2FGL J0846.0+2820: A new neutron star binary with a giant secondary and variable γ\gamma-ray emission

We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated \emph{Fermi}-Large Area Telescope (LAT) $\gamma$-ray source 2FGL J0846.0+2820, selected for study based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric ($e$ = 0.06) 8.133 day orbit with an invisible primary. Modeling the spectroscopy and photometry together lead us to infer a heavy neutron star primary of $\sim 2 M_{\odot}$ and a partially stripped giant secondary of $\sim 0.8 M_{\odot}$. H$\alpha$ emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find the $\gamma$-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then it has not been detected by \emph{Fermi}. The long period and giant secondary are reminiscent of the $\gamma$-ray bright binary 1FGL J1417.7--4407, which hosts a millisecond pulsar apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of millisecond pulsar binaries that are the likely progenitors of typical field millisecond pulsars.Comment: 12 pages, 8 figures, 3 tables. Accepted for publication in Ap

UGPS J194310+183851 : an Unusual Optical and X-ray Faint Cataclysmic Variable?

©2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is the final published pdf, which was originally published at https://doi.org/10.1093/mnras/stac1718 Funding Information: We acknowledge the use of public data from the Swift data archive. We also acknowledge the use of the WHT: the William Herschel Telescope and its service programme are operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. We would like to thank the operations teams at both facilities for the quick and efficient observations. CM acknowledges support from the UK's Science and Technology Facilities Council (ST/S505419/1). NM and WJC are funded by University of Hertfordshire studentships; furthermore CM, PWL, NM, WJC, ZG, and JED recognize the computing infrastructure provided via STFC grant ST/R000905/1 at the University of Hertfordshire. JS acknowledges support from the P ackard F oundation and National Science Foundation grant AST-1714825. Portions of this work were performed while SJS held a NRC Research Associateship award at the Naval Research Laboratory. Work at the Naval Research Laboratory is supported by NASA DPR S-15633-Y. ZG acknowledges the financial support from ANID (CONICYT) through the FONDECYT project No. 3220029. Publisher Copyright: © 2022 The Author(s).The growing number of multi-epoch optical and infrared sky surveys are uncovering unprecedented numbers of new variable stars, of an increasing number of types. The short interval between observations in adjacent near-infrared filters in the UKIDSS Galactic Plane Survey (UGPS) allows for the discovery of variability on the time-scale of minutes. We report on the nature of one such object, through the use of optical spectroscopy, time series photometry, and targeted X-ray observations. We propose that UGPS J194310.32+183851.8 is a magnetic cataclysmic variable star of novel character, probably featuring a longer than average spin period and an orbital period likely to be shorter than the period gap (i.e. Porb < 2 h). We reason that the star is likely a member of the short-period intermediate-polar subclass that exists below this period boundary, but with the additional feature that system's spectral energy distribution is fainter and redder than other members of the group.Peer reviewe

Zurek-Kibble domain structures: The Dynamics of Spontaneous Vortex formation in Annular Josephson Tunnel Junctions

Phase transitions executed in a finite time show a domain structure with defects, that has been argued by Zurek and Kibble to depend in a characteristic way on the quench rate. In this letter we present an experiment to measure the Zurek-Kibble scaling exponent sigma. Using symmetric and long Josephson Tunnel Junctions, for which the predicted index is sigma = 0.25, we find sigma = 0.27 +/- 0.05. Further, there is agreement with the ZK prediction for the overall normalisation.Comment: To be published in Phys. Rev. Lett

Electronic density of states derived from thermodynamic critical field curves for underdoped La-Sr-Cu-O

Thermodynamic critical field curves have been measured for $La_{2-x}Sr_{x}CuO_{4+\delta}$ over the full range of carrier concentrations where superconductivity occurs in order to determine changes in the normal state density of states with carrier concentration. There is a substantial window in the $H-T$ plane where the measurements are possible because the samples are both thermodynamically reversible and the temperature is low enough that vortex fluctuations are not important. In this window, the data fit Hao-Clem rather well, so this model is used to determine $H_c$ and $\kappa_c$ for each temperature and carrier concentration. Using N(0) and the ratio of the energy gap to transition temperature, $\Delta (0)/k_BT_c$, as fitting parameters, the $H_c vs T$ curves give $\Delta (0)/k_BT_c \sim 2.0$ over the whole range of $x$. Values of N(0) remain rather constant in the optimum-doped and overdoped regime, but drops quickly toward zero in the underdoped regime.

Strong Electron-Phonon Coupling in Superconducting MgB2_2: A Specific Heat Study

We report on measurements of the specific heat of the recently discovered superconductor MgB$_2$ in the temperature range between 3 and 220 K. Based on a modified Debye-Einstein model, we have achieved a rather accurate account of the lattice contribution to the specific heat, which allows us to separate the electronic contribution from the total measured specific heat. From our result for the electronic specific heat, we estimate the electron-phonon coupling constant $\lambda$ to be of the order of 2, significantly enhanced compared to common weak-coupling values $\leq 0.4$. Our data also indicate that the electronic specific heat in the superconducting state of MgB$_2$ can be accounted for by a conventional, s-wave type BCS-model.Comment: 4 pages, 4 figure

First experimental evidence of one-dimensional plasma modes in superconducting thin wires

We have studied niobium superconducting thin wires deposited onto a SrTiO$_{3}$ substrate. By measuring the reflection coefficient of the wires, resonances are observed in the superconducting state in the 130 MHz to 4 GHz range. They are interpreted as standing wave resonances of one-dimensional plasma modes propagating along the superconducting wire. The experimental dispersion law, $\omega$ versus $q$, presents a linear dependence over the entire wave vector range. The modes are softened as the temperature increases close the superconducting transition temperature. Very good agreement are observed between our data and the dispersion relation predicted by Kulik and Mooij and Sch\"on.Comment: Submitted to Physical review Letter

EVALUATION OF ANTHELMINTIC FISHMEAL POLYMER BAITS FOR THE CONTROL OF \u3ci\u3eBAYLISASCARIS PROCYONIS\u3c/i\u3e IN FREE-RANGING RACCOONS (\u3ci\u3ePROCYON LOTOR\u3c/i\u3e)

Baylisascaris procyonis is a common gastrointestinal parasite of raccoons (Procyon lotor) and is a zoonotic helminth with the potential to cause severe or fatal infection. Raccoons thrive in human-dominated landscapes, and the fecal-oral transmission pathway and lack of effective treatment make B. procyonis a serious threat to public health. The distribution of medicinal baits has emerged as a socially acceptable and cost-effective method for managing disease in free-ranging wildlife. We assessed the suitability of a mass-producible anthelmintic bait for B. procyonis mitigation by evaluating the willingness of free-ranging raccoons to consume anthelmintic baits and determining whether bait consumption successfully cleared B. procyonis infections from raccoons. Anthelmintic baits were modified from standard fishmeal polymer baits, the food attractant commonly used in oral rabies vaccine baits, with the introduction of 220 mg of pyrantel pamoate into the fishmeal mixture. We captured 16 naturally infected raccoons, presented one anthelmintic bait, and monitored B. procyonis infection over 90 d by screening feces for eggs. Treatment cleared B. procyonis infections for nine of 12 raccoons that consumed \u3e10 g of the 15 g bait. We used remote cameras to monitor in situ patterns of bait consumption for anthelmintic baits relative to standard baits. Both anthelmintic and standard baits were rapidly consumed, with no differences in the rate of consumption between bait types. However, after bait contact, raccoons demonstrated a greater willingness to consume standard baits while ignoring anthelmintic baits more frequently (P=0.06). Initial trials of anthelmintic baits show promise, although refinement in both dose and palatability is needed. At mass production scales, the addition of pyrantel pamoate to fishmeal polymer baits would be inexpensive, potentially making anthelmintic baits a viable management option when coupled with an oral rabies vaccine or used independently for B. procyonis mitigation