Introduction

Introduction

Abstract

Content

Analysis

Personal Comments

There are many topics of in current astronomical research which would be interesting to work on. There are also so many papers that searching through them all was prohibitively difficult. At first I considered several topics including dark matter and cosmology, yet upon sampling a few of those papers, I found the content advanced to a point where it would have been considerably difficult to understand them. So I limited my search to those on the topic of gravitational lensing for several reasons:

1. It provides evidence for the existence of dark matter apart from galaxy rotation curves, which is interesting to me.

2. It is conceptually easy.

3. The topic is more accessible than others to those with a little experience in Astrophysics (like Undergraduate Sophomore students).

With that limitation and the stipulation that the article have been published in the last year, that narrowed down the search considerably (probably around 50 in the The Astrophysical Journal (ApJ) and The Astronomical Journal (AJ)). Of these, I wanted to choose an article about general results, not about particular data, since it would be intrinsically more useful over the long term.  This led me to Gravitational Lensing Magnification without Multiple Imaging. There were several other attractions about this article. I am fond of work that involves the Principle of Least Astonishment in Astrophysics. For the bright z~6 quasars in the Sloan Digital Sky Survey (SDSS) the "astonishing" hypothesis is that these quasars are actually as bright as they seem, implying very massive black holes (10⁹ M_Sol) in the early universe. Another hypothesis, that this paper addresses, is that these quasars are actually magnified without being multiply imaged, so the observed magnitude is larger than it should be, and thus their mass is overestimated. Given these two hypothesis, the Principle of Least Astonishment selects the latter. However, this paper shows that this hypothesis is improbable, thus it implies some very interesting results that cosomology must attempt to incorporate. I chose this paper's because of its links to many different regions of astronomy.

The paper reference:

Charles R. Keeton, Michael Kuhlen and Zoltán Haiman
Gravitational Lensing Magnification Without Multiple Imaging
      The Astrophysical Journal, 621:559-573, 2005 March 10.