signals of cosmic strings in the sky: probe of particle ... · of particle physics beyond the...

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures

Signals inCMBPolarization

Signatures in21cm

Loops

Conclusions

Signals of Cosmic Strings in the Sky: Probeof Particle Physics Beyond the Standard

Model

Robert BrandenbergerMcGill University, Montreal, Canada

ETH Colloquium, May 25 2018

1 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Outline

1 Introduction

2 Cosmic String Review

3 Kaiser-Stebbins Effect and Cosmic String Wakes

4 Signatures of Strings in CMB Temperature Maps

5 Signature of Cosmic Strings in High z Large-ScaleStructure Surveys

6 Signatures of Cosmic String Wakes in CMB Polarization

7 Signatures of Cosmic String Wakes in 21cm Maps

8 Effects of Cosmic String Loops

9 Conclusions

2 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

3 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Cosmic StringsT. Kibble, J. Phys. A 9, 1387 (1976); Y. B. Zeldovich, Mon. Not. Roy. Astron.Soc. 192, 663 (1980); A. Vilenkin, Phys. Rev. Lett. 46, 1169 (1981).

Cosmic string = linear topological defect in a quantumfield theory.1st analog: line defect in a crystal2nd analog: vortex line in superfluid or superconductorCosmic string = line of trapped energy density in aquantum field theory.Trapped energy density→ gravitational effects onspace-time→ important in cosmology.

4 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Relevance to Particle Physics I

Cosmic string solutions exist in many particle physicsmodels beyond the “Standard Model".Cosmic strings are predicted to form at the end ofinflation in many inflationary models.Cosmic strings may survive as cosmic superstrings inalternatives to inflation such as string gas cosmology.In models which admit cosmic strings, cosmic stringsinevitably form in the early universe and persist to thepresent time.Seeing a cosmic string in the sky would provide a guideto particle physics beyond the Standard Model!

5 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Relevance to Particle Physics II

Cosmic strings are characterized by their tension µwhich is associated with the energy scale η at whichthe strings form (µ ∼ η2).Searching for the signatures of cosmic strings is a toolto probe physics beyond the Standard Model at energyranges complementary to those probed by the LHC.Cosmic strings are constrained from cosmology:Gµ ≤ 1.3× 10−7 otherwise a conflict with the observedacoustic oscillations in the CMB angular powerspectrum (Dvorkin, Hu and Wyman, 2011).Existing upper bound on the string tension rules outlarge classes of “Grand Unified” models.

Lowering the upper bound on the string tension by twoorders of magnitude would rule out all grand unified modelsyielding cosmic string solutions.

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Relevance to Cosmology

Cosmic strings can produce many good things forcosmology:

Explanation for the origin of primordial magnetic fieldswhich are coherent on galactic scales (X.Zhang andR.B. (1999)).Origin of high redshift supermassive black holes (S.Bramberger, R.B., P. Jreidini and J. Quintin, 2015).Origin of globular clusters (A. Barton, R.B. and L. Lin,2015; R.B., L. Lin and S. Yamanouchi, 2015).Origin of fast radio bursts (R.B., B. Cyr and A. Iyer,2017).

It is interesting to find evidence for the possible existence ofcosmic strings.

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Preview

Important lessons from this talk:

Cosmic strings→ nonlinearities already at highredshifts.Signatures of cosmic strings more pronounced at highredshifts.Cosmic string wakes lead to perturbations which arenon-Gaussian.Cosmic string wakes predict specific geometricalpatterns in position space.21 cm surveys provide an ideal arena to look for cosmicstrings (R.B., R. Danos, O. Hernandez and G. Holder,2010).

8 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

9 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Cosmic String IA. Vilenkin and E. Shellard, Cosmic Strings and other Topological Defects(Cambridge Univ. Press, Cambridge, 1994).

Cosmic strings form after symmetry breaking phasetransitions.Prototypical example: Complex scalar field φ with“Mexican hat" potential:

V (φ) =λ

4(|φ|2 − η2)2

Vacuum manifoldM: set up field values whichminimize V .

10 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Scalar Field Potential

11 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Cosmic String IA. Vilenkin and E. Shellard, Cosmic Strings and other Topological Defects(Cambridge Univ. Press, Cambridge, 1994).

Cosmic strings form after symmetry breaking phasetransitions.Prototypical example: Complex scalar field φ with“Mexican hat" potential:

V (φ) =λ

4(|φ|2 − η2)2

Vacuum manifoldM: set up field values whichminimize V .At high temperature: φ = 0.At low temperature: |φ| = η - but phase uncorrelated onsuper-Hubble scales.→ defect lines with φ = 0 left behind.

12 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Particle Physics Criterium for the Existence ofStrings

Existence of cosmic strings requires: Π1(M) 6= 1.

13 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Formation of StringsT. Kibble, Phys. Rept. 67, 183 (1980).

By causality, the values of φ inM cannot be correlatedon scales larger than t .Hence, there is a probability O(1) that there is a stringpassing through a surface of side length t .Causality→ network of cosmic strings persists at alltimes.

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Scaling Solution I

Correlation length ξ(t) < t for all times t > tc .

Dynamics of ξ(t) is governed by a Boltzmann equationwhich describes the transfer of energy from long strings tostring loops

15 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Scaling Solution IIR. H. Brandenberger, Int. J. Mod. Phys. A 9, 2117 (1994)[arXiv:astro-ph/9310041].

Analysis of the Boltzmann equation shows that ξ(t) ∼ t forall t > tc :

If ξ(t) << t then rapid loop production and ξ(t)/tincreases.If ξ(t) >> t then no loop production and ξ(t)/tdecreases.

Sketch of the scaling solution:

16 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

History I

Cosmic strings were popular in the 1980’s as analternative to inflation for producing a scale-invariantspectrum of cosmological perturbations.Cosmic strings lead to incoherent and activefluctuations (rather than coherent and passive like ininflation).Reason: strings on super-Hubble scales are entropyfluctuations which seed an adiabatic mode which isgrowing until Hubble radius crossing.Boomerang CMB data (1999) on the acousticoscillations in the CMB angular power spectrum ruledout cosmic strings as the main source of fluctuations..Interest in cosmic strings collapsed.

17 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

History II

Supergravity models of inflation typically yield cosmicstrings after reheating (R. Jeannerot et al., 2003).Brane inflation models typically yield cosmic strings inthe form of cosmic superstrings (Sarangi and Tye,2002; Copeland, Myers and Polchinski, 2004).String Gas Cosmology may lead to a remnant scalingnetwork of cosmic superstrings (R.B. and C. Vafa,1989: A. Nayeri, R.B. and C. Vafa, 2006).→ renewed interest in cosmic strings as supplementarysource of fluctuations.Best current limit from angular spectrum of CMBanisotropies: ∼ 5% of the total power can come fromstrings (see e.g. Dvorkin, Hu and Wyman, 2011, Planckcollab., 2013).Leads to limit Gµ<1.3× 10−7.

18 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

19 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Geometry of a Straight StringA. Vilenkin, Phys. Rev. D 23, 852 (1981).

Space away from the string is locally flat (cosmic stringexerts no gravitational pull).

Space perpendicular to a string is conical with deficit angle

α = 8πGµ ,

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Kaiser-Stebbins EffectN. Kaiser and A. Stebbins, Nature 310, 391 (1984).

Photons passing by the string undergo a relative Dopplershift

δTT

= 8πγ(v)vGµ ,

21 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

→ network of line discontinuities in CMB anisotropymaps.N.B. characteristic scale: comoving Hubble radius atthe time of recombination→ need good angularresolution to detect these edges.

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Signature in CMB temperature anisotropy mapsR. Moessner et al, 1994; R. J. Danos and R. H. Brandenberger,arXiv:0811.2004 [astro-ph].

100 x 100 map of the sky at 1.5’ resolution

23 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

→ network of line discontinuities in CMB anisotropymaps.Characteristic scale: comoving Hubble radius at thetime of recombination→ need good angular resolutionto detect these edges.Need to analyze position space maps.Edges produced by cosmic strings are masked by the“background" noise.

24 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Temperature map Gaussian + strings

25 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

→ network of line discontinuities in CMB anisotropymaps.Characteristic scale: comoving Hubble radius at thetime of recombination→ need good angular resolutionto detect these edges.Need to analyze position space maps.Edges produced by cosmic strings are masked by the“background" noise.Edge detection algorithms: a promising way to searchfor stringsApplication of Canny edge detection algorithm tosimulated data (SPT/ACT specification)→ limitGµ < 2× 10−8 may be achievable [S. Amsel, J. Bergerand R.B. (2007), A. Stewart and R.B. (2008), R. Danosand R.B. (2008)]

26 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Cosmic String WakeJ. Silk and A. Vilenkin, Phys. Rev. Lett. 53, 1700 (1984).

Consider a cosmic string moving through the primordial gas:

Wedge-shaped region of overdensity 2 builds up behind themoving string: wake.

27 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Closer look at the wedge

Consider a string at time ti [trec < ti < t0]moving with velocity vs

with typical curvature radius c1ti

4!Gµtivs"s

tivs"s

c 1ti

v

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Gravitational accretion onto a wakeL. Perivolaropoulos, R.B. and A. Stebbins, Phys. Rev. D 41, 1764 (1990).

Initial overdensity→ gravitational accretion onto thewake.Accretion computed using the Zeldovich approximation.Result: comoving thickness qnl(t) ∼ a(t).

29 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

30 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Temperature Map Strings from Strings,Gµ = 10−7

L. Hergt, ETH Zurich, 2016

31 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Signature: Network of line discontinuities in CMBanisotropy maps.Characteristic scale: comoving Hubble radius at thetime of recombination.Need good angular resolution to detect these edges.Need to analyze position space maps.Edges produced by cosmic strings are masked by the“background" noise.

32 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Temperature Map GaussianL. Hergt, ETH Zurich, 2016

33 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Temperature Map Gaussian + Strings,Gµ = 10−5


34 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Temperature Map Gaussian + Strings,Gµ = 10−7


35 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Signature: Network of line discontinuities in CMBanisotropy maps.Characteristic scale: comoving Hubble radius at thetime of recombination.Need good angular resolution to detect these edges.Need to analyze position space maps.Edges produced by cosmic strings are masked by the“background" noise.Wavelets and Curvelets: a promising way to search forstrings.

36 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Wavelet Analysis of Simulated CMB DataGµ = 10−7


37 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Signature: Network of line discontinuities in CMBanisotropy maps.Characteristic scale: comoving Hubble radius at thetime of recombination. Need good angular resolution todetect these edges.Need to analyze position space maps.Edges produced by cosmic strings are masked by the“background" noise.Wavelets and Curvelets: a promising way to search forstringsApplication of Wavelet analysis to simulated data(SPT/ACT specification)→ limit Gµ < 3× 10−8 may beachievable [L. Hergt, R.B., A. Amara and A. Refregier,2016]

38 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

39 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

No Direct Effect of WakesF. Duplessis and R.B., arXiv:1302.3467 [astro-ph.CO].

Model: wakes form and fragment into spherical clumpswhose radius at time t equals the width of the wake at timet .

Wake temperature obtained by conversion of infallkinetic energy into thermal energy.Halo temperature given by virialization of the energy inthe clumps.Result: for z > 5, T < 700K for a value of Gµ = 10−7 ,too low for atomic cooling.→ no independent star formation in the clumpsproduced by wakes.

Note: See B. Shlaer, A. Vilenkin and A. Loeb(arXiv:1202.1346) for a similar analysis for string loops.

40 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Indirect Signal of WakesD. Cunha, J. Harnois-Deraps, R.B., A. Amara and A. Refregier,arXiv:1804.00083

The presence of a string wake causes a displacementin the distribution of galaxies formed by theGaussian fluctuations.N-body simulation of structure formation in a ΛCDMcosmology with the addition of a string wake.By eye the effect of the wake is visible at redshift ofz = 7 for Gµ = 8× 10−7.Using adapted statistics the presence of string wakes isvisible for significantly smaller values of Gµ. At thecurrent resolution the limit is z = 7 for Gµ = 10−7.

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Distribution of galaxies at z = 3 for Gµ = 10−5.

42 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Distribution of galaxies at z = 0 for Gµ = 10−5.

43 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Details on the SimulationsD. Cunha, J. Harnois-Deraps, R.B., A. Amara and A. Refregier,arXiv:1804.00083

CUBEP3M N-body codezi = 63, Lbox = 64h−1Mpc, 10243 cellsSimulations with ΛCDM initial conditions, and with thesame initial conditions + wake inserted at a redshiftz = 31 with Gµ = 10−7

Goal: down to which redshift is the wake signalidentifiable in a statistically significant way?

44 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Details on the Statistical AnalysisD. Cunha, J. Harnois-Deraps, R.B., A. Amara and A. Refregier,arXiv:1804.00083

Step 1: Project out 2 dimensions onto the axisperpendicular to the wake.→ narrow peak at the position of the wake.Step 2: Wavelet transform of the curves from Step 1.→ effects of ΛCDM fluctuations may be larger inamplitude, but also less narrow.Step 3: Filter the wavelet maps to eliminate lowfrequency contributions.Step 4: Reconstruct the filtered curves.→ the string wake peak is now visible to lower redshift.Step 5: Significance evaluation of the differencebetween the simulations.

45 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

1 d Projection - Wake with Gµ = 10−7

D. Cunha 2018

46 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

1 d Projection - Wake without wakeD. Cunha 2018

47 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Wavelet transform of 1 d Projection - Wake withGµ = 8× 10−7

D. Cunha 2018

48 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Wavelet transform of 1 d Projection - Wake withGµ = 10−7

D. Cunha 2018

49 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Filtered and Reconstructed 1 d Projection -Wake with Gµ = 8× 10−7

D. Cunha 2018

50 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Filtered and Reconstructed 1 d Projection -Wake with Gµ = 10−7

D. Cunha 2018

51 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Indirect Signal of WakesD. Cunha, J. Harnois-Deraps, R.B., A. Amara and A. Refregier,arXiv:1804.00083

The presence of a string wake causes a displacementin the distribution of galaxies formed by the Gaussianfluctuations.N-body simulation of structure formation in a ΛCDMcosmology with the addition of a string wake.By eye the effect of the wake is visible at redshift ofz = 7 for Gµ = 8× 10−7.Using adapted statistics the presence of string wakes isvisible for significantly smaller values of Gµ. At thecurrent resolution the limit is z = 7 for Gµ = 10−7.

52 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

53 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Signature in CMB PolarizationR. Danos, R.B. and G. Holder, arXiv:1003.0905 [astro-ph.CO].

Wake is a region of enhanced free electrons.CMB photons emitted at the time of recombinationacquire extra polarization when they pass through awake.Statistically an equal strength of E-mode and B-modepolarization is generated.Consider photons which at time t pass through a stringsegment laid down at time ti < t .

PQ

' 24π25( 3

4π)1/2

σT fGµvsγs

×ΩBρc(t0)m−1p t0

(z(t) + 1

)2(z(ti) + 1)1/2

.

54 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Signature in CMB Polarization II

Inserting numbers yields the result:

PQ∼ fGµvsγsΩB

(z(t) + 1103

)2(z(ti) + 1103

)3107 .

Characteristic pattern in position space:

55 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Angular Power Spectrum of B-ModePolarization from StringsR.B., N. Park and G. Salton, arXiv:1308.5693 [astro-ph.CO].

1 5 10 50 100 500 1000

2 ´ 10-6

5 ´ 10-6

1 ´ 10-5

2 ´ 10-5

5 ´ 10-5

1 ´ 10-4

H

+1L

C

2Π

Qqu

ad-

1n w

-1

2

56 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Is B-mode Polarization the Holy Grail ofInflation?R.B., arXiv:1104.3581 [astro-ph.CO].

Cosmic strings produce direct B-mode polarization.→ gravitational waves not the only source of primordialB-mode polarization.Cosmic string loop oscillations produce ascale-invariant spectrum of primordial gravitationalwaves with a contribution to δT/T which is comparableto that induced by scalar fluctuations (see e.g. A.Albrecht, R.B. and N. Turok, 1986).→ a detection of gravitational waves through B-modepolarization is more likely to be a sign of somethingdifferent than inflation.If the spectrum of gravitational waves is blue this wouldrule out standard inflation and confirm a prediction firstmade in the context of superstring theory (R.B., et al,2006).

57 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

58 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

MotivationR.B., D. Danos, O. Hernandez and G. Holder, arXiv:1006.2514; O.Hernandez, Yi Wang, R.B. and J. Fong, arXiv:1104.3337.

21 cm surveys: new window to map the high redshiftuniverse, in particular the “dark ages".Cosmic strings produce nonlinear structures at highredshifts.These nonlinear structures will leave imprints in 21 cmmaps. (Khatri & Wandelt, arXiv:0801.4406, A.Berndsen, L. Pogosian & M. Wyman, arXiv:1003.2214)21 cm surveys provide 3-d maps→ potentially moredata than the CMB.→ 21 cm surveys is a promising window to search forcosmic strings.

59 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

The Effect

103 > z > 10: baryonic matter dominated by neutral H.Neutral H has hydrogen hyperfine absorption/emissionline.CMB radiation passing through a cold gas cloud will bepartially absorbed by exciting a 21cm transition. A hotgas cloud will produce 21cm radiation by ade-excitation transition.21cm redshift surveys map the density distribution ofneutral H.21cm surveys: method to probe baryonic matterdistribution before the epoch of star formation (i.e. inthe "dark ages").

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

The Effect (II)

String wake is a nonlinear overdensity in the baryondistribution with special geometry which emits/absorbs21cm radiation.Whether signal is emission/absorption depends on thetemperature of the gas cloud.At high redshifts the strings dominate the nonlinearstructure and hence will dominate the 21cm redshiftmaps.

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

!v’

!v’

t

62 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Geometry of the signal

x x x x

ti2ti

c c

!

1

2

x x 2 1

"!

t

12

!

!

#

s2

s1

t0

63 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Brightness temperature

Brightness temperature:

Tb(ν) = TS(1− e−τν)+ Tγ(ν)e−τν ,

Spin temperature:

TS =1 + xc

1 + xcTγ/TKTγ .

TK : gas temperature in the wake, xc collision coefficient

Relative brightness temperature:

δTb(ν) =Tb(ν)− Tγ(ν)

1 + z

64 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Application to Cosmic String Wakes

Wake temperature TK :

TK ' [20 K](Gµ)26(vsγs)2 zi + 1

z + 1,

determined by considering thermalization at the shockwhich occurs after turnaround when w = 1/2wmax (seeEulerian hydro simulations by A. Sornborger et al, 1997).

Thickness in redshift space:

δν

ν=

24π15

Gµvsγs(zi + 1

)1/2(z(t) + 1)−1/2

' 3× 10−5(Gµ)6(vsγs) ,

using zi + 1 = 103 and z + 1 = 30 in the second line.65 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Relative brightness temperature:

δTb(ν) = [0.07 K]xc

1 + xc

(1− Tγ

TK

)(1 + z)1/2

∼ 200mK for z + 1 = 30 .

Signal is emission if TK > Tγ and absorption otherwise.

66 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Scalings of various temperatures

100 60 50 30 20 10

5

10

50

100

500

z

T!K"

Top curve: (Gµ)6 = 1, bottom curve: (Gµ)6 = 0.3

67 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

68 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Loops as Seeds for Globular ClustersA. Barton, R.B. and L. Lin., arXiv:1502.07301 (2015) .

Globular clusters: oldest, most dense star clusters in agalaxy, distributed in the halo.Loops are nonlinear seeds at high redshifts.Loops seed the accretion of compact dense objects atearly times.Hypothesis: String Loops are the Seeds which developinto Globular ClustersLoops swept up into galactic halo at late times.Explains why globular clusters are old, dense anddistributed in the halo.Free parameter Gµ fixed by demanding that the peak inthe mass distribution of objects seeded by string loopsagrees with the peak of the observed mass function inthe Milky Way.

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CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

ResultsA. Barton, R.B. and L. Lin, arXiv:1502.07301 (2015) .

0

2

4

6

8

10

12

Nu

mb

er

log(M)

Histogram

Experimental Theoretical

104.03 105.02 106.01

70 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Prediction

The mass distribution of globular clusters is independent ofgalaxy.

71 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Loops as the Seeds for High RedshiftSuper-Massive Black HolesA. Barton, R.B., P. Jreidini and J. Quintin, arXiv:1503.02317 (2015) .

Observations: More than 40 black holes at z > 6 andmass M > 109M0 discovered.In the standard ΛCDM paradigm of structure formationnonlinearities form late.It is challenging to explain the origin of the massiveseeds with only standard Gaussian fluctuations.Hypothesis: String Loops are the Seeds for theAccretion of high z super-massive black holes.

72 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Nonlinear Mass with the Number Density ofGalaxiesA. Barton, R.B., P. Jreidini and J. Quintin, arXiv:1503.02317 (2015) .

zi

100101

Ms(z

i)

10-4

10-2

100

102

104

106

108

1010

Gaussian .uctuationsG7 = 10!9:5

G7 = 10!12

G7 = 10!13

73 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Loops as Sources of Fast Radio Bursts

Fast Radio Bursts

Bursts of electromagnetic radiation observed by radiotelescopes (Parkes)Energy flux > 1Jy

Duration < 1ms

Rate: > 10 detected over the past few years.The CHIME telescope is coming online and willdetect many every month

74 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Cusp Decay as Sources of Fast Radio Bursts(FRB)

Hypothesis: Cosmic string loop cusp decay is the source ofFRBs (R.B., B. Cyr and A. V. Iyer, 2017).

For every string loop there is one cusp per looposcillation time.Cusp: string segments overlap over a distancelc ∼ R1/2w1/2

Cusp looks locally like string-antistring overlap→instantaneous decay.Decay→ jet of particles, in particular photons.Jets characterized by given N(E) ∼ E−3/2.

75 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Calculations

Given n(R, t)→ compute mean separation dR

Given Gµ can compute distance s(R) for which theradio flux exceeds 1Jy.1st result: dR < s(R)

Compute rate of cusps for loops with R < s(R)

Result: rate > 1 per year for a wide range of interestingvalues of Gµ.Consistency check: intrinsic time scale of burst 1ms.

Prediction: optical counterparts should be seen if radio andoptical telescopes look at the same patch of the sky.

76 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

String Loops and Global 21cm SignalR.B., B. Cyr and T. Schaeffer, preliminary (2018) .

Global Signal of Neutral Hydrogen:Consider the intensity of CMB photons in the redshifted21cm range.

δTb = 27xHI(1− Tr

Ts

)√0.25(1 + z)

10Ωmh2

( Ωbh2

0.023)mK

Observations: enhanced absorption feature for z ∼ 17(Bowman et al, 2018).

77 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

String Loops and Global 21cm SignalR.B., B. Cyr and T. Schaeffer, preliminary (2018) .

In the redshift range z ∼ 15 we have Ts < Tr .Enhanced absorption signal can be explained bydecreasing Ts (a lot of work on this related to darkmatter).Or by increasing Tr in z ∼ 15 temperature range (C.Fang and G. Holder, arXiv:1802.07432)Cusp annihilation from string loops provides anon-thermal photon spectrum which peaks in the IR.The magnitude of the contribution increases as thestring tension decreases.→ lower bound on the cosmic string tension:Gµ > 10−18, i.e. η > 109GeV.

78 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Plan

1 Introduction








9 Conclusions

79 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Conclusions I

Searching for cosmic strings in the sky is a way toprobe particle physics beyond the Standard Model fromtop down.Current bounds on the cosmic string tension alreadyrule out a large class of GUT models.Improving the bounds will allow us to better constrainparticle physics beyond the Standard Model.(preliminary) lower bound on the cosmic string tensionexists, not only an upper bound.

80 / 81

CosmicStrings

R. Branden-berger

Introduction

Cosmic StringReview

KS Effect andWakes

CMB T Maps

LSSSignatures


Signatures in21cm

Loops

Conclusions

Conclusions II

Cosmic strings→ nonlinearities already at highredshifts.Signatures of cosmic strings more pronounced at highredshifts.Cosmic string wakes lead to perturbations which arenon-Gaussian.Cosmic string wakes predict specific geometricalpatterns in position space.Cosmic string wakes produce distinct wedges inredshift space with enhanced 21cm absorption oremission.Cosmic string loops may play a role in globular clusterand supermassive black hole formation.Cosmic string loop cusp decay provide explanation forthe recently observed fast radio bursts.

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signals of cosmic strings in the sky: probe of particle ... · of particle physics beyond the...

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