The Effect of Large Optical Depths on the Non-Gaussian 21-cm signal from Cosmic Dawn
Fuente:
arXiv
Gespeichert in:
| Hauptverfasser: | , , , , , , , , |
|---|---|
| Format: | Preprint |
| Veröffentlicht: |
2025
|
| Schlagworte: | |
| Online-Zugang: | |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| _version_ | 1866915578333102080 |
|---|---|
| author | Nasreen, Iffat Datta, Kanan K. Shaw, Abinash K. Noble, Leon Ghara, Raghunath Ali, Sk. Saiyad Mishra, Arnab Kamran, Mohd Majumdar, Suman |
| author_facet | Nasreen, Iffat Datta, Kanan K. Shaw, Abinash K. Noble, Leon Ghara, Raghunath Ali, Sk. Saiyad Mishra, Arnab Kamran, Mohd Majumdar, Suman |
| contents | During the Cosmic Dawn (CD), the HI 21-cm optical depth ($τ$ ) in the intergalactic medium can become significantly large. Consequently, the second and higher-order terms of $τ$ appearing in the Taylor expansion of the HI 21-cm differential brightness temperature ($δT_{\rm b}$ ) become important. This introduces additional non-Gaussianity into the signal. We study the impact of large $τ$ on statistical quantities of HI 21-cm signal using a suite of standard numerical simulations that vary X-ray heating efficiency and the minimum halo mass required to host radiation sources. We find that the higher order terms suppress statistical quantities such as skewness, power-spectrum and bispectrum. However, the effect is found to be particularly strong on the non-Gaussian signal. We find that the change in skewness can reach several hundred percent in low X-ray heating scenarios, whereas for moderate and high X-ray heating models changes are around $\sim40\%$ and $60\%$, respectively, for $M_{\rm h,min}=10^{9}\, {\rm M}_{\odot}$. This change is around $\sim 75\%$, $25\%$ and $20\%$ for low, moderate and high X-ray heating models, respectively, for $M_{\rm h,min}=10^{10}\, {\rm M}_{\odot}$. The change in bispectrum in both the halo cutoff mass scenarios ranges from $\sim 10\%$ to $\sim 300\%$ for low X-ray heating model. However, for moderate and high X-ray heating models the change remains between $\sim 10\%$ to $\sim 200\%$ for both equilateral and squeezed limit triangle configuration. Finally, we find that up to third orders of $τ$ need to be retained to accurately model $δT_{\rm b}$, especially for capturing the non-Gaussian features in the HI 21-cm signal. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_23011 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Effect of Large Optical Depths on the Non-Gaussian 21-cm signal from Cosmic Dawn Nasreen, Iffat Datta, Kanan K. Shaw, Abinash K. Noble, Leon Ghara, Raghunath Ali, Sk. Saiyad Mishra, Arnab Kamran, Mohd Majumdar, Suman Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology During the Cosmic Dawn (CD), the HI 21-cm optical depth ($τ$ ) in the intergalactic medium can become significantly large. Consequently, the second and higher-order terms of $τ$ appearing in the Taylor expansion of the HI 21-cm differential brightness temperature ($δT_{\rm b}$ ) become important. This introduces additional non-Gaussianity into the signal. We study the impact of large $τ$ on statistical quantities of HI 21-cm signal using a suite of standard numerical simulations that vary X-ray heating efficiency and the minimum halo mass required to host radiation sources. We find that the higher order terms suppress statistical quantities such as skewness, power-spectrum and bispectrum. However, the effect is found to be particularly strong on the non-Gaussian signal. We find that the change in skewness can reach several hundred percent in low X-ray heating scenarios, whereas for moderate and high X-ray heating models changes are around $\sim40\%$ and $60\%$, respectively, for $M_{\rm h,min}=10^{9}\, {\rm M}_{\odot}$. This change is around $\sim 75\%$, $25\%$ and $20\%$ for low, moderate and high X-ray heating models, respectively, for $M_{\rm h,min}=10^{10}\, {\rm M}_{\odot}$. The change in bispectrum in both the halo cutoff mass scenarios ranges from $\sim 10\%$ to $\sim 300\%$ for low X-ray heating model. However, for moderate and high X-ray heating models the change remains between $\sim 10\%$ to $\sim 200\%$ for both equilateral and squeezed limit triangle configuration. Finally, we find that up to third orders of $τ$ need to be retained to accurately model $δT_{\rm b}$, especially for capturing the non-Gaussian features in the HI 21-cm signal. |
| title | The Effect of Large Optical Depths on the Non-Gaussian 21-cm signal from Cosmic Dawn |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2506.23011 |