Omer Tzuk's Personal Information

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Omer Tzuk

PhD Student
Advisor: Prof. Ehud Meron

Office: 54/317

PhD Information

Advisor: Prof. Ehud Meron

Ecological Integrity is a new concept in ecology that aims to capture the degree to which an ecosystem is in a state of self-organization that represents a high level of ecosystem functioning in terms of functional diversity, bio-productivity, resource-use efficiency, resilience to varying environments, etc. Water-limited ecosystems provide a good case study for putting the integrity concept on firm mathematical grounds and studying factors that affect ecosystem integrity and means for increasing it. This is because they allow for spatial self-organization, in addition to community-structure self-organization, and because well-developed mathematical models are available.
The approach to be pursued will be based on the identification of the eigenmodes that control various forms of self-organization and on the study of factors that affect their amplitudes and growth rates. Specific contexts to be considered include rehabilitation of degraded landscapes by water harvesting methods, the structure of spatially uniform plant communities, the coupling of this structure to spatial self-organization, and development of biomimetic approach to agro-ecology. We will study ecological integrity in these contexts using the mathematical model introduced by Gilad et al. (2007), and various extensions and simplifications thereof. The studies will include mathematical analysis along with numerical studies using continuation methods and integration in time. We intend to cooperate with ecologists who will monitor ecosystem states using field studies and remote sensing methods, and to confront theoretical predictions with empirical observations.

MSc Information

Advisor: Prof. Shin'ichiro Ando

Distortion of CMB spectrum due to dark matter annihilation

The monopole signal of the cosmic microwave background (CMB) is a probe to the early Universe. The energy spectrum of the CMB holds the information of energy release pisodes from redshift of about z ∼ (2 × 10^6) till the epoch of recombination, and an analysis of the energy spectrum allows us to test various hypotheses about physical processes during this time span. One of the scenarios that can be put into test is the presence of dark matter particle in the early Universe. If dark matter is made of weakly interacting massive particles (WIMPs), we can expect them to inject energy into the primordial medium by self annihilation. This energy is expected to cause a distortion of the CMB spectrum. In this scenario, the expected distortion is characterize by a non-zero
chemical potential (μ) at the photons energy distribution function (a Bose-Einstein spectrum), and so this distortion is termed μ-type distortion. We provide here a forecast for μ-type distortion for WIMPs that arise from supersymmetric model. In addition, an analysis of μ-type distortion in the presence of Ultracompact Primordial Dark Matter Minihalos (UCMHs) is presented, and the possibility of constraining cosmological parameters through μ-type distortion observations is explained.