1210.0535
Disentangling the stellar populations in the counter-rotating disc galaxy NGC 4550
Johnston, Merrifiled, et al
Long-slit spectral observations of the counter-rotating stellar discs in the S0 galaxy. Kinematically decompose the spectra into two counter-rotating stellar components plus a gaseous component, to study both their kinematics and populations. Confirm known kinematics, but observe to larger radii, also trace H emission line, which are found to follow the same strange kinematics seen in the [OIII] line. Two separate stellar components, secondary disc has a significantly younger mean age than the primary disc, consistent with later star formation from the associated gaseous material. It is also somewhat brighter, consistent with additional SF. "Separatrix-crossing" model ruled out [box-orbit stars in an triaxial elliptical galaxy would split into tube orbits, making the system axi-symmetric and generating a pari of identical counter-rotating stellar populations], some form of unusual gas accretion history is the most likely formation mechanism.
From the intro: likely that two equal co-planar spirals in a specific parabolic orbit merged to form this galaxy.
1210.0543
The rise and fall of the star formation histories of blue galaxies at redshifts 0.2<z<1.4
Pacifici, Kassin, Weiner, et al
Constrain SFH of 4.5k blue galaxies of 0.2<z_spec<1.4 from AEGIS, in the context that galaxies form hierarchically from the merger of many progenitors, each with their own unique SFH. Bayesian analysis of observed SED with a comprehensive synthetic spectra from most recent models of SF and chemical enrichment histories, SPS, nebular emission, and attenuation by dust. Constrain SFH from BRIK bands and rest-frame optical emission-line luminosities with 1e6 model SED. Find: average SFH of high-mass galaxies rise and fall in a roughly symmetric bell-shaped manner, while those of low-mass galaxies rise progressively in time, consistent with the typically stronger activity of SF in low-mass galaxies. For galaxies of all masses, the SF activity rises more rapidly at high than at low redshift. Imply: standard approximation of exponentially declining SFHs widely used to interpret observed galaxy SEDs is not appropriate to constrain the physical parameters of SF galaxies at intermediate z.
1210.0544
Dark matter and cosmic structure
Frenk, White
Review of current standard model for the evolution of cosmic structure. Numerical simulations, nature of DM.
1210.0549
The star formation relation in nearby galaxies
Schruba
Review of observational studies of LS SF process in nearby galaxies. ISM and young stellar populations interact on few 100 pc scales in 100+ galaxies of all types. Observations enable us to relate detailed studies of SF in MW to the galaxies in the distant universe. Within disks, recent SF strongly scales with the local amount of molecular gas (traced by CO), with a depletion time of ~2Gyr. Consistent with the picture that stars form in giant molecular clouds. Galaxy centers and SF galaxies deviate from this normal trend, as they show enhanced SF per unit gas mass suggesting systematic changes in the molecular gas properties and especially the dense gas fraction. In the outer disks of spirals and dwarf galaxies, the decreasing availability of atomic gas inevitably limits the amount of SF, though with large local variations. The critical step for the gas-stars circle seems therefore is the formation of a molecular gas phase that shows complex dependencies on various environmental properties.
1210.0608
Baryon impact on weak lensing peaks and power spectrum: low-bias statistics and self-calibration in future surveys
Yang, Kratochvil, Huffenberger, Haiman, May
WL peak maps contain cosmological information, as demonstrated using N-body sims w/o baryonic effects. Employ ray-tracing N-body sims with manually steepened density profile of each DM halo, mimicking the cooling and concentration of baryons into DM potential wells. Find: in agreement with previous works, that this causes a significant increase in the amplitude of the WL power spectrum on small scales (spherical harmonic index l>1000). Study the impact of the halo concentration increase on the peak counts, and find: (i) low peaks (0.02<max kappa<0.08) remain nearly unaffected. These are generated from 1e12-13 Msun halo, and large angular offsets from peak center (>0.5 R_vir); insensitive to the central halo density profiles. These peak provide most of the cosmological information. (ii) The number of high peaks (max_kappa>0.08) is increase. But when the baryon effects are neglected, then the high peaks lead to a modest bias, comparable to that from the power spectrum on l<2000 scales, and much smaller than the bias from the power spectrum on smaller scales. (iii) In (sigma_8, Omega_m, w) space, the biases from the high peaks and and the power spectra are in different directions---possible "self calibration" (combination of peak counts and power spectrum can simultaneously constraining baryonic physics and cosmological parameters).
1210.0784
Be stars: rapidly rotating pulsators
Rivinius
Review talk. Be stars are without exception, a class of rapidly rotating stars, mostly pulsating, and none seem to posses a large scale B-field.
1210.0820
What have we learned from helioseismology, what have we really learned, and what do we aspire to learn?
Gough
How the sound speed and matter density vary throughout almost all of solar interior. How the sun rotates. The thermal stratification of a sunspot, and an indication of material flow around it. Test of GR via planetary orbit precession, the solar neutrino problem, the manner of transport of energy from the centre to the surface of the Sun, the mechanisms of angular-momentum redistribution, and the workings of the solar dynamo. The first two are successes, the rest are in a state of flux.
1210.0832
Creating white dwarf photospheres in the laboratory: strategy for astrophysics applications
Falcon, et al
As the title says, currently underway [!].
1210.0872
Constraints on dark matter annihilation in clusters of galaxies from diffuse radio emission
Storm, Jeltema, Profumo, Rudnick
As the title says. [Not clear how annihilation signal is separated from regular radio emission from, e.g., AGN sources.] Diffuse emission from groups M49 and NGC4636 reported.
1210.0879
On the survival of brown dwarfs and planets engulfed by their giant host star
Passy, Mac Low, De Marco
See if companions have been stripped of significant amounts of mass when they orbit the dense inner envelopes of the host giant, but disruption of gravitationally bound objects by ram pressure. Find that specific examples are unlikely to have lost significant mass during the common envelope phase, but one example could be the remnant of one or two Jovian mass planets that lost extensive mass during the common envelope phase.
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