Cosmology) from a Bayesian Perspective

The near ﬁeld (cosmology) from a Bayesian perspective

Yehuda Hoﬀman (Racah Inst. of Physics, Hebrew University)

Ofer@60 (April 9, 2019)

1 / 30 Work with Ofer in the early 90s

2 / 30 WF/CRs applied to the CMB (COBE 1st year data)

COBE (raw data) COBE (WF) COBE (CRs)

3 / 30 CLUES (in a nutshell)

Key ingredients

Data: peculiar velocities of galaxies Prior model: ΛCDM Bayesian construction of the (linear) large scale structure (LSS) from noisy, sparse and incomplete data Time machine: from the (present epoch) reconstructed LSS to initial conditions (ICs) Constrained simulations: from ICs to the present epoch nearby universe Construct an ensemble of constrained simulations The mean (or median) over the ensemble of constrained simulation = estimator of the QL nearby universe

4 / 30 Bayesian inference: WF/CRs/Constrained simulations

In the Bayesian approach one is interested in the posterior probability of a model given observational data:

P(model | data) ∝ P(data | model) P(model)

P(model) is the prior probability (knowledge) of the model P(data | model) is the likelihood of the data given the (prior) model: how likely is a data given the model P(model | data) is the posterior probability: how likely is a model given the data and one’s prior knowledge. The model is a mathematical abstraction that describes a physical system (e.g. density or velocity ﬁeld).

Model: Gaussian random field, with the ΛCDM power spectrum Data: peculiar velocities of galaxies (Cosmicflows database) Sampling the posterior probability (linear regime): by constrained realizations (CRs) of Gaussian fields Posterior probability distribution function (linear regime): mean and most probable field are given by the Wiener filter (WF) Sampling the posterior probability (non-linear regime): by constrained simulations

5 / 30 Data: Cosmicﬂows project (PIs: Brent Tully & Helene Courtois)

1200 CF1 Cosmicﬂows project: database of galaxies with estimated CF2 CF3 distances: 1000 SFI++ Cosmicﬂows-1 (CF1): 1797 galaxies within 3000

800 km s−1 (575 grouped data)

Cosmicﬂows-2 (CF2): ≈8000 galaxies with median

N 600 redshift of 5895 km s−1 (4814 grouped)

400 Cosmicﬂows-3 (CF3): ≈18000 galaxies with median

redshift of ≈8000 km s−1 (≈ 11000 grouped) 200 Cosmicﬂows-4 (CF4): in progress

0 0 5000 10000 15000 20000 VCMB (km/s)

6 / 30 CF3 data and Planck ΛCDM model

Comparison of the monopole (−∇ · ~v/H0) and dipole (bulk velocity) moments (in top-hat spheres of radius R) of constrained realizations with random ones.

7 / 30 Hawaii Scientist Maps, Names Laniakea, Our Home Supercluster of Galaxies

IfA Publications University of Hawaii at Manoa astronomer R. Brent Tully, who recently shared the 2014 Newsletters Gruber Cosmology Prize and the 2014 Victor Ambartsumian International Prize, has led Scientific Preprints an international team of astronomers in defining the contours of the immense supercluster of galaxies containing our own Milky Way. They have named the Recent Publications supercluster “Laniakea,” meaning “immense heaven” in Hawaiian. The paper explaining Annual Reports this work is the cover story of the September 4 issue of the prestigious journal Nature. Press Releases Galaxies are not distributed randomly throughout the universe. Instead, they are found Front Page Stories in groups, like our own Local Group, that contain dozens of galaxies, and in massive In the Media clusters containing hundreds of galaxies, all interconnected in a web of filaments in which galaxies are strung like pearls. Where these filaments intersect, we find huge

Maintained by LG structures, called “superclusters.” These structures are interconnected, but they have poorly defined boundaries. For immediate release September 3, 2014 The researchers are proposing a new way to evaluate these large-scale structures by examining their impact on the motions of galaxies. A galaxy between two such Contacts: structures will be caught in a gravitational tug-of-war in which the balance of the gravitational forces from the surrounding large-scale structures determines the galaxy’s Dr. Brent Tully motion. By mapping the velocities of galaxies throughout our local universe, the team +1 808-956-8606 [email protected] was able to define the region of space where each supercluster dominates. Dr. Roy Gal The Milky Way resides in the outskirts of one such supercluster, whose extent has for Two views of the Laniakea Supercluster. +1 808-956-6235 The outer surface shows the region cell: +1 301-728-8637 the first time been carefully mapped using these new techniques. This Laniakea dominated by Laniakea’s gravity. For [email protected] Supercluster is 500 million light-years in diameter and contains the mass of 1017 (a more information, see caption for Figure Ms. Talia Ogliore hundred quadrillion) suns in 100,000 galaxies. Media Contact 1 below. Credit: SDvision interactive (808) 956-4531 [email protected] This study clarifies the role of the Great Attractor, a problem that has kept astronomers visualization software by DP at busy for 30 years. Within the volume of the Laniakea Supercluster, motions are directed CEA/Saclay, France. Illustrations: inwards, as water streams follow descending paths toward a valley. The Great Attractor region is a large flat bottom gravitational valley with a sphere of attraction that extends across the Laniakea Supercluster. The name Laniakea was suggested by Nawa‘a Napoleon, an associate professor of Hawaiian Language and chair of the Department of Languages, Linguistics, and Literature at Kapiolani Community College, a part of the University of Hawaii system.

8 / 30 Newly Discovered Intergalactic Void Repels Milky Way

IfA Publications For decades, astronomers have known Newsletters that our Milky Way galaxy - along with our Scientiﬁc Preprints companion galaxy, Andromeda - is moving through space at about 1.4 million miles Recent Publications per hour with respect to the expanding Annual Reports universe. Scientists generally assumed Press Releases that dense regions of the universe, Front Page Stories populated with an excess of galaxies, are pulling us in the same way that gravity In the Media made Newton's apple fall toward earth. In a groundbreaking study published in Contacts: Nature Astronomy, a team of researchers, Dr. Brent Tully including Brent Tully from the University of [email protected] Hawaii Institute for Astronomy, reports the Ofﬁce +1 808-956-8606 discovery of a previously unknown, nearly Dr. Roy Gal empty region in our extragalactic Media Contact +1 808-956-6235 neighborhood. Largely devoid of galaxies, cell: +1 301-728-8637 this void effectively exerts a repelling force, [email protected] pushing our Local Group of galaxies

through space. EMBARGOED UNTIL 0500HST 30 JANUARY 2017 Astronomers initially attributed the Milky Way's motion to the Great Attractor, a region of a half-dozen rich clusters of Maintained by RRG galaxies 150 million light-years away. Soon after, attention was drawn to a much larger structure called the Shapley Concentration, located 600 million light- years away, in the same direction as the Great Attractor. However, there has been ongoing debate about the relative importance of these two attractors and whether they sufﬁce to explain our motion.

9 / 30 A face-on view of a slice ±30h−1Mpc thick, normal to the direction of the pointing vector

ˆr = (0.604, 0.720, −0.342). Three different elements of the flow are presented: streamlines, red and grey surfaces present the knots and filaments of the V-web, and equipotential surfaces are shown in green and yellow. The yellow arrow indicates the direction of the CMB dipole.

The Dipole Repeller (DR) is located at: [SGX , SGY , SGZ] ≈ [110, −60, 100] ± 25h−1Mpc

10 / 30 The Cosmic Velocity Web

IfA Publications The cosmic web - the distribution of matter Newsletters on the largest scales in the universe - has Scientific Preprints usually been defined through the distribution of galaxies. Now, a new study Recent Publications by a team of astronomers from France, Annual Reports Israel, and Hawaii demonstrates a novel Press Releases approach. Instead of using galaxy Front Page Stories positions, they mapped the motions of thousands of galaxies. Because galaxies In the Media are pulled toward gravitational attractors and move away from empty regions, these FOR IMMEDIATE RELEASE 10 AUGUST 2017 motions allowed the team to locate the denser matter in clusters and filaments Contacts: and the absence of matter in regions Dr. Brent Tully called voids. [email protected] Office +1 808-956-8606 Matter was distributed almost homogeneously in the very early universe, Dr. Roy Gal Media Contact with only miniscule variations in density. +1 808-956-6235 Over the 14 billion year history of the cell: +1 301-728-8637 [email protected] universe, gravity has been acting to pull matter together in some places and leave other places more and more empty. Today, the matter forms a network of knots and connecting filaments referred to as the The cosmic velocity web is represented by surfaces of knots in red and surfaces of Maintained by RRG cosmic web. Most of this matter is in a filaments in grey. The black lines with arrows illustrate local velocity flows within mysterious form, the so-called "dark filaments and toward knots. The Laniakea Supercluster basin of attraction that matter". Galaxies have formed at the includes our Milky Way galaxy is represented by a blue surface. The region being highest concentrations of matter and act displayed extends across one billion light years. as lighthouses illuminating the underlying Credit: Daniel Pomarede, Yehuda Hoffman, R. Brent Tully, Helene Courtois. cosmic structure. The newly defined cosmic velocity web defines the structure of the universe from velocity information alone. In those regions with abundant observations, the structure of the velocity web and the web inferred from the locations of the galaxy lighthouses are

11 / 30 CF2 (V-web) and the large scale structure (LSS)

A 3D map of the Cosmic Web represented in terms of knots (red surfaces) and ﬁlaments (grey surface).

Orientation and dimensions are provided by the three-arrows signpost located at the origin of the supergalactic

coordinate system with its 2000 km/s long arrows pointing to the three cardinal directions (red, green, blue for

SGX, SGY, SGZ, respectively).

12 / 30 Planes of satellite galaxies and the cosmic (V-)web

13 / 30 The merits of cosmography

One can argue that it is a nice and noble ’hobby’ - mapping the universe - that results in beautiful maps and movies. But - the comparison of the reconstructed large scale structure with the observed distribution of galaxies constitutes a ’sanity’ check on the data and its analysis. Often the the comparison uncovers ’bugs’ and ’glitches’ in the data.

14 / 30 Constrained simulations of the local universe

Methodology

Constraints: Cosmicﬂows (CF2, grouped data) Model: ΛCDM (Planck parameters) Assumption: linear theory (virial motions in groups & clusters are suppressed) Revised Zeldovich approximation (RZA): undo Zeldovich displacements Constrained realizations of Gaussian ﬁelds → constrained initial condition → constrained simulations

15 / 30 Virgo mass assembly history (Sorce, Gottloeber, Hoﬀman & Yepes 2016)

Virgo model How do we deﬁne a Virgo-like object? Mass: ≈ (1 − 5) × 14 −1 10 h M ? Prediction: mass assembly history (MAH)

Mass assembly histories obtained with 100 random Virgo-like haloes (light grey), 15 constrained Virgo haloes from

simulations built with diﬀerent large scale random ﬁelds (dark grey) and 10 Virgo haloes from simulations sharing

the same large scale random ﬁeld (black). The mean MAH are plotted on top of the regions (green dotted line for

random, blue dotdashed line for constrained with diﬀerent large scale random ﬁelds and red triple dot-dashed line

for constrained sharing the same large scale random ﬁeld).

16 / 30 Quasi-linear construction of the LSS: motivation

Extension of the linear WF/CRs to the quasi-linear (QL) regime It is the ﬁrst time that the actual (non-lnear) large scale density ﬁeld is predicted from velocities A tool for studying the bias in the galaxy distribution

17 / 30 Quasi-linear construction of the LSS

Methodology - Run an ensemble of constrained simulations. - The ensemble samples the posterior distribution of the non-linear LSS (given the CF2 data and the prior model) - Calculate the mean of the (log) density and the velocity ﬁeld. Three-dimensional visualization of the density ﬁeld by means of - Calculate scatter around the mean. isosurfaces. The surface shown in grey is associated with a density of - Quasi-linear (QL) ∆ = 1.2, while surfaces shown in nuances of red are associated with construction of the LSS higher values of ∆ = 1.7, 2, 2.3, 2.7, 3. The red, green, blue 3 - BOX500 Mpc/h, N=512 , 20 50h−1Mpc-long arrows materialize the SGX, SGY, SGZ axes of the simulations supergalactic coordinate system. The QL nearby universe

18 / 30 The QL density ﬁeld: mean and scatter

log ∆ S/N

QL QL Left panel: The log10 ∆ ﬁeld of a slice on the Supergalactic Plane. Contour spacing of log10 ∆ is 0.2.

Prominent objects are theVirgo, Centaurus and Coma clusters, the Shapley concentration and Perseus - Pisces

supercluster. Right panel: the signal-to-noise contour map shows the ratio of the mean to the scatter,

QL (∆ − 1)/σ∆, with contour spacing 2.0.

19 / 30 The QL vs 2M++ density ﬁelds

”Cosmological parameters from the comparison of peculiar velocities with predictions from the 2M++ density ﬁeld” (Carrick, Turnbull, Lavaux & Hudson, MNRAS, 2015)

QL 2M++

√ −1 Density ﬁelds are Gaussian smoothed at Rs = 4 2h Mpc.

20 / 30 The QL density ﬁeld and the 2M++ galaxies: biasing

Non-linear bias Linear bias Linear bias model ∆ = C∆α g ∆ = 1 + δ δg = bδ α = 0.58 ± 0.04 1 δ ≈ αδ b = C = 0.84 ± 0.02 g α

21 / 30 The Local Group factory (Carlesi et al 2016)

Aim: To run a very large number

of constrained simulations that

‘mimic’ the nearby universe.

Motivation: Statistics of look-alike

Local Groups

22 / 30 Local Group model

What is a LG? Simplest model: two halos, distance d = (0.35 − 0.70)h−1Mpc, −1 physical radial velocity vr = (−135 − −80) km s , isolation

More advanced: add tangential velocity (vtan) Even more advanced and less observationally motivated: add mass

More physical: (M, d, vr , vtan) → (energy, angular momentum) i.e. an orbit. Observationally constrained physical model: ﬁx the phase on the orbit (to get the correct d, vr , vtan) Add galaxy formation considerations: e.g. quite recent merging history, disks

23 / 30 Bayesian inference: posterior distribution

Pconstrained XLG | ΛCDM, Cosmicﬂows data, LG model Prandom XLG | ΛCDM, LG model

XLG = mass, tangential velocity, merging history, ... of the LG

The sampling of the posterior distribution function is done by looking for pairs of halos that obey the LG model at the LG position in constrained or random simulations.

24 / 30 HESTIA project - constrained zoom hydro simulations of the Local Group (Libeskind +)

m CLUES + Springer et al: High resolution hydro (AREPO/Auriga galaxy formation code) zoom constrained simulations of the LG. mass assembly history (MAH)

Numerical model: BOX=100h−1Mpc, 4 simulations with N = 40963 and 3 6 −1 4 with N = 8192 particles corresponding to mDM ∼ 1.2 × 10 h M 5 −1 and 1.5 × 10 h M (Planck ΛCDM model). Data: Cosmicﬂows2 25 / 30 Reionization of the local universe 1744 T. Dawoodbhoy et al.

1 that are 4 h− Mpc on a side and centered on some object of interest, such as the Milky Way (‘MW’). These cutouts were identiﬁed by evolving the same CLUES constrained initial conditions to z = MNRAS 480, 1740–1753 (2018) doi:10.1093/mnras/sty1945 0 in a separate N-body simulation – the CoDa I-DM2048 GADGET

Advance Access publication 2018 July 20 simulation, as described in Ocvirk et al. (2016) – and tracing that Downloaded from https://academic.oup.com/mnras/article-abstract/480/2/1740/5056733 by Leibniz-Institute for Astrohysics Potsdam user on 07 December 2018 region’s Lagrangian mass at z 0 back to its location during the EOR. As can be seen, these regions= not only reionized at different Suppression of star formation in low-mass galaxies caused by the times, but the nature of their reionization was different, as well. Cutouts 43 and 448 (the two right-most curves) represent overdense reionization of their local neighbourhood regions, with mean overdensities δ ρ/ρ¯ 1 0.64 and 0.74, Downloaded from https://academic.oup.com/mnras/article-abstract/480/2/1740/5056733 by Leibniz-Institute for Astrohysics Potsdam user on 07 December 2018 respectively, at z 11.4. They started≡ reionizing− at= an early redshift, and did so gradually,= reaching volume-weighted ionized fraction 1‹ 1‹ 2 2 Taha Dawoodbhoy, Paul R. Shapiro, Pierre Ocvirk, Dominique Aubert, Xion 0.9 at zre 6.8 and 7.1, respectively. Cutouts 29 and 82 Nicolas Gillet,2,3 Jun-Hwan Choi,1 Ilian T. Iliev,4 Romain Teyssier,5 Gustavo Yepes,6 (the two= left-most= curves), on the other hand, represent underdense 7 1,8 1,9 10 1742 T. Dawoodbhoy et al. regions, with mean overdensities of -0.25 and -0.12, respectively, Stefan Gottlober,¨ Anson D’Aloisio, Hyunbae Park and Yehuda Hoffman at z 11.4. They did not start reionizing until rather late, and did 1 = Department of Astronomy, University of Texas at Austin, Austin, TX 78712-1083, USA A so abruptly, reaching an ionized fraction of 1 at an almost vertical 2ObservatoireMNRAS Astronomique000, 1–18 de (2018) Strasbourg, Preprint Universite´ de29 Strasbourg, November CNRS 2018 UMR 7550, Compiled 11 rue de l’Universit using MNRASe,´ F-67000 Strasbourg, L TEX France style file v3.0 slope (at z 4.6 and 4.8, respectively). Further analysis suggests re = 3Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy Figure 4. Ionization histories (volume-weighted ionized fraction Xion vs that these different local reionization histories reflect the relative 4 redshift) for a selection of different cutouts of the CoDa I simulation, along AstronomyCosmic Center,Dawn Department II (CoDa of Physics II): &a Astronomy,new radiation-hydrodynamics Pevensey II Building, University of simulation Sussex, Falmer, Brightonof the BN1self-consistent 9QH, UK coupling of importance of the contributions to local reionization from sources 5Institute for Theoretical Physics, University of Zurich,¨ Winterthurerstrasse 190, CH-8057 Zurich,¨ Switzerland with the globally-averaged history, for comparison. These cutouts are each 1 which are either ‘internal’ or ‘external’ to each local subvolume. 6 4 h Mpc on a side and centered on some objects of interest, such as Downloaded from https://academic.oup.com/mnras/article-abstract/480/2/1740/5056733 by Leibniz-Institute for Astrohysics Potsdam user on 07 December 2018 Departamento de F´ısica Teorica´ and CIAFF, Modulo´ 15 Universidad Autonoma´ de Madrid, E-28049, Madrid, Spain − Histories like those of cutouts 43 and 448, which begin early, are 7 ¨ the Milky Way (‘MW’) and M31, as identified by evolving the same I.C.’s Leibniz-Institutegalaxy formation fur Astrophysik and Potsdamreionization (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany gradual, and approach the end of reionization (X 1) with a slope 8Department of Physics & Astronomy, University of California, Riverside, CA 92521, USA forward in time to z 0 by a separate high-resolution N-body simulation, ion = of zero, correspond to regions which were ‘internally’→ reionized. 9Korea Astronomy and Space Science Institute, Daejeon, 305-348, Korea CoDa I-DM2048. 10Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel At the other extreme, those like cutout 29, which start late, rise 1 1 1,2,3 4 1 more, their zoom-in simulations were not allowed to react back on abruptly from Xion 0.1 to Xion 1 almost instantly, approaching Pierre Ocvirk , Dominique Aubert , Jenny G. Sorce , Paul R. Shapiro , Nicolas Deparis , Taha the coarser-grained background simulation or influence it in any the end with an infinite∼ slope,∼ correspond to regions which are way, so it is difficult to compare these results directly with ours. Accepted 2018 July 16.4 Received 2018 May 12;1 in original form 2018 May5 12 6,7 3 8 ‘externally’ reionized. In that case, the rise-time is so short because Dawoodbhoy , Joseph Lewis , Romain Teyssier , Gustavo Yepes , Stefan Gottlö ber , Kyungjin AhnLow-mass, halo suppression was not apparent in the simulations by the externally-driven I-front swept across the comoving distance of 1 9 10 Jaacks, Nagamine & Choi (2012), but their low-mass halo results 4h− Mpc in too little time for the plot to resolve it visually on the z- Ilian T. Iliev , Yehuda Hoffman . consisted of halos with stellar masses in the range 106.8M < axis. The histories for the MW and M31 cutout volumes in the Local ABSTRACT 8 ⊙2 M⋆ < 10 M .Assumingtypicalstellarmassfractionsof10− – Group are intermediate between these two extremes, consistent with 3 ⊙ The Astrophysical Journal Letters,Photoheating856:L22 associated(6pp), with 2018 reionization April 1 suppressed star formation in low-mass galaxies.10− ,https: this stellar//doi.org mass range/10.3847 could very/2041-8213 well consist/ mostlyaab14d of ha- asignificant,perhapsevendominant,contributionfrom‘internal’ Reionization was inhomogeneous, however, affecting different regions at different times. Tolos that are massive enough to avoid suppression according to our © 2018. The American Astronomical Society. All rights reserved. sources but a non-negligible contribution from ‘external’ sources, establish the causal connection between reionization and suppression, we must take this localresults. Finally, Gnedin & Kaurov (2014)foundthatreionization too. They finished reionization a bit earlier (at z 5.2 and 5.1, re = variation into account. We analyze the results of CoDa (‘Cosmic Dawn’) I, the first fullyfeedback had a very modest impact on low-mass galaxies in the respectively, for Xion 0.9) than the globally-averaged history (for CROC simulation, but a direct comparison with CoDa I is difficult = coupled radiation-hydrodynamical simulation of reionization and galaxy formation in the which Xion 0.9 at zre 4.9) but are qualitatively similar to the since they studied the UV luminosity function but do not report the = = Local Universe, in a volume large enough to model reionization globally but with enough latter. The mean densities of the MW and M31 cutouts are closer to SFR-halo mass relation. The difference between their results and the cosmic mean density as well, with overdensities of 0.16 and 0.09, The Inhomogeneousresolving power to follow all Reionization atomic-cooling galactic halos Times in that volume. of Present-dayFor every halo Galaxies ours is discussed further in Ocvirk et al. (2016). respectively, at z 11.4. We discuss the correspondence between identified at a given time, we find the redshift at which the surrounding IGM reionized, = 1 1 1 2 TheFigure globally-averaged 1. AvisualizationofaslicethroughtheCoDasimulationwhenhalfoftheIGMwasionized(3 results presented in this section demon-Signatureslocal ofoverdensity reionization andz reionization5.44) in theshowing LG timing the cosmic further873 web in and Section the ‘patchiness’ 3.2.2. of = Dominiquealong Aubert with its instantaneous, Nicolas star Deparis formation, rate Pierre (‘SFR’) Ocvirk and baryonic, Paul gas-to-dark R. Shapiro matter ratiostrate,reionization. Ilian a correlation T. Gas Iliev between overdensity, theδ, end, increases of global from reionization blue to red. andThe colourSFR brightnessAs depends illustrated on the by ionized these differentfraction, χ outcomes,, with the darkest which regions correlate corresponding with M /M 4 5 < 9 6 suppressionto completely in low-mass neutral7 gas halos. and the Thanks brightest to regions its large corresponding volume andto completely ionized gas. These extremes are indicated in the legend to the right. Gustavo( gas YepesDM). The average, Stefan SFR Gottlöberper halo with ,M Yehuda10 M Hoffmanwas steady in, regions and Romain not yet Teyssier the large-scale patchiness of the EOR, we are required to treat every 1 reionized, but declined sharply following local reionization.⊙ For M > 1010M ,thisSFRdynamic range, CoDa I makes it possible to go well beyond these point in space as having a unique reionization history. We define Universite de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, F-67000⊙ Strasbourg, France; [email protected] 4 2 9 < M

geneous, so must the effects of reionization suppression have been. Downloaded from https://academic.oup.com/mnras/article-abstract/477/1/867/4911532 by Astrophysikalisches Institut Potsdam Bibliothek user on 07 December 2018 MNRAS3 477, 867–881 (2018)1010M doi:10.1093/mnras/sty494,theSFRgenerallyincreasedmodestlythroughreionization,followedbyamodest Advance Access publication ⊙ of the universe large enough to sample the full range of experiences smallto volume resolve surrounding the mass motions position associatedx first reached with pressure ionized fraction and gravity Astronomy Center, Department of Physics & Astronomy, Pevensey II Building, University of Sussex,By studyingFalmer, the Brighton inhomogeneity BN1 of 9QH, reionization UK and its impact on X 0.9. Because of the intimate⃗ connection between structure 4 ⊙ of individual halos while following the spatial inhomogeneity of ion forces. Forcing the simulation to use the smaller of these two step 2018 February 27 decline. In general, halo SFRs were higher for regions that reionized earlier. A similar patternindividual halo properties, we will make a more compelling case for = Departamento de Fisica Teorica and CIAFF, Modulo M-15, Universidad Autonoma de Madrid,9 E-28049reionization Cantoblanco, on large scales, Spain with enough resolution to track the formationsizes for and both reionization, is computationally this field resembles prohibitive the and underlying wasteful. cos- CoDa 5 was found for Mgas/MDM,whichdeclinedsharplyfollowinglocalreionizationforM < 10 M the. causal relationship between reionization feedback and suppres- Leibniz-Institute für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482⊙ Potsdam,formation Germany of all star-forming halos in that volume, as well as the micI web is based of dark onmatter, the hybrid galaxies, CPU-GPU and the code, IGMRAMSES (see- Fig.CUDATON5):, the which Local reionization6 time correlates with local matter overdensity, which determines the local Reionization of the Milky Way, M31,Racah and Institutetheir satellites of Physics, – I. Reionization Hebrew University, history Jerusalem 91904, Israelsionmutual and its feedback environmental of these dependence. halos and reionization We do this onbyeach monitoring other, with highestovercame density this peaks problem in the by early performing universe hundredsreionized of first, RT while steps on rates of structure formation and ionizing photon consumption. The earliest patches to developthe direct and immediate effects of reionization feedback in many 7 Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich,fully coupled Switzerland radiation-hydrodynamics from cosmological initial voidsthe were GPUs the per last gravito-hydrodynamics to reionize, as we will step show on in the the CPUs, following on each structure and reionize ultimately produced more stars than they needed to finish and maintainsmall patches, each reionized at a different time and place (with dif- sections. and star formationReceived 2017 November 27; revised 2018 February 14; accepted 2018 February 20; publishedconditions. 2018 To March sample reionization 26 inhomogeneity fairly, a comov- of 8192 nodes of the CPU-GPU hybrid, massively-parallel super- their own reionization, exporting their ‘surplus’ starlight to help reionize regions that developedferenting overdensities, volume of order halo mass 100 Mpc functions, on a haloside gasis required fractions, (Iliev etc.). et al. computer Titan at OLCF. It has a resolution of 40963 cells for structure later. In the2014 following). Resolving sections, all atomic-cooling we will show halos that the (i.e. suppression those with masses of hydrodynamics and radiative transfer and the same number of dark low-mass halos8 universally follows local reionization, regardless of 3.1 Methodology 5 M ! 10 M )withhundredsofN-body particles requires a particle matter particles (each with a mass of 3.49 10 M ) in a comov- 1,2‹ Key words:2 cosmology: theory3 – dark ages, reionization,Abstract4,5,6 first stars. when or where⊙ it occurs. 6 11 × ⊙ Keri L. Dixon, Ilian T. Iliev, Stefan Gottlö ber, Gustavo Yepes, mass smaller than 10 M , implying as many as 10 particles for 3.1.1ing Generating box 91 cMpc the reionization on a side, andredshift is simulated field down to a redshift such a large volume. ⊙ fi ∼ of 4.23. Today’s galaxies experienced cosmic reionization at different times in different locations. For the rst time, To track the effect of reionization on low-mass halos, we use the 4,5,6 3 7 3LOCALREIONIZATIONOur goal is to quantify the dependence of the SFRs and halo The initial conditions (I.C.’s) for CoDa I were a realization of Alexanderreionization Knebe,(50%Noam ionized Libeskind) redshifts,and YehudazR, at Hoffman the location of their progenitors are derivedgas-to-dark from matter new, ratios fully of individual coupled galaxies on their local reion- instantaneousGaussian locations randomnoise of halos density identified fluctuations in the CoDa in the I simulation#CDM uni- into the surrounding intergalactic medium (IGM) and photoionizedThe history of reionization was different in different places, as can be 1INTRODUCTION ization histories. For that, we must be able to subdivide the total verse, assuming cosmological parameters from the case ‘WMAP radiation-hydrodynamics simulation of galaxyH atoms formation there, heating the and gas to reionization temperatures T 10 at4 K,z to> start6, theseen matched in Fig. 4. This to N plot-body shows the simulation ionization histories of a selection number of halos identified at each redshift in this simulated volume +BAO+SN’inHinshawetal.(2009) (i.e. $m 0.279, $bary ∼ 4 Whento thez first= galaxies0. Constrained born from the growth initial of density conditions fluctuations wereEpoch of chosen Reionization to (EOR). form Over the time, well-known as more galaxies formed structuresof differentinto bins CoDa of cosmic Ithe simulation time local (or ‘cutouts’ redshift) universe, –regions during which of the simulationtheir surround- This reionization0.046, $ redshift0.721, field wash also0.7, discussedσ by0.817, Battaglian et= al.0.96). (2013). They 3 # 8 s in theincluding early universe formed the stars, Local some of Group their UV starlight and escapedVirgo, inmore a stars,(91 the Mpc H II regions) volume surrounding large them grew enough and overlapped, to modelings were both reionized, global and then and subdivide local these bins further into bins were= a ‘constrained= realization’= produced= by the CLUES= (‘Con- led by the expansion of highly supersonic ionization fronts that MNRASof common480, 1740–1753 halo mass,3 (2018) with enough halos in each bin to enable us to strained Local UniversE Simulations’) consortium (Gottlober,¨ Hoff- reionization. Reionization simulation CoDaraced I-AMR, ahead of the hydrodynamical by CPU-GPU back-reaction code of the EMMA, IGM to its average used over(2048 the halo-to-halo) particles scatter in andtheir SFRs and gas fractions. man & Yepes 2010), derived from observations of galaxies in 3 photoheating. Inside these H II regions, however, that back-reaction 3 ⋆ E-mail:([email protected]) initial cells,(TD); [email protected] refined, while N-body simulation CoDa I-DM2048,This by requirement Gadget2, is yet used another( reason2048 the) simulation must have a our Local Universe, and designed to reproduce its observed fea- was inescapable. Current evidence suggests that the entire IGM was (PRS) fi very large volume.8 tures when evolved cosmologically over time to the present (e.g. particles, to nd reionization times for all galaxies at z=0 with masses M(z=0) 10 Me. Galaxies with 26 / 30 11 1 the Local Group, containing structures resembling the Milky Way C 2018 The Author(s) fi Mz()= 0 10 M reionized earlier than the universe as a whole, by⃝ up to ∼500 Myr, with signi cant scatter. and M31, and the Virgo and Fornax clusters). This allows us to Published by Oxford University Press on behalf of the Royal Astronomical Society 112.2 CoDa I fits the bill compare features of CoDa I with Local Group observations di- For Milky Way–like galaxies, zR ranged from 8 to 15. Galaxies with Mz= 0 10 M typically reionized as () The combination of such a large volume and high resolution in a rectly, in a volume large enough to model global reionization, too late or later than globally averaged 50% reionization at ázRñ=7.8, in neighborhoodsfully coupled where radiation-hydro reionization simulation was of reionization has only (see Ocvirk et al. 2016). 2 completed by external radiation. The spread of reionization times within galaxies wasrecently sometimes become computationally as large feasible.as theCoDa (Cosmic Dawn) Figure 4. Map of the reionizationI, described redshifts in Ocvirk throughout et al. our(2016 volume), is the for firstmodels such LG1 simulation (upper left), to LG2, (upper right), LG3 (lower left), and LG4 (lower galaxy-to-galaxy scatter. The Milky Way and M31 reionized earlier thanright). global The slice reionization depth is 0.36 Mpc (a singlebut pixellater width), than and the typical entire box is shown, making each side 91 Mpc. The small (blue) and large (purple) circles meet all of these requirements. There is a fundamental mismatch 2Towards this end, these same CLUES I.C.’s were recently used by another approximately represent the Lagrangian volume that will end up within 2.86 Mpc of the LG and Virgo, respectively. The insets are a 14 comoving Mpc square for their mass, neither dominated by external radiation. Their most-massive progenitorsbetween the atsmallz time> steps6 had requiredzR to= resolve radiative transfer CoDa simulation, CoDa I-AMR, based on the hybrid CPU-GPU, AMR zoom of the LG region (dotted circle) for each model. The MW (green, upper) and M31 (yellow, lower) with a 0.8 Mpc comoving radius (not Lagrangian) are and non-equilibrium ionization in the presence of highly super- radiation-hydrodynamics code EMMA, as described by Aubert et al. (2018), 9.8 (MW) and 11 (M31), while their total masses had z =8.2 (both).represented by the circles and reionize early with respect to the rest of LG. The surrounding dark area are low-density, late-reionizing regions. R sonic ionization fronts and the larger time steps which are sufficient where objects in the Local Universe at z 0 were matched to their pro- = Key words: dark ages, reionization, first stars – galaxies: high-redshift – methods: numerical Virgo progenitors are markedMNRAS by480, the small1740–1753 (blue)and (2018) large (purple) reionize earlier, which is characteristic of an inside-out reionization circles, respectively. The LG1, LG2, LG4, and LG3 are displayed profile. The Spearman rank-order correlation coefficient quantifies clockwise, starting with the top-left panel. Immediately obvious is this relationship, with zero implying no correlation and 1mono- 1. Introduction full-physics RHDthe fact that simulation. LG3, with its higherWe combined efficiencies and CoDa large number I-AMR of withtonic negative a correlation. Although we are limited by the− number sources, reionizes the earliest. Also, in all models, the Virgo pro- of bound structures given our resolution at z 0, we find a coeffi- dark-matter-only N-body simulation to z=0 by Gadget2, CoDa = Different patches of the universe reionized at different times, genitors tend to be some of the earliest reionized regions. The LG cient of 0.20, 0.26, 0.32, and 0.29 for LG1, LG2, LG3, and I-DM2048,as from a whole the does notsame reionize initial especially conditions early, though this(ICs result),tomatch is LG4, respectively,− − indicating− that all− are somewhat correlated and over a wide range of redshifts, and this local reionization time today’s galaxiesnot spatially with uniform. their reionization The insets are a 14 histories Mpc comoving self-consistently. square LG3 is the most strongly correlated. Note that these exact numbers left its imprint on galaxies at z=0. Reionization photoheating zoom of the LG region (dotted circle) for each model. The MW3 and are sensitive to the chosen radius of inclusion and the ionization ReionizationM31 simulation are represented CoDa by the I-AMR upper and lower used circle,(2048 respectively.) particlesthreshold. and For all models, the external sweep of reionization ac- suppressed baryonic infall and star formation in low-mass 3 (2048) initialThe cells,radius of while these circlesN-body is 0.8 Mpc simulation comoving and not CoDa the rough I-DM2048counts for the reionization of a significant fraction of the satellites, galaxies and caused reionization to self-regulate (e.g., Shapiro 3Lagrangian volume as with the LG and Virgo, and this distance is meaning many satellites will have similar zreion within the shaded used (2048) chosenparticles to exclude to thefind satellites reionization at the redshift times of reionization and durations (see band. for Several satellite progenitors at roughly the same present-day et al. 1994; Iliev et al. 2007). The stellar populations of their −1 3 all the galaxiesFigs 7 inand a8).( The64 MWh andMpc M31 reionize∼91 early Mpc with) respectvolume to the at zdistance=0 can have vastly different zreion, represented by the vertical satellites, for example, were dramatically affected by when rest81 of- LG, and the dark areas are lower in density and reionize later. scatter. with MhM 10 The MW and M31. satellites’ progenitors may have a reionization The zreion for the MW’s own progenitors is shown as the (red) reionization occurred and whether instantaneous or extended These ICshistory are distinct afromconstrained the average of the LG volume.realization In Fig. 5, we of plot ΛCDM,square. For LG1, the MW reionizes before any of the satellite pro- (see, e.g., Koposov et al. 2009; Busha et al. 2010; Ocvirk & zreion of the MW satellites, compared to their present-day distance genitors. For LG3, the MW reionizes at an average time compared constructedfrom by the the MW, Constrainedr . The darkest Local (purple) UniversE to lightest (yellow) Simulationsto the satellites. For LG2 and LG4, the MW reionizes right around ˜MWz 0 Aubert 2011; Ocvirk et al. 2014). Reionization suppression is = (CLUEs) projectcolour dots from are the leastobservations to most massive ofMz galaxies0,respectively.The in thethe local time that reionization of the LG accelerates (the shaded band), grey band represents the global x 0.4–0.6,= where the LG reion- along with most of its satellites. thought to reconcile the observed paucity of satellites in the universe, to form familiar structuresm = within it, including the LG ization accelerates indicating external influence (c.f. Fig. 2). The We also find that zreion is loosely correlated with the satellite Local Group (LG) with their overprediction by N-body with the Milkyfour source Way models(MW LG1,) and LG2, M31,LG3, and in LG4 a are volume shown from large left enoughmass, with the more massive (lighter circles) satellites generally simulations of ΛCDM (Bullock & Boylan-Kolchin 2017). In to model bothto right. global There is and some indication local reionization. that satellites nearer The to the MW reionizationreionizing earlier. Some large satellites have progenitors capable a global context, where the contribution of low-mass galaxies history of the LG in its authentic environment is thereby to reionization is still debated (see, e.g., Bouwens et al. 2015; modeled, to assess how representative it is, as the most MNRAS 477, 867–881 (2018) Finkelstein et al. 2015), these effects must be understood in accessible place to observe galaxies and their satellites today to order to interpret observations of high-z galaxies. deduce their histories. We are therefore able to compare the LG For the first time, we are able to perform a complete study of to a population of analog galaxies in different environments the reionization history of z=0 galaxies and the LG in and to establish, as shown hereafter, that LG galaxies are particular, using a full-physics simulation. We produced a new, reionized later than reference galaxies of similar masses and state-of-the-art, fully coupled radiative hydrodynamics (RHD) that the LG is reionized without influence from external simulation of galaxy formation and reionization at z>6, incoming fronts. named CoDa I-AMR (“Cosmic Dawn”), by CPU-GPU Ocvirk et al. (2016) reported our first attempt to model both adaptive mesh refinement (AMR) code EMMA (Aubert global reionization and its impact on the LG, using the first et al. 2015). This new code is able to take advantage of the RHD simulation of reionization of the Local universe (CoDa I) GPU-driven hybrid architecture of Titan supercomputer with high-enough resolution in a large-enough volume. This (ORNL) and required 20 million core hours to produce this first breakthrough used CPU-GPU code Ramses-Cudaton with

1 Mon. Not.Cosmic-Ray R. Astron. Soc. 000, 1–?? (2002) Printed 21 November Anisotropy 2018 (MN LaTEX style ﬁle v2.2) from Large Scale Structure

Cosmic-Ray Anisotropy from Large Scale Structure and the e↵ect of magnetic horizons

N. Globus,1? T. Piran,1 Y. Ho↵man,1 E. Carlesi2, D. Pomarède3 1 Racah Institute of Physics, The Hebrew University ofMon. Jerusalem, Not. R. Astron. 91904 Soc. 000 Jerusalem,, 1–?? (2002) Israel Printed 21 November 2018 (MN LaTEX style ﬁle v2.2) 2Leibniz Institut für Astrophysik, An der Sternwarte 16, 14482 Potsdam, Germany 3Institut de Recherche sur les Lois Fondamentales de l’Univers, CEA Saclay, F-91191 Gif-sur-Yvette, France Cosmic-Ray Anisotropy from Large Scale Structure and the e↵ect of magnetic horizons Released 21 November 2018 N. Globus,1? T. Piran,1 Y. Ho↵man,1 E. Carlesi2, D. Pomarède3 1Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel ABSTRACT2Leibniz Institut für Astrophysik, An der Sternwarte 16, 14482 Potsdam, Germany Motivated3 byInstitut the de Recherche7% sur dipole les Lois Fondamentales anisotropy de l’Univers, in the CEA distribution Saclay, F-91191 Gif-sur-Yvette, of ultra-high France energy cosmic-rays (UHECRs) above⇠ 8 EeV, we explore the anisotropy induced by the large scale structure, using

constrainedReleased simulations 21 November 2018 of the local Universe and taking into account the e↵ect of magnetic fields. The value of the intergalactic magnetic field (IGMF) is critical as it determines the ↵ UHECR cosmic horizon. We calculateABSTRACT the UHECR sky maps for di erent values of the IGMF variance and show the e↵ectMotivated of the by theUHECR7% dipole horizon anisotropy on in the the distribution observed of ultra-highanisotropy. energy The cosmic-rays (UHECRs) above⇠ 8 EeV, we explore the anisotropy induced by the large scale structure, using footprint of the local (. 350 Mpc)constrained Universe simulations on theof the UHECR local Universe background, and taking into accounta small the angulare↵ect of magnetic scale enhancement in the Northernfields. Hemisphere, The value of the is intergalactic seen. At magnetic 11.5 EeV field (IGMF) (the median is critical as value it determines of the the energy bin at which the dipoleUHECR has beencosmic reported), horizon. We calculatethe LSS-induced the UHECR sky dipole maps for amplitude di↵erent values is of the IGMF variance and show the e↵ect of the UHECR horizon on the observed anisotropy. The A1 10%, for IGMF in the rangefootprint [0.3-3] of the nG local for (. protons,350 Mpc) Universe helium on and the UHECR nitrogen, background, compatible a small angular with⇠ the rms value derived from thescale cosmic enhancement power in thespectrum. Northern Hemisphere, However is seen. at At these 11.5 EeV energies (the median the value of the energy bin at which the dipole has been reported), the LSS-induced dipole amplitude is UHECRs are also influenced by theA Galactic10%, for IGMF Magnetic in the range Field [0.3-3] (GMF) nG forand protons, we helium discuss and nitrogen, its e↵ect compatible 1 ⇠ on the LSS-induced anisotropy. Cosmic-Raywith the rms valueAnisotropy derived from the Large cosmic Scale power Structure spectrum. and However the e↵ atect these of magnetic energies the horizons 7 UHECRs are also influenced by the Galactic Magnetic Field (GMF) and we discuss its e↵ect Key words: cosmic-rays on the LSS-induced anisotropy. Key words: cosmic-rays

1 INTRODUCTION mean free path in the photons backgrounds (Farrar & Piran 2000; 1 INTRODUCTION mean free path in the photonsParizot backgrounds 2004; Piran 2010;(Farrar Harari et al. & 2014, Piran 2015) 2000;. Di↵erent nu- The origin of the ultra-high energy cosmic-rays (UHECRs) is still clei don’t experience the same energy losses,↵ and therefore, even if unknown. To identify a source we needParizot to know 2004; the arrival Piran direc- 2010; Harari et al. 2014, 2015). Di erent nu- The origin of the ultra-high energy cosmic-rays (UHECRs) is still they have the same rigidity E/Z (i.e. they behave the same way in tion of the UHECRs. However, UHECRs are deflected on their way ⇠ clei don’t experience the samethe IGMF), energy they have losses, di↵erent and horizons. therefore, This situation even is if unique to unknown. To identify a source we need to knowto the Earth arrival by the direc- intervening Galactic and intergalactic magnetic they have the same rigidityUHECRs:E/Z di(i.e.↵erent they energy behave and nuclei the species same probe way di in↵erent dis- fields (GMF and IGMF, respectively). The only observed statis- tion of the UHECRs. However, UHECRs are deflected on their way tances.⇠ Therefore, it has been suggested that, at a given energy and tically significant deviation from isotropythe IGMF), is a large they scale have dipole di↵erent horizons. This situation is unique to

arXiv:1808.02048v2 [astro-ph.HE] 19 Nov 2018 composition, the anisotropy in the UHECR background probes the to the Earth by the intervening Galactic and intergalacticanisotropy (Pierre magnetic Auger Collaboration 2017, hereafter PAO17), of UHECRs: di↵erent energysource and distribution nuclei species within the probe cosmic-ray di↵ horizonerent (Waxman dis- et al. the order of a few percent, reported at 5 significance level for fields (GMF and IGMF, respectively). The only observed statis- ⇠ 1997). We investigate this possibility, assuming that the distribu- UHECR energies E >8 EeV. tances. Therefore, it has been suggested that, at a given energy and tically significant deviation from isotropy is a large scale dipole tion of UHECR sources follow the LSS. We calculate the UHECR We can expect that extragalactic UHECR sources follow, up arXiv:1808.02048v2 [astro-ph.HE] 19 Nov 2018 composition, the anisotropydipole in anisotropy the UHECR induced background by the matter distribution, probes taking the into ac- anisotropy (Pierre Auger Collaboration 2017, hereafterto a biasing PAO17) factor, the, largeof scale structure (LSS) of the Universe. count the di↵usive propagation of the UHECRs in the IGMF. We Both the energy and composition ofsource the cosmic-rays distribution change during within the cosmic-ray horizon (Waxman et al. the order of a few percent, reported at 5 significance level for derive the amplitude and direction of the UHECR dipole, for dif- the extragalactic propagation because of their interaction with the ⇠ 1997). We investigate thisferent possibility, IGMF values assuming and di↵erent thatcompositions. the distribu- We then estimate UHECR energies E >8 EeV. cosmological photons backgrounds (GZK e↵ect). Moreover, con- tion of UHECR sources followthe e↵ect the of the LSS. GMF We on the calculate LSS-induced the UHECR UHECR anisotropy, for trarily to the photons, neutrinos and gravitational waves, UHECRs We can expect that extragalactic UHECR sources follow, up proton and nitrogen at 11.5 EeV. are deflected by the IGMF, and enterdipole a di↵usion anisotropy regime after a induced time by the matter distribution, taking into ac- to a biasing factor, the large scale structure (LSS) of the2 Universe. of a few D/c (DFigureis the di 6.↵Skyusion maps, coecount in Galacticcient). the coordinates, di↵usive of the LSS-inducedpropagation UHECRIn a of previous anisotropy the UHECRs study taking (Globus into account in & Piranthe the e IGMF.↵ 2017,ect of hereafterthe GalacticWe GP17), magnetic field of Jansson Both the energy and composition of the cosmic-raysThe change observed during& UHECR Farrar (2012a). dipole Left, anisotropy from top is to set bottom: by the the size LSS-induced of we UHECR derived anisotropy the expected for protons UHECR at 11.5 extragalactic Eev in 1 nG dipole IGMF, from nitrogen the inob- 0.2 and 3 nG IGMF the UHECR observablerespectively. Universe. Right: the Thederive anisotropy "cosmic-ray the after amplitude reconstruction horizon", the by and the GMFserved direction of Jansson LSS density of & Farrar the power (2012a). UHECR spectrum. The amplitude dipole, We foundA1 and for a maximum direction dif- of value the dipole are marked by the extragalactic propagation because of their interactionlargest distance with thatthe black the the UHECR dot. The can observed propagate Augerat dipole a given direction energy is figured, byfor the the red rms circle. dipole amplitude of 8b% for IGMF strength & 1 ferent IGMF values and di↵erent compositions. We⇠ then estimate cosmological photons backgrounds (GZK e↵ect).depends Moreover, on their di con-↵usion coecient in the IGMF and on their nG, for helium and nitrogen at energies greater than 8 EeV. Here the e↵ect of the GMF on the LSS-induced UHECR anisotropy, for trarily to the photons, neutrinos and gravitational waves, UHECRs b is the bias factor. 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c 2002 RAS, MNRAS 000, 1–?? CLUES and Near Field Cosmology

The initial conditions of the Near Field are very well constrained by the CLUES/Cosmicflows machinery. CLUES is the near field cosmology on the computer - numerical laboratory for experimenting with the physics of galaxy formation. The constrained simulations test the Copernican hypothesis on the nature of the near-field.

28 / 30 TODA (thank you) Ofer for an inspiring and enjoyable collaboration.

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