ALFALFA Team Website

ALFALFA Team Project

Proposal Title:	Blended HI signals from distant clusters
Project Leader:	Lyle Hoffman
Institution:	Lafayette College
Other Co-Authors (if any):	Josh Goldstein, future Lafayette students
Time frame:	Roughly 1 year after second pass is complete on each cluster
Publication expected:	AJ paper on the complete set roughly 1.5 years after the second ALFALFA pass on the last cluster

Description:

This is conceived as a pilot project for eventual studies of galaxy clusters at redshifts high enough that most signals detected by ALFA will be blends of several galaxies. At the redshift limit of ALFALFA, 18,000 km/s, and the sensitivity resulting from two passes, we can expect to detect a couple of individual galaxies in the outskirts of each cluster with a significant probability that any detection is a blend of a large spiral with a few HI-rich dwarf galaxies within the same beam. Smoothing in position and redshift should increase the HI signal. We should be able to compare, statistically, the HI content per spiral inside vs. outside the virial radius (or X-ray emitting region) and correlate that with cluster richness and X-ray flux.

The analysis will be complicated by the presence of FAA radar in the middle of the redshift range. Standard flagging excludes too much redshift space, so we will explore procedures to retain as much redshift space as possible in each drift. Bandpass removal in the vicinity of the RFI may also need to be improved.

ALFALFA region:	Approximately 1 square degree around each cluster in the whole ALFALFA sky and 13,000 to 18,000 km/s. See cluster list
ALFALFA data to be used:	Level I data (flagged drifts and pos structures); Raw data if needed.
Other data sets to be used:	SDSS and X-ray data in public archives
Products to be delivered:	HI catalog for each cluster Optical (SDSS) identification of galaxies contributing to each HI detection

Milestones (if duration is > 1 yr):

Milestone	Description	Goal	Status
Analysis of each cluster (62 in total)	within about 1 yr after completion of pass 2 for that part of the sky
Publication of the set	within about 0.5 yr after the analysis of all clusters is complete (about 1.5 yr after completion of pass 2 for the last cluster)

This page created and maintained by members of the Cornell ExtraGalactic Group

Last modified: Sun Oct 2 12:23:02 EDT 2005 by martha