Recent content by sketos

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...

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...

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 )...

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...

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...

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 ...

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...

Thank you!

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...

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...

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...

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...

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...

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.

Hello, i am relatively new linux user so please be as thoroughly descriptive as you can. i am starting a project and i have a file "file.hdf5" which contains velocity data i need to process in my fortran program. What do i have to do in order to use the data inside this file? i normally use...