Friday. And Saturday.
1209.4351
The SLUGGS survey: kinematics for over 2500 globular clusters in twelve early-type galaxies
Pota et al
Spectro--photometric survey of 2522 extragalactic GCs (globular clusters) around 12 early-type galaxies. Average of 160 GC radial velocities per galaxy with precision of 15 km/s per GC. Focus on the kinematics of metal-poor (blue) and metal-rich (red) GC systems (spatial and color distributions); focus on the kinematics of metal-poor and metal-rich subpopualations to ~8 effective radii from the galaxy center. Results: kinematics of red GC subpopulation strongly coupled with host galaxy stellar kinematics. Blue subpop dominated by random motions, especially in the outer regions, decoupled from the red GCs. Peculiar GC kinematic profiles seen in some galaxies; rotation-supported motion in a lenticular gal, or rotation around minor axis of blue GCs. GC kinematics are coupled with the host galaxy properties; velocity kurtosis and the slope of their velocity dispersion profiles is different between the 2 GC subpopulations in more massive galaxies.
1209.4353
A catalog of extended clusters and ultra-compact dwarf galaxies - An analysis of their parameters in early- and late-type galaxies
Bruens, Kroupa
Extended (>10pc) stellar clusters comparable to globular clusters in mass are called "extended clusters" (ECs), while objects with masses in the dwarf galaxy regime are called ultra-compact dwarf galaxies. Analyse observational parameters (luminosity, effective radius, and projected distance to the host galaxy) of all known ECs and UCDs. No clear distinction between ECs and UCDs: name them together as "extended stellar objects" (EOs). 813 EO, or which 171/642 are associated with late/early type galaxies, respectively. Most cover a luminosity range of MV=-4 to -14 mag. Vast majority of EOs < -10 mag are associated with ellipticals. The more luminous the EO, the large is its upper size limit. Luminosity functions peak at -6.4 mag (similar for early and late-related EOs), which is about one magnitude fainter than the peak of the GC luminosity function. EOs and GCs form a coherent structure in the r_eff vs. MV parameter space, while there is a clear gap between EOs and early type dwarf galaxies. Potential overlap with dwarf galaxies at high mass end. Compare EO sample with numerical models, conclude that parameters of EO sample can be well explained by star cluster origin (results of merged cluster complexes).
1209.4357
Cores and kinematics of early-types galaxies
Lauer
In early type galaxies, find that "core galaxies" rotate slowly, while "power-law galaxies" rotate rapidly (core existence based on HST classification, from ATLAS3D rotation measures); results from Faber+ confirmed. Amplitude of rotation sharply discriminates between the two types in the -19>Mv>-22 domain. Slow rotation: small set of core galaxies with Mv>-20 in concordance with more massive core galaxies... both rotation and central structure of early-type galaxies should be used together to separate systems that appear to have formed from "wet" versus "dry" mergers.
1209.4371
Implications and applications of kinematic galaxy scaling relations
Zaritsky
[Spotlight review] Galaxy scaling relations: connection between ostensibly unrelated physical characteristics of galaxies, testifies to an underlying order of galaxy formation. Review development of scaling relation that (1) unites the well-known Fundamental Plane (FP) relation of giant elliptical galaxies and Tully Fisher (TF) relation of disk galaxies, (2) Fits low mass spheroidal galaxies, including the ultra-faint satellites of our Galaxy, (3) explains the apparent shift of lenticular (S0) galaxies relative to both FP or TF, (4) describes all stellar dynamical systems, including systems with no dark matter (stellar clusters) (5) associates the numerical coefficients that account for the "tilt" of the FP away from the direct expectation drawn from virial theorem with systematic variations in the M/L ratio, (6) connects with independent results that demonstrate the robustness of mass estimators when applied at the half-light radius, and (7) results in smaller scatter for disk galaxies than the TF relation. The relation develops naturally from the virial theorem, but implies the existence of additional galaxy formation physics that must now be a focus of galaxy formation studies. Relation can be used to measure distances and galaxy masses. 2 applications: (1) cross-calibration of distance measurement methods, and (2) the determination of mass-to-light ratios of simple stellar populations as a function of age; implication for stellar initial mass function.
1209.4381
Modeling the onset of photosynthesis after the Chicxulub asteroid impact
Perez, Cardenas, Martin, Rojas
The great resilience of the unicellular biosphere against huge environmental perturbations.
1209.4434
Three-dimensional filamentation analysis of SDSS DR5 survey
Wu, Batuski, Khalil
New way to calculate the multi-scale 3d filamentation of SDSS galaxy clusters, and also to N-body sims. Compare mock to observation on 8-30 Mpc scales. SDSS has large filamentation at 10 Mpc scale, not found from either mock samples or random samples.
1209.4518
Superbubble bynamics in globular cluster infancy I. How do globular clusters first lose their cold gas?
Krause, et al
Early evolution of globular clusters: current scenarios require at least 2 generations of stars of which the first generation (1G) has been much more massive than the currently predominating 2G. Fast gas expulsion is thought to unbind the majority of the 1G stars. Gas expulsion also mandatory to remove metal-enriched supernova ejecta, which are not found in the 2G stars. Previously SN assumed to be the agent of gas expulsion; here, assume that gas expulsion happens via the formation of a super bubble [what causes the super-bubble???], and describe the kinematics by a thin-shell model. SNe driven shells are destroyed by RT instability before they reach escape speed for all but perhaps the least massive and most extended clusters. More power is required to expel the gas, which might plausibly be provided by a coherent onset of accretion onto the stellar remnants. The resulting kpc-sized bubbles might be observable in Faraday rotation maps with the planned SKA.
1209.4562
Is the 130 GeV line real? A search for systematics in the Fermi-LAT data
FInkbeinder, Su, Weniger
Galactic center feature at approximately 130 GeV: a discovery. This requires additional data, but a thorough investigation of LAT systematics. Any suspicious trends indicating spurious signal? Consider several hypothesis that might cause such artifact, find them all implausible. Search for instrumental signature in the Earth limb photons, which provide a smooth reference spectrum for null tests. Find no significant 130 GeV feature in Earth limb sample, but marginally significant 130 GeV feature with a limited range of detector incidence angles. Raises concerns about the 130 GeV galactic center feature, even though no plausible model of instrumental behavior that connects the two. Requires additional limb data; if the limb feature persists, can raise doubts about the Pass 7 processing of E>100 GeV events. At present, no instrumental systematics found that could plausible explain the excess Galactic center emission at 130 GeV.
1209.4548
Fermi-LAT gamma-ray signal from Earth limb, systematic detector effects and their implications for the 130 GeV gamma-ray excess
Hektor, Raidal, Tempel
Find no new statistically significant signal 130 GeV signal from nearby brightest galaxies, AGNs, unassociated sources, H clouds and Earth limb; known sources for Galactic center and nearby galaxy clusters. Put effort into studying Earth limb photons; in agreement with PAMELA measurement, confirming the physical origin of Limb gamma-rays. Small photon incidence angle from Earth Limb can have spurious signal (including 130 GeV), but the BG has large uncertainties in this case. Can be (likely) statistical fluctuations.
1209.4596
The large-scale cross-correlation of damped Lyman alpha systems with the Lyman alpha forest: first measurements from BOSS
Font-Ribera (Andreu), Miralda-Escude, Lee (Khee-Gan), Ross, Schneider, White, York
First measurement of large-scale cross-correlation of Lyman slpha forest absorption and Damped Lyman alpha systems (DLA), using SDSS DR9 (BOSS). X-corr detected up to scales of 40 Mpc/h, and is well fitter by linear theory prediction of standard CDM of structure formation with the expected redshiftdistortions, confirming its origin in the gravitational evolution of structure. Amplitude of DLA-Lyman alpha cross-correlation depends on only one free parameter, the bias factor of the DLA systems, once the Lyman alpha forest bias factors are known from independent Lyman alpha forest correlation measurements. Measure the DLA bias factor to be b_D=2.17 beta_F^0.22, where the Lyman alpha forest redshift distortion parameter beta_F is expected to be above unity. This bias factor implies a typical host halo mass for DLAs that is much larger than expected in present DLA models, and is reproduced if the DLA cross section scales with halo mass as M_h^alpha, which alpha=1.1 for beta_F=1. Matching the observed DLA bias factor and rate of incidence requires that atomic gas remains extended in massive haloes over larger areas than predicted in present simulations of galaxy formation, with typical DLA proper sizes larger than 20 kpc in host haloes of masses ~ 1e12 solar masses. Infer that typical galaxies at z~2 to 3 are surrounded by systems of atomic clouds that are much more extended than the luminous parts of galaxies and contain ~10% of the baryons in the host halo.
1209.4351
The SLUGGS survey: kinematics for over 2500 globular clusters in twelve early-type galaxies
Pota et al
Spectro--photometric survey of 2522 extragalactic GCs (globular clusters) around 12 early-type galaxies. Average of 160 GC radial velocities per galaxy with precision of 15 km/s per GC. Focus on the kinematics of metal-poor (blue) and metal-rich (red) GC systems (spatial and color distributions); focus on the kinematics of metal-poor and metal-rich subpopualations to ~8 effective radii from the galaxy center. Results: kinematics of red GC subpopulation strongly coupled with host galaxy stellar kinematics. Blue subpop dominated by random motions, especially in the outer regions, decoupled from the red GCs. Peculiar GC kinematic profiles seen in some galaxies; rotation-supported motion in a lenticular gal, or rotation around minor axis of blue GCs. GC kinematics are coupled with the host galaxy properties; velocity kurtosis and the slope of their velocity dispersion profiles is different between the 2 GC subpopulations in more massive galaxies.
1209.4353
A catalog of extended clusters and ultra-compact dwarf galaxies - An analysis of their parameters in early- and late-type galaxies
Bruens, Kroupa
Extended (>10pc) stellar clusters comparable to globular clusters in mass are called "extended clusters" (ECs), while objects with masses in the dwarf galaxy regime are called ultra-compact dwarf galaxies. Analyse observational parameters (luminosity, effective radius, and projected distance to the host galaxy) of all known ECs and UCDs. No clear distinction between ECs and UCDs: name them together as "extended stellar objects" (EOs). 813 EO, or which 171/642 are associated with late/early type galaxies, respectively. Most cover a luminosity range of MV=-4 to -14 mag. Vast majority of EOs < -10 mag are associated with ellipticals. The more luminous the EO, the large is its upper size limit. Luminosity functions peak at -6.4 mag (similar for early and late-related EOs), which is about one magnitude fainter than the peak of the GC luminosity function. EOs and GCs form a coherent structure in the r_eff vs. MV parameter space, while there is a clear gap between EOs and early type dwarf galaxies. Potential overlap with dwarf galaxies at high mass end. Compare EO sample with numerical models, conclude that parameters of EO sample can be well explained by star cluster origin (results of merged cluster complexes).
1209.4357
Cores and kinematics of early-types galaxies
Lauer
In early type galaxies, find that "core galaxies" rotate slowly, while "power-law galaxies" rotate rapidly (core existence based on HST classification, from ATLAS3D rotation measures); results from Faber+ confirmed. Amplitude of rotation sharply discriminates between the two types in the -19>Mv>-22 domain. Slow rotation: small set of core galaxies with Mv>-20 in concordance with more massive core galaxies... both rotation and central structure of early-type galaxies should be used together to separate systems that appear to have formed from "wet" versus "dry" mergers.
1209.4371
Implications and applications of kinematic galaxy scaling relations
Zaritsky
[Spotlight review] Galaxy scaling relations: connection between ostensibly unrelated physical characteristics of galaxies, testifies to an underlying order of galaxy formation. Review development of scaling relation that (1) unites the well-known Fundamental Plane (FP) relation of giant elliptical galaxies and Tully Fisher (TF) relation of disk galaxies, (2) Fits low mass spheroidal galaxies, including the ultra-faint satellites of our Galaxy, (3) explains the apparent shift of lenticular (S0) galaxies relative to both FP or TF, (4) describes all stellar dynamical systems, including systems with no dark matter (stellar clusters) (5) associates the numerical coefficients that account for the "tilt" of the FP away from the direct expectation drawn from virial theorem with systematic variations in the M/L ratio, (6) connects with independent results that demonstrate the robustness of mass estimators when applied at the half-light radius, and (7) results in smaller scatter for disk galaxies than the TF relation. The relation develops naturally from the virial theorem, but implies the existence of additional galaxy formation physics that must now be a focus of galaxy formation studies. Relation can be used to measure distances and galaxy masses. 2 applications: (1) cross-calibration of distance measurement methods, and (2) the determination of mass-to-light ratios of simple stellar populations as a function of age; implication for stellar initial mass function.
1209.4381
Modeling the onset of photosynthesis after the Chicxulub asteroid impact
Perez, Cardenas, Martin, Rojas
The great resilience of the unicellular biosphere against huge environmental perturbations.
1209.4434
Three-dimensional filamentation analysis of SDSS DR5 survey
Wu, Batuski, Khalil
New way to calculate the multi-scale 3d filamentation of SDSS galaxy clusters, and also to N-body sims. Compare mock to observation on 8-30 Mpc scales. SDSS has large filamentation at 10 Mpc scale, not found from either mock samples or random samples.
1209.4518
Superbubble bynamics in globular cluster infancy I. How do globular clusters first lose their cold gas?
Krause, et al
Early evolution of globular clusters: current scenarios require at least 2 generations of stars of which the first generation (1G) has been much more massive than the currently predominating 2G. Fast gas expulsion is thought to unbind the majority of the 1G stars. Gas expulsion also mandatory to remove metal-enriched supernova ejecta, which are not found in the 2G stars. Previously SN assumed to be the agent of gas expulsion; here, assume that gas expulsion happens via the formation of a super bubble [what causes the super-bubble???], and describe the kinematics by a thin-shell model. SNe driven shells are destroyed by RT instability before they reach escape speed for all but perhaps the least massive and most extended clusters. More power is required to expel the gas, which might plausibly be provided by a coherent onset of accretion onto the stellar remnants. The resulting kpc-sized bubbles might be observable in Faraday rotation maps with the planned SKA.
1209.4562
Is the 130 GeV line real? A search for systematics in the Fermi-LAT data
FInkbeinder, Su, Weniger
Galactic center feature at approximately 130 GeV: a discovery. This requires additional data, but a thorough investigation of LAT systematics. Any suspicious trends indicating spurious signal? Consider several hypothesis that might cause such artifact, find them all implausible. Search for instrumental signature in the Earth limb photons, which provide a smooth reference spectrum for null tests. Find no significant 130 GeV feature in Earth limb sample, but marginally significant 130 GeV feature with a limited range of detector incidence angles. Raises concerns about the 130 GeV galactic center feature, even though no plausible model of instrumental behavior that connects the two. Requires additional limb data; if the limb feature persists, can raise doubts about the Pass 7 processing of E>100 GeV events. At present, no instrumental systematics found that could plausible explain the excess Galactic center emission at 130 GeV.
1209.4548
Fermi-LAT gamma-ray signal from Earth limb, systematic detector effects and their implications for the 130 GeV gamma-ray excess
Hektor, Raidal, Tempel
Find no new statistically significant signal 130 GeV signal from nearby brightest galaxies, AGNs, unassociated sources, H clouds and Earth limb; known sources for Galactic center and nearby galaxy clusters. Put effort into studying Earth limb photons; in agreement with PAMELA measurement, confirming the physical origin of Limb gamma-rays. Small photon incidence angle from Earth Limb can have spurious signal (including 130 GeV), but the BG has large uncertainties in this case. Can be (likely) statistical fluctuations.
1209.4596
The large-scale cross-correlation of damped Lyman alpha systems with the Lyman alpha forest: first measurements from BOSS
Font-Ribera (Andreu), Miralda-Escude, Lee (Khee-Gan), Ross, Schneider, White, York
First measurement of large-scale cross-correlation of Lyman slpha forest absorption and Damped Lyman alpha systems (DLA), using SDSS DR9 (BOSS). X-corr detected up to scales of 40 Mpc/h, and is well fitter by linear theory prediction of standard CDM of structure formation with the expected redshiftdistortions, confirming its origin in the gravitational evolution of structure. Amplitude of DLA-Lyman alpha cross-correlation depends on only one free parameter, the bias factor of the DLA systems, once the Lyman alpha forest bias factors are known from independent Lyman alpha forest correlation measurements. Measure the DLA bias factor to be b_D=2.17 beta_F^0.22, where the Lyman alpha forest redshift distortion parameter beta_F is expected to be above unity. This bias factor implies a typical host halo mass for DLAs that is much larger than expected in present DLA models, and is reproduced if the DLA cross section scales with halo mass as M_h^alpha, which alpha=1.1 for beta_F=1. Matching the observed DLA bias factor and rate of incidence requires that atomic gas remains extended in massive haloes over larger areas than predicted in present simulations of galaxy formation, with typical DLA proper sizes larger than 20 kpc in host haloes of masses ~ 1e12 solar masses. Infer that typical galaxies at z~2 to 3 are surrounded by systems of atomic clouds that are much more extended than the luminous parts of galaxies and contain ~10% of the baryons in the host halo.
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