B-mode from strings Levon Pogosian Simon Fraser University with - - PowerPoint PPT Presentation

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Apr 24, 2023 230 likes •450 views

B-mode from strings Levon Pogosian Simon Fraser University with H. Tye (Cornell) T. Vachaspati (Case) I. Wasserman (Cornell) M. Wyman (Perimeter) SFU Cosmology V. P. Frolov D. Pogosyan A. V. Frolov L. Pogosian The spectrum Primordial

SLIDE 1

B-mode from strings

Levon Pogosian Simon Fraser University with

H. Tye (Cornell)
T. Vachaspati (Case)
I. Wasserman (Cornell)
M. Wyman (Perimeter)

SLIDE 2

SFU Cosmology

A. V. Frolov
L. Pogosian
V. P. Frolov
D. Pogosyan

SLIDE 3

The spectrum

Primordial perturbations:

predominantly passive (not active)
nearly adiabatic
nearly scale-invariant

SLIDE 4

Active perturbations

SLIDE 5

CMB temperature anisotropy from strings

M.Wyman, L.Pogosian, I.Wasserman, astro-ph/0604141

SLIDE 6

Strings vs WMAP

Wiggly local cosmic strings Inflation

String spectrum from Pogosian & Vachaspati, PRD’99

SLIDE 7

String induced CMB temperature anisotropy can’t exceed ~10%

f the total

The corresponding bound on depends on the string model Gµ

Gµ < 0.7 106

Conservatively,

SLIDE 8

Do we need cosmic strings?

Produced after hybrid inflation

I. Tkachev, S. Khlebnikov, L. Kofman, A. Linde (‘95-’98)

(KKLMMT, SUSY GUT,…) Source of B-mode polarization

SLIDE 9

The segment model

Vincent, Hindmarsh, Sakellariadou (1996) Albrecht, Battye, Robinson (1997) Pogosian & Vachaspati (1999) Straight, randomly oriented, moving string segments Density, correlation length, wiggliness, rms v matched to simulated networks Incorporated into CMBFAST: publicly available as CMBACT Good enough for large scale features

SLIDE 10

DASI 2002

CMB polarization

SLIDE 11

from M. Zaldarriaga, astro-ph/0305272

E (gradient) and B (curl) modes

SLIDE 12

Sources of B-mode

The ISW effect from gravity waves (tensor modes) Anisotropic stress produced by defects (vector and tensor modes) Lensing of E-mode by large scale structures (scalar modes) Magnetic fields (vector and tensor modes)

SLIDE 13

B-mode CMB polarization

Sourced by strings

Lensing by matter

Sourced by Gravity Waves

M.Wyman, L.Pogosian, I.Wasserman, astro-ph/0604141

SLIDE 14

What determines the shape?

Contributing factors: correlation length, velocity, density, tension, wiggliness

reionization peak recombination peak

SLIDE 15

Strings at last scattering

t , O(1)

Gµ

vt v

SLIDE 16

Where is the main peak?

SLIDE 17

Global strings

(Seljak, Pen, Turok, PRL’97) “Standard” CDM: h=0.5, ΩM=1, Ωb=0.05

SLIDE 18

Field theory simulations, local U(1)

(Bevis, Hindmarsh, Kunz, Urrestilla, 0704.3800) B

SLIDE 19

Prospects of detection

from Seljak & Slozar, astro-ph/0604143

reionization peak recombination peak

r = 106, Gµ = 108

SLIDE 20

Summary

In Hybrid Inflation models, including Brane Inflation, string generated vector B-mode can exceed the GW contribution String B-mode spectrum has a distinct shape, with a pronounced main peak at 500<l<1000 The magnitude and the exact peak position are determined by properties of cosmic string networks at last scattering