The JCMT Nearby Galaxies Legacy Survey -- XI. -- Environmental Variations in the Atomic and Molecular Gas Radial Profiles of Nearby Spiral Galaxies

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. ©: 2017 The Author (s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We present an analysis of the radial profiles of a sample of 43 HI-flux selected spiral galaxies from the Nearby Galaxies Legacy Survey (NGLS) with resolved James Clerk Maxwell Telescope (JCMT) CO $J=3-2$ and/or Very Large Array (VLA) HI maps. Comparing the Virgo and non-Virgo populations, we confirm that the HI disks are truncated in the Virgo sample, even for these relatively HI-rich galaxies. On the other hand, the H$_{2}$ distribution is enhanced for Virgo galaxies near their centres, resulting in higher H$_{2}$ to HI ratios and steeper H$_{2}$ and total gas radial profiles. This is likely due to the effects of moderate ram pressure stripping in the cluster environment, which would preferentially remove low density gas in the outskirts while enhancing higher density gas near the centre. Combined with H$\alpha$ star formation rate data, we find that the star formation efficiency (SFR/H$_{2}$) is relatively constant with radius for both samples, but Virgo galaxies have a $\sim40\%$ lower star formation efficiency than non-Virgo galaxies.Peer reviewedFinal Published versio

Spectroscopic variability of two Oe stars

The Oe stars HD45314 and HD60848 have recently been found to exhibit very different X-ray properties: whilst HD60848 has an X-ray spectrum and emission level typical of most OB stars, HD45314 features a much harder and brighter X-ray emission, making it a so-called gamma Cas analogue. Monitoring the optical spectra could provide hints towards the origin of these very different behaviours. We analyse a large set of spectroscopic observations of HD45314 and HD60848, extending over 20 years. We further attempt to fit the H-alpha line profiles of both stars with a simple model of emission line formation in a Keplerian disk. Strong variations in the strengths of the H-alpha, H-beta, and He I 5876 emission lines are observed for both stars. In the case of HD60848, we find a time lag between the variations in the equivalent widths of these lines. The emission lines are double peaked with nearly identical strengths of the violet and red peaks. The H-alpha profile of this star can be successfully reproduced by our model of a disk seen under an inclination of 30 degrees. In the case of HD45314, the emission lines are highly asymmetric and display strong line profile variations. We find a major change in behaviour between the 2002 outburst and the one observed in 2013. This concerns both the relationship between the equivalent widths of the various lines and their morphologies at maximum strength (double-peaked in 2002 versus single-peaked in 2013). Our simple disk model fails to reproduce the observed H-alpha line profiles of HD45314. Our results further support the interpretation that Oe stars do have decretion disks similar to those of Be stars. Whilst the emission lines of HD60848 are explained by a disk with a Keplerian velocity field, the disk of HD45314 seems to have a significantly more complex velocity field that could be related to the phenomenon that produces its peculiar X-ray emission.Comment: Accepted for Publication in A&

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs

We describe the design and performance of the near-infrared (1.51--1.70 micron), fiber-fed, multi-object (300 fibers), high resolution (R = lambda/delta lambda ~ 22,500) spectrograph built for the Apache Point Observatory Galactic Evolution Experiment (APOGEE). APOGEE is a survey of ~ 10^5 red giant stars that systematically sampled all Milky Way populations (bulge, disk, and halo) to study the Galaxy's chemical and kinematical history. It was part of the Sloan Digital Sky Survey III (SDSS-III) from 2011 -- 2014 using the 2.5 m Sloan Foundation Telescope at Apache Point Observatory, New Mexico. The APOGEE-2 survey is now using the spectrograph as part of SDSS-IV, as well as a second spectrograph, a close copy of the first, operating at the 2.5 m du Pont Telescope at Las Campanas Observatory in Chile. Although several fiber-fed, multi-object, high resolution spectrographs have been built for visual wavelength spectroscopy, the APOGEE spectrograph is one of the first such instruments built for observations in the near-infrared. The instrument's successful development was enabled by several key innovations, including a "gang connector" to allow simultaneous connections of 300 fibers; hermetically sealed feedthroughs to allow fibers to pass through the cryostat wall continuously; the first cryogenically deployed mosaic volume phase holographic grating; and a large refractive camera that includes mono-crystalline silicon and fused silica elements with diameters as large as ~ 400 mm. This paper contains a comprehensive description of all aspects of the instrument including the fiber system, optics and opto-mechanics, detector arrays, mechanics and cryogenics, instrument control, calibration system, optical performance and stability, lessons learned, and design changes for the second instrument.Comment: 81 pages, 67 figures, PASP, accepte

Inflation with racetrack superpotential and matter field

Several models of inflation with the racetrack superpotential for the volume modulus coupled to a matter field are investigated. In particular, it is shown that two classes of racetrack inflation models, saddle point and inflection point ones, can be constructed in a fully supersymmetric framework with the matter field F-term as a source of supersymmetry breaking and uplifting. Two models of F-term supersymmetry breaking are considered: the Polonyi model and the quantum corrected O'Raifeartaigh model. In the former case, both classes of racetrack inflation models differ significantly from the corresponding models with non-supersymmetric uplifting. The main difference is a quite strong dominance of the inflaton by the matter field. In addition, fine-tuning of the parameters is relaxed as compared to the original racetrack models. In the case of the racetrack inflation models coupled to the O'Raifeartaigh model, the matter field is approximately decoupled from the inflationary dynamics. In all of the above models the gravitino mass is larger than the Hubble scale during inflation. The possibility of having the gravitino much lighter than the Hubble scale is also investigated. It is very hard to construct models with light gravitino in which the volume modulus dominates inflation. On the other hand, models in which the inflationary dynamics is dominated by the matter field are relatively simple and seem to be more natural.Comment: 40 pages, 13 figures, references added, typos corrected, version to be publishe

Observing Strategy for the SDSS-IV/MaNGA IFU Galaxy Survey

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) is an integral-field spectroscopic survey that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). MaNGA's 17 pluggable optical fiber-bundle integral field units (IFUs) will observe a sample of 10,000 nearby galaxies distributed throughout the SDSS imaging footprint (focusing particularly on the North Galactic Cap). In each pointing these IFUs are deployed across a 3° field; they yield spectral coverage 3600−10300 Å at a typical resolution R ~ 2000, and sample the sky with 2'' diameter fiber apertures with a total bundle fill factor of 56%. Observing over such a large field and range of wavelengths is particularly challenging for obtaining uniform and integral spatial coverage and resolution at all wavelengths and across each entire fiber array. Data quality is affected by the IFU construction technique, chromatic and field differential refraction, the adopted dithering strategy, and many other effects. We use numerical simulations to constrain the hardware design and observing strategy for the survey with the aim of ensuring consistent data quality that meets the survey science requirements while permitting maximum observational flexibility. We find that MaNGA science goals are best achieved with IFUs composed of a regular hexagonal grid of optical fibers with rms displacement of 5 μm or less from their nominal packing position; this goal is met by the MaNGA hardware, which achieves 3 μm rms fiber placement. We further show that MaNGA observations are best obtained in sets of three 15 minute exposures dithered along the vertices of a 1.44 arcsec equilateral triangle; these sets form the minimum observational unit, and are repeated as needed to achieve a combined signal-to-noise ratio of 5 Å-1 per fiber in the r-band continuum at a surface brightness of 23 AB arcsec-2. In order to ensure uniform coverage and delivered image quality, we require that the exposures in a given set be obtained within a 60 minute interval of each other in hour angle, and that all exposures be obtained at airmass ≲ 1.2 (i.e., within 1–3 hr of transit depending on the declination of a given field)

Polarisation Patterns and Vectorial Defects in Type II Optical Parametric Oscillators

Previous studies of lasers and nonlinear resonators have revealed that the polarisation degree of freedom allows for the formation of polarisation patterns and novel localized structures, such as vectorial defects. Type II optical parametric oscillators are characterised by the fact that the down-converted beams are emitted in orthogonal polarisations. In this paper we show the results of the study of pattern and defect formation and dynamics in a Type II degenerate optical parametric oscillator for which the pump field is not resonated in the cavity. We find that traveling waves are the predominant solutions and that the defects are vectorial dislocations which appear at the boundaries of the regions where traveling waves of different phase or wave-vector orientation are formed. A dislocation is defined by two topological charges, one associated with the phase and another with the wave-vector orientation. We also show how to stabilize a single defect in a realistic experimental situation. The effects of phase mismatch of nonlinear interaction are finally considered.Comment: 38 pages, including 15 figures, LATeX. Related material, including movies, can be obtained from http://www.imedea.uib.es/Nonlinear/research_topics/OPO

A Functional Link between AMPK and Orexin Mediates the Effect of BMP8B on Energy Balance

AMP-activated protein kinase (AMPK) in the ventromedial nucleus of the hypothalamus (VMH) and orexin (OX) in the lateral hypothalamic area (LHA) modulate brown adipose tissue (BAT) thermogenesis. However, whether these two molecular mechanisms act jointly or independently is unclear. Here, we show that the thermogenic effect of bone morphogenetic protein 8B (BMP8B) is mediated by the inhibition of AMPK in the VMH and the subsequent increase in OX signaling via the OX receptor 1 (OX1R). Accordingly, the thermogenic effect of BMP8B is totally absent in ox-null mice. BMP8B also induces browning of white adipose tissue (WAT), its thermogenic effect is sexually dimorphic (only observed in females), and its impact on OX expression and thermogenesis is abolished by the knockdown of glutamate vesicular transporter 2 (VGLUT2), implicating glutamatergic signaling. Overall, our data uncover a central network controlling energy homeostasis that may be of considerable relevance for obesity and metabolic disorders

Evidence for the h_b(1P) meson in the decay Upsilon(3S) --> pi0 h_b(1P)

Using a sample of 122 million Upsilon(3S) events recorded with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we search for the $h_b(1P)$ spin-singlet partner of the P-wave chi_{bJ}(1P) states in the sequential decay Upsilon(3S) --> pi0 h_b(1P), h_b(1P) --> gamma eta_b(1S). We observe an excess of events above background in the distribution of the recoil mass against the pi0 at mass 9902 +/- 4(stat.) +/- 2(syst.) MeV/c^2. The width of the observed signal is consistent with experimental resolution, and its significance is 3.1sigma, including systematic uncertainties. We obtain the value (4.3 +/- 1.1(stat.) +/- 0.9(syst.)) x 10^{-4} for the product branching fraction BF(Upsilon(3S)-->pi0 h_b) x BF(h_b-->gamma eta_b).Comment: 8 pages, 4 postscript figures, submitted to Phys. Rev. D (Rapid Communications

Variability monitoring of OB stars during the Mons campaign

We present preliminary results of a 3-month campaign carried out in the framework of the Mons project, where time-resolved Halpha observations are used to study the wind and circumstellar properties of a number of OB stars.Comment: 2 pages, 1 figure. To appear in proceedings of IAUS272 'Active OB Stars: Structure, Evolution, Mass Loss and Critical Limits