Unanswered Questions
146 questions with no upvoted or accepted answers
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Observed instances of massive gas inflow and AGN restart due to cluster-cluster merger?
Works such as Acreman et al. (2003) have demonstrated via simulations the possibility of gas being stripped off a galaxy due to interaction with a galaxy cluster.
Have there been confirmed instances ...
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56
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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 ...
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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 ...
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84
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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 ...
2
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55
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What will be the eventual result of the Milky Ways future mergers?
I am wondering, after the Milky Way merges with Andromeda and other near by dwarf galaxies and globular clusters, will it then merge with galaxies in the Virgo cluster and even Laniakea? And if so ...
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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, ...
2
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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 ...
2
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324
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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 + ...
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 ...
2
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138
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Efficiently calculating power spectra from galaxy catalogs
I am dealing with a problem which requires calculating either the correlation function or the power spectrum. At times, the 2-point-correlator seems the better route, at others, the PS. Right now I am ...
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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 >...
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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 ...