Final published version, 2.1 MB, PDF document
Available under license: CC BY: Creative Commons Attribution 4.0 International License
Final published version
Licence: CC BY: Creative Commons Attribution 4.0 International License
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Enhanced primordial gravitational waves from a stiff post-inflationary era due to an oscillating inflaton
AU - Chen, Chao
AU - Dimopoulos, Konstantinos
AU - Eröncel, Cem
AU - Ghoshal, Anish
PY - 2024/9/15
Y1 - 2024/9/15
N2 - We investigate two classes of inflationary models, which lead to a stiff period after inflation that boosts the signal of primordial gravitational waves (GWs). In both families of models studied, we consider an oscillating scalar condensate, which when far away from the minimum is overdamped by a warped kinetic term, á la α-attractors. This leads to successful inflation. The oscillating condensate is in danger of becoming fragmented by resonant effects when non-linearities take over. Consequently, the stiff phase cannot be prolonged enough to enhance primordial GWs at frequencies observable in the near future for low orders of the envisaged scalar potential. However, this is not the case for a higher-order scalar potential. Indeed, we show that this case results in a boosted GW spectrum that overlaps with future observations without generating too much GW radiation to destabilize big bang nucleosynthesis. For example, taking α=O(1), we find that the GW signal can be safely enhanced up to Ω_GW (f) ∼ 10^{−11} at frequency f ∼ 10^2 Hz, which will be observable by the Einstein Telescope. Our mechanism ends up with a characteristic GW spectrum, which if observed, can lead to the determination of the inflation energy scale, the reheating temperature, and the shape (steepness) of the scalar potential around the minimum.
AB - We investigate two classes of inflationary models, which lead to a stiff period after inflation that boosts the signal of primordial gravitational waves (GWs). In both families of models studied, we consider an oscillating scalar condensate, which when far away from the minimum is overdamped by a warped kinetic term, á la α-attractors. This leads to successful inflation. The oscillating condensate is in danger of becoming fragmented by resonant effects when non-linearities take over. Consequently, the stiff phase cannot be prolonged enough to enhance primordial GWs at frequencies observable in the near future for low orders of the envisaged scalar potential. However, this is not the case for a higher-order scalar potential. Indeed, we show that this case results in a boosted GW spectrum that overlaps with future observations without generating too much GW radiation to destabilize big bang nucleosynthesis. For example, taking α=O(1), we find that the GW signal can be safely enhanced up to Ω_GW (f) ∼ 10^{−11} at frequency f ∼ 10^2 Hz, which will be observable by the Einstein Telescope. Our mechanism ends up with a characteristic GW spectrum, which if observed, can lead to the determination of the inflation energy scale, the reheating temperature, and the shape (steepness) of the scalar potential around the minimum.
KW - gravitational waves
KW - cosmic inflation
U2 - 10.1103/PhysRevD.110.063554
DO - 10.1103/PhysRevD.110.063554
M3 - Journal article
VL - 110
JO - Physical Review D
JF - Physical Review D
SN - 1550-7998
IS - 6
M1 - 063554
ER -