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Originally Posted by rtomes
Selection effects might make some ranges of redshifts more easy to observe than others. But there is no way that they will cause the observation of z=0.8349, 0.8424, 0.8463 and then blot out everything between there and 0.9578 and 0.9662 and so on.
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Please list all the effects which affect the detectability of a GRB in a waveband where its redshift can be observed. Please identify which effects are based on models of GRBs, which on waveband-redshift detectability, and others.
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This is a red herring argument. Even more, selection effects will not cause the appearance of a delta z=.131 periodicity in most of the events. The events are clearly not random to anyone who is not already comitted to an irrationally held belief, whether or not there are selection events. If you dispute that, then make a selection model that can produce similarly clumped observations and I will show you where you built a periodicity into your model.
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Here is the entire Bloom abstract:
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The 26 long-duration gamma-ray bursts (GRBs) with known redshifts form a distinct cosmological set, selected differently than other cosmological probes such as quasars and galaxies. Since the progenitors are now believed to be connected with active star formation and since burst emission penetrates dust, one hope is that with a uniformly selected sample, the large-scale redshift distribution of GRBs can help constrain the star formation history of the universe. However, we show that strong observational biases in ground-based redshift discovery hamper a clean determination of the large-scale GRB rate and hence the connection of GRBs to the star formation history. We then focus on the properties of the small-scale (clustering) distribution of GRB redshifts. When corrected for heliocentric motion relative to the local Hubble flow, the observed redshifts appear to show a propensity for clustering: eight of 26 GRBs occurred within a recession velocity difference of 1000 km s-1 of another GRB. That is, four pairs of GRBs occurred within 30 h-165 Myr in cosmic time, despite being causally separated on the sky. We investigate the significance of this clustering using a simulation that accounts for at least some of the strong observational and intrinsic biases in redshift discovery. Comparison of the numbers of close redshift pairs expected from the simulation with that observed shows no significant small-scale clustering excess in the present sample; however, the four close pairs occur in only about 20% of the simulated data sets (the precise significance of the clustering is dependent on the modeled biases). We conclude with some impetuses and suggestions for future precise GRB redshift measurements.
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I want to be quite clear on this ... are you claiming that there is a
model-independent*
statistically significant "
delta z=.131 periodicity" in the redshift data of these 26 GRBs?
*
Selection effects are models.