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Title: Oscillatory attractors: a new cosmological phase

Abstract

In expanding FRW spacetimes, it is usually the case that homogeneous scalar fields redshift and their amplitudes approach limiting values: Hubble friction usually ensures that the field relaxes to its minimum energy configuration, which is usually a static configuration. Here we discover a class of relativistic scalar field models in which the attractor behavior is the field oscillating indefinitely, with finite amplitude, in an expanding FRW spacetime, despite the presence of Hubble friction. This is an example of spontaneous breaking of time translation symmetry. We find that the effective equation of state of the field has average value ( w )=−1, implying that the field itself could drive an inflationary or dark energy dominated phase. This behavior is reminiscent of ghost condensate models, but in the new models, unlike in the ghost condensate models, the energy-momentum tensor is time dependent, so that these new models embody a more definitive breaking of time translation symmetry. We explore (quantum) fluctuations around the homogeneous background solution, and find that low k -modes can be stable, while high k -modes are typically unstable. We discuss possible interpretations and implications of that instability.

Authors:
 [1];  [2];  [3]
  1. Center for the Fundamental Laws of Nature, Harvard University, 17 Oxford St, Cambridge, MA 02138 (United States)
  2. Institute of Cosmology, Department of Physics and Astronomy, Tufts University, 574 Boston Ave, Medford, MA 02155 (United States)
  3. Center for Theoretical Physics, Department of Physics, MIT, 77 Massachusetts Ave, Cambridge, MA 02139 (United States)
Publication Date:
OSTI Identifier:
22676227
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 05; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATTRACTORS; COSMOLOGICAL MODELS; ENERGY-MOMENTUM TENSOR; EQUATIONS OF STATE; FLUCTUATIONS; FRICTION; INSTABILITY; MATHEMATICAL SOLUTIONS; NONLUMINOUS MATTER; RED SHIFT; RELATIVISTIC RANGE; SCALAR FIELDS; SPACE-TIME; SYMMETRY; TIME DEPENDENCE

Citation Formats

Bains, Jasdeep S., Hertzberg, Mark P., and Wilczek, Frank, E-mail: bains@physics.harvard.edu, E-mail: mark.hertzberg@tufts.edu, E-mail: wilczek@mit.edu. Oscillatory attractors: a new cosmological phase. United States: N. p., 2017. Web. doi:10.1088/1475-7516/2017/05/011.
Bains, Jasdeep S., Hertzberg, Mark P., & Wilczek, Frank, E-mail: bains@physics.harvard.edu, E-mail: mark.hertzberg@tufts.edu, E-mail: wilczek@mit.edu. Oscillatory attractors: a new cosmological phase. United States. doi:10.1088/1475-7516/2017/05/011.
Bains, Jasdeep S., Hertzberg, Mark P., and Wilczek, Frank, E-mail: bains@physics.harvard.edu, E-mail: mark.hertzberg@tufts.edu, E-mail: wilczek@mit.edu. Mon . "Oscillatory attractors: a new cosmological phase". United States. doi:10.1088/1475-7516/2017/05/011.
@article{osti_22676227,
title = {Oscillatory attractors: a new cosmological phase},
author = {Bains, Jasdeep S. and Hertzberg, Mark P. and Wilczek, Frank, E-mail: bains@physics.harvard.edu, E-mail: mark.hertzberg@tufts.edu, E-mail: wilczek@mit.edu},
abstractNote = {In expanding FRW spacetimes, it is usually the case that homogeneous scalar fields redshift and their amplitudes approach limiting values: Hubble friction usually ensures that the field relaxes to its minimum energy configuration, which is usually a static configuration. Here we discover a class of relativistic scalar field models in which the attractor behavior is the field oscillating indefinitely, with finite amplitude, in an expanding FRW spacetime, despite the presence of Hubble friction. This is an example of spontaneous breaking of time translation symmetry. We find that the effective equation of state of the field has average value ( w )=−1, implying that the field itself could drive an inflationary or dark energy dominated phase. This behavior is reminiscent of ghost condensate models, but in the new models, unlike in the ghost condensate models, the energy-momentum tensor is time dependent, so that these new models embody a more definitive breaking of time translation symmetry. We explore (quantum) fluctuations around the homogeneous background solution, and find that low k -modes can be stable, while high k -modes are typically unstable. We discuss possible interpretations and implications of that instability.},
doi = {10.1088/1475-7516/2017/05/011},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 05,
volume = 2017,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}