Photon densities within galtactic disc compared to CMB

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Discussion Overview

The discussion centers on the average photon densities within galactic environments, particularly in the galactic disc, and how these densities compare to the Cosmic Microwave Background (CMB). The implications of these photon densities on cosmic ray phenomenology are also explored, focusing on the rates of photo-pion production and the potential enhancement of attenuation of ultra-high energy cosmic rays.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about the average photon densities in galactic environments compared to the CMB, suggesting that local sources may contribute significantly in denser areas like the galactic disc.
  • Another participant asks for clarification on how the photon density comparison might impact cosmic ray phenomenology.
  • A different participant raises the idea that enhanced rates of photo-pion production in the galactic disc could explain discrepancies in cosmic ray flux and composition observed at extreme energies.
  • One participant expresses difficulty in providing assistance and wishes the original poster luck in their search for information.
  • The original poster expresses gratitude and hopes to find relevant information, inviting others to share insights if they have any.

Areas of Agreement / Disagreement

The discussion does not reach a consensus, as participants express varying levels of knowledge and engagement with the topic, and no definitive answers or agreements are established.

Contextual Notes

There is a noted lack of existing literature on broad spectrum photon intensities in galactic environments, which may limit the discussion's depth and breadth.

UHECRon
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I am interested in what the average photon densities are within galactic environments due to non CMB sources. In extra galactic environments, the CMB certainly dominates, however as you enter more dense and luminous areas (e.g. , the galactic disc) broad spectrum photon densities from local sources must climb. My question is how does this compare on average to CMB?

I ask as the answer may have implications on cosmic ray phenomenology.
 
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UHECRon said:
I ask as the answer may have implications on cosmic ray phenomenology.

In what way?
 
I was wondering about the rates of photo-pion production in the galactic disc as opposed to those more traditionally calculated in extra galactic spaces. The thought being that a significant enhancement of attenuation of Ultra high energy cosmic rays in the regime could help to explain some discrepancies observed in both flux and composition at these extreme energies in the northern and southern hemispheres.

A lazy literature search hasn't turned up much on broad spectrum photon intensities in galactic environments so I was hoping someone would point me in a helpful direction.
 
I see. Well, I doubt I can help you at all. Best of luck on your search!
 
Thanks! Hope I find something. If I do, I will report it here.

If anyone reads this and has any insights, I would be most thankful for some information.
 

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