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Proposal Identification No.:

A2941 Arecibo Observatory

Date Received: 2014-Aug-29 09:18:32 William E. Gordon Telescope Observing Time Request COVER SHEET

Section I - General Information
Submitted for Sep 1 2014. This proposal has not been submitted before. Proposal Type: General Category: Sub-Category: Observation Category: Time Requested this semester: Hours Next Semester: Hours already used for this pro ject: Additional Hours required to complete pro ject: Minimum Useful Time: Expected Data Storage: Prop osal Title: ABSTRACT: Regular Astronomy Spectroscopy Extragalactic 61.5 0 0 0 2 hours less than 100 GB

What SDSS Misses: A Pilot Program to Find More Low Mass Galaxies

Numerical cosmological simulations make clear predictions of the number of halos of given mass. While reionization, stripping or feedback could explain the lack of the lowest mass halos, more massive halos that should survive reionization are also missing, even in the field (the `Too Big to Fail' problem). Obtaining a more complete census of the nearby low mass population is critical to explore systematically the halo regime where the baryon-to-dark matter fraction plummets. Observationally the low mass population quickly disappears with distance in optical flux-limited spectroscopic surveys (e.g., SDSS). However the baryon content of low mass star-forming galaxies is dominated by HI, and that population is accessible in HI within 80 Mpc. We thus propose to carry out a pilot program of targeted LBW observations of low mass gas-rich galaxies within 80 Mpc selected from SDSS, that are too faint to have been detected by ALFALFA at their distances. Outreach Abstract: Astronomers are seeking to understand the number, distribution, and matter content of galaxies observed in the Universe. Numerical models based on our current cosmological understanding predict that there should be many more small, faint galaxies than we have so far detected. Such galaxies have few stars and that makes measurement of properties like distance difficult when using optical surveys like the Sloan Digital Sky Survey (SDSS). However these galaxies often have plentiful neutral hydrogen gas that can be detected by Arecibo to distances of 250 million light years. This program will search for hydrogen in a pilot sample of faint galaxies of unknown distance selected from the SDSS. If successful, it can be extended to provide a census of gas-rich galaxies that will contribute greatly to our understanding of the number, distribution, and dark matter content of low mass galaxies.

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Name Rebecca A Koopmann Michael G Jones

Institution Union College Cornell University

E-mail koopmanr@union.edu mgj37@cornell.edu

Phone 518-388-6786 607-255-6472

Student no G

Additional Authors
Riccardo Giovanelli (Cornell U.) riccardo@astro.cornell.edu * Lukas Leisman (Cornell PhD student) leisman@astro.cornell.edu Gregory Hallenbeck (Union Coll.) hallenbg@union.edu Elizabeth Adams (ASTRON) adams@astron.nl Thomas Balonek (Colgate U.) tbalonek@colgate.edu John Cannon (Macalester Coll.) jcannon@macalester.edu Kim Coble (Chicago State U.) kcoble@csu.edu Mary Crone Odekon (Skidmore) mcrone@skidmore.edu David Craig (West Texas A and M U) dcraig@mail.wtamu.edu Adriana Durbala (U. Wisconsin-Stevens Point) Adriana.Durbala@uwsp.edu Rose Finn (Siena Coll.) rfinn@siena.edu James Higdon (Georgia Southern U.) jhigdon@georgiasouthern.edu +14 additional authors; due to the character limit on the on-line coversheet form, find the complete list at http://egg.astro.cornell.edu/alfalfa/ docs/prop.sep14.authorlist.html

This work is not part of a thesis.

Remote Observing Request

X

Observer will travel to AO Remote Observing In Absentia (instructions to operator)

Section I I - Time Request
The following times are in LST. For these observations night-time is required.

Begin End IntervalInterval 8.0 8.0 12.5 16.0

Days Needed at This Interval 3 6

Time Constraints (Must Be Justified in the Prop osal Text) 2

Considering the sky distribution of the target fields and in order to allow UAT faculty and students to participate in on-site observing, our request of 61.5 hours is distributed as follows: 3 sessions 08h00m
Section I I I - Instruments Needed
L-wide Atmospheric Observation Instruments:

Sp ecial Equipment or setup:

none

Section IV - RFI Considerations Frequency Ranges Planned
1350-1435 MHz This proposal requires coordination with Punta Salinas radar within the band 1222-1381 MHz.. This proposal requires coordination with GPS L3 at 1381 MHz.

Section V - Observing List Target List
163 sources with 08
3