![]() ![]() If an assumption needs making (such as the meaning of 'distance' to be applied, or the zero point used for time: BB or end of inflation etc) please make an assumption most likely to help me, and I'll edit the question to clarify if needed, once I see what is too vague in the question as initially worded. So the only question will (hopefully) be, which convention or type of metric/distance will be appropriate. In other words, I suspect/hope that any differences in answers due to model variation, won't significantly change the answer to this question. They might differ more due to assumptions about very early times, but redshift is inherently >~380 k years, and if they did vary a lot for times beyond that timeframe, we'd have real issues. H (z) H0E (z)is the Hubble constant as measured by a hypothetical astronomer working at redshift z.) Since dz da, dz / E (z)is proportional to the time-of-flight of a photon traveling across the redshift interval dz, divided by the scale factor at that time. My assumption is that most current models and their parameters, that are mainstream accepted and used, will be based on very similar parameters of very similar models (if not the same model), such as latest Planck parameters, or similar. ![]() I'm aware that this is an inherently vague question, since the times and distances depend on the model and convention chosen, and also that I'm not specifying proper distances/comoving coordinates, etc. Hubble's law is a statement of a direct correclation between the distance (r ) to a galaxy and its recessional velocity as determined by the red shift (Z). I'm looking for some form of "rough and ready" formula to convert between redshift z value, years since BB, and distance, so that when I read an astronomy paper and it discusses an event that occurred at z=10+/-0.5, or a quasar at z=7, I can get a rough idea when the event occurred and how far away they are saying the quasar is, as context. In the first place, it calculates the redshift from Einstein field equations (EFE) assuming a FriedmanLemaitreRobertsonWalkerTrinchera (FLRWT) metric. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |