NOAO >   Observing Info >   Approved Programs >   2017A-0060

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Program Information for 2017A-0060


PI: Denija Crnojevic, Texas Technical University, denija.crnojevic@ttu.edu
Address: Physics Department, Box 41051, Lubbock, Texas 79049 USA

CoI: Jeffrey Carlin, LSST
CoI: Jonathan Hargis, STScI
CoI: David Sand, Texas Technical University
CoI: Beth Willman, LSST
CoI: Kristine Spekkens, Royal Military College of Canada
CoI: Allie Hughes, Texas Technical University
CoI: Jay Strader, Michigan State U.
CoI: Annika Peter, Ohio State U.
CoI: Evan Kirby, California Institute of Technology
CoI: Eric Bell, U. of Michigan
CoI: Duncan Forbes, Swinburne U.
CoI: Aaron Romanowsky, University of California Observatories
CoI: Jean Brodie, University of California Observatories
CoI: Robert Lupton, Princeton U.
CoI: Paul Price, Princeton U.

Title: Dwarfs around Dwarfs: Satellite galaxies and stellar halos around dwarf galaxies

Abstract: We propose to use the CTIO-4m+DECam to obtain comprehensive stellar halo maps and measure the satellite galaxy luminosity functions for three relatively isolated dwarf galaxies in the Local Volume: Sextans A and B ($D=1.3$~Mpc, $M_*$$sim$3/6$times$10$^7 M_odot$) and IC~4662 ($D=2.4$~Mpc, $M_*$$sim$5$times$10$^8 M_odot$). We will use resolved red giant branch stars to trace their stellar halos out to $sim65- 100$~kpc (i.e. $sim80-100%$ of their virial radii) and to detect dwarf satellite galaxies as faint as $M_V=-6/-7$ (or $M_*sim10^{4/5} M_odot$) for SexA+B and IC~4662, respectively (the latter has brighter detection limits due to its larger distance). Motivated by the success of both our 2015A observations of NGC~3109 (at $D=1.3$~Mpc; which have resulted in a prompt publication and upcoming Hubble Space Telescope, Keck and Green Bank Telescope observations), and our Subaru/HyperSuprimeCam observations of NGC~2403 ($D=3.2$~Mpc, which led to the discovery of a $M_Vsim-7$ satellite), as well as by predictions from theoretical models, we expect our targets to host detectable faint dwarf galaxies, and that their stellar halos may show observational signatures of accretion. The proposed observations are part of a larger program to understand the substructure properties of sub-Milky Way mass galaxies within $sim4$~Mpc (MADCASH; Carlin et al. 2016). In this semester, our sample was chosen to complete the census of the major galaxies in the NGC~3109 group (SexA+B) and to survey a galaxy with comparable mass to, but more isolated than NGC~3109 (IC4662). Our observations will place new and robust constraints on formation scenarios for dwarf galaxy stellar halos and their satellite luminosity functions.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2017A):  CT-4m/DECam -- 4n on Apr 23 - Apr 26 2017


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NOAO >   Observing Info >   Approved Programs >   2017A-0060

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