{"title":"21厘米再电离模拟光锥历元中快照间隔的量化和缓解影响","authors":"Suman Pramanick, Rajesh Mondal, Somnath Bharadwaj","doi":"10.1007/s12036-025-10087-3","DOIUrl":null,"url":null,"abstract":"<div><p>Epoch of reionization (EoR) neutral hydrogen (H <span>i</span>) 21-cm signal evolves significantly along the line-of-sight (LoS) due to the light-cone (LC) effect. It is important to accurately incorporate this in simulations to correctly interpret the signal. 21-cm LC simulations are typically produced by stitching together slices from a finite number <span>\\((N_{\\textrm{RS}})\\)</span> of ‘reionization snapshot’, each corresponding to a different stage of reionization. In this paper, we have quantified the errors in 21-cm LC simulation due to the finite value of <span>\\(N_{\\textrm{RS}}\\)</span>. We show that this can introduce large discontinuities (>200%) at the stitching boundaries when <span>\\(N_{\\textrm{RS}}\\)</span> is small <span>\\((=2,4)\\)</span> and the mean neutral fraction jumps by <span>\\(\\delta \\bar{x}_{\\textrm{H}\\,\\textsc {i}} =0.2,0.1\\)</span>, respectively, at the stitching boundaries. This drops to 17% for <span>\\(N_{\\textrm{RS}}=13\\)</span>, where <span>\\(\\delta \\bar{x}_{\\textrm{H}\\,\\textsc {i}}=0.02\\)</span>. We found that we can achieve <span>\\(\\delta \\bar{x}_{\\textrm{H}\\,\\textsc {i}} \\le 0.01\\)</span> with <span>\\(N_{\\textrm{RS}}=26\\)</span>, and we use this as reference for comparing the other simulations. We presented and also validated a method for mitigating this error by increasing <span>\\(N_{\\textrm{RS}}\\)</span> without a proportional increase in the computational costs, which are mainly incurred in generating the dark matter and halo density fields. Our method generates these fields, only at a few redshifts, and interpolates them to generate reionization snapshots at closely spaced redshifts. We used this to generate 21-cm LC simulations with <span>\\(N_{\\textrm{RS}}=51\\)</span>, 101, 201, and showed that the errors reduce as <span>\\(N_{\\textrm{RS}}^{-1}\\)</span>.</p></div>","PeriodicalId":610,"journal":{"name":"Journal of Astrophysics and Astronomy","volume":"46 2","pages":""},"PeriodicalIF":1.6000,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Quantifying and mitigating the effect of snapshot interval in light-cone epoch of reionization 21-cm simulations\",\"authors\":\"Suman Pramanick, Rajesh Mondal, Somnath Bharadwaj\",\"doi\":\"10.1007/s12036-025-10087-3\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Epoch of reionization (EoR) neutral hydrogen (H <span>i</span>) 21-cm signal evolves significantly along the line-of-sight (LoS) due to the light-cone (LC) effect. It is important to accurately incorporate this in simulations to correctly interpret the signal. 21-cm LC simulations are typically produced by stitching together slices from a finite number <span>\\\\((N_{\\\\textrm{RS}})\\\\)</span> of ‘reionization snapshot’, each corresponding to a different stage of reionization. In this paper, we have quantified the errors in 21-cm LC simulation due to the finite value of <span>\\\\(N_{\\\\textrm{RS}}\\\\)</span>. We show that this can introduce large discontinuities (>200%) at the stitching boundaries when <span>\\\\(N_{\\\\textrm{RS}}\\\\)</span> is small <span>\\\\((=2,4)\\\\)</span> and the mean neutral fraction jumps by <span>\\\\(\\\\delta \\\\bar{x}_{\\\\textrm{H}\\\\,\\\\textsc {i}} =0.2,0.1\\\\)</span>, respectively, at the stitching boundaries. This drops to 17% for <span>\\\\(N_{\\\\textrm{RS}}=13\\\\)</span>, where <span>\\\\(\\\\delta \\\\bar{x}_{\\\\textrm{H}\\\\,\\\\textsc {i}}=0.02\\\\)</span>. We found that we can achieve <span>\\\\(\\\\delta \\\\bar{x}_{\\\\textrm{H}\\\\,\\\\textsc {i}} \\\\le 0.01\\\\)</span> with <span>\\\\(N_{\\\\textrm{RS}}=26\\\\)</span>, and we use this as reference for comparing the other simulations. We presented and also validated a method for mitigating this error by increasing <span>\\\\(N_{\\\\textrm{RS}}\\\\)</span> without a proportional increase in the computational costs, which are mainly incurred in generating the dark matter and halo density fields. Our method generates these fields, only at a few redshifts, and interpolates them to generate reionization snapshots at closely spaced redshifts. 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引用次数: 0
摘要
再电离时期(EoR)中性氢(H i) 21 cm信号由于光锥(LC)效应沿视距(LoS)显著演化。在模拟中准确地结合这一点以正确地解释信号是很重要的。21厘米的LC模拟通常是通过将有限数量的\((N_{\textrm{RS}})\)“再电离快照”的切片拼接在一起产生的,每个切片对应于再电离的不同阶段。在本文中,我们量化了21 cm LC模拟中由于\(N_{\textrm{RS}}\)的有限值而产生的误差。我们证明这可以引入大的不连续(&gt;200%) at the stitching boundaries when \(N_{\textrm{RS}}\) is small \((=2,4)\) and the mean neutral fraction jumps by \(\delta \bar{x}_{\textrm{H}\,\textsc {i}} =0.2,0.1\), respectively, at the stitching boundaries. This drops to 17% for \(N_{\textrm{RS}}=13\), where \(\delta \bar{x}_{\textrm{H}\,\textsc {i}}=0.02\). We found that we can achieve \(\delta \bar{x}_{\textrm{H}\,\textsc {i}} \le 0.01\) with \(N_{\textrm{RS}}=26\), and we use this as reference for comparing the other simulations. We presented and also validated a method for mitigating this error by increasing \(N_{\textrm{RS}}\) without a proportional increase in the computational costs, which are mainly incurred in generating the dark matter and halo density fields. Our method generates these fields, only at a few redshifts, and interpolates them to generate reionization snapshots at closely spaced redshifts. We used this to generate 21-cm LC simulations with \(N_{\textrm{RS}}=51\), 101, 201, and showed that the errors reduce as \(N_{\textrm{RS}}^{-1}\).
Quantifying and mitigating the effect of snapshot interval in light-cone epoch of reionization 21-cm simulations
Epoch of reionization (EoR) neutral hydrogen (H i) 21-cm signal evolves significantly along the line-of-sight (LoS) due to the light-cone (LC) effect. It is important to accurately incorporate this in simulations to correctly interpret the signal. 21-cm LC simulations are typically produced by stitching together slices from a finite number \((N_{\textrm{RS}})\) of ‘reionization snapshot’, each corresponding to a different stage of reionization. In this paper, we have quantified the errors in 21-cm LC simulation due to the finite value of \(N_{\textrm{RS}}\). We show that this can introduce large discontinuities (>200%) at the stitching boundaries when \(N_{\textrm{RS}}\) is small \((=2,4)\) and the mean neutral fraction jumps by \(\delta \bar{x}_{\textrm{H}\,\textsc {i}} =0.2,0.1\), respectively, at the stitching boundaries. This drops to 17% for \(N_{\textrm{RS}}=13\), where \(\delta \bar{x}_{\textrm{H}\,\textsc {i}}=0.02\). We found that we can achieve \(\delta \bar{x}_{\textrm{H}\,\textsc {i}} \le 0.01\) with \(N_{\textrm{RS}}=26\), and we use this as reference for comparing the other simulations. We presented and also validated a method for mitigating this error by increasing \(N_{\textrm{RS}}\) without a proportional increase in the computational costs, which are mainly incurred in generating the dark matter and halo density fields. Our method generates these fields, only at a few redshifts, and interpolates them to generate reionization snapshots at closely spaced redshifts. We used this to generate 21-cm LC simulations with \(N_{\textrm{RS}}=51\), 101, 201, and showed that the errors reduce as \(N_{\textrm{RS}}^{-1}\).
期刊介绍:
The journal publishes original research papers on all aspects of astrophysics and astronomy, including instrumentation, laboratory astrophysics, and cosmology. Critical reviews of topical fields are also published.
Articles submitted as letters will be considered.