Title

Probing Distant Galaxies Using Gravitationally Lensed Quasars

Author(s)

Sienna BrentFollow

School Name

South Carolina Governor's School for Science & Mathematics

Grade Level

12th Grade

Presentation Topic

Physics

Presentation Type

Mentored

Oral Presentation Award

1st Place

Abstract

Quasar absorption line spectroscopy is a powerful tool to probe the gas in and around distant or faint galaxies because the galaxy can be studied independent of its brightness. Identifying the gas composition is crucial for understanding the evolution process of galaxies. The quasar serves as a background light source, enabling us to measure the column densities of chemical elements along the line of sight through which the quasar shines. Gravitationally lensed quasars (GLQs) are especially useful as they provide multiple lines of sight through the galaxy and other foreground absorption systems allowing observation of smaller-scale structure in a galaxy's interstellar medium. Measuring element abundances and their projected separations yield estimates of gradients in H I column density and metallicity. Determining element abundances requires both metal line and neutral hydrogen column densities. This project identifies GLQs with significant metal line absorption (Mg II, Fe II, Ca II, and Na I) as possible targets for having significant hydrogen absorption as well. Hydrogen absorption lines in low redshift lens galaxies typically have wavelengths in the ultraviolet and require space-based observation. Spectra of 70 GLQs from the Sloan Digital Sky Survey (SDSS) were searched for metal lines and their equivalent width was measured using SPECP. Ten GLQs have multiply lensed images (>2). GLQs with metal line absorption in their spectra are possible targets for future observing proposals to identify and measure the H I and metal line column densities of the lens galaxy and any other significant absorbers along the lines of sight.

Location

Founders Hall 210 B

Start Date

3-30-2019 11:15 AM

Presentation Format

Oral Only

Group Project

No

COinS
 
Mar 30th, 11:15 AM

Probing Distant Galaxies Using Gravitationally Lensed Quasars

Founders Hall 210 B

Quasar absorption line spectroscopy is a powerful tool to probe the gas in and around distant or faint galaxies because the galaxy can be studied independent of its brightness. Identifying the gas composition is crucial for understanding the evolution process of galaxies. The quasar serves as a background light source, enabling us to measure the column densities of chemical elements along the line of sight through which the quasar shines. Gravitationally lensed quasars (GLQs) are especially useful as they provide multiple lines of sight through the galaxy and other foreground absorption systems allowing observation of smaller-scale structure in a galaxy's interstellar medium. Measuring element abundances and their projected separations yield estimates of gradients in H I column density and metallicity. Determining element abundances requires both metal line and neutral hydrogen column densities. This project identifies GLQs with significant metal line absorption (Mg II, Fe II, Ca II, and Na I) as possible targets for having significant hydrogen absorption as well. Hydrogen absorption lines in low redshift lens galaxies typically have wavelengths in the ultraviolet and require space-based observation. Spectra of 70 GLQs from the Sloan Digital Sky Survey (SDSS) were searched for metal lines and their equivalent width was measured using SPECP. Ten GLQs have multiply lensed images (>2). GLQs with metal line absorption in their spectra are possible targets for future observing proposals to identify and measure the H I and metal line column densities of the lens galaxy and any other significant absorbers along the lines of sight.