Direct Shear Mapping - a new weak lensing tool
We have developed a new technique called Direct Shear Mapping (DSM) to measure gravitational lensing shear directly from observations of a single background source. The technique assumes the velocity map of an un-lensed, stably-rotating galaxy will be rotationally symmetric. Lensing distorts the vel...
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ftdatacite:10.48550/arxiv.1505.06501 2023-05-15T18:12:41+02:00 Direct Shear Mapping - a new weak lensing tool de Burgh-Day, Catherine O. Taylor, Edward N. Webster, Rachel L. Hopkins, Andrew M. 2015 https://dx.doi.org/10.48550/arxiv.1505.06501 https://arxiv.org/abs/1505.06501 unknown arXiv arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences Preprint Article article CreativeWork 2015 ftdatacite https://doi.org/10.48550/arxiv.1505.06501 2022-04-01T12:14:44Z We have developed a new technique called Direct Shear Mapping (DSM) to measure gravitational lensing shear directly from observations of a single background source. The technique assumes the velocity map of an un-lensed, stably-rotating galaxy will be rotationally symmetric. Lensing distorts the velocity map making it asymmetric. The degree of lensing can be inferred by determining the transformation required to restore axisymmetry. This technique is in contrast to traditional weak lensing methods, which require averaging an ensemble of background galaxy ellipticity measurements, to obtain a single shear measurement. We have tested the efficacy of our fitting algorithm with a suite of systematic tests on simulated data. We demonstrate that we are in principle able to measure shears as small as 0.01. In practice, we have fitted for the shear in very low redshift (and hence un-lensed) velocity maps, and have obtained null result with an error of $\pm 0.01$. This high sensitivity results from analysing spatially resolved spectroscopic images (i.e. 3D data cubes), including not just shape information (as in traditional weak lensing measurements) but velocity information as well. Spirals and rotating ellipticals are ideal targets for this new technique. Data from any large IFU or radio telescope is suitable, or indeed any instrument with spatially resolved spectroscopy such as SAMI, ALMA, HETDEX and SKA. : 14 pages, 12 figures, 2 tables Report sami DataCite Metadata Store (German National Library of Science and Technology) |
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DataCite Metadata Store (German National Library of Science and Technology) |
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Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences |
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Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences de Burgh-Day, Catherine O. Taylor, Edward N. Webster, Rachel L. Hopkins, Andrew M. Direct Shear Mapping - a new weak lensing tool |
topic_facet |
Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences |
description |
We have developed a new technique called Direct Shear Mapping (DSM) to measure gravitational lensing shear directly from observations of a single background source. The technique assumes the velocity map of an un-lensed, stably-rotating galaxy will be rotationally symmetric. Lensing distorts the velocity map making it asymmetric. The degree of lensing can be inferred by determining the transformation required to restore axisymmetry. This technique is in contrast to traditional weak lensing methods, which require averaging an ensemble of background galaxy ellipticity measurements, to obtain a single shear measurement. We have tested the efficacy of our fitting algorithm with a suite of systematic tests on simulated data. We demonstrate that we are in principle able to measure shears as small as 0.01. In practice, we have fitted for the shear in very low redshift (and hence un-lensed) velocity maps, and have obtained null result with an error of $\pm 0.01$. This high sensitivity results from analysing spatially resolved spectroscopic images (i.e. 3D data cubes), including not just shape information (as in traditional weak lensing measurements) but velocity information as well. Spirals and rotating ellipticals are ideal targets for this new technique. Data from any large IFU or radio telescope is suitable, or indeed any instrument with spatially resolved spectroscopy such as SAMI, ALMA, HETDEX and SKA. : 14 pages, 12 figures, 2 tables |
format |
Report |
author |
de Burgh-Day, Catherine O. Taylor, Edward N. Webster, Rachel L. Hopkins, Andrew M. |
author_facet |
de Burgh-Day, Catherine O. Taylor, Edward N. Webster, Rachel L. Hopkins, Andrew M. |
author_sort |
de Burgh-Day, Catherine O. |
title |
Direct Shear Mapping - a new weak lensing tool |
title_short |
Direct Shear Mapping - a new weak lensing tool |
title_full |
Direct Shear Mapping - a new weak lensing tool |
title_fullStr |
Direct Shear Mapping - a new weak lensing tool |
title_full_unstemmed |
Direct Shear Mapping - a new weak lensing tool |
title_sort |
direct shear mapping - a new weak lensing tool |
publisher |
arXiv |
publishDate |
2015 |
url |
https://dx.doi.org/10.48550/arxiv.1505.06501 https://arxiv.org/abs/1505.06501 |
genre |
sami |
genre_facet |
sami |
op_rights |
arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
op_doi |
https://doi.org/10.48550/arxiv.1505.06501 |
_version_ |
1766185181865050112 |