arXiv subjects

Sebastian Trujillo-Gomez

Publications and source records attributed to Sebastian Trujillo-Gomez.

40 records · Page 3Linked to original sources

arXiv2013

MAGIICAT III. Interpreting Self-Similarity of the Circumgalactic Medium with Virial Mass using MgII Absorption

In Churchill et al., we used halo abundance matching applied to 182 galaxies in the MgII Absorber-Galaxy Catalog (MAGIICAT, Nielsen et al.) and showed that the mean MgII 2796 equivalent width follows a tight inverse-square power law, W_r(2796) ~ (D/R_vir)^-2, with projected location relative to the galaxy virial radius and that the MgII absorption covering fraction is invariant with galaxy virial mass, M_h, over the range 10.7 < M_h/M_solar < 13.9. In this work, we explore multivariate relationships between W_r(2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T=10^{4-4.5} K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the MgII absorbing gas such that the mean W_r(2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass. The majority of the absorbing gas resides within D ~ 0.3 R_vir, independent of both virial mass and minimum absorption threshold; inside this region, and perhaps also in the region 0.3 < D/R_vir = 1, the mean W_r(2796) is independent of virial mass. Contrary to absorber-galaxy cross-correlation studies, we show there is no anti-correlation between W_r(2796) and virial mass. We discuss how simulations and theory constrained by observations fully support self-similarity of the cool/warm CGM via the physics governing star formation, gas-phase metal enrichment, recycling efficiency of galactic scale winds, filament and merger accretion, and overdensity of local environment as a function of virial mass.

astro-ph.GA↗

arXiv2013

The Self-Similarity of the Circumgalactic Medium with Galaxy Virial Mass: Implications for Cold-Mode Accretion

We apply halo abundance matching to obtain galaxy virial masses, M_h, and radii, Rvir, for the 183 isolated galaxies in the "MgII Absorber-Galaxy Catalog" (MAGIICAT, Nielsen et al.). All galaxies have spectroscopic redshifts (0.1 < z < 1.1) and their circumgalactic medium (CGM) is probed in MgII absorption within projected galactocentric distances D < 200 kpc. We examine the behavior of equivalent width, W(2796), and covering fraction, f_c, as a function of D, D/Rvir, and M_h. We find: [1] systematic segregation of M_h on the W(2796)-D plane (4.0 sigma); high-mass halos are found at higher D with larger W(2796) compared to lower mass halos. On the W(2796)-D/Rvir plane, mass segregation vanishes and we find W(2796) ~ (D/Rvir)^-2 (8.9 sigma); [2] higher mass halos have larger f_c at a given D, whereas f_c is independent of M_h at all D/Rvir; [3] f_c is constant with M_h over the range 10.7 < log(M_h/Msun) < 13.8 within a given D or D/Rvir. The combined results suggest that the MgII absorbing CGM is self-similar with halo mass, even above log(M_h/Msun)~12, where cold mode accretion is theoretically predicted to be quenched. If theory is correct, either outflows or sub-halos must contribute to absorption in high-mass halos such that low- and high-mass halos are observationally indistinguishable using MgII absorption strength once impact parameter is scaled by halo mass. Alternatively, the data may indicate that predictions of a universal shut down of cold-mode accretion in high-mass halos may require revision.

astro-ph.CO↗

arXiv2012

Quenched Cold Accretion of a Large Scale Metal-Poor Filament due to Virial Shocking in the Halo of a Massive z=0.7 Galaxy

Using HST/COS/STIS and HIRES/Keck high-resolution spectra, we have studied a remarkable HI absorbing complex at z=0.672 toward the quasar Q1317+277. The HI absorption has a velocity spread of 1600 km/s, comprises 21 Voigt profile components, and resides at an impact parameter of D=58 kpc from a bright, high mass [log(M_vir/M_sun) ~ 13.7] elliptical galaxy that is deduced to have a 6 Gyr old, solar metallicity stellar population. Ionization models suggest the majority of the structure is cold gas surrounding a shock heated cloud that is kinematically adjacent to a multi-phase group of clouds with detected CIII, CIV and OVI absorption, suggestive of a conductive interface near the shock. The deduced metallicities are consistent with the moderate in situ enrichment relative to the levels observed in the z ~ 3 Ly-alpha forest. We interpret the HI complex as a metal-poor filamentary structure being shock heated as it accretes into the halo of the galaxy. The data support the scenario of an early formation period (z > 4) in which the galaxy was presumably fed by cold-mode gas accretion that was later quenched via virial shocking by the hot halo such that, by intermediate redshift, the cold filamentary accreting gas is continuing to be disrupted by shock heating. Thus, continued filamentary accretion is being mixed into the hot halo, indicating that the star formation of the galaxy will likely remain quenched. To date, the galaxy and the HI absorption complex provide some of the most compelling observational data supporting the theoretical picture in which accretion is virial shocked in the hot coronal halos of high mass galaxies.

astro-ph.CO↗

arXiv2011

Galaxies in LCDM with Halo Abundance Matching: luminosity-velocity relation, baryonic mass-velocity relation, velocity function and clustering

It has long been regarded as difficult for a cosmological model to account simultaneously for the galaxy luminosity, mass, and velocity distributions. We revisit this issue using a modern compilation of observational data along with the best available large-scale cosmological simulation of dark matter. We find that the standard cosmological model, used in conjunction with halo abundance matching (HAM) and simple dynamical corrections, fits all basic statistics of galaxies with circular velocities Vcirc > 80 km/s. Our observational constraint is the luminosity-velocity relation which allows all types of galaxies to be included. We have compiled data for a variety of galaxies ranging from dwarf irregulars to giant ellipticals. The data present a clear monotonic luminosity-velocity relation from 50 km/s to 500 km/s, with a bend below 80 km/s and a systematic offset between late- and early-type galaxies. For comparison to theory, we employ our LCDM "Bolshoi" simulation of dark matter, which has unprecedented mass and force resolution. We use halo abundance matching to assign rank-ordered galaxy luminosities to the dark matter halos. The resulting predictions for the luminosity-velocity relation are in excellent agreement with the available data on both early-type and late-type galaxies for the luminosity range from Mr = -14-22. We also compare our predictions for the "cold" baryon mass (i.e., stars and cold gas) of galaxies as a function of circular velocity with the available observations, again finding a very good agreement. The predicted circular velocity function is in agreement with the galaxy velocity function for 80-400 km/s. However, we find that the dark matter halos with Vcirc < 80 km/s are much more abundant than observed galaxies with the same Vcirc . We find that the two-point correlation function of galaxies in our model matches very well the results from the SDSS.

astro-ph.CO↗