The Discovery of Water Maser Emission from Eight Nearby Galaxies

Using the Green Bank Telescope, we conducted a ``snapshot'' survey for water maser emission toward the nuclei of 611 galaxies and detected eight new sources. The sample consisted of nearby (v < 5000 km/s) and luminous (M_B < -19.5) galaxies, some with known nuclear activity but most not previously known to host AGNs. Our detections include both megamasers associated with AGNs and relatively low luminosity masers probably associated with star formation. The detection in UGC 3789 is particularly intriguing because the spectrum shows both systemic and high-velocity lines indicative of emission from an AGN accretion disk seen edge-on. Based on six months of monitoring, we detected accelerations among the systemic features ranging from 2 to 8 km/s/yr, the larger values belonging to the most redshifted systemic components. High-velocity maser lines in UGC 3789 show no detectable drift over the same period. Although UGC 3789 was not known to be an AGN prior to this survey, the presence of a disk maser is strong evidence for nuclear activity, and an optical spectrum obtained later has confirmed it. With follow up observations, it may be possible to measure a geometric distance to UGC 3789.Comment: to appear in Astrophysical Journal, 1 May 200

Outflow 20--2000 AU from a High-Mass Protostar in W51-IRS2

We present the results of the first high angular resolution observations of SiO maser emission towards the star forming region W51-IRS2 made with the Very Large Array (VLA) and Very Long Baseline Array (VLBA). Our images of the water maser emission in W51-IRS2 reveal two maser complexes bracketing the SiO maser source. One of these water maser complexes appears to trace a bow shock whose opening angle is consistent with the opening angle observed in the distribution of SiO maser emission. A comparison of our water maser image with an image constructed from data acquired 19 years earlier clearly shows the persistence and motion of this bow shock. The proper motions correspond to an outflow velocity of 80 km/s, which is consistent with the data of 19 years ago (that spanned 2 years). We have discovered a two-armed linear structure in the SiO maser emission on scales of ~25 AU, and we find a velocity gradient on the order of 0.1 km/s/AU along the arms. We propose that the SiO maser source traces the limbs of an accelerating bipolar outflow close to an obscured protostar. We estimate that the outflow makes an angle of <20 degrees with respect to the plane of the sky. Our measurement of the acceleration is consistent with a reported drift in the line-of-sight velocity of the W51 SiO maser source.Comment: 19 pages, 5 figures (including 3 color). Accepted for publication in ApJ (April 1, 2001 issue

The Social Supply Chain and the Future High Street

Purpose: The paper examines how independent social and commercial activities have developed in response to the perceived decline in the UK High Street and in response to the challenges of increasing digital retailing opportunities. This examination is undertaken through the lens of the social supply chain as a means to understanding, suggesting and expanding on current research regarding retailing and the UK High Street. We reveal some of the challenges being posed by the changing patterns of growth and consumption in cities and couple these with shifting supply chain trends. Design: A case study approach is employed to explore the rapid advances and influence of digital technologies on businesses operating on the primary business street of suburban centre, towns or cities (described in the UK collectively as the ‘high street’). The study is conducted through the analytical lens of the social supply chain. Originality: For the purpose of this paper we use two distinct strategies relating to delivery and balancing and in relation to the actions of co-creation, co-production and co-consumption to emphasise and analyse changes currently occurring in the UK high street. We take a social supply chain management perspective to undertake a systematic critical review of the various recent efforts undertaken by local governments, communities and traders groups to revitalise the high street. Findings: Theoretically extending the ‘social’ in the social supply chain we illustrate the usefulness of the nuanced concept of the ‘social supply chain’ with two related strategies concerning delivery and balance. These strategies are themselves interlinked with the actions of co-creation, co-production and co-consumption. Examples of social supply chain strategies presented include retail businesses giving away something as an incentive, where the underlying requirement from the customer is that they will bring their own specialist product, skill or social network to a specified location (real or virtual)

An ``outside-in'' outburst of Aql X--1

We present optical spectroscopy and optical and infrared photometry of the neutron star soft X-ray transient Aql X--1 during its X-ray outburst of August 1997. By modelling the X-ray, optical, and IR light curves, we find a 3 day delay between the IR and X-ray rise times, analogous to the UV-optical delay seen in dwarf novae outbursts and black hole X-ray transients. We interpret this delay as the signature of an ``outside-in'' outburst, in which a thermal instability in the outer disc propagates inward. This outburst is the first of this type definitively identified in a neutron star X-ray transient.Comment: 6 pages latex, 2 figures, Accepted by MNRA

21cm Absorption by Compact Hydrogen Disks Around Black Holes in Radio-Loud Nuclei of Galaxies

The clumpy maser disks observed in some galactic nuclei mark the outskirts of the accretion disk that fuels the central black hole and provide a potential site of nuclear star formation. Unfortunately, most of the gas in maser disks is currently not being probed; large maser gains favor paths that are characterized by a small velocity gradient and require rare edge-on orientations of the disk. Here we propose a method for mapping the atomic hydrogen distribution in nuclear disks through its 21cm absorption against the radio continuum glow around the central black hole. In NGC 4258, the 21cm optical depth may approach unity for high angular-resolution (VLBI) imaging of coherent clumps which are dominated by thermal broadening and have the column density inferred from X-ray absorption data, ~10^{23}/cm^2. Spreading the 21cm absorption over the full rotation velocity width of the material in front of the narrow radio jets gives a mean optical depth of ~0.1. Spectroscopic searches for the 21cm absorption feature in other galaxies can be used to identify the large population of inclined gaseous disks which are not masing in our direction. Follow-up imaging of 21cm silhouettes of accelerating clumps within these disks can in turn be used to measure cosmological distances.Comment: 4 page

First Detection of Millimeter/Submillimeter Extragalactic H2O Maser Emission

We report the first detection of an extragalactic millimeter wavelength H2O maser at 183 GHz towards NGC 3079 using the Submillimeter Array (SMA), and a tentative submillimeter wave detection of the 439 GHz maser towards the same source using the James Clerk Maxwell Telescope (JCMT). These H2O transitions are known to exhibit maser emission in star-forming regions and evolved stars. NGC 3079 is a well-studied nuclear H2O maser source at 22 GHz with a time-variable peak flux density in the range 3 -- 12 Jy. The 183 GHz H2O maser emission, with peak flux density $\sim$0.5 Jy (7$\sigma$ detection), also originates from the nuclear region of NGC 3079 and is spatially coincident with the dust continuum peak at 193 GHz (53 mJy integrated). Peak emission at both 183 and 439 GHz occurs in the same range of velocity as that covered by the 22 GHz spectrum. We estimate the gas to dust ratio of the nucleus of NGC 3079 to be $\approx$150, comparable to the Galactic value of 160. Discovery of maser emission in an active galactic nucleus beyond the long-known 22 GHz transition opens the possibility of future position-resolved radiative transfer modeling of accretion disks and outflows $<1$ pc from massive black holes.Comment: 12 pages, 3 figures, ApJ Letters accepte

Compassion, Dominance/Submission, and Curled Lips: A Thematic Analysis of Dacryphilic Experience

Paraphilias are often discussed in the psychological literature as pathological problems, yet relatively little research exists that looks into non-pathological paraphilias (i.e., non-normative sexual interests). Empirical evidence suggests that many individuals incorporate a range of non-normative sexual interests into their sexual lifestyles. Dacryphilia is a non-normative sexual interest that involves enjoyment or arousal from tears and crying, and to date has never been researched empirically. The present study set out to discover the different interests within dacryphilia and explore the range of dacryphilic experience. A set of online interviews was carried out with individuals with dacryphilic preferences and interests (six females and two males) from four countries. The data were analysed for semantic and latent themes using thematic analysis. The respondents' statements focused attention on three distinct areas that may be relevant to the experience of dacryphilia: (i) compassion; (ii) dominance/submission; and (iii) curled-lips. The data provided detailed descriptions of features within all three interests, which are discussed in relation to previous quantitative and qualitative research within emotional crying and tears, and the general area of non-normative sexual interests. The study suggests new directions for potential research both within dacryphilia and with regard to other non-normative sexual interests

A Survey for H2O Megamasers III. Monitoring Water Vapor Masers in Active Galaxies

We present single-dish monitoring of the spectra of 13 extragalactic water megamasers taken over a period of 9 years and a single epoch of sensitive spectra for 7 others. Our data include the first K-band science observations taken with the new 100 m Green Bank Telescope (GBT). In the context of a circumnuclear, molecular disk model, our results suggest that either (a) the maser lines seen are systemic features subject to a much smaller acceleration than present in NGC 4258, presumably because the gas is farther from the nuclear black hole, or (b) we are detecting ``satellite'' lines for which the acceleration is in the plane of the sky. We also report a search for water vapor masers towards the nuclei of 58 highly inclined, nearby galaxies.Comment: accepted by ApJ