Computing Gravitational Wave Frequencies of Neutron Stars

Vibration modes of single neutron stars are important sources of continuous gravi- tational waves for detectors like the Laser Interferometer Gravitational-Wave Observa- tory (LIGO). In order for LIGO to identify the weak signal buried in the noise, they rely on a theoretical template of the signal amplitude and frequency. In this thesis, we utilize a technique rst described by Chandrasekhar to calculate the frequency of the quasi- normal mode oscillations of a single neutron star. We calculate the normalized (complex) frequency for the l=2 (quadrupole) oscillation of the entire family of general relativistic polytropes with polytropic index 1.5 and a central density to central pressure ratio of 9. We nd the real part of this normalized frequency to be =0.3383, compared to Chan- drasekhar's result in his paper from 1991 of =0.3248. We nd the imaginary part of this normalized frequency to be =1.448010[Special character(s) omitted]4, compared to Chandrasekhar's result in his paper from 1991 of =1.02610[Special character(s) omitted]4. The slight dierence is likely due to higher computa- tional accuracy of modern day computers

NOMAD, an Integrated Suite of Three Spectrometers for the ExoMars Trace Gas Mission: Technical Description, Science Objectives and Expected Performance

International audienceThe NOMAD (“Nadir and Occultation for MArs Discovery”) spectrometer suite on board the ExoMars Trace Gas Orbiter (TGO) has been designed to investigate the composition of Mars’ atmosphere, with a particular focus on trace gases, clouds and dust. The detection sensitivity for trace gases is considerably improved compared to previous Mars missions, compliant with the science objectives of the TGO mission. This will allow for a major leap in our knowledge and understanding of the Martian atmospheric composition and the related physical and chemical processes. The instrument is a combination of three spectrometers, covering a spectral range from the UV to the mid-IR, and can perform solar occultation, nadir and limb observations. In this paper, we present the science objectives of the instrument and explain the technical principles of the three spectrometers. We also discuss the expected performance of the instrument in terms of spatial and temporal coverage and detection sensitivity