1201.6357
The milky way project first data release: a bubblier galactic disk
Simpson et al
A new catalog of 5k IR bubbles created through visual classification via the online citizen science website 'The Milky Way Project'. Independent identification by at least 5 people. Will enable better statistical analysis of Galactic star-formation sites.
* what do the IR bubbles mean? "H II regions ionized by young, OB stars provide the most readily observable tracers of SF in the MW and other galaxies. Ionized gas produces strong emission in optical and IR recombination lines, forbidden lines and thermal (free-free) radio continuum. Dust mixed with ionized gas and heated by the hard radiation field makes H II regions bright sources of thermal IR emission.
1201.6359
Metallicity gradients in disks: do galaxies form inside-out?
Pilkington, et al
Examine radial and vertical metallicity gradients using a suite of disk galaxy simulations, supplemented with two classic chemical evolution approaches. Determine rante of change of gradient and reconcile differences between extant models and observatons within the 'inside-out' disk growth paradigm [?]. Two chemical evolution models of inside-out disk growth were employed to contrast the temporal evolution of their radial gradients with those of the simulations. Find majority of the models predict radial gradients today which are consistent with those observed in late-type disks, but they evolve to this self-similarity in different fashions, despite each adhering to classical 'inside-out' growth. Find: radial dependence of the efficiency with which stars form as a function of time drives the differences seen in the gradients; systematic difference in the sub-grid physics between the various codes are responsible for setting these gradients. Recent data at z=1.5 are consistent with the steeper gradients seen in the SPH sample, suggesting a model revision of the classical chemical evolution model.
1201.6361
Stellar population profiles and radial migrations in disk galaxies
Roediger, Courteau, Sanchez-Blazquez
Using 62 Virgo cluster disk galaxies, constrain disk galaxy formation models based on age and metallicity profiles derived from optical and near IR observation. 1/3 of galaxies with light profile breaks (Type IIs) show age profile inversions, while most galaxies without such breaks (Type Is) have either flat or rising age profile with radius. Breaks in galaxy luminosity profiles can be attributed to fundamental processes as angular momentum conservation and redistribution, SF efficiencies, gas flows, feedback, disk heating and more. The existence of flat and inverted age profiles in Type I and II disks, respectively, agrees well with recent models involving some of these processes but no explanation exists for Type I galaxies with positive age gradients. Most existing data lack the discriminating power to distinguish between the formation models which predict inverted age profiles in Type II disks. ... No single model of stellar migration, gas accretion or warping ing galaxy disks can account for the diversity of luminosity and stellar population profiles observed in Type I and II galaxies.
* bleah. Apparently upturns in disk luminosity profiles are called Type III. Don't even know what that means.
1201.6365
The evolution of the rest-frame V-band luminosity function from z=4: a constant faint-end slope over the last 12 Gyr of cosmic history
Marchesini, Stefanon, Brammer, Whitaker
Present V-band luminosity function of galaxies at 0.4<z<4.0, measured from NIR with high-quality optical to mid-IR data. Data allows (1) minimize uncertainties due to cosmic variance, (2) simultaneously constrain the bright and faint ends with unprecedented accuracy over the z range, probing down to 0.1 L* at z~3.9. Find: (1) faint end is fairly flat and with a constant slope from z=4, (2) the characteristic magnitude has dimmed by 1.3 mag from z~3.7 to z=0.1, (3) the characteristic density has increased by a factor of ~8 from z~3.7 to z=0.1, with 50% of increase from z~4 to 1.8, and (4) the luminosity density peaks at z~1-1.5, increasing by a factor of 4 from z=4.0 to z~1-1.5, and subsequently decreasing by a factor of ~1.5 by z=0.1. Find no evidence for a steepening of the faint-end slope with redshift out to z=4, in contrast with previous observational claims and theoretical predictions. The constant faint-end slope suggests that the efficiency of stellar feedback may evolve with redshift. Alternative interpretations discussed. Alternative interpretations: different masses of the halos hosting faint galaxies at low and high z and/or environmental effects.
1201.6372
Testing the proposed connection between DE and BHs
Aykutalp, Spaans
Extension of GR that predicts the DE density Lambda to vary linearly with the total number of macroscopic BHs in the universe proposed; explore this prediction and find that Lambda must be roughly constant after the bulk of stellar mass BHs are in place (z<1). ...
1201.6377
The progenitor of the type Ia SN that created SNR 0519-69.0 in the LMC
Edwards, Pagnotta, Schaefer
System known to be a remnant of Ia SN from light echos and X-ray spectra. If a single degenerate system, the ex-companion star must be within 4.7" at 99.73% CL, but is not found. Hence the system was either a supersoft source or a double-degenerate progenitor system.
1201.6383 (similar to 1201.6074)
Constraining the nature of the most distant GRB host galaxies
Basa, et al
3 GRB at z>5, constrain SFR of host galaxy. No detection of the host (despite deep imaging). Observations indicate that the GRB host galaxies evolve with time and have lower SFR at z>5 than at z<5.
1201.6393
Black holes in pseudobulges: demography and models
Shankar, Marulli, Mathur, Bernardi, Bournaud
Significant fraction of BHs live in late-type galaxies, including bulge-less galaxies and those hosting pseudobulges, and are significantly undermassive wrt the scaling relations followed by their counterpart BHs in classical bulges of similar stellar (or even bulge) mass. DIscuss the predictions of 2 state-of-the-art hierarchical galaxy formation models in which BHs grow via mergers and, in one, also via disk instability. (to understand new data on local BH demography) Follow merger trees of representative subsamples of BHs and compute the fractional contributions of different processes to the final BH mass. Show: models in which BHs always closely follow the growth of their host bulsges, also during late disk instabilities (bars), produces too narrow a distribution of BHs at fixed stellar mass. Models with a looser connection between BH growth and bar instability instead predict the existence of a larger number of undermassive BHs, in agreement with observations. ... BH mass function models may need revision.
1201.6406
The evolution of the hubble sequence: morpho-kinematics of distant galaxies (Thesis)
Delgado-Serrano
Create new morphological classification. Find morpho-kinematic correlation better with new classification. Results suggest more than half of the present-day siprals had peculiar morphologies 6 Gyr ago. Estimated distant baryonic TF relation does not to appear to evolve over the past 6 Gyr.
1201.6407
Local 2d particl-in-cell simulations of the collisionless MRI
Riquelme, Quataert, Sharma, Spitkovsky
Magnetorotational instability (MRI) is a crucial mechanism of angular momentum transport in a variety of astrophysical accretion disks. In systems accreting at well below the Eddington rate, such as Sgr A*, the rate of Coulomb collisions between particles is very small, making the disk evolve essentially as a collisionless plasma. Present a NL sutdy of the collisionless MRI using PIC plasma simulations, in 2d only (3d future work). Amplification of the magnetic field by the MRI generates a significant pressure anisotropy in the plasma (perp pressure larger than parallel). This anisotropy excites mirror modes, and the volume averaged pressure anisotropy remains near the threshold for mirror mode excitation [???]. Particle energization is due to both reconnection and viscous heating associated with the pressure anisotropy. Reconnection produces a distinctive power-law component in the energy distribution function of the particles, indicating the likelihood of non-thermal ion and electron acceleration in collisionless accretion disks. Important implications for interpreting the observed emission.
1201.6416
A panchromatic catalog of early-type galaxies at intermediate redshift in the HST WFC3 early release science field
Rutkowski, et al
panchromatic catalog of 102 visually-selected early-type galaxies (ETGs) from HST GOODS-S field, spanning 0.35<z<1.5, with each redshift spectroscopically confirmed by previous published surveys of the ERS field. Combine measured WFC3 ERS and ACS GOODS-S photometry to gain continuous sensitivity from the rest-frame far-UV to near-IR emission for each ETG. Determine: average masses of the ETGs are comparable to the characteristic stellar mass of massive galaxies, 1e11 to 1e12 Msun. Noteworthy diversity in the rest-frame UV-optical colors. The blue are evidence for SF during the preceding Gyr, but no major recent starbursts found.
1201.6526
Multiple populations in globular clusters. Lessons learned from the MW globular clusters
Gratton, Carretta, Bragalia
Recent development of globular cluster observations, that show multiple SF epochs. Review article. To be understood: nature of the polluters of the abundance pattern, typical timescale, range of cluster masses where this phenomenon is active, and the relation between globular clusters and other satellites of our Galaxy.
1201.6582
Exoplanets bouncing between binary stars
Moeckel, Veras
As the title says. Cool video.
1201.6605
The fate of high redshift massive compact galaxies in dense environments
Kaufmann, Maer, Carollo, Feldmann
Massive compant galaxies more common at high z than in the local universe, especially in denser environments. Use hydrosim to analyse the evolution. At z~2 the population of galaxies with M*>2e10 Msun is diverse in terms of mass, velocity dispersion, SF and effective radius, containing both compact and relatively extended objects. In each simulation all the compact satellite galaxies have merged into the central galaxy by z=0. Satellites of similar mass ta z=0 are all less compact than their high z counterparts (dynamical friction time > Hubble time). By z=0 the central galaxies have increased substantially their radius via in situ SF and mergers. In a group environment descendants of compact galaxies either evolve towards larger sizes or disappear as a result of the environment. Since the group-sized halos considered are representative of dense environments in the LCDM cosmology, conclude that the majority of high z compact massive galaxies do not survive until today as a result of the environment.
* what exactly do they mean by "environment"?
1201.6416
A panchromatic catalog of early-type galaxies at intermediate redshift in the HST WFC3 early release science field
Rutkowski, et al
panchromatic catalog of 102 visually-selected early-type galaxies (ETGs) from HST GOODS-S field, spanning 0.35<z<1.5, with each redshift spectroscopically confirmed by previous published surveys of the ERS field. Combine measured WFC3 ERS and ACS GOODS-S photometry to gain continuous sensitivity from the rest-frame far-UV to near-IR emission for each ETG. Determine: average masses of the ETGs are comparable to the characteristic stellar mass of massive galaxies, 1e11 to 1e12 Msun. Noteworthy diversity in the rest-frame UV-optical colors. The blue are evidence for SF during the preceding Gyr, but no major recent starbursts found.
1201.6526
Multiple populations in globular clusters. Lessons learned from the MW globular clusters
Gratton, Carretta, Bragalia
Recent development of globular cluster observations, that show multiple SF epochs. Review article. To be understood: nature of the polluters of the abundance pattern, typical timescale, range of cluster masses where this phenomenon is active, and the relation between globular clusters and other satellites of our Galaxy.
1201.6582
Exoplanets bouncing between binary stars
Moeckel, Veras
As the title says. Cool video.
1201.6605
The fate of high redshift massive compact galaxies in dense environments
Kaufmann, Maer, Carollo, Feldmann
Massive compant galaxies more common at high z than in the local universe, especially in denser environments. Use hydrosim to analyse the evolution. At z~2 the population of galaxies with M*>2e10 Msun is diverse in terms of mass, velocity dispersion, SF and effective radius, containing both compact and relatively extended objects. In each simulation all the compact satellite galaxies have merged into the central galaxy by z=0. Satellites of similar mass ta z=0 are all less compact than their high z counterparts (dynamical friction time > Hubble time). By z=0 the central galaxies have increased substantially their radius via in situ SF and mergers. In a group environment descendants of compact galaxies either evolve towards larger sizes or disappear as a result of the environment. Since the group-sized halos considered are representative of dense environments in the LCDM cosmology, conclude that the majority of high z compact massive galaxies do not survive until today as a result of the environment.
* what exactly do they mean by "environment"?
No comments:
Post a Comment