Recent content by sketos

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    Spectroscopic system, AB magnitudes

    The treatment that is described in those link concerns the apparent magnitudes, where clearly K-corrections play an important role. However in the exercise that i described we already have the absolute magnitudes in the AB system of the sun and the galaxy ( which are already related with the...
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    Spectroscopic system, AB magnitudes

    Suppose we have a galaxy at redshift z=4 with monochromatic UV luminosity λUV *LUV = 4.2×1046 erg /s and an absolute K -band magnitude of K = −23.5 mag (in the AB system). Assuming a K -band absolute magnitude M⊙,AB = 5.14 for the sun, how can i determine the luminosity L_K of the galaxy ?? I...
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    How can I plot the Voigt Profile function with varying values of a in Python?

    import numpy as np import pylab as pl from math import exp from scipy.integrate import quad def voigt( u , a ): def integrand( y ): return exp(-y**2)/( a**2 + ( u - y )**2 ) return quad( integrand ,-np.inf , np.inf )x = np.linspace(-100 , 100 ) Func = voigt( x , 0.1 )...
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    How can I plot the Voigt Profile function with varying values of a in Python?

    I very new to python and this might look relatively easy to some of you. I need to write a code so that H(a,u) = \frac{a}{\pi} \int_{-\infty}^{\infty} \frac{e^{-y^2}}{a^2+(u-y)^2}dy it plots the above function for different values of the a parameter, so that ultimately i will have a graph of...
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    High redshift galaxies in the HUDF

    In the Hubble Ultra Deep Field ( http://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field ) there are almost 10.000 galaxies and some of them with redshift Z>6 . Making some approximations i need to compute the number of galaxies with redshift z = 7. If the source density ( number / arcmin^2 ) at...
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    Observing proposal for globular clusters in M31

    Hello, As part of a course I have been asked to make a observing proposal which aims to detect globular clusters in the bulge of M31. The "virtual" observation will be conducted using the Hubble telescope and the WFC3 To begin with we aim to acquire a sample of globular clusters down to 10^6...
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    Fortran Useful and Extensive MPI tutorial/notes in FORTRAN

    this is one the best i could find online, but still doesn't cover many examples. I will have to post process a quite huge N-Body simulation and i assume i need to go deeper into the subject ...
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    Fortran Useful and Extensive MPI tutorial/notes in FORTRAN

    Hello Everyone, I am a new user of MPI in fortran ( i have used fortran for an adequate time ) and I want to make myself familiar with the subject. Has anyone you stumbled upon a useful tutorial in MPI for fortran but simultaneously extensive ? Or maybe someone has used a textbook that...
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    Gnuplot: reflexion of a graph in a quadrant to the other

    Hello everyone, I have generated a graph in one quadrant and i need to generate the reflexion of it in the other quadrants. I need to generate a graph like the one found in (http://arxiv.org/pdf/astro-ph/0103143v1.pdf) figure 2. The figure below show the graph i have i one quadrant...
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    Perpendicular peculiar velocity

    My final goal is to compute the pairwise peculiar velocity dispersion. Normally in real galaxy surveys, one has to model the pairwise velocity dispersion with the two-point correlation function but since i have simulated data should be able to compute it directly. If you define the pairwise...
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    Perpendicular peculiar velocity

    unfortunately i don't have such a vector in the data i received ( that would make my life easier ). I have distances, angular coordinates, observational and cosmological redshift and various other properties (i.e. luminocities, SFR, etc). I am not sure if i can measure the tangential component...
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    Perpendicular peculiar velocity

    I don't think we are on the same page here. Since we are talking about mock catalogues of galaxies produced in simulation we have knowledge of individual velocity of the galaxies. For example as I mentioned above we have the cosmological redshift of each Galaxy which corresponds to the velocity...
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    Perpendicular peculiar velocity

    Hello, I have data from a simulation of galaxies with various properties and I want to retrieve the peculiar velocity. If we want to relate with real galaxy surveys, what we can measure from real data is the radial peculiar velocity. My question is, since we have a simulation i imagine we can...
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    Pairwise velocity dispersion in Cosmological simulations

    i have a mock catalogue so i think the way the data are constructed it assumes that there is an observer. So i have data points which correspond to (xi,yi,zi) and (uxi,uyi,uzi). so i guess i need to find how r is related to rp.
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