Objectives & Methodology:

1. Improving Quasar Selection Methods. By: Kenechukwu C. Obi, Grinnell College, Iowa Mentor: Dr. Julia Kennefick. University of Arkansas, Fayetteville Objectives & Methodology: We aim to identify formerly unknown quasars from select databases, using previously known techniques that have been slightly modified. Similar work has been done using color-color diagrams. A color-color diagram is an x-y plot of one color versus another of a set of sky objects. These diagrams are useful because they separate out these sky objects based on the different characteristics they possess, thus they enable us to sift out the quasars from the stars. Below is an example of a color-color diagram, with known and speculated quasars: Previous work done in the optical range suffered from low optical efficiency of objects with redshifts 2-3. Such surveys are more efficient when done in the infrared. After selecting quasar candidates, we must then verify if they are indeed quasars using spectroscopic analysis. We then discard any objects which are not quasars. • Future Work: • We have been granted some observatory time in the fall at the Kitt peak observatory at Tucson, Arizona. At the observatory, we will take the spectra of each of our candidates, and from the spectra we will determine if they are indeed quasars, stars, or some other object. Below are samples of the spectra of typical quasars and stars, which show some of the distinct features of each of these objects’ spectra, and their differences: Introduction: Quasi-stellar objects alsoknown as quasars are extremely distant and bright active nuclei of young galaxies. They are powered by accretion of matter into massive black holes. Quasars were first discovered in the middle of the last century and provide interesting insights into the nature of the cosmos and the history of our universe. • Background: • What are the bases for classification of objects in the sky? • Morphology: This refers to the shape, size, and general physical characteristics of cosmological objects. • Magnitude: Magnitude is a measure of the amount of flux in a particular wavelength range which is received from the object. • Color: Color refers to the ratio of the magnitudes of flux received from one bandwidth to another. • Spectroscopy: Spectroscopy in astronomy involves looking at the light emitted from an object and separating this light into its constituents in the electromagnetic spectrum. Studying spectra of objects is often the most decisive way to classify an object. An object’s spectra can provide information about its constituents (gases it contains), its temperature, its speed of recession (red shift), and it can even give insights into the material contained in the spaces between the object and us. Quasar Spectrum Star Spectrum Acknowledgements: I would like to thank my mentor, Dr. Julia Kennefick, for her patience in helping me understand the project material; my project partner, Ashley Stewart, whose reassuring words kept me sane when huge piles of data nearly drove me to the edge, and lastly; 2-MASS & SDSS, for providing the data used in this work.