What Does the h Subscript 70 to the Power of 3 Mean in Supernova Units?

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Discussion Overview

The discussion revolves around the interpretation of the notation h703 in the context of supernova rates, specifically in units of SN rate per year per Mpc3. Participants seek clarification on the meaning and implications of this notation.

Discussion Character

  • Conceptual clarification, Technical explanation

Main Points Raised

  • One participant asks for clarification on the meaning of h703 in supernova rate units.
  • Another participant explains that h70 is a dimensionless number related to the current rate of expansion, defined as the current Hubble rate divided by 70 km/s/Mpc.
  • A follow-up question is posed regarding the significance of the exponent 3 in this context.
  • Another participant comments that a dimension can be viewed as another reference frame.

Areas of Agreement / Disagreement

The discussion includes some agreement on the definition of h70 as a dimensionless number, but the significance of the exponent 3 and the implications of dimensions remain less clear, indicating unresolved aspects of the topic.

Contextual Notes

Participants have not fully explored the implications of the exponent 3 in relation to the units, nor have they clarified how dimensions relate to reference frames in this specific context.

resurgance2001
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Hi
This is a really basic question about units. I have been reading a paper about supernova rates and the units are given as:

SN rate per yr MPC^3. h_70^3 (10^ -4)

Could someone tell me what the h subscript 70 to the power of 3 means?

Thanks
 
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It is a dimensionless number denoting the current rate of expansion. It is equal to the current Hubble rate divided by 70 km/s/Mpc.
 
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To the power of 3?
 
Thanks
 
A dimension is just another reference frame
 

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