provided a categorisation in four classes with distinctive group properties. -
Arxiv:1108.2222V3 [Astro-Ph.CO] 4 Jan 2012 Space of Solutions That fit the Small-Angle CMB
The kSZ effect as a test of general radial inhomogeneity in LTB cosmology Philip Bull,∗ Timothy Clifton,y and Pedro G. Ferreira.z Department of Astrophysics, University of Oxford, OX1 3RH, UK. (Dated: November 15, 2011) The apparent accelerating expansion of the Universe, determined from observations of distant su- pernovae, and often taken to imply the existence of dark energy, may alternatively be explained by the effects of a giant underdense void if we relax the assumption of homogeneity on large scales. Re- cent studies have made use of the spherically-symmetric, radially-inhomogeneous Lema^ıtre-Tolman- Bondi (LTB) models to derive strong constraints on this scenario, particularly from observations of the kinematic Sunyaev-Zel'dovich (kSZ) effect which is sensitive to large scale inhomogeneity. However, most of these previous studies explicitly set the LTB `bang time' function to be constant, neglecting an important freedom of the general solutions. Here we examine these models in full generality by relaxing this assumption. We find that although the extra freedom allowed by varying the bang time is sufficient to account for some observables individually, it is not enough to simulta- neously explain the supernovae observations, the small-angle CMB, the local Hubble rate, and the kSZ effect. This set of observables is strongly constraining, and effectively rules out simple LTB models as an explanation of dark energy. I. INTRODUCTION as modeled by the Lema^ıtre-Tolman-Bondi (LTB) solu- tions of general relativity [4{6]. These are the general spherically-symmetric solutions of Einstein's equations Observations of distant type-Ia supernovae are often with dust.