Séminaire Doctorants / Seminar PhD students |
| « Weak Lensing Without Shape Noise » |
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Pranjal Rajendra Singh |
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The unknown intrinsic shape of source galaxies is one of the largest uncertainties of weak gravitational lensing (WL). It results in the so-called shape noise at the level of s_e^WL \approx 0.26, whereas the shear effect of interest is of order percent.
Kinematic lensing (KL) is a new technique that combines photometric shape measurements with resolved spectroscopic observations to infer the intrinsic galaxy shape and directly estimate the gravitational shear. This work presents a KL inference pipeline that jointly forward-models galaxy imaging and slit spectroscopy to extract the shear signal. We build a set of realistic mock observations and show that the KL inference pipeline can robustly recover the input shear. To quantify the shear measurement uncertainty for KL, we average the shape noise over a population of randomly oriented disc galaxies and estimate it to be s_e^KL 0.022-0.038 depending on emission line signal-to-noise. This order of magnitude improvement over traditional WL makes a KL observational program feasible with existing spectroscopic instruments. To this end, we characterize the dependence of KL shape noise on observational factors and discuss implications for the survey strategy of future KL observations. In particular, we find that prioritizing quality spectra of low inclination galaxies is more advantageous than maximizing the overall number density. |
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vendredi 18 novembre 2022 - 16:00 Salle des séminaires Évry Schatzman, Institut d'Astrophysique |
| Page web du Séminaire / Seminar's webpage |