86 GHz SiO maser survey of late-type stars in the Inner Galaxy. IV. SiO emission and infrared data for sources in the Scutum and Sagittarius-Carina arms, 20 deg < l < 50 deg

We present an 86 GHz SiO (v = 1, J = 2 ---> 1) maser search toward late-type stars located within |b|<0.5 deg and 20 deg < l < 50 deg. This search is an extension at longer longitudes of a previously published work. We selected 135 stars from the MSX catalog using color and flux criteria and detected 92 (86 new detections). The detection rate is 68%, the same as in our previous study. The last few decades have seen the publication of several catalogs of point sources detected in infrared surveys (MSX, 2MASS, DENIS, ISOGAL, WISE, GLIMPSE, AKARI, and MIPSGAL). We searched each catalog for data on the 444 targets of our earlier survey and for the 135 in the survey reported here. We confirm that, as anticipated, most of our targets have colors typical of oxygen-rich asymptotic giant branch (AGB) stars. Only one target star may have already left the AGB. Ten stars have colors typical of carbon-rich stars, meaning a contamination of our sample with carbon stars <=1.7%.Comment: 13 pages, 6 Figures, A&A accepte

The sub-millimeter properties of broad absorption line quasars

We have carried out the first systematic survey of the sub-millimeter properties of broad absorption line (BAL) quasars. 30 BAL quasars drawn from a homogeneously selected sample from the Sloan Digital Sky Survey at redshifts 2<z<2.6 were observed with the SCUBA array at the JCMT to a typical rms sensitivity of 2.5 mJy. Eight quasars were detected at > 2 sigma significance, four of which are at > 3 sigma significance. The far-infrared luminosities of these quasars are > 10^{13} L_solar. There is no correlation of sub-millimeter flux with either the strength of the broad absorption feature or with absolute magnitude in our sample. We compare the sub-millimeter flux distribution of the BAL quasar sample with that of a sample of quasars which do not show BAL features in their optical spectra and find that the two are indistinguishable. BAL quasars do not have higher sub-millimeter luminosities than non-BAL quasars. These findings are consistent with the hypothesis that all quasars would contain a BAL if viewed along a certain line-of-sight. The data are inconsistent with a model in which the BAL phenomenon indicates a special evolutionary stage which co-incides with a large dust mass in the host galaxy and a high sub-millimeter luminosity. Our work provides constraints on alternative evolutionary explanations of BAL quasars.Comment: 8 pages, 2 figures, ApJ, in pres

On the nature of infrared-faint radio sources in the SXDF and VLA-VVDS fields

Infrared-Faint Radio Sources (IFRSs) are an unusual class of objects that are relatively bright at radio wavelengths but have faint or undetected infrared counterparts even in deep surveys. We identify and investigate the nature of IFRSs using deep radio (S$_{\rm 1.4~GHz}$ $\sim$ 100 $\mu$Jy beam$^{-1}$ at 5$\sigma$), optical (m$_{\rm r}$ $\sim$ 26 - 27.7 at 5$\sigma$), and near-IR (S$_{\rm 3.6~{\mu}m}$ $\sim$ 1.3 - 2.0 $\mu$Jy beam$^{-1}$ at 5$\sigma$) data available in two deep fields namely the Subaru X-ray Deep Field (SXDF) and the Very Large Array - VIMOS VLT Deep Survey (VLA-VVDS) field. In 1.8 deg$^{2}$ of the two fields we identify a total of nine confirmed and ten candidate IFRSs. We find that our IFRSs are high-redshift radio-loud AGN, with 12/19 sources having redshift estimates in the range of $z$ $\sim$ 1.7 - 4.3, while a limit of $z$ $\geq$ 2.0 is placed for the remaining seven sources. Notably, our study finds, for the first time, IFRSs with measured redshift $>$ 3.0, and also, the redshift estimates for IFRSs in the faintest 3.6 $\mu$m flux regime i.e., S$_{\rm 3.6~{\mu}m}$ $<$ 1.3 ${\mu}$Jy. Radio observations show that our IFRSs exhibit both compact unresolved as well as extended double-lobe morphologies, and have predominantly steep radio spectra between 1.4 GHz and 325 MHz. The non-detection of all but one IFRSs in the X-ray band and the optical-to-MIR colour (m$_{\rm r}$ - m$_{\rm 24~{\mu}m}$) suggest that a significant fraction of IFRSs are likely to be hosted in dusty obscured galaxies.Comment: 20 pages, 8 figures, 4 tables, accepted for publication in MNRA

Experimental verification of minima in excited long-range Rydberg states of Rb_2

Recent theoretical studies with alkali atoms A$^{\ast}$ excited to high Rydberg states predicted the existence of ultra long-range molecular bound states. Such excited dimers have large electric dipole moments which, in combination with their long radiative lifetimes, make them excellent candidates for manipulation in applications. This letter reports on experimental investigations of the self-broadening of Rb principal series lines, which revealed multiple satellites in the line wings. The positions of the satellites agree quantitatively with theoretically-predicted minima in the excited long-range Rydberg states of Rb$_2$.Comment: 3 figures, 5 pages in two-column forma

Generalized Pseudopotentials for Higher Partial Wave Scattering

We derive a generalized zero-range pseudopotential applicable to all partial wave solutions to the Schroedinger equation based on a delta-shell potential in the limit that the shell radius approaches zero. This properly models all higher order multipole moments not accounted for with a monopolar delta function at the origin, as used in the familiar Fermi pseudopotential for s-wave scattering. By making the strength of the potential energy dependent, we derive self-consistent solutions for the entire energy spectrum of the realistic potential. We apply this to study two particles in an isotropic harmonic trap, interacting through a central potential, and derive analytic expressions for the energy eigenstates and eigenvalues.Comment: RevTeX 4 pages, 1 figure, final published versio

Interstellar extinction towards the inner Galactic Bulge

DENIS observations in the J (1.2 micron) and K_S (2.15 micron) bands together with isochrones calculated for the RGB and AGB phase are used to draw an extinction map of the inner Galactic Bulge. The uncertainty in this method is mainly limited by the optical depth of the Bulge itself. A comparison with fields of known extinction shows a very good agreement. We present an extinction map for the inner Galactic Bulge (approx. 20 sq. deg.)Comment: 4 pages, 4 figures, accepted for publication in A&A as a letter, see also http://www-denis.iap.fr/articles/extinction

86 GHz SiO masers in Galactic Centre OH/IR stars

We present results on a search for 86.243 GHz SiO (J = 2 -- 1, v = 1) maser emission toward 67 OH/IR stars located near the Galactic Centre. We detected 32 spectral peaks, of which 28 correspond to SiO maser lines arising from the envelopes of these OH/IR stars. In OH/IR stars, we obtained an SiO maser detection rate of about 40%. We serendipitously detected two other lines from OH/IR stars at 86.18 GHz, which could be due to a CCS-molecule transition at 86.181 GHz or probably to an highly excited OH molecular transition at 86.178 GHz. The detection rate of 86 GHz maser emission is found to be about 60% for sources with The Midcourse Space Experiment (MSX) A - E < 2.5 mag; but it drops to 25% for the reddest OH/IR stars with MSX A - E > 2.5 mag. This supports the hypothesis by Messineo et al. (2002) that the SiO masers are primarily found in relatively thinner circumstellar material.Comment: 4 figures, 14 page

Deep Galaxy survey at 6.75 micron with the ISO satellite

Deep 6.75um mid-IR ISOCAM observations were obtained of the Canada-France Redshift Survey (CFRS) 1415+52 field with the Infrared Space Observatory. The identification of the sources with optical counterparts is described in detail, and a classification scheme is devised which depends on the S/N of the detection and the inverse probability of chance coincidence. 83% of the 54 ISOCAM sources are identified with Iab<23.5 counterparts. The (I-K)ab colors, radio properties, spectrophotometric properties and frequency of nuclear activity of these counterparts differ on average from those of typical CFRS galaxies. CFRS spectra are available for 21 of the sources which have Iab <= 22.5 (including 7 stars). Most of the strongest sources are stars or AGN. Among the non--stellar counterparts with spectra, 40% are AGNs, and 53% are galaxies that display star formation activity and/or significant contributions of A stars. The ISOCAM sources also display an IR excess, even when compared with heavily-reddened local starburst galaxies. An upper limit of 30% of extragalactic ISO sources could be at z>1 of the 44 S6.75um > 150uJy sources which are non-stellar (7 "spectroscopic" and 3 "photometric" stars excluded)Comment: 13 pages, 12 figures. Accepted for publication in A