Friday, March 17, 2023

Cold Dark Matter Predictions Fail Again At The Center Of The Milky Way

Once again, predictions made about the inferred distribution of cold dark matter in galaxies has turned out to be grossly off the mark now that our astronomy data is better.

MOND which predicts no dark matter phenomena near the galactic center beyond the baseline prediction of general relativity without dark matter, is a much more accurate description of what is observed.
Precise measurements of the stellar orbits around Sagittarius A* have established the existence of a supermassive black hole (SMBH) at the Galactic centre (GC). Due to the interplay between the SMBH and dark matter (DM), the DM density profile in the innermost region of the Galaxy, which is crucial for the DM indirect detection, is still an open question. Among the most popular models in the literature, the theoretical spike profile proposed by Gondolo and Silk (1999; GS hereafter) is well adopted. 
In this work, we investigate the DM spike profile using updated data from the Keck and VLT telescopes considering that the presence of such an extended mass component may affect the orbits of the S-stars in the Galactic center. We examine the radius and slope of the generalized NFW spike profile, analyze the Einasto spike, and discuss the influence of DM annihilation on the results. 
Our findings indicate that an initial slope of γ≳0.92 for the generalized NFW spike profile is ruled out at a 95% confidence level. Additionally, the spike radius R(sp) larger than 21.5 pc is rejected at 95% probability for the Einasto spike with α=0.17, which also contradicts the GS spike model. 
The constraints with the VLT/GRAVITY upper limits are also projected. Although the GS NFW spike is well constrained by the Keck and VLT observation of S2, an NFW spike with a weak annihilation cusp may still be viable, as long as the DM annihilation cross section satisfies ⟨σv⟩≳7.7×10^−27 cm^3s^−1(m(DM)/100 GeV) at 95% level.
Zhao-Qiang Shen, Guan-Wen Yuan, Cheng-Zi Jiang, Yue-Lin Sming Tsai, Qiang Yuan, Yi-Zhong Fan, "Exploring dark matter spike distribution around the Galactic centre with stellar orbits" arXiv:2303.09284 (March 16, 2023) (To be submitted to MNRAS).

2 comments:

neo said...

you never post papers that support cdm

i.e


The Milky Way’s plane of satellites is consistent with ΛCDM

Till Sawala, Marius Cautun, Carlos Frenk, John Helly, Jens Jasche, Adrian Jenkins, Peter H. Johansson, Guilhem Lavaux, Stuart McAlpine & Matthieu Schaller

Nature Astronomy (2022)Cite this article

Abstract

The Milky Way is surrounded by 11 ‘classical’ satellite galaxies in a remarkable configuration: a thin plane that is possibly rotationally supported. Such a structure is thought to be highly unlikely to arise in the standard (ΛCDM) cosmological model (Λ cold dark matter model, where Λ is the cosmological constant). While other apparent discrepancies between predictions and observations of Milky Way satellite galaxies may be explained either through baryonic effects or by invoking alternative forms of dark matter particles, there is no known mechanism for making rotating satellite planes within the dispersion-supported dark matter haloes predicted to surround galaxies such as the Milky Way. This is the so-called ‘plane of satellites problem’, which challenges not only the ΛCDM model but the entire concept of dark matter. Here we show that the reportedly exceptional anisotropy of the Milky Way satellites is explained, in large part, by their lopsided radial distribution combined with the temporary conjunction of the two most distant satellites, Leo I and Leo II. Using Gaia proper motions, we show that the orbital pole alignment is much more common than previously reported, and reveal the plane of satellites to be transient rather than rotationally supported. Comparing with new simulations, where such short-lived planes are common, we find the Milky Way satellites to be compatible with standard model expectations.

https://www.nature.com/articles/s41550-022-01856-z

andrew said...

A lot of them are methodologically weak and ignore or at least fail to refute other results.

Also, as the default and paradigm, papers that support it are un-notable.

"Here we show that the reportedly exceptional anisotropy of the Milky Way satellites is explained, in large part, by their lopsided radial distribution combined with the temporary conjunction of the two most distant satellites, Leo I and Leo II. Using Gaia proper motions, we show that the orbital pole alignment is much more common than previously reported, and reveal the plane of satellites to be transient rather than rotationally supported. Comparing with new simulations, where such short-lived planes are common, we find the Milky Way satellites to be compatible with standard model expectations."

I think that this paper is probably wrong in the conclusion that this is temporary and transient as their model dependent simulations and calculations suggest and contrary to analysis of the same problem in other papers.