SEARCHING FOR OPTICAL COUNTERPARTS TO ULTRA-COMPACT HIGH VELOCITY CLOUDS: POSSIBLE DETECTION OF A COUNTERPART TO AGC 198606

William Janesh; Katherine L. Rhode; John J. Salzer; Steven Janowiecki; Elizabeth A. K. Adams; Martha P. Haynes; Riccardo Giovanelli; John M. Cannon; Ricardo R. Munoz

doi:10.1088/0004-637X/811/1/35

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SEARCHING FOR OPTICAL COUNTERPARTS TO ULTRA-COMPACT HIGH VELOCITY CLOUDS: POSSIBLE DETECTION OF A COUNTERPART TO AGC 198606

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SEARCHING FOR OPTICAL COUNTERPARTS TO ULTRA-COMPACT HIGH VELOCITY CLOUDS: POSSIBLE DETECTION OF A COUNTERPART TO AGC 198606

William Janesh, Katherine L. Rhode, John J. Salzer, Steven Janowiecki, Elizabeth A. K. Adams, Martha P. Haynes, Riccardo Giovanelli, John M. Cannon and Ricardo R. Munoz

The Astrophysical journal, Vol.811(1), pp.1-11

09/20/2015

DOI: 10.1088/0004-637X/811/1/35

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Abstract

We report initial results from a campaign to obtain optical imaging of Ultra Compact High Velocity Clouds (UCHVCs) discovered by the Arecibo Legacy Fast ALFA (ALFALFA) HI survey. UCHVCs have properties consistent with their being low-mass dwarf galaxies in the Local Volume, but do not have identified optical counterparts. We are using the WIYN 3.5 m telescope to image these objects and search for an associated stellar population. Here we present our observational strategy and method for searching for resolved stellar counterparts to the UCHVCs. We combine careful photometry, a color-magnitude filter, and spatial smoothing techniques to search for stellar overdensities in the g- and i-band images. We also run statistical tests to quantify the likelihood that detected overdensities are real and not chance superpositions of sources. We demonstrate the method by applying it to WIYN imaging of two objects: Leo P, a UCHVC discovered by ALFALFA and shown to be a star-forming dwarf galaxy in the Local Volume and AGC 198606, an ALFALFA source near in position and velocity to the Local Group dwarf galaxy Leo T. Applying the search method to the Leo P data yields an unambiguous detection (>99% confidence) of the galaxy's stellar population. Applying the method to the AGC 198606 imaging yields a possible detection (92% confidence) of an optical counterpart located similar to 2.5 arcmin from the centroid of AGC 198606's HI distribution and within the HI disk. We estimate a distance to the stellar counterpart of 373-393 kpc, an absolute magnitude M-i = -4.67 +/- 0.09, and an HI-to-stellar mass ratio of similar to 45-110.

Astronomy & Astrophysics

Physical Sciences

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Title: Subtitle: SEARCHING FOR OPTICAL COUNTERPARTS TO ULTRA-COMPACT HIGH VELOCITY CLOUDS: POSSIBLE DETECTION OF A COUNTERPART TO AGC 198606
Creators: William Janesh - Indiana University Bloomington
Katherine L. Rhode - Indiana University Bloomington
John J. Salzer - Indiana University Bloomington
Steven Janowiecki - Indiana University Bloomington
Elizabeth A. K. Adams - Netherlands Institute for Radio Astronomy
Martha P. Haynes - Cornell University
Riccardo Giovanelli - Cornell University
John M. Cannon - Macalester College
Ricardo R. Munoz - University of Chile
Resource Type: Journal article
Publication Details: The Astrophysical journal, Vol.811(1), pp.1-11
Publisher: Iop Publishing Ltd
DOI: 10.1088/0004-637X/811/1/35
ISSN: 0004-637X
eISSN: 1538-4357
Number of pages: 11
Grant note: ODI-PPA 1211683 / Direct For Mathematical & Physical Scien; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS) Brinson Foundation AST-0847109 / NSF Faculty Early Career (CAREER) award AST-0607007; AST-1107390; AST-1211683 / NSF; National Science Foundation (NSF)
Language: English
Date published: 09/20/2015
Academic Unit: Physics and Astronomy
Record Identifier: 9984627345002771

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