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Effect of Wavelength Dependent Point Spread Function on Shear Measurements

Munir, Riffat
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1462532342

Abstract Details

2016, Master of Science (MS), Ohio University, Physics and Astronomy (Arts and Sciences).
Weak lensing is one of the powerful tools for measuring mass energy content of galaxies and galaxy cluster. Light is deflected by gravity when passing by massive objects(galaxy,galaxy cluster). Shear measurement due to distortion of light depends upon the Point spread Function(PSF) which is caused by telescope optics and atmosphere. Previous work had been done on how monochromatic PSF affects shear measurements. But each star has different spectral energy distribution and galaxy has internal colour gradient. We have taken these two effects into consideration in our study. To find the dependence upon wavelength of PSF we took different stellar spectra. The AB magnitude was calculated using two infrared regions(1.24-1.57)µm and (1.57-2.00)µm. We found that the size of PSf does not vary linearly with wavelength. This implies that based upon stellar spectra we can not estimate the PSF for a galaxy. In the simulation we considered one wavelength range in the infrared region(1.57-2.00)µm and divided the region into 21 parts . We took galaxies which have internal colour gradients.The convolution was done with wavelength dependent PSF. We found that the ratio of monochromatic and chromatic shear vs radius from the center of lens, the ratio varies around 0.1 but needs to be below 0.001. This implies that the colour dependence of PSF and galaxy internal colour gradients needs to be studied more.
Douglas Clowe (Advisor)
55 p.
Physics
Weak Lensing; Galaxy, Point Spread Function; Spectral Energy Distribution; Bias; Shear

Recommended Citations

Citations

  • Munir, R. (2016). Effect of Wavelength Dependent Point Spread Function on Shear Measurements [Master's thesis, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1462532342

    APA Style (7th edition)

  • Munir, Riffat. Effect of Wavelength Dependent Point Spread Function on Shear Measurements. 2016. Ohio University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1462532342.

    MLA Style (8th edition)

  • Munir, Riffat. "Effect of Wavelength Dependent Point Spread Function on Shear Measurements." Master's thesis, Ohio University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1462532342

    Chicago Manual of Style (17th edition)

ohiou1462532342
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© 2016, some rights reserved.Creative Commons License Effect of Wavelength Dependent Point Spread Function on Shear Measurements by Riffat Munir is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Ohio University and OhioLINK.
Release 3.2.12