Using the Simba cosmological simulations to measure the planar relation between stellar specific angular momentum, mass and effective surface brightness
E. Elson
备注：
7 pages, 4 figures. Accepted for publication in MNRAS
Stellar mass and specific angular momentum are two properties of a galaxy that are directly related to its formation history, and hence morphology. In this work, the tight planar relationship between stellar specific angular momentum (j*), mass (M*) and mean effective surface brightness (mu_eff) that was recently constrained using ALFALFA galaxies is measured more accurately using galaxies from the Simba cosmological simulation. The distribution of 179 Simba galaxies in log(j*)-log(M*)-mu_eff space is shown to be very tightly planar with j* proportional to M*^0.694 and the distribution of perpendicular distances between the galaxies and the plane being approximately Gaussian with rms=0.057 dex. The parameterised distribution is used with existing j* and mu_eff measurements of 3607 ALFALFA galaxies and 84 SPARC galaxies to reliably predict their published stellar masses to within ~0.1 to 0.2 dex over several decades of stellar mass. Thus, this work presents a new method of easily generating accurate galaxy stellar mass estimates for late-type galaxies and provides a new measurement of the fundamental link between galaxy morphology, mass and angular momentum.
We examine the evolution of intragroup gas X-ray scaling relations for group-sized halos ($M_{500}=10^{12.3-15}M_{\odot}$) in the Simba galaxy formation simulation. X-ray luminosity $L_X$ vs $M_{500}$ shows increasing deviation from self-similarity from $z=3\to 0$, with $M_{500}<10^{13.5} M_{\odot}$ halos exhibiting a large reduction in $L_X$ and slight increase in X-ray luminosity-weighted temperature $T_X$. These shifts are driven by a strong drop in $f_{\rm gas}$ with time for these halos, and coincides with the onset of black hole jet feedback in these systems at $z\sim 1.5$ in Simba. The …
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The low surface brightness visible wavelength Universe below 29 mag arcsec$^{-2}$ is teeming with unexplored astrophysical phenomena. Structures fainter than this surface brightness are extremely difficult to image due to systematic errors of sky subtraction and scattered light in the atmosphere and in the telescope. In Chapter 1, I show how The Dragonfly Telephoto Array (Dragonfly for short) addresses these systematics via a combination of hardware and software and is able to image at a level of 30 mag arcsec$^{-2}$ or fainter. In Chapter 2, I describe the Dragonfly Pipeline and how it is opt…
Superthin galaxies are a class of bulgeless, low surface brightness galaxies with strikingly high values of planar-to-vertical axes ratio $\rm(b/a> 10 - 20)$, possibly indicating the presence of an ultra-cold stellar disc. Using the multi-component galactic disc model of gravitationally-coupled stars and gas in the force field of the dark matter halo as well as the stellar dynamical code AGAMA (Action-based Galaxy Modelling Architecture), we determine the vertical velocity dispersion of stars and gas as a function of galacto-centric radius for five superthin galaxies (UGC 7321, IC 5249, FGC 15…
The fine details of the large-scale structure in the local universe provide important empirical benchmarks for testing cosmological models of structure formation. Dwarf galaxies are key object for such studies. Enlarge the sample of known dwarf galaxies in the local universe. We performed a search for faint, unresolved low-surface brightness dwarf galaxies in the M101 group complex, including the region around the major spiral galaxies M101, M51, and M63 lying at a distance 7.0, 8.6, and 9.0 Mpc, respectively. The new dwarf galaxy sample can be used in a first step to test for significant subs…
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