1207.2147
MAGIC observations of the giant radio galaxy M87 in a low-emission state between 2005 and 2007
MAGIC collaboration, et al
* MAGIC telescope: gamma-ray astronomy at La Palma, Canary Islands, 2200m above sea level (Major Atmospheric Gamma-ray Imaging Cherenkov Telescopes). 17m diameter reflecting surface for Cherenkov radiation, sensitive to 50 GeV and 30 TeV (size helps). Two telescopes (stereoscopic). Spain, Germany, Italy, Finland, Switzerland, Bulgaria, Croatia.
No flaring activity found during campaign. Simple power law with index Gamma=2.2.
1207.2149
Tritium as an Anthropic probe
Gould
* really?
If T were just 20keV lighter relative to 3He, then current deuterium burning phase of pre-MS stellar evolution would be replaced by D+T burning; at same temperature, but last 4-8 times longer than D burning, yield total energies comparable to the binding energy of solar-type pre-MS stars; radially affecting proto-planetary disk. A "finely-tuned" parameter for intelligent life! Suggest deep connection between fundamental physics and the search for extrasolar life/intelligence.
* I want to vote for this one (to talk about it), but I don't want to vote for this one (because of the topic).
1207.2154
Evolution of the quasar luminosity function over 3<z<6 in the COSMOS survey field
Masters, Capak, ... Scoville, et al
High-z quasar LF (QLF) down to I(AB)=25 in COSMOS. 155 likely quasars at z>3.1, 39 have spectra. Compute rest-frame UV QLF in 3.1<z<3.5 and 3.5<z<5. Faint quasars decrease from z=3.2 to z=4. Evolution similar to X-ray LF, but normalization different, implying that 75% of X-ray bright AGN at 3<z<4 are optically obscured. This fraction higher than what is found at low-z; may imply that obscured type-2 fraction continues to increase with redshift at least to z=4. Contribution of quasars to cosmic reionizaton discussed.
1207.2155
HST narrow-band search for extended Ly-alpha emission around two z>6 quasars
Decarli, .. Fan, Hennawi, .. Rix, Strauss, .. et al
No evidence for extended Ly-alpha emission. Given the SFR typically inferred from rest-frame FIR of z=6 quasars, these limits are well below the intrinsic bright Ly-alpha emission expected from the recombination of gas photo ionized by quasars or by the SF in the host galaxies, and point towards significant Ly-alpha suppression or dust attenuation. But small extinction values observed along the LoS, so reddening has to be coupled with other mechanisms for Ly-alpha suppression (e.g., resonance scattering).
1207.2157
X-ray emission from star-forming galaxies - III. calibration of the Lx-SFR relation up to redshift z$\simeq$1.3
Mineo, Gilfanov, Sunyaev
For late-type galaxies and ULIRGS and SF galaxies in CDF, construct a sample of 54 galaxies from 0<z<1.3, and find Lx-SFR relation, which is consistent with linear for z=0 and 0.1<z<1.3 CDF galaxies. X-ray observations can measure SFR in normal SF galaxies that dominate the source counts at faint fluxes.
1207.2160
The connection between galaxies and dark matter structures in the local universe
Reddick, Wechsler, Tinker, Behroozi
New constraints on connection between galaxies and DM haloes in WMAP7 LCDM. Take N-body simulation (Bolshoi) and its halos/subhalos, populate with galaxies using sub halo abundance matching (SHAM), then investigate underlying assumptions of this technique including (i) which halo property is most closely associated with galaxy stellar masses and luminosities, (ii) how much scatter in this relationship, (iii) how much sub haloes can be stripped before their galaxies are destroyed. Models constrained by 2pt galaxy clustering and observed conditional stellar mass function of galaxies in groups. Tight constraint on satellite fraction as a function of stellar mass, halo and galaxy property scatter, and underlying conditional stellar mass function. Abundance matching model that associates galaxies with peak circular velocity of halos, with 0.20 dex scatter in stellar mass, is in good agreement with data.
1207.2174
Discovery of "Warm Dust" galaxies in clusters at z~0.3: evidence for stripping of cool dust in the dense environment?
Rawle, Rex, et al
* Marie!
In merging and relaxed clusters at z~0.3 (one each, the merging one is the Bullet Cluster), study dust properties of cluster members using FIR Herschel imaging. Some of the Bullet cluster SF sub-LIRG galaxy dust temperatures warmer (T_dust>37K), most (~90%) are T~30K. X-ray and MIR data show obscured AGN do not contribute significantly to the IR flux of these "warm dust" galaxies. Such dust temperature are not observed in the relaxed cluster, but significance too low to speculate on an origin involving recent cluster merging. "Warm dust" galaxies are statistically rare in field samples (> 3 sigma), so it may relate to dense environments. Preferentially located in the cluster periphery, the galaxy hosts tend towards lower stellar mass (M*<1e10 Msun). Dust stripping and heating responsible for warm dust? (30-50% less dust than normal SF galaxy) preferentially stripped on the outside, where it is cooler, to get "warm dust" SED.
1207.2175
FIRST-2MASS red quasars: transitional objects emerging from the dust
Glikman, ... Ross, ... Schneider, York, et al
120 dust-reddened quasars identified by matching radio (FIRST) and NIR (2MASS) and color-selecting red sources. Spans 0.1<z<3 and reddening 0.1<E(B-V)<1.5; at every redshift, dust-reddened quasars are intrinsically the most luminous quasars. Merger-driven quasar/galaxy co-evolution---reddened quasars revealing an emergent phase, heavily obscured quasar is shredding cocoon of dust prior to becoming a "normal" blue quasar. These red quasars make up <15-20% of the luminous quasar population.
1207.2196
Compact groups of galaxies selected by stellar mass: the 2MASS compact group catalogue
Diaz-Gimenez, et al
262 candidates from photometric catalogue, 230 survive visual inspection, only 1/4 previously known CGs (p2MCGs. 85 have 4 or more accordant galaxies (velocity-filtered sub sample, v2MCG). In comparison with Millennium CG sample (mvCGs), 2/3 or the groups are physically dense, 4x that of the Hickson sample. v2MCG show wide magnitude gaps between central and 1st-ranked galaxy, consistent with mvCGs.
No comments:
Post a Comment