http://arxiv.org/abs/1711.00860
We discuss an alternative approach for future systematic searches of low mass dwarf galaxies, $\lesssim 10^6 \textrm{ M}{\odot}$. By exploring the limiting surface brightness-spatial resolution ($\mu{\textrm{eff,lim}}-\theta$) parameter space, we suggest that dwarfs in the Local Volume, between $3$ and $10 \textrm{ Mpc}$, are expected to be detected very effectively and in large numbers using integrated light photometric surveys, complementary to the classical star counts method. We use a sample of dwarf galaxies in the Local Group to construct relations between their photometric and structural parameters, $\textrm{M}{*}$-$\mu{\textrm{eff,V}}$ and $\textrm{M}{*}$-$\textrm{R}{\textrm{eff}}$. We use these relations, along with assumed functional forms for the halo mass function and the stellar mass-halo mass relation, to calculate the lowest detectable stellar masses in the Local Volume and the expected number of galaxies as a function of the limiting surface brightness and spatial resolution. The number of detected galaxies depends mostly on the limiting surface brightness for distances $>3 \textrm{ Mpc}$ while spatial resolution starts to play a role for galaxies at distances $>8 \textrm{ Mpc}$. Surveys with $\mu_{\textrm{eff,lim}} \sim 30 \textrm{ mag arcsec}^{-2}$ should be able to detect galaxies with stellar masses down to $ \sim 10^4 \textrm{ M}_*$ in the Local Volume. Depending on the form of the SMHM relation, the expected number of dwarf galaxies with distances between $3$ and $10 \textrm{ Mpc}$ is $0.04-0.35$ per square degree, assuming a limiting surface brightness of $\sim 29-30 \textrm{ mag arcsec}^{-2}$ and a spatial resolution $< 4”$. We plan to search for a population of low mass dwarfs by performing a blank photometric survey with the Dragonfly Telephoto Array, an imaging system optimized for the detection of extended ultra-low surface brightness structures.
S. Danieli, P. Dokkum and C. Conroy
Mon, 6 Nov 17
39/53
Comments: 9 pages, 7 figures. Submitted to Apj
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