%0 Generic %1 munoz2019standard %A Muñoz, Julian B. %D 2019 %K library %T A Standard Ruler at Cosmic Dawn %U http://arxiv.org/abs/1904.07868 %X The matter in our Universe comes in two flavors: dark and baryonic. Of these, only the latter couples to photons, giving rise to the well-known baryon acoustic oscillations (BAOs) and, in the process, generating supersonic relative velocities between dark matter and baryons. These velocities---imprinted with the acoustic scale in their genesis---impede the formation of the first stars during cosmic dawn ($z20$), modulating the expected 21-cm signal from this era. In a companion paper we showed, combining numerical simulations and analytic models, that this modulation takes the form of striking velocity-induced acoustic oscillations (VAOs), with a well-understood shape that is frozen at recombination, and unaffected by the unknown astrophysics of star formation. Here we propose using these VAOs as a standard ruler at cosmic dawn. We find that three years of 21-cm power-spectrum data from the upcoming HERA interferometer will be able to measure the Hubble expansion rate $H(z)$ at $z=15-20$ to percent-level precision, ranging from 0.3\% to 11\% depending on the strength of astrophysical feedback processes and foregrounds. This would provide a new handle on the expansion rate of our Universe during an otherwise unprobed epoch, opening a window to the mysterious cosmic-dawn era.

@misc{munoz2019standard, abstract = {The matter in our Universe comes in two flavors: dark and baryonic. Of these, only the latter couples to photons, giving rise to the well-known baryon acoustic oscillations (BAOs) and, in the process, generating supersonic relative velocities between dark matter and baryons. These velocities---imprinted with the acoustic scale in their genesis---impede the formation of the first stars during cosmic dawn ($z\sim 20$), modulating the expected 21-cm signal from this era. In a companion paper we showed, combining numerical simulations and analytic models, that this modulation takes the form of striking velocity-induced acoustic oscillations (VAOs), with a well-understood shape that is frozen at recombination, and unaffected by the unknown astrophysics of star formation. Here we propose using these VAOs as a standard ruler at cosmic dawn. We find that three years of 21-cm power-spectrum data from the upcoming HERA interferometer will be able to measure the Hubble expansion rate $H(z)$ at $z=15-20$ to percent-level precision, ranging from 0.3\% to 11\% depending on the strength of astrophysical feedback processes and foregrounds. This would provide a new handle on the expansion rate of our Universe during an otherwise unprobed epoch, opening a window to the mysterious cosmic-dawn era.}, added-at = {2019-04-18T04:58:38.000+0200}, author = {Muñoz, Julian B.}, biburl = {https://www.bibsonomy.org/bibtex/237dcc9285e34ab6b15d6df642c1b1635/gpkulkarni}, description = {A Standard Ruler at Cosmic Dawn}, interhash = {b24130776fa983ec6f65e0dbe9a44ac0}, intrahash = {37dcc9285e34ab6b15d6df642c1b1635}, keywords = {library}, note = {cite arxiv:1904.07868Comment: 7 pages, 3 figures. Comments are welcome}, timestamp = {2019-04-18T04:58:38.000+0200}, title = {A Standard Ruler at Cosmic Dawn}, url = {http://arxiv.org/abs/1904.07868}, year = 2019 }