NIR and optical observations of the failed outbursts of black hole binary XTE J1550-564

A number of low mass X-ray binaries (LMXBs) undergo "failed outbursts" in which, instead of evolving through the canonical states, they remain in a hard state throughout the outburst. While the sources of X-ray and radio emission in the hard state are relatively well understood, the origin of the near infrared (NIR) and optical emission is more complex though it likely stems from an amalgam of different emission processes, occurring as it does, at the intersecting wavelengths of those processes. We aim to identify the NIR/optical emission region(s) during a number of failed outbursts of one such low mass X-ray binary and black hole candidate, XTE J1550-564, in order to confirm or refute their classification as hard-state, failed outbursts. We present unique NIR/optical images and spectra, obtained with the ESO-New Technology Telescope, during the failed outbursts of 2001 and 2000. We compare the NIR/optical photometric, timing, and spectral properties with those expected for the different emission mechanisms in the various LMXB states. The NIR/optical data are consistent with having come from reprocessing of X-rays in the accretion disk, with no evidence of direct thermal emission from the disk itself. However, the observed variability in high-cadence NIR light curves suggest that the radio jet extends and contributes to the NIR wavelengths. We find that these failed outbursts did not transition to an intermediate state but remained in a true, hard state where there was no sign of jet quenching or deviation from the observed hard state correlations.Comment: Accepted to Astronomy & Astrophysics (8 pages

Development of LANDSAT Derived Forest Cover Information for Integration into Adirondack Park GIS

Based upon observed changes in timber harvest practices partially attributable to forest biomass removable for energy supply purposes, the Adirondack Park Agency began in 1979 a multi-year project to implement a digital geographic information system (GIS). An initial developmental task was an inventory of forest cover information and analysis of forest resource change and availability. While developing the GIS, a pilot project was undertaken to evaluate the usefulness of LANDSAT derived land cover information for this purpose, and to explore the integration of LANDSAT data into the GIS. The prototype LANDSAT analysis project involved: (1) the use of both recent and historic data to derive land cover information for two dates; and (2) comparison of land cover over time to determine quantitative and geographic changes. The "recent data," 1978 full foliage data over portions of four LANDSAT scenes, was classified, using ground truth derived training samples in various forested and non-forested categories. Forested categories include the following: northern hardwoods, pine, spruce-fir, and pine plantation, while nonforested categories include wet-conifer, pasture, grassland, urban, exposed soil, agriculture, and water

Stereoisomer libraries: Total synthesis of all 16 stereoisomers of the pine sawfly sex pheromone by a fluorous mixture-synthesis approach

All 16 stereoisomers of the sex pheromone of pine sawfly (3,7,11-trimethylundecanol propanoate ester) have been synthesized on a 10- to 20-mg scale by a split-parallel fluorous mixture-synthesis approach. Spectral data obtained for all 32 compounds (16 alcohols and the corresponding propionates) matched well with published data, thereby validating the fluorous-tag encoding of diastereoisomers. This fluorous-tag encoding method is recommended for the efficient synthesis of multiple stereoisomers for spectroscopic studies, biological tests, or other structure-function relationships

A search for near infrared counterparts of 3 pulsar wind nebulae

While pulsar wind nebulae (PWNe) and their associated isolated pulsars are commonly detected at X-ray energies, they are much rarer at near infrared (nIR) and optical wavelengths. Here we examine three PWN systems in the Galactic plane - IGR J14003-6326, HESS J1632-478 and IGR J18490-0000 - in a bid to identify optical/nIR emission associated with either the extended PWNe or their previously detected X-ray point sources. We obtain optical/nIR images of the three fields with the ESO - New Technology Telescope and apply standard photometric and astrometric calibrations. We find no evidence of any extended emission associated with the PWNe in any of the fields; neither do we find any new counterparts to the X-ray point sources, except to confirm the magnitude of the previously identified counterpart candidate of IGR J18490-0000. Further observations are required to confirm the association of the nIR source to IGR J18490-0000 and to detect counterparts to IGR J14003-6326 and HESS J1632-478, while a more accurate X-ray position is required to reduce the probability of a chance superposition in the field of the latter.Comment: Accepted to A&A (4 pages, 1 figure

Observed Faraday Effects in Damped Lyman-Alpha Absorbers and Lyman Limit Systems: The Magnetised Environment of Galactic Building Blocks at Redshift=2

Protogalactic environments are typically identified using quasar absorption lines, and these galactic building blocks can manifest as Damped Lyman-Alpha Absorbers (DLAs) and Lyman Limit Systems (LLSs). We use radio observations of Faraday effects to test whether DLAs and LLSs host a magnetised medium, by combining DLA and LLS detections throughout the literature with 1.4 GHz polarization data from the NRAO VLA Sky Survey (NVSS). We obtain a control, a DLA, and a LLS sample consisting of 114, 19, and 27 lines-of-sight respectively - all of which are polarized at $\ge8\sigma$ to ensure Rician bias is negligible. Using a Bayesian framework, we are unable to detect either coherent or random magnetic fields in DLAs: the regular coherent magnetic fields within the DLAs must be $\le2.8$ $\mu$G, and the lack of depolarization is consistent with the weakly magnetised gas in DLAs being non-turbulent and quiescent. However, we find mild suggestive evidence that LLSs have coherent magnetic fields: after controlling for the redshift-distribution of our data, we find a 71.5% probability that LLSs have a higher RM than a control sample. We also find strong evidence that LLSs host random magnetic fields, with a 95.5% probability that LLS lines-of-sight have lower polarized fractions than a control sample. The regular coherent magnetic fields within the LLSs must be $\le2.4$ $\mu$G, and the magnetised gas must be highly turbulent with a typical scale on the order of $\approx5$-20 pc, which is similar to that of the Milky Way. This is consistent with the standard dynamo pedagogy, whereby magnetic fields in protogalaxies increase in coherence and strength as a function of cosmic time. Our results are consistent with a hierarchical galaxy formation scenario, with the DLAs, LLSs, and strong magnesium II (MgII) systems exploring three different stages of magnetic field evolution in galaxies.Comment: Submitted to Ap

Muon-spin rotation measurements of the vortex state in Sr2_2RuO4_4: type-1.5 superconductivity, vortex clustering and a crossover from a triangular to a square vortex lattice

Muon-spin rotation has been used to probe vortex state in Sr$_2$RuO$_4$. At moderate fields and temperatures a lattice of triangular symmetry is observed, crossing over to a lattice of square symmetry with increasing field and temperature. At lower fields it is found that there are large regions of the sample that are completely free from vortices which grow in volume as the temperature falls. Importantly this is accompanied by {\it increasing} vortex density and increasing disorder within the vortex-cluster containing regions. Both effects are expected to result from the strongly temperature-dependent long-range vortex attractive forces arising from the multi-band chiral-order superconductivity.Comment: 13 pages, 4 figure

Detection of broad 21-cm absorption at z = 0.656 in the complex sight-line towards 3C336

We report the detection of 21-cm absorption at z = 0.656 towards 1622+238 (3C336). The line is very broad with a Full-Width Half Maximum (FWHM) of 235 km/s, giving a velocity integrated optical depth of 2.2 km/s. The centroid of the line is offset from that of the known damped Lyman-alpha absorption (DLA) system by 50 km/s, and if the Lyman-alpha and 21-cm absorption are due to the same gas, we derive a spin temperature of < 60 K, which would be the lowest yet in a DLA. The wide profile, which is over four times wider than that of any other DLA, supports the hypothesis that the hydrogen absorption is occurring either in the disk of a large underluminous spiral or a group of dim unidentified galaxies, associated with the single object which has been optically identified at this redshift.Comment: 5 pages, 3 figures, accepted by MNRAS Letter