https://insu.hal.science/insu-03645338Datta, Kanan K.Kanan K.DattaJensen, HannesHannesJensenMajumdar, SumanSumanMajumdarMellema, GarreltGarreltMellemaIliev, Ilian T.Ilian T.IlievMao, YiYiMaoIAP - Institut d'Astrophysique de Paris - INSU - CNRS - Institut national des sciences de l'Univers - SU - Sorbonne Université - CNRS - Centre National de la Recherche ScientifiqueShapiro, Paul R.Paul R.ShapiroAhn, KyungjinKyungjinAhnLight cone effect on the reionization 21-cm signal - II. Evolution, anisotropies and observational implicationsHAL CCSD2014methods: numericalmethods: statisticalcosmology: theorydark agesreionizationfirst starsdiffuse radiationAstrophysics - Cosmology and Nongalactic Astrophysics[SDU] Sciences of the Universe [physics][SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]Sorbonne Université, Gestionnaire HAL 42022-04-25 10:02:442023-05-01 03:58:012022-04-25 10:02:52enJournal articleshttps://insu.hal.science/insu-03645338/document10.1093/mnras/stu927application/pdf1Measurements of the H I 21-cm power spectra from the reionization epoch will be influenced by the evolution of the signal along the line-of-sight direction of any observed volume. We use numerical as well as seminumerical simulations of reionization in a cubic volume of 607 Mpc across to study this so-called light-cone effect on the H I 21-cm power spectrum. We find that the light-cone effect has the largest impact at two different stages of reionization: one when reionization is ∼20 per cent and other when it is ∼80 per cent completed. We find a factor of ∼4 amplification of the power spectrum at the largest scale available in our simulations. We do not find any significant anisotropy in the 21-cm power spectrum due to the light-cone effect. We argue that for the power spectrum to become anisotropic, the light-cone effect would have to make the ionized bubbles significantly elongated or compressed along the line of sight, which would require extreme reionization scenarios. We also calculate the two-point correlation functions parallel and perpendicular to the line of sight and find them to differ. Finally, we calculate an optimum frequency bandwidth below which the light-cone effect can be neglected when extracting power spectra from observations. We find that if one is willing to accept a 10 per cent error due to the light-cone effect, the optimum frequency bandwidth for k = 0.056 Mpc<SUP>-1</SUP> is ∼7.5 MHz. For k = 0.15 and 0.41 Mpc<SUP>-1</SUP>, the optimum bandwidth is ∼11 and ∼16 MHz, respectively.