Speaker
Description
The Lyman-$\alpha$ forest provides constraints on cosmological models on both small spatial scales and large. Because the Ly$\alpha$ forest traces ionized intergalactic hydrogen, its statistical signatures are sensitive to both the metagalactic photoionization rate and the intergalactic gas temperature. The large-scale influence of QSO sources effects both of these. We show that QSO heating following photoionization induces uncertainties in the small scale power comparable to the difference in the signatures of weak dark matter vs cold dark matter, and so must be taken into account in constraints on warm dark matter particle masses. On Baryonic Acoustic Oscillation scales, the QSO contribution to the metagalactic photoionization rate induces excess power. While the effect is small at redshifts $z \sim 2.3$ as measured by eBOSS and DESI, we show the influence is expected to be detectable at $z > 3$, providing a novel means of constraining the mean lifetimes and beaming angles of QSOs.
| Other topic / keywords: | intergalactic medium |
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