Connecting GRBs and galaxies: the probability of chance coincidence

Studies of GRB host galaxies are crucial to understanding GRBs. However, since they are identified by the superposition in the plane of the sky of a GRB afterglow and a galaxy there is always a possibility that an association represents a chance alignment, rather than a physical connection. We examine a uniform sample of 72 GRB fields to explore the probability of chance superpositions. There is typically a ~1% chance that an optical afterglow will coincide with a galaxy by chance. While spurious host galaxy detections will, therefore, be rare, the possibility must be considered when examining individual GRB/host galaxy examples. It is also tempting to use the large and uniform collection of X-ray afterglow positions to search for GRB-associated galaxies. However, we find that approximately half of the 14 superpositions in our sample are likely to occur by chance, so in the case of GRBs localized only by an X-ray afterglow, even statistical studies are suspect.Comment: edited, accepted by Ap

The Mississippian fin de siècle in the middle Cumberland region of Tennessee

Bayesian chronological modeling is used to investigate the chronology for a large-scale human depopulation event during the Mississippian period (AD 1000–1600) known as the Vacant Quarter phenomenon. The Middle Cumberland region (MCR) of Tennessee is within the Vacant Quarter area, and six villages from the final phase of Mississippian activity in the MCR have been subjected to radiocarbon dating. Complete radiocarbon datasets from these sites are presented within an interpretative Bayesian statistical framework. The results provide a unique history of each settlement and demonstrate that Mississippian occupations at each site likely terminated in the mid- to late fifteenth and possibly early sixteenth centuries AD, which is 50 to 100 years later than the most recent estimate for the timing of the Vacant Quarter. Mississippian abandonment in the MCR was relatively quick, likely occurring over less than a century. The exact reasons for abandonment are not entirely clear but appear to be linked to climate change. A radiocarbon simulation experiment indicates that future robust radiocarbon dating with well-selected samples could greatly improve the chronological precision for this late Mississippian activity. More broadly, this example demonstrates that model building with radiocarbon simulations can be used to address regional-scale chronological issues within the American Southeast and beyond

\u3cem\u3eRethinking Individuals and Agents in Archaeology\u3c/em\u3e, by A.B. Knapp and P. van Dommelen

A comment on Rethinking Individuals and Agents in Archaeology, by A.B. Knapp and P. van Dommelen

Talks From The Bible: Why The Church Means So Much?

https://digitalcommons.acu.edu/crs_books/1472/thumbnail.jp

Talks From The Bible: The Elements Of Christian Worship

https://digitalcommons.acu.edu/crs_books/1473/thumbnail.jp