Unanswered Questions
158 questions with no upvoted or accepted 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 ...
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What is the mass for a celestial body to definitely achieve hydrostatic equilibrium?
While these posts (attempt to) answer what the minimum mass is to be able to achieve an ellipsoidal shape, my question asks for the mass at which a body definitely collapses into an ellipsoid. Meaning,...
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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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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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If time is not absolute and depends on the gravitational field, then why we keep using our own (particular) time in cosmology?
Sorry if my question is not really clear, but indeed it is not clear in my mind neither.
But maybe some of you can help.
Time is not absolute and can be affected by the gravitational potential.
Now ...
CommunityBot
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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 ...
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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 ...
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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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Is there a way to calculate how much damage black hole merger shockwaves inflict on nearby objects?
Black hole mergers lose respective rotational energy during a merger. I understand that the energy 'emitted' is scattered as gravitational 'energy' that can henceforth be detected by gravitational ...
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What is the meaning of ellipticity of a galaxy being more than 1?
I was recently doing a project on calculating ellipticities of galaxies using SDSS data. I downloaded the stokes parameter values (q and u) from data
$e = 1 - \frac{b}{a} = 1 - \frac{1 - \sqrt{Q^2 + ...
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How to write a normalized, dimensionless form of Binet's relativistic equation?
$$\frac{\delta^2 u}{\delta \theta^2} + u = \frac{\mu}{h^2} + 3 \mu u^2$$
This is Binet's relativistic equation. Here $u = 1/r$ where $r$ is the radial distance, and $\mu$ is the reduced mass of the ...
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A high-temperature isolated neutron star could be super-Eddington?
If the surface temperature of a young neutron star is hot enough, say, several KeV, its blackbody radiation could be super-Eddington?
Did any paper discuss this scenario before?
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What are the procedures and protocols to use with Gauss'method and personal observations?
I would like to use the Gauss' method to determine the orbit of planets of solar system.
I would like to calculate their orbits with personal observations.
What is the methodology/procedure/protocol ...
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What's the profound reason(s) why the star formation rate drives the scatter of the mass-metallicity relation in galaxies?
Since decades it's well known that a correlation between stellar mass and metallicity (Z; both stellar and gas-phase Z, but here I focus on the gas-phase Z) exists (e.g., Tremonti+04; analysis of >...
CommunityBot
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What is known about the angular momentum distribution within galaxy clusters?
I recently saw a 3D-plot of proper motions of galaxies within the Laniakea super-cluster (https://sketchfab.com/models/754cb85550fb42588175f8a215718521). Is a similar 3D map of the vector field of ...
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