Towards observable signatures of other bubble universes

Aguirre, Anthony; Johnson, Matthew C.; Shomer, Assaf

doi:10.1103/physrevd.76.063509

Cited by 72 publications

(104 citation statements)

References 26 publications

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“…Recently, the observable signals of the collision of bubble universes have been discussed [18], [19], [27], [28]. The resonant production of particles during the bubbles collision might bring some distinct observable signals or impacts on the CMB, which will be explored in the future.…”

Section: Figmentioning

confidence: 99%

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Preheating in bubble collisions

Zhang

Piao

2010

Phys. Rev. D

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In a landscape with metastable minima, the bubbles will inevitably nucleate. We show that during the bubbles collide, due to the dramatically oscillating of the field at the collision region, the energy deposited in the bubble walls can be efficiently released by the explosive production of the particles. In this sense, the collision of bubbles is actually highly inelastic. The cosmological implications of this result are discussed.When the universe is initially set in a metastable minimum of certain landscape of scalar fields, it will undergo a dS expansion, bubbles with lower energy minima will inevitably nucleate in this background [1]. When the radius of bubble is larger than its critical radius, the bubble will expand outwards, and eventually collide with other expanding bubbles. In general, it is expected that during the bubbles collide, the energy deposited in the bubble walls will be released, e.g. The bubble collision has been studied earlier in [9], [10]. In general, when the bubbles collide, the walls of bubbles will pass through each other or be reflected. The region between outgoing walls remains in high energy metastable minimum, while other region is not affected. However, there is a net force, which will compel the walls to rest, and then back and move towards each other. Thus the collision of walls will inevitably occur again and again. This oscillation of walls has be displayed in the numerical simulations for bubble collision [9], [11], [12], [13]. In general, it is thought that during the bubble collision the energy deposited in the walls will be released by the direct decaying of scalar wave into other particles, e.g. [11], [14], or the gravitational radiation, e.g. [12], [15], [16], [17]. However, this release of the energy might be more dramatic than expected. In this paper, we show that due to the oscillation of the background field at the collision region, the energy can be efficiently released by the explosive production of the particles.We begin with a brief review of the numerically simulation of the collision of bubbles nucleating in a given potential in Fig.1, in which the high energy metastable minimum is φ F and the low energy minimum is φ T . We only care the numerical results of the evolution of field at the collision region during the bubble collision. Thus the details of the equations of the nucleation and evolution of bubble are neglected, see e.g. [18], [19].The field φ is initially in φ F . Thus the universe is inflating. Then the bubbles with φ T will be expected to nucleate. The radius of bubble is determined by the *

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Section: Figmentioning

confidence: 99%

“…Thus the details of the equations of the nucleation and evolution of bubble are neglected, see e.g. [18], [19].…”

mentioning

confidence: 99%

Preheating in bubble collisions

Zhang

Piao

2010

Phys. Rev. D

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“…The cosmological implications of bubble formation and collision were studied recently in [5][6][7][9][10][11][12][13][14][15][16][17]. Specifically, [5] derived the approximate CMB temperature anisotropy due to a collision-the effect is confined to a disk that is either hot or cold relative to the average, with an intensity that decreases linearly with cosine of the angular radius from the center of the disk, reaching zero at its edge.…”

Section: B Previous Workmentioning

confidence: 99%

Polarizing bubble collisions

Czech

Kleban

Larjo

et al. 2010

J. Cosmol. Astropart. Phys.

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We predict the polarization of cosmic microwave background (CMB) photons that results from a cosmic bubble collision. The polarization is purely E-mode, symmetric around the axis pointing towards the collision bubble, and has several salient features in its radial dependence that can help distinguish it from a more conventional explanation for unusually cold or hot features in the CMB sky. The anomalous "cold spot" detected by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite is a candidate for a feature produced by such a collision, and the Planck satellite and other proposed surveys will measure the polarization on it in the near future. The detection of such a collision would provide compelling evidence for the string theory landscape.

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“…While this is in general true, one prospect for probing this epoch lies in the observation of the collisions between vacuum bubbles. These collisions produce inhomogeneities in the innerbubble cosmology, raising the possibility that their effects are imprinted in the cosmic microwave background (CMB) [2]. In this Letter we describe a robust algorithm designed to test the hypothesis that there are bubble collisions in the Wilkinson Microwave Anisotropy Probe (WMAP) 7-year data [3].…”

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confidence: 99%

First Observational Tests of Eternal Inflation

et al. 2011

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The eternal inflation scenario predicts that our observable Universe resides inside a single bubble embedded in a vast inflating multiverse. We present the first observational tests of eternal inflation, performing a search for cosmological signatures of collisions with other bubble universes in cosmic microwave background data from the WMAP satellite. We conclude that the WMAP 7-year data do not warrant augmenting the cold dark matter model with a cosmological constant with bubble collisions, constraining the average number of detectable bubble collisions on the full sky " N s < 1:6 at 68% C.L. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis.

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Towards observable signatures of other bubble universes

Cited by 72 publications

References 26 publications

Preheating in bubble collisions

Preheating in bubble collisions

Polarizing bubble collisions

First Observational Tests of Eternal Inflation

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