1506.00652
The effect of stellar feedback on a Milky Way-like galaxy and its gaseous halo
Marasco, et al
Present the study of a set of N-body+SPH sims of a MW-like system produced by the radiative cooling of hot gas embedded in a DM halo. The galaxy and its gases halo evolve for 10 Gyr in isolation, which allows study of how internal processes affect the evolution of the system. Show how the morphology, the kinematics and the evolution of the galaxy are affected by they put SN feedback energy E_SN, and compare its properties with those of the MW. Different values of E_SN do not significantly affect the SFH of the system, but the disc of cold gas gets thicker and more turbulent as feedback increases. Main result is that, for the highest value of E_SN considered, the galaxy shows a prominent layer of extra-planar cold (log(T)<4.3) gas extended up to a few kpc above the disc at column densities of 1e19 cm^2. The kinematics of this material is in agreement with that inferred for the HI halos of the Galaxy and NGC 891, although its mass is lower. Also, the location, the kinematics and the typical column densities of the hot (5.3<log(T)<5.7) gas are in good agreement with those determined from the O_VI absorption systems in the halo of the MW and external galaxies. In contrast with the observations, however, gas at log(T)<5.3 is lacking in the circumgalactic region of the systems.
1506.00656
Starbursts are preferentially interaction: confirmation from the nearest galaxies
Knapen, Cisternas
Overall conclusion: interactions can and do increase the number of starburst galaxies, and that this results is extremely robust. By far most starburst galaxies, however, show no evidence of a present interaction.
1506.00854
Z>~7 galaxies with red Spitzer/IRAC [3.6]-[4.5] colors in the full CANDELS data set: the brightest-known galaxies at Z~7-9 and a probably spectroscopic confirmation at Z=7.48
Roberts-Borsani, et al
Identify 4 unusually bright (H<~25.5) galaxies from HST and Spitzer CANDELS data with probable redshifts z~7-9. These identifications constitute the birghtest-nown galaxies to date at z>~7.5. Y-band observations are not available over the full DANCSL program to perform a standard Lyman-break selection of z>7 galaxies; employ an alternate strategy using the deep Spitzer/IRAC data. Identify z~7.1-9.1 galaxies by selecting z>~6 galaxies from the HST CANDELS data that show quite red IRAC [3.6]-[4.5] colors, indicating a strong [OIII] line in the 4.5 mu band. This selection strategy was validated using a modest sample for which there are deep Y-band coverage. Focus on using this criterion to select the brightest z>~7 sources. Applying the IRAC criteria to all HST-selected optical-dropout galaxies over the full ~900 arcmin^2 of the 5 CANDELS fields revealed four unusually bright z~7.1, 7.6, 7.9 and 8.6 candidates. The median [3.6]-[4.5] color of the selected z~7.1-9.1 sample is consistent with rest-frame [OIII]+Hbeta EWs of ~1600A in the [4.5] band. Keck/MOSFIRE spectroscopy has already been reported for one of the selected sources, showing Lya at z of 7.7302±0.0006. Present similar Keck/MOSFIRE spectroscopy for a second selected galaxy with a probable 4.7 sigma Lya-line at a z of 7.4770±0.0008. Both have H-band magnitudes of ~25 mag and are ~0.5 mag more luminous (M(UV)~~-22.0) than any previously discovered z~8 galaxy, with important implications for the UV LF. The 3 brightest, highest z>~7 galaxies all lie within the CANDELS EGS field, providing a dramatic illustration of the potential impact of field-to-field variance.
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