HII Regions, Embedded Protostars, and Starless Cores in Sharpless 2-157

We present arcsecond resolution 1.4mm observations of the high mass star forming region, Sharpless 2-157, that reveal the cool dust associated with the first stages of star formation. These data are compared with archival images at optical, infrared, and radio wavelengths, and complemented with new arcsecond resolution mid-infrared data. We identify a dusty young HII region, numerous infrared sources within the cluster envelope, and four starless condensations. Three of the cores lie in a line to the south of the cluster peak, but the most massive one is right at the center and associated with a jumble of bright radio and infrared sources. This presents an interesting juxtaposition of high and low mass star formation within the same cluster which we compare with similar observations of other high mass star forming regions and discuss in the context of cluster formation theory.Comment: accepted to ApJ; 6 pages, 3 figure

Submillimetre galaxies as laboratories for dust grain coagulation

Coagulation in the dense interstellar medium (ISM) is an important process that determines the size of the largest grains. We use submillimetre galaxies (SMGs) as laboratories of grain coagulation, since some of them host the densest ISM on a galactic scale among various populations of galaxies known. We examine how large the grains can be in such dense environments based on the mean ISM density estimated from the observed typical dust mass density in SMGs. We also consider local density enhancement based on a model of supersonic turbulence, which is expected from strong stellar feedback. In the unlimited coagulation model, in which we do not impose any coagulation threshold velocity, grains as large as $\sim 30~\mu$m can form under the observationally estimated mean gas density if the Mach number of turbulence is $\mathcal{M}\gtrsim 3$. We exclude this possibility since the observed emissivity index $\beta\simeq 2$ in the far infrared (FIR) indicates that such large grains cannot actively form in SMGs. This means that coagulation does not proceed in an unlimited way: 30-$\mu$m grains should have velocities larger than the coagulation threshold. If we use a coagulation threshold (upper limit) grain velocity ($\sim 0.08$ km s$^{-1}$) taken from a theoretical study, grains likely grow only up to $\mu$m size, which is small enough not to affect the FIR emissivity index. The above results indicate that SMGs can be used to constrain the physical processes relevant to coagulation.Comment: 8 pages, 4 figures, accepted for publication in MNRA

Neutrino masses, muon g-2, dark matter, lithium problem, and leptogenesis at TeV-scale

Observational evidences of nonzero neutrino masses and the existence of dark matter request physics beyond standard model. A model with extra scalars and leptonic vector-like fermions is introduced. By imposing a Z_2 symmetry, the neutrino masses as well as anomalous muon magnetic moment can be generated via one-loop effects at TeV-scale. An effort of explaining dark matter, Lithium problem, and leptogenesis is presented. This scenario can be tested at LHC and/or future experiments.Comment: 5 pages, 5 figure

Submillimeter Sources behind the Massive Lensing Clusters A370 and A2390

We report 850 μm Submillimeter Array (SMA) observations of four gravitationally lensed submillimeter galaxies (SMGs), A370-2, A2390-1, A2390-3, and A2390-4, which were originally discovered with the Submillimeter Common-User Bolometer Array (SCUBA). Our SMA detection of A370-2 with a submillimeter flux of 7.95 ± 0.60 mJy unambiguously identifies the counterparts to this source at optical and radio wavelengths. A2390-1 is an ultraluminous infrared galaxy with a submillimeter flux of 5.55 ± 0.92 mJy and a redshift of 1.8 ± 0.2 computed from submillimeter/radio flux ratio analysis. We resolve A2390-3 into two components, A2390-3a and A2390-3b, with fluxes of 3.15 ± 0.63 mJy and 1.92 ± 0.60 mJy, respectively. The structure of the system could be consistent with morphological distortion by gravitational lensing. The lack of counterparts in the optical and infrared indicates a heavily dust-enshrouded nature, and a non-detection in the radio implies that these two sources probably lie at z > 4.7, which would make them among the most distant SMGs known to date. Our non-detection of A2390-4 suggests either that there are multiple fainter submillimeter sources within the SCUBA beam or that the SCUBA detection may have been false. Our precise positions allow us to determine accurate amplifications and fluxes for all of our detected sources. Our new results give a shallower power-law fit (–1.10) to the faint-end 850 μm cumulative number counts than previous work. We emphasize the need for high-resolution observations of single dish detected SMGs in order to measure accurately the faint end of the 850 μm counts

A model of CP Violation from Extra Dimension

We construct a realistic model of CP violation in which CP is broken in the process of dimensional reduction and orbifold compactification from a five dimensional theories with $SU(3)\times SU(3) \times SU(3)$ gauge symmetry. CP violation is a result of the Hosotani type gauge configuration in the higher dimension.Comment: 5 page

JCMT/SCUBA-2 uncovers an excess of 850μ850\mum counts on megaparsec scales around high-redshift quasars. Characterization of the overdensities and their alignment with the quasars' Lyα\alpha nebulae

We conducted a systematic survey of the environment of high-z quasars at submillimeter wavelengths to unveil and characterize the surrounding distribution of dusty submillimeter galaxies (SMGs). We took sensitive JCMT/SCUBA-2 observations for 3 enormous Lyman-alpha nebulae (ELANe) and 17 quasar fields in the redshift range 2<z<4.2 selected from recent Ly$\alpha$ surveys. These observations uncovered 523 and 101 sources at 850$\mu$m and 450$\mu$m, respectively, with S/N>4 or detected in both bands at S/N>3. We ran Monte Carlo simulations to construct 850$\mu$m number counts and unveil an excess of sources in 75% of the targeted fields. Overall, regions around ELANe and quasars are overabundant with respect to blank fields by a factor of $3.4\pm0.4$ and $2.5\pm0.2$, respectively. Therefore, the excess of SMGs is likely part of the Mpc-scale environment around these systems. By combining all fields and repeating the count analysis in radial apertures, we find a decrease in the overdensity factor from >3 within $\sim 2$ cMpc to $\sim2$ at the edge of the surveyed field ($\sim10$ cMpc), suggesting that the physical extent of the overdensities is larger than our maps. We computed preferred directions for the overdensities of SMGs from the positions of the sources and used them to orient and create stacked maps of source densities for the quasars' environment. This stacking unveils an elongated structure reminiscent of a large-scale filament with a scale width of $\approx 3$ cMpc. Finally, the directions of the overdensities are roughly aligned with the major axis of the Ly$\alpha$ nebulae, suggesting that the latter trace, on hundreds of kpc, the central regions of the projected large-scale structure described by the SMGs on Mpc scales. Confirming member associations of the SMGs is required to further characterize their spatial and kinematic distribution around ELANe and quasars.Comment: 37 pages, 12 figures, 8 appendix; A&A in pres