%0 Generic %1 irsic2019early %A Iršič, Vid %A Xiao, Huangyu %A McQuinn, Matthew %D 2019 %K library %T Early Structure Formation Constraints on the Ultra-Light Axion in the Post-Inflation Scenario %U http://arxiv.org/abs/1911.11150 %X Many works have concentrated on the observable signatures of the dark matter being an ultralight axion-like particle (ALP). We concentrate on a particularly dramatic signature in the late-time cosmological matter power spectrum that occurs if the symmetry breaking that establishes the ALP happens after inflation -- white-noise density fluctuations that dominate at small scales over the adiabatic fluctuations from inflation. These fluctuations alter the early history of nonlinear structure formation. We find that for symmetry breaking scales of $f_A 10^13-10^15$GeV, which requires a high effective maximum temperature after inflation, ALP dark matter with particle mass of $m_A 10^-13-10^-20$eV could significantly change the number of high-redshift dwarf galaxies, the reionization history, and the Ly$\alpha$ forest. We consider all three observables. We find that the Ly$\alpha$ forest is the most constraining of current observables, excluding $f_A \gtrsim 10^15$GeV ($m_A 10^-17$eV) in the simplest model for the ALP and considerably lower values in models coupled to a hidden strongly interacting sector ($f_A 10^13$GeV and $m_A 10^-13$eV). Observations that constrain the extremely high-redshift tail of reionization may disfavor similar levels of isocurvature fluctuations as the forest. Future $z20-30$ 21cm observations have the potential to improve these constraints further using that the supersonic motions of the isocurvature-enhanced abundance of $\sim10^4M_ødot$ halos would shock heat the baryons, sourcing large BAO features.

@misc{irsic2019early, abstract = {Many works have concentrated on the observable signatures of the dark matter being an ultralight axion-like particle (ALP). We concentrate on a particularly dramatic signature in the late-time cosmological matter power spectrum that occurs if the symmetry breaking that establishes the ALP happens after inflation -- white-noise density fluctuations that dominate at small scales over the adiabatic fluctuations from inflation. These fluctuations alter the early history of nonlinear structure formation. We find that for symmetry breaking scales of $f_A \sim 10^{13}-10^{15}$GeV, which requires a high effective maximum temperature after inflation, ALP dark matter with particle mass of $m_A \sim 10^{-13}-10^{-20}$eV could significantly change the number of high-redshift dwarf galaxies, the reionization history, and the Ly$\alpha$ forest. We consider all three observables. We find that the Ly$\alpha$ forest is the most constraining of current observables, excluding $f_A \gtrsim 10^{15}$GeV ($m_A \lesssim 10^{-17}$eV) in the simplest model for the ALP and considerably lower values in models coupled to a hidden strongly interacting sector ($f_A \gtrsim 10^{13}$GeV and $m_A \lesssim 10^{-13}$eV). Observations that constrain the extremely high-redshift tail of reionization may disfavor similar levels of isocurvature fluctuations as the forest. Future $z\sim 20-30$ 21cm observations have the potential to improve these constraints further using that the supersonic motions of the isocurvature-enhanced abundance of $\sim10^4M_\odot$ halos would shock heat the baryons, sourcing large BAO features.}, added-at = {2019-11-27T09:53:47.000+0100}, author = {Iršič, Vid and Xiao, Huangyu and McQuinn, Matthew}, biburl = {https://www.bibsonomy.org/bibtex/2be9c49e2aabd7cae99e6405074f1de4a/gpkulkarni}, description = {Early Structure Formation Constraints on the Ultra-Light Axion in the Post-Inflation Scenario}, interhash = {18ac82e6d025a1e6ea08f3a9b6297868}, intrahash = {be9c49e2aabd7cae99e6405074f1de4a}, keywords = {library}, note = {cite arxiv:1911.11150Comment: 15 pages, 8 figures}, timestamp = {2019-11-27T09:53:47.000+0100}, title = {Early Structure Formation Constraints on the Ultra-Light Axion in the Post-Inflation Scenario}, url = {http://arxiv.org/abs/1911.11150}, year = 2019 }