[astro-ph/0603213] Comments on "Dark matter: A phenomenological existence proof"

 Authors: R. G. Vishwakarma Abstract: A recent paper by Ahluwalia-Khalilova (astro-ph/0601489) is examined where he claims that the standard FRW cosmology with a $\Lambda$ predicts existence of dark matter without invoking the data on galactic rotation curves and gravitational lensing. However, we find that his claims are not correct. He has already assumed (without realizing) in the very outset what he wants to prove. [PDF]  [PS]  [BibTex]  [Bookmark]

Discussion related to specific recent arXiv papers
D. V. Ahluwalia-Khalilova
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Joined: May 28 2005
Affiliation: ASGBG/CIU University of Zacatecas
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[astro-ph/0603213] Comments on \"Dark matter: A phenome

In astro-ph/0601489, within the framework of the Einsteinian general relativity, we made the observation that if the universe is described by a spatially flat Friedmann-Robertson-Walker (FRW) cosmology with Einsteinian cosmological constant then the resulting cosmology predicts a significant dark matter component in the universe. Furthermore, the phenomenologically motivated existence proof refrained from invoking the data on galactic rotational curves and gravitational lensing, but used as input the age of the universe as deciphered from the studies on globular clusters. This claim has been challenged in astro-ph/0603213 by Vishwakarma. The raised objection is invalid. It, at best, constitutes a trivial consistency check. As such, we stand by our analysis, and by our conclusions, without reservations.

The details are to appear soon in astro-ph/0603256.

Garth Antony Barber
Posts: 59
Joined: July 19 2005
Affiliation: Published independent

[astro-ph/0603213] Comments on \"Dark matter: A phenome

the resulting cosmology predicts a significant dark matter component in the universe
Is that predicts or requires?

Garth

D. V. Ahluwalia-Khalilova
Posts: 4
Joined: May 28 2005
Affiliation: ASGBG/CIU University of Zacatecas
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Re: [astro-ph/0603213] Comments on \\\\\\\"Dark matter:

Garth Antony Barber wrote:
the resulting cosmology predicts a significant dark matter component in the universe
Is that predicts or requires?

Garth
Garth, what happens is that for the present epoch I find a Omega_m which is some 4 to 7 times larger than Omega_baryonic. The deficit, by definition dark matter, is then some non-relativstic form of matter outside the standard model. Does this answer your question?

Dharam

Garth Antony Barber
Posts: 59
Joined: July 19 2005
Affiliation: Published independent

D. V. Ahluwalia-Khalilova wrote:
Garth Antony Barber wrote:
the resulting cosmology predicts a significant dark matter component in the universe
Is that predicts or requires?

Garth
Garth, what happens is that for the present epoch I find a Omega_m which is some 4 to 7 times larger than Omega_baryonic. The deficit, by definition dark matter, is then some non-relativstic form of matter outside the standard model. Does this answer your question?

Dharam
Yes, but you make the (very reasonable) mainstream model assumption that
$|Omega_{Total} = 1$,
$\omega \sim 1$ and
$|Omega_{baryon} = 0.04$.

A true prediction of the Friedmann models would leave these parameters open.

Garth

D. V. Ahluwalia-Khalilova
Posts: 4
Joined: May 28 2005
Affiliation: ASGBG/CIU University of Zacatecas
Contact:

Garth Antony Barber wrote:
D. V. Ahluwalia-Khalilova wrote:
Garth Antony Barber wrote:
the resulting cosmology predicts a significant dark matter component in the universe
Is that predicts or requires?

Garth
Garth, what happens is that for the present epoch I find a Omega_m which is some 4 to 7 times larger than Omega_baryonic. The deficit, by definition dark matter, is then some non-relativstic form of matter outside the standard model. Does this answer your question?

Dharam
Yes, but you make the (very reasonable) mainstream model assumption that
$|Omega_{Total} = 1$,
$\omega \sim 1$ and
$|Omega_{baryon} = 0.04$.
A true prediction of the Friedmann models would leave these parameters open.

Garth
Thanks for the clarification. My result can be interpreted two ways. A $\Omega_m > 0.05$ necessarily requires dark matter; or, as a breakdown of the standard cosmology. Specifically, for $\Lambda = 3 (8 \pi G) 10^{-47}\;GeV^4$ (which gives present cosmic epoch of about $13.5\; Gyr$ for $h=0.72$ )I find $\Omega_m \approx 0.28$. The standard model contribution of $\Omega_{sm}\approx 0.05$ falls too short. So there is either some unkown non-relativiistic matter (dark matter, $\Omega_{dm}\approx 0.23$), or the LCDM fails.

I hope to write up these details and more under the title 'Dark matter, and its darkness' in a week or so. When done, I plan to archive these on arXiv for comments before a formal submission.

Dharam