Unanswered Questions
136 questions with no upvoted or accepted answers
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How do I calculate the flux density of a substellar object?
I am currently trying to generate photometric passband colors for brown dwarfs and planets generated through MESA (Modules for Experiments in Stellar Astrophysics). I believe I understand the ...
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How to use astropy to join data tables based on sky coordinates?
I have 2 astronomical tables, from a fits file and a csv file, that look something like this
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The necessary conditions for driving winds with dust (Dust-driven Wind)
So lately I've read Intro to stellar winds (particularly chapter 7 Dust-driven winds) by Lamers & cassinelli, I forget how many times I've read this but I still don't really understand. So in the ...
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Where can I find definitions of minimum detectable flux sensitivity and signal to noise ratio?
I am struggling to find references that give precise definitions to these concepts. Even in PhD theses on the subject of gamma-ray astrophysics, for example, students do not define it precisely or ...
- 2,169
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Is it possible to infer information about the structure of the universe beyond the observable one?
Is it possible to infer information about the structure of the universe beyond the observable one, by observing its effects on the parts we can see? Can for example gravity from sources we cannot see ...
- 2,522
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Cosmology context plotting : Covariance matrix - Script to plot Omega_m vs Omega_Lambda diagram in Python
I have covariance matrices and Markov chains coming from the SCP (Supernova Cosmology Project) and I would like to plot all these data
in the particular diagram Omega_Lambda vs Omega_m or w vs Omega_m....
CommunityBot
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2
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57
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What is the sun's maximum influence on a magnetic object?
How much magnetic repulsion could the sun's magnetic field produce on an magnetic object? Consider the object is ideal: It could be flat, to create more resistance, balanced, to stay on the opposing ...
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Looking for analytical expression of Cosmic Variance - Poisson distribution?
I have an expression of Matter Angular power spectrum which can be computed numerically by a simple rectangular integration method (see below). I make appear in this expression the spectroscopic ...
CommunityBot
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2
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Poisson noise for a squared contrast of density - expression of variance equal to $1/n^2$
I manage to compute the Poisson noise of a density field like this :
If I take $N$ the density of galaxies and compute the Shot noise with a Poisson distribution, I get :
$\langle N^2\rangle - \...
CommunityBot
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2
votes
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answers
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Anatomy of a galaxy cluster: understanding the relationship between dark matter halos and subhalos and galaxies within the clusters?
In my understanding, galaxy clusters contain dark matter halos, which in turn contain subhalos, and the subhalos are what surrounds individual galaxies. I know that is a simplified picture, but I am ...
- 30.7k
2
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Demonstration of scales for the two components (transverse and perpendicular) of Baryonic Acoustic Oscillations (BAO)
I transfer here a post that has not had any answer pn physics exchange, so I am going to delete this latter. Maybe I will have more luckiness here.
In an astrophysics context about BAO (Baryonic ...
CommunityBot
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2
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answers
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How thick are the intergalactic filaments?
Recently, in October, news came out about the faint intergalactic filaments finally being 'found'.
Then, in June, astronomers announced that these things had enough normal matter in them to solve the '...
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How common is it for large objects (few kilometers wide) in a young protoplanetary disk or debris disk to collide with one another?
If enough time has passed for gravitational forces to allow the formation of planetesimals(proto-planets) in orbit around the proto-star, how likely is it that two of them would collide with one ...
- 359
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Spectral Energy Distribution (SED) characteristics of Disk and Elliptical Galaxies
Quick questions about the spectral energy distributions of galaxies:
What characteristics do we look for in SEDs that provide information on that galaxy's morphology?
For example, in spiral galaxy ...
- 30.7k
2
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Force to fix $\sigma_{8}$ or $A_{s}$ for Forecasts
In the context of Forecasts with Fisher's formalism, I make vary cosmological parameters to compute the elements of the Fisher matrix.
First, I generate with CAMB code a linear power spectrum. Then, ...
CommunityBot
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