Friday. I feel like I'm in middle school. Or elementary school. I want to be at least a college student. Maybe there is no difference.
1207.2762
Threshing in action - the tidal disruption of a dwarf galaxy by the Hydra I cluster
Koch et al
As the title says. Tidally disrupted by the galaxy cluster's potential itself (not the nearby galaxy).
1207.2767
Gas reservoirs and star formation in a forming galaxy cluster at z=0.2
Jaffe et al
Blind Ultra Deep HI Environmental Survey (BUDHIES) at WSRT (Westerbork Syntesis Radio Telescope): direct imaging study of neutral atomic H gas in galaxies at z where evolutionary processes begin to show. Investigate SF, HI content, galaxy morphology as a function of environment in Abell 2192 (z=0.18). A cluster in process of forming. 4 structure separated in z and/or space. Baby cluster itself has a core of Ell galaxies with X-ray emission and almost no HI, suppressed SF. Find a compact group surrounding the cluster, where galaxies are pre-processed before falling into the cluster; clattered population of "field-like" galaxies showing more SF and HI. Understanding the fate of HI gas in the framework of galaxy evolution. Clearly see that the HI gas and the SF correlate with morphology and environment at z=0.2. Fraction of HI-detections significantly affected by environment. Results suggest that by the time the group galaxies fall into the cluster, they are already devoid of HI.
1207.2768
Identifying local group field galaxies which have interacted with the Milky Way
Teyssier, Johnston, Kuhlen
* Mike!
Distinguish between Local Group galaxies which have and have not passed by the virial volume of MW, via a statistical comparison against DM haloes in Via Lactea II (VLII) simulation with known orbital histories. Escaped population: contribute 13% of the galactic population between 300 and 1500 kpc from MW, so 7/54 known LG galaxies in that distance range are likely to be MW escapees; expected to have positive radial velocities. Tucana, Cetus, NGC3109, SextansA, SextansB, Antlia, NGC8622, Phoneix, LeoT, and NGC185 very likely passed by MW. Most of these dwarfs have lower HI mass fraction than the majority of dwarfs lying at similar distances than other dwarfs lying at similar distances. Several of these galaxies (esp. those of lower mass) contain signatures in their morphology, SFH and/or gas content indicative of evolution seen in simulations of satellite/parent galactic interactions. Dwarfs of different types form a sequence in morphology and gas content, with evolution along the sequence being driven by interaction history.
1207.2770
Jupiter will become a hot Jupiter: consequences of post-main-sequence stellar evolution on gas giant planets
Spiegel, Madhusudhan
* zonal wind: the component of a wind along a particular parallel of latitude. <=> meridinal wind
As the title says--when the sun goes into RGB or AGB stage, Jupiter will be irradiated strongly (not to forget that Earth will be engulfed) to atmospheric temperatures of ~1000K or more. Massive planets around post-MS stars can accrete a non-negligible amount of material from the enhanced stellar winds, altering their atmospheric chemistry, as well as causing significant accretion luminosity during the intense stellar mass loss. Future IR observatories might be able to probe the thermal and chemical structure of such hot Jupiters' atmospheres. Red-giant hot Jupiters should have multiple, narrow jets of zonal winds (usually, they are few, broad, planetary-scale jets) and efficient day-night redistribution.
1207.2772
The coupling between the core/cusp and missing satellite problems
Penarrubia, Pontzen, Walker, Koposov
Calculate energy needed to remove centrally-divergent DM cusps in CDM haloes in dSphs. While SNeII explosions can in principle generate this energy, the actual contribution is limited by the low SF efficiency. "Core/cusp" and "missing satellite" problems place opposing demands on SF efficiencies. Existing observational evidences for large cores in the most luminous dSphs require CDM models invoke some combination of the following: (i) efficient coupling of SNeII energy into kinetic energy of gas, (ii) SFH peaking at unexpectedly high redshifts (z>6), (iii) a top-heavy stellar IMF, and/or (iv) substantial satellite disruption or other stochastic effect to ease the substructure abundance constraints. Models show that the tension between CDM problems on small scales would increase if cored DM were to be found in fainter dwarves.
1207.2777
Cool dust n the outer ring of NGC 1291
Hinz et al
Mass of cool dust in the ring dominates the total dust mass of the galaxy (70%), at T=19.5K, cooler than that of the inner galaxy (25K).
1207.2787
Solar stereoscopy with STERO/EUVI A and B spacecraft from small (6 deg) to large (170 deg) spacecraft separation angles
Aschwanden, Wülser, Nitta, Lemen
* STEREO (Solar TErrestrial RElations Observatory): solar observation mission; two nearly identical spacecraft launched into orbits around the sun that cause them to respectively pull farther ahead of, and fall gradually behind, the Earth. Enables stereoscopic imaging of the Sun and solar phenomena, such as CME. Separates at 44 deg/year, passed 90 deg separation in 2009, Lagrangian points L4 and L5 in late 2009. At 2011, they were 180 deg apart. Will return to earth in 2023.
Stereoscopic triangulation of coronal loops at separation angles 6,43,89,127, and 170. Optimum range of 22-125 deg. Best accuracy generally obtained when an active region passes the central meridian (from Earth) which yields a symmetric view for both STEREO space craft and causes minimum horizontal foreshortening.
1207.2790
First 3D reconstructions of coronal loops with the STEREO A+B spacecraft: IV. magnetic modeling with twisted force-free fields
Aschwanden et al
As the title says. Provides strong constraints for B-field models of active regions in the solar corona. ...
1207.2811
The red supergiant progenitor of Supernova 2012aw (PTF12bvh) win Messier 95
Van Dyk, Cenko, .. Gal-Yam, Filippenko, ... Marcy, ... et al
Detection and characterization of probably red supergiant progenitor of SN IIP in the nearby spiral galaxy M95 (10 Mpc). HST image from 17-18 yr prior and NIR ground-based images from 6-12 yr prior to explosion. Evidence for substantial circumstellar dust (excess LoS extinction). The effective total-to-selective ratio of extinction to the star was R'_V ~ 4.35, significantly different from diffuse interstellar dust (R_V=3.1) and th total extinction to the star was A_V~3.1 mag. Observed spectral energy distribution for the progenitor star is consistent with an effective temperature of 3600K (M3), and the star had a bolometric magnitude of -8.29. Infore the progenitor has initial mass of 17-18 Msun. Curcumstellar dust around the progenitor must have been destroyed in the explosion, as the visual extinction to the SN is found to be low (A_V=0.24 with R_V=3.1).
1207.2959
Towards a model of population of astrophysical sources of ultra-high-energy cosmic rays
Kalashev, Ptitsyna, Troitsky
Assume CR particles accelerated in magnetospheres of SMBH in galactic nuclei, acceleration key parameter being BH mass. Use BH mass function to describe the population of CR accelerators; compare with CR data.
1207.2925
2004 KV18 - A visitor from the scattered disk to the Neptune Trojan population
Hornder, Lykawka
* Centaur population: unstable orbital class of minor planets that behave with characteristics of both asteroids and comments. Have transient orbits that cross or have crossed the orbits of one or more of the giant planets, and a dynamic lifetimes of a few million years.
Second object found to librate around L5; moving on a highly unstable orbit; mostly likely captured from the Centaur population, would probably leave Neptune Trojan in 0.1-0.3 Myr.
1207.3000
How flat is our universe really?
Okouma, Fantaye, Bassett
Distance measures provide no constraints on curvature independent of assumptions about DE. How flat is the universe if we make no DE assumptions? CMB and SNe data alone imply -0.12<Omega_k<0.01 (2 sig); while adding HST H0 prior tightens Omega_k to 0.002 pm 0.009. Curvature dynamics degeneracy broken by current data, with a key role played by ISW. If -1<w(z)<1 prior allowed, then Omega_k=0.013 pm 0.012 from WMAP7 and SNe data alone. All datasets consistent wit hHarrison-Zel'dovich spectral index, n_s=1, at 2 sig.
1207.3023
Atomic hydrogen, star formation and feedback in the lowest mass Blue Compact Dwarf galaxies
Roychowdhury, et al
Search for HI emission from M81 group dwarf galaxies. HI found in 3 galaxies, all of which are BCDs, with HI mass 1e6 Msun, some of the lowest mass BCDs known. H-alpha emission is very faint, and could be produce by a single O star. Find offsets between the peak of FUV emission and H-alpha emission, each tracing SF at different times. Offsets described by stochasticity. Only see tentative evidence of outflowing HI gas associated with the SF region in one of the galaxies, although it should be more prominent for low mass galaxies such as these.
1207.3025
Probing the origin of giant radio haloes through radio and gamma-ray data : the case of the Coma cluster
Brunetti, Blasi, et al
Combine spectral shape and morphology of the radio halo of Coma with gamma-ray upper limits from Fermi-LAT and B-field derived from Faraday rotation measures (RM). Radio halo possibly due to synchrotron emission of secondary electrons generated via p-p collisions in ICM. If pure secondary model, then require steep CR spectrum to explain halo spectrum, the broad spatial distribution result in gamma-ray excess of present limits (unless cluster B-field sufficiently large, but that is also inconsistent with RM). More complex model: secondary particles, CR protons and their secondaries all reaccelerated by MHD turbulence. Under these conditions, possible to reproduce the radio data and predict gamma-rays in agreement with Fermi-LAT limits. Requires spatial distribution of CRs much flatter than that of the ICM.
1207.3074
Properties of z~3-6 Lyman break galaxies. II. Testing star formation histories and the SFR-mass relation with ALMA and near-IR spectroscopy
Schaerer, de Barros, Sklias
How does LBGs physical parameters (derived) depend on assumed SFHs? What does it imply for the SFR-mass relation? Propose observational tests to better constrain these quantities. Use SED-fitting tool (including nebular emission) to analyze a large sample of LBGs. Assume 5 different SFHs (extends the first analysis of this sample, de Barros + 2012, Paper I). Also predict IR luminosity that are consistent with SED fits. "Standard" assumes constant SFR and no nebular lines. Assuming variable SFHs yield systematically lower stellar masses, higher extinction, higher SFR, higher IR luminosities, and wider range of EWs for optical emission lines. Different SFHs yield differences in the derived SFR-mass relation and the sSFR; this can be tested/constrained observationally with future IR observations with ALMA; Halpha and OII emission lines would also help. The large scatter in SFR-mass at high-z (and increase of sSFR) for z>3 can be tested observationally.
[Fri **/48] Jul 13
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