Lyman alpha absorbers in motion: consequences of gravitational lensing for the cosmological redshift drift experiment - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




Lyman alpha absorbers in motion: consequences of gravitational lensing for the cosmological redshift drift experiment - Astrophysics > Cosmology and Nongalactic Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: The evolution of the expansion rate of the Universe results in a drift in theredshift of distant sources over time. A measurement of this drift wouldprovide us with a direct probe of expansion history. The Lyman alpha forest hasbeen recognized as the best candidate for this experiment, but the signal wouldbe weak and it will take next generation large telescopes coupled withultra-stable high resolution spectrographs to reach the cm-s resolutionrequired. One source of noise that has not yet been assessed is the transversemotion of Lyman alpha absorbers, which varies the gravitational potential inthe line of sight and subsequently shifts the positions of backgroundabsorption lines. We examine the relationship between the pure cosmic signaland the observed redshift drift in the presence of moving Lyman alpha clouds,particularly the collapsed structures associated with Lyman limit systemsLLSs and damped Lyman alpha systems DLAs. Surprisingly, the peculiarvelocities and peculiar accelerations both enter the expression, although theacceleration term stands alone as an absolute error, whilst the velocity termappears as a fractional noise component. An estimate of the magnitude of thenoise reassures us that the motion of the Lyman alpha absorbers will not pose athreat to the detection of the signal.



Autor: Madhura Killedar, Geraint F. Lewis

Fuente: https://arxiv.org/



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