The Inflationary Origin of the Cold Spot

Transcription

1 The Inflationary Origin of the Cold Spot (based on arxiv: 1310.XXXX) Juan C. Bueno Sánchez Cambridge, 4/09/2013

2 The CMB Cold Spot Simplest S mplest single-field s ngle f eld inflationary nflat onary models supported by Planck, lanck, + anomalies anomal es Cold Spot: Extremely cold & big spot in WMAP 1-yr data (P.Vielva 10 for a review) (WMAP 1: Vielva et al. 04) (WMAP 3: Cruz et al. 07) ((Planck 13 XXIII)) (ESA Planck collaboration) A posteriori issues: Demand a clear, clear robust theoretical prediction Topological defects (Cruz et al. 07), multifield inflation (Afshordi et al 11),, New mechanism in single single-field field inflation based on robust, generic predictions of inflation and particles theories BSM Deficit of power at low l Link between anomalies?

3 An earthly, small scale cold spot A rare fluctuation of the wheat, or something with a different origin?

4 A mechanism for the Cold Spot 1. Interacting spectator σ during inflation (H cte) (JBS and Enqvist 13) (initially) patches with Quasi-free fluctuations of σ grows σ becomes heavy (σ trapping) (Kofman et al. 04) ~ gaussian eq. fluct. σ obtains large out-of-equilibrium VEV where it fluctuates free if σ trapped at x if σ performs quasi-free fluctuations at x

5 A mechanism for the Cold Spot 2. Generic SUGRA-corrected scalar masses: (Copeland et al. 94, Dine et al. 95) Difficulty: A mass ~ H results in expectation values of order H, at best. Patches with large out-of-eq. fluctuations of σ emerge only if (Enqvist et al 12, JBS and Enqvist 13) The mechanismm needs to address the initial condition problem! Generic features Inflationary potentials Deficit of power at low l provides circumstantial evidence Generating the IC may require less fine-tuning than slow-roll inflation!

6 A mechanism for the Cold Spot 3. Coupling σ to the inflaton: inflaton s decay rate Γ= Γ(σ) Γ(σ(x)) = Γ eq = Γ(σ eq ) in patches with σ trapped during inflation Γ out = Γ(σ out ) > Γ eq in patches with quasi-free fluct. of σ Warning: This is NOT conventional inhomogeneous reheating The inflaton generates the Gaussian part of the spectrum Inhomogeneous rehating (Dvali et al. 03, Kofman 03) Reheating surface Curvature pert.

7 A mechanism for the Cold Spot 3. Coupling σ to the inflaton: inflaton s decay rate Γ= Γ(σ) Γ(σ(x)) = Γ eq = Γ(σ eq ) in patches with σ trapped during inflation Γ out = Γ(σ out ) > Γ eq in patches with quasi-free fluct. of σ Warning: This is NOT conventional inhomogeneous reheating The inflaton generates the Gaussian part of the spectrum Cold Spot Mechanism Reheating surface Locally enhanced redshift Cold Spot

8 A mechanism for the Cold Spot 3. Coupling σ to the inflaton: inflaton s decay rate Γ= Γ(σ) Γ(σ(x)) = Γ eq = Γ(σ eq ) in patches with σ trapped during inflation Γ out = Γ(σ out ) > Γ eq in patches with quasi-free fluct. of σ Warning: This is NOT conventional inhomogeneous reheating The inflaton generates the Gaussian part of the spectrum Cold Spot Mechanism Within the MSSM: Locally enhanced redshift Cold Spot

9 Requirements of the mechanism * Appropriate couplings to the inflaton * Persistance of the out-of-eq distribution of σ until inflaton decay - Appropriate (model dependent) post-inflation evolution - Non-perturbative decay of σ can be blocked - Perturbative ti evaporation of the condensate may beavoided d * Generate initial condition for σ

10 Towards the initial condition Generic SUGRA-corrected inflaton mass: fast-roll inflation (Linde 01) Bad for observations, but might be Ok to generate IC for slow-roll Signature of a fast rolling inflaton? Deficit of power in pert. spectrum (Contaldi et al. 03) Inflation begins at the Planck scale but slow-roll occurs several orders below (Lyth & Riotto 99, Linde 01) Field equation Background Perturbation modes Superhorizon: tachyonic instability

11 Towards the initial condition becomes tachyonic for Rapid decrease of H triggers growth of perturbation modes above H Condensate growth above H IC

12 Conclusions * The Cold Spot, along with other anomalies, are now confirmed by Planck. * In this talk I introduce a new mechanism (localized inhomogeneous reheating) whereby the Cold Spot is generated by meansof a localizedli variation of the inflaton s decay rate. * LIR is different from inhomogeneous reheating because it can produce non-gaussian fluctuations in localized patches of the CMB without challenging current bounds on f nl * The mechanism requires that the field controlling Γ begins with a VEV above the Hubble scale. Such an initial condition can be generated through a stage of fast-roll inflation (expected in SUGRA theories) * Moderately heavy scalar fields can be substantially produced during inflation, depending on the rate of change of H. * VEVs above H at the onset of observable inflation might shed some light on the origin of other CMB anomalies...

13