New answers tagged galaxy
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Can the collapse of a gascloud lead to an elliptical structure?
You said "Due to the conservation of angular momentum disk structures are more likely to form" . Well, there may not be any angular momentum in the first place, so disc structures can not ...
- 2,707
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Accepted
Can the collapse of a gascloud lead to an elliptical structure?
The shape of a collapsing object is influenced by various factors, including the initial shape, angular momentum, ability to dissipate heat, and sub-clumping processes. When an object collapses, it ...
- 3,066
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Accepted
What is the unit of the correlation function between logarithmically rebinned galaxy spectrum and stellar template spectrum?
The unit is that of a velocity. If you have bins of equal $\ln \lambda$ (which equals $\Delta \lambda/\lambda =\Delta v/c$), then each of your pixels (in your spectrum and in the template) represents ...
- 136k
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How does superfluid dark matter keep stars orbiting at high speeds in galaxies?
The theory is wrong, for multiple reasons.
Why the theory is wrong:
We need a complete revision of what a Bose-Einstein condensate actually is.
A Bose-Einstein condensate is basically a dilute gas of ...
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When two galaxies with dark matter halos merge do they provide evidence for fermionic or bosonic dark matter?
There is no law of physics that prevents fermions getting arbitrarily close to each other. The Pauli Exclusion Principle says that no two fermions can occupy the same quantum state. Basically, this ...
- 136k
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How to construct optimal Wiener Filter?
To construct the optimal Wiener Filter $W(k)$:
1.) compute power spectrum of the crosscorrelation(between a galaxy spectrum and a stellar template spectrum peak) $X_{G, S}(z) = \int dx \, G(x+z)S(x)$, ...
- 799
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Can someone explain the strange case of NGC 4319 and Markarian 205 and its controversial redshifts and later convinced by reddening?
Some details about the image you have shown can be found here.
The gist of this is that the image shows a nearby galaxy, NGC 4319 (estimated to be about 77 million light years away) in the centre and ...
- 136k
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If a supernova explodes close to the centre of the milky way does its light get blueshifted by dark matter by the time it reaches the Earth?
Light from the Galactic Center is gravitationally redshifted (not blueshifted) by a little over one part in a million as it climbs the Galactic potential to reach us. While dark matter contributes, ...
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Is the mass function of dark matter halos fundamental or an approximation based on experimental data?
Assuming you know the statistics of the cosmological initial conditions (e.g. the matter power spectrum), the halo mass function can be predicted from first principles using so-called excursion set ...
- 2,512
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Accepted
How to construct optimal Wiener Filter?
update: This may not yet be the complete answer, stay tuned...
tl;dr:
To make this work and get the smooth "knee" near the "cutoff" at $k = \pm 0.005$ employ the oft-used trick of ...
- 30.8k
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Accepted
What am I doing wrong in this ppxf application?
The velscale keyword defines the spacing of the spectrum's wavelength vector, in velocity (km/s) units. Look in the ppxf code (in ppxf.ppxf_util) for the log_rebin ...
- 15.9k
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