تقرير
Impact of Self-shielding Minihalos on the Ly$\alpha$ Forest at High Redshift
| العنوان: | Impact of Self-shielding Minihalos on the Ly$\alpha$ Forest at High Redshift |
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| المؤلفون: | Park, Hyunbae, Lukić, Zarija, Sexton, Jean, Alvarez, Marcelo, Shapiro, Paul R. |
| سنة النشر: | 2023 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Cosmology and Nongalactic Astrophysics |
| الوصف: | Dense gas in minihalos with masses of $10^6-10^8~M_\odot$ can shield themselves from reionization for $\sim100$ Myr after being exposed to the UV background. These self-shielded systems, often unresolved in cosmological simulations, can introduce strong absorption in quasar spectra. This paper is the first systematic study on the impact of these systems on the Ly$\alpha$ forest. We first derive the HI column density profile of photoevaporating minihalos by conducting 1D radiation-hydrodynamics simulations. We utilize these results to estimate the Ly$\alpha$ opacity from minihalos in a large-scale simulation that cannot resolve self-shielding. When the ionization rate of the background radiation is $0.03\times10^{-12}~{\rm s}^{-1}$, as expected near the end of reionization at $z\sim5.5$, we find that the incidence rate of damped Ly$\alpha$ absorbers increases by a factor of $\sim2-4$ compared to at $z=4.5$. The Ly$\alpha$ flux is, on average, suppressed by $\sim 3\%$ of its mean due to minihalos. The absorption features enhance the 1D power spectrum up to $\sim5\%$ at $k\sim0.1~h~{\rm Mpc}^{-1}~({\rm or}~10^{-3}~{\rm km}^{-1}~{\rm s})$, which is comparable to the enhancement caused by inhomogeneous reionization. The flux is particularly suppressed in the vicinity of large halos along the line-of-sight direction at separations of up to $10~h^{-1}~{\rm Mpc}$ at $r_\perp\lesssim2~h^{-1}~{\rm Mpc}$. However, these effects become much smaller for higher ionizing rates ($\gtrsim0.3\times10^{-12}~{\rm s}^{-1}$) expected in the post-reionization Universe. Our findings highlight the need to consider minihalo absorption when interpreting the Ly$\alpha$ forest at $z\gtrsim5.5$. Moreover, the sensitivity of these quantities to the ionizing background intensity can be exploited to constrain the intensity itself. Comment: 16 pages; 11 figures; Accepted for publication in ApJ |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2309.04129 |
| رقم الأكسشن: | edsarx.2309.04129 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |