Simulation of galactic Sample Clauses

Simulation of galactic radio background reception‌ 1)). We obtain the background brightness B as maps of brightness temperature TB in equatorial coordinates. The brightness is the spectral irradiance per unit solid angle and is given by the Rayleigh-Jeans law: B(ν, α, δ ) = 2k ν2 TB [B] = Wm—2sr—1Hz—1 , (6.2) where k is the Boltzmann constant. In comparison to alternative descriptions of the galactic radio background given by Cane [50] and the global sky model GSM [51] we find an agreement of the three models at a level of ~ 1 dB by considering the spectral irradiance integrated over the full sky. An exemplary map of the galactic radio background generated at 55 MHz is displayed in figure 18. Besides the brightness, the dashed curve indicates the field of view that contributes 2012 JINST Figure 18. Map of galactic noise intensity generated with LFmap at 55 MHz. Temperatures have been translated to intensities following the Rayleigh-Jeans law. The colored data show noise intensities in the field of view of the Nanc¸ay Radio Observatory at a specific time. The horizon is displayed as a dashed line, the star symbol denotes the local zenith direction. The shade over the colored data indicates the relative antenna sensitivity of the Small Black Spider LPDA at the corresponding frequency oriented in east-west direction at Nanc¸ay. The measured side lobe in figure 10 (middle) is here pointing in the direction of the galactic center (Sgr A*). Please refer to a colored version of this plot. to the recorded noise power at the location of the Nanc¸ay Radio Observatory at the given time. The relative directionality of the Small Black Spider antenna for the corresponding frequency is represented by the gray shade. P10011 The noise that is recorded in the measurement is the convolution of the currently visible radio background and the projection of the antenna characteristics onto the sky. The received power spectral density is given by: Pν (ν) = 1 ∫ B(ν, α, δ ) Ae(ν, θ, φ ) dΩ , (6.3) 2)). The factor 1/2 is introduced explicitly in eq. (6.3) to take the polarization mismatch between the antenna and an unpolarized radio brightness into account [52]. Using the result from appendix F, the recorded power spectral density can also be expressed using the VEL: ∫ν P (ν) = 1 Z0 2 ZL B(ν, α, δ ) |7→ a(ν, θ, φ )|2 dΩ . (6.4) We have compared the measured and simulated average power spectral density as function of frequency based on eq. (6.4) using the same simulated VELs as for the discussion of the tr...