SMALL-SCALE STRUCTURE IN THE SLOAN DIGITAL SKY SURVEY AND ΛCDM: ISOLATED ∼L_*GALAXIES WITH BRIGHT SATELLITES

Abstract

We use a volume-limited spectroscopic sample of isolated galaxies in the Sloan Digital Sky Survey (SDSS) to investigate the frequency and radial distribution of luminous (M r −18.3) satellites like the Large Magellanic Cloud (LMC) around ∼ L * Milky Way analogs and compare our results object-by-object to ΛCDM predictions based on abundance matching in simulations. We show that 12% of Milky Way-like galaxies host an LMC-like satellite within 75 kpc (projected), and 42% within 250 kpc (projected). This implies ∼ 10% have a satellite within the distance of the LMC, and ∼ 40% of L * galaxies host a bright satellite within the virialized extent of their dark matter halos. Remarkably, the simulation reproduces the observed frequency, radial dependence, velocity distribution, and luminosity function of observed secondaries exceptionally well, suggesting that ΛCDM provides an accurate reproduction of the observed Universe to galaxies as faint as L ∼ 10 9 L on ∼ 50 kpc scales. When stacked, the observed projected pairwise velocity dispersion of these satellites is σ 160 km s −1 , in agreement with abundance-matching expectations for their host halo masses. Finally, bright satellites around L * primaries are significantly redder than typical galaxies in their luminosity range, indicating that environmental quenching is operating within galaxy-size dark matter halos that typically contain only a single bright satellite. This redness trend is in stark contrast to the Milky Way's LMC, which is unusually blue even for a field galaxy. We suggest that the LMC's discrepant color might be further evidence that it is undergoing a triggered star-formation event upon first infall.

The mass dependence of satellite quenching in Milky Way-like haloes

“…As highlighted by previous studies of satellite galaxies in the local Universe, predominantly in more-massive halos, we find that satellites are preferentially passive relative to the field population (e.g. Weinmann et al 2006;Tollerud et al 2011;Geha et al 2012;Wang & White 2012).…”

An Optically Obscured Agn in a Low Mass, Irregular Dwarf Galaxy: A Multi-Wavelength Analysis of J1329+3234

“…The absolute g band magnitude is −16.3, almost two magnitudes fainter than the LMC (Tollerud et al 2011), and is fainter than about ≈98% of the host galaxies in the sample of dwarfs with optical AGNs from Reines et al (2013), which ranges from −15.2 to −21.2 (mean −18.2, σ = 0.8, number of galaxies N = 151). These are in turn considerably fainter than previous sample of low mass optically identified AGNs from , which range from −17.6 to −21.4 (mean −19.7, σ = 0.8, N = 229), and the sample of Dong et al (2012), which range from −17.4 to −22.4 (mean −20.3, σ = 0.9, N = 309).…”

Taking care of business in a flash : constraining the time-scale for low-mass satellite quenching with ELVIS

“…While the stel-lar mass or surface mass density of a galaxy may be more closely connected to quenching for massive systems (Peng et al 2010;Cheung et al 2012;Woo et al 2013), recent work has shown that environment is likely the dominant driver of quenching at the lowest mass scales (M < 10 9 M , Geha et al 2012). For example, studies comparing satellite galaxies to isolated field systems of similar stellar mass in the local Universe find that satellites tend to exhibit lower star formation rates, more bulge-dominated morphologies, as well as older and more metal-rich stellar populations (Baldry et al 2006;van den Bosch et al 2008;Cooper et al 2010b;Pasquali et al 2010;Tollerud et al 2011;Phillips et al 2014). This observed suppression of star formation in satellite galaxies is commonly referred to as "environmental quenching".…”