Speaker
Description
The cosmological 21-cm forest, a series of absorption lines in the spectra of high-z radio-loud sources arising from the hyperfine structure of neutral hydrogen residing in the intergalactic medium (IGM), has a potential to be a unique probe of the neutral IGM during the Epoch of Reionization. While there are no detections of this signal up to date, I will argue that the prospects of detecting the 21-cm forest signal are improving because of (1) recent evidence that reionization ended as late as z<5.5, (2) increase in the number of known high-z radio-loud quasars and (3) the improving sensitivity of radio telescopes such as the uGMRT and SKA. In this context, I will present our models of the 21-cm forest signal based on cosmological simulations, in which we simultaneously vary the X-ray background radiation efficiency and ionization state of the IGM. I will discuss the detectability of this signal by the uGMRT and SKA1-low, both direct detection of individual absorption lines and statistical detection. I will finish this talk by showing that the spectroscopical observations of the 21-cm forest signal provide a unique opportunity to constrain the cosmic heating and reionization history at z≥6 even in the case of a null-detection.
| Topics | Epoch of Reionization and Cosmic Dawn |
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