Year: 2003
Type: article
Abstract: Recently, a “CDM crisis” is being discussed. The main point of this crisis is that the number of substructures presented by cosmological $N$-body simulations based on the CDM scenario for structure formation is much larger than the observed substructures. Therefore, it is crucial for this crisis to discriminate whether the expected number of CDM substructures really exist without detectable radiation, or do not exist. In this paper, we present a new idea to detect such invisible substructures by utilizing gravitational lensing. Here, we consider quasars that are gravitationally lensed by a foreground galaxy. A substructure around a lensing galaxy may superposed on one of the lensed images of such quasars. In this situation, additional image splitting should occur in the image behind the substructure, and additional multiple images are created. From our estimations, the separation and time delay between the additional multiple images are expected to be $1 \hbox{--} 30$ milli-arcsecond and $1 \hbox{--} 10^3$ second, respectively. Furthermore, we evaluate that the optical depth for such events is $\sim 0.1$. Consequently, future fine-resolution imaging and/or high-speed monitoring will unable us to find invisible substructures in one of a few multiple quasars.
Authors: Atsunori Yonehara, Masayuki Umemura, Hajime Susa
Institutions: University of Tsukuba, Rikkyo University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2122513065