Identification of the X-ray pulsar in Hercules: A new optical pulsar

A series of photographic, photoelectric, and spectroscopic observations beginning June 1, 1972 has led to the optical identification of Her X-1 (2U 1705 + 34), a pulsed X-ray source in an eclipsing binary system, with the thirteenth magnitude blue variable star HZ Herculis. The detection of optical pulses at the frequency of the X-ray pulsar on three nights makes the identification conclusive and establishes HZ Her as the second known optical pulsar. The strength of the optical pulses may be correlated with the orbital phase but is not obviously related to the high or low intensity states of the X-ray source

Infrared to Ultraviolet Wavelength-Dependent Variations Within the Pulse Profile Peaks of the Crab Nebula Pulsar

We present evidence of wavelength-dependent variations within the infrared, optical, and ultraviolet pulse profile peaks of the Crab Nebula pulsar. The leading and trailing edge half-width half-maxima of the peaks display clear differences in their wavelength dependences. In addition, phase-resolved infrared-to-ultraviolet color spectra show significant variations from the leading to trailing edges of the peaks. The color variations between the leading and trailing edges remain significant over phase differences smaller than 0.0054, corresponding to timescales of $<180 \mu$s. These results are not predicted by any current models of the pulsar emission mechanism and offer new challenges for the development of such models.Comment: 12 pages, 4 figure

The detection of aquatic animal species using environmental DNA – a review of eDNA as a survey tool in ecology

1. Knowledge of species distribution is critical to ecological management and conservation biology. Effective management requires the detection of populations, which can sometimes be at low densities and is usually based on visual detection and counting. 2. Recently, there has been considerable interest in the detection of short species-specific environmental DNA (eDNA) fragments to allow aquatic species monitoring within different environments due to the potential of greater sensitivity over traditional survey methods which can be time-consuming and costly. 3. Environmental DNA analysis is increasingly being used in the detection of rare or invasive species and has also been applied to eDNA persistence studies and estimations of species biomass and distribution. When combined with next-generation sequencing methods, it has been demonstrated that entire faunas can be identified. 4. Different environments require different sampling methodologies, but there remain areas where laboratory methodologies could be standardized to allow results to be compared across studies. 5. Synthesis and applications. We review recently published studies that use eDNA to moni- tor aquatic populations, discuss the methodologies used and the application of eDNA analysis as a survey tool in ecology. We include innovative ideas for how eDNA can be used for conservation and management citing test cases, for instance, the potential for on-site analyses, including the application of eDNA analysis to carbon nanotube platforms or laser transmission spectroscopy to facilitate rapid on-site detections. The use of eDNA monitoring is already being adopted in the UK for ecological surveys

Is T Leonis a superoutbursting intermediate polar?

We present an XMM-Newton analysis of the cataclysmic variable T Leo. The X-ray light curve shows sinusoidal variation on a period P_x equal to 0.89^{+0.14}_{-0.10} times the previously spectroscopically determined orbital period. Furthermore, we find a signal in the power spectrum at 414 sec that could be attributed to the spin period of the white dwarf. If true, T Leo would be the first confirmed superoutbursting intermediate polar IP). The spin profile is double-peaked with a peak separation of about 1/3 spin phases. This appears to be a typical feature for IPs with a small magnetic field and fast white dwarf rotation. An alternative explanation is that the 414 sec signal is a Quasi-periodic Oscillation (QPO) that is caused by mass transfer variation from the secondary, a bright region (``blob'') rotating in the disc at a radius of approximately ~9 Rwd or - more likely - a travelling wave close to the inner disc edge of a dwarf nova with a low field white dwarf. The XMM-Newton RGS spectra reveal double peaked emission for the O VIII Ly alpha line. Scenarios in the IP and dwarf nova model are discussed (an emitting ring in the disc, bright X-ray spot on disc edge, or emitting accretion funnels), but the intermediate polar model is favoured. Supported is this idea by the finding that only the red peak appears to be shifted and the `blue' peak is compatible with the rest wavelength. The red peak thus is caused by emission from the northern accretion spot when it faces the observer. Instead, the peak at the rest wavelength is caused when the southern accretion funnel is visible just on the lower edge of the white dwarf - with the velocity of the accreting material being perpendicular to the line of sight.Comment: 11 pages, 15 figures, accepted by A&

Observations of Six Glitches in PSR B1737-30

Six glitches have been recently observed in the rotational frequency of the young pulsar PSR B1737-30 (J1740-3015) using the 25-m Nanshan telescope of Urumqi Observatory. With a total of 20 glitches in 20 years, it is one of the most frequently glitching pulsars of the about 1750 known pulsars. Glitch amplitudes are very variable with fractional increases in rotation rate ranging from 10^{-9} to 10^{-6}. Inter-glitch intervals are also very variable, but no relationship is observed between interval and the size of the preceding glitch. There is a persistent increase in |\dot\nu|, opposite in sign to that expected from slowdown with a positive braking index, which may result from changes in the effective magnetic dipole moment of the star during the glitch.Comment: 7 pages, 10 figure

Observations of microglitches in HartRAO radio pulsars

A detailed observation of microglitch phenomenon in relatively slow radio pulsars is presented. Our analyses for these small amplitude jumps in pulse rotation frequency ($\nu$) and/or spin down rate ($\dot{\nu}$) combine the traditional manual detection method (which hinges on careful visual inspections of the residuals of pulse phase residuals) and a new, and perhaps more objective, automated search technique (which exploits the power of the computer, rather than the eyes, for resolving discrete events in pulsar spin parameters). The results of the analyses of a sample of 26 radio pulsars reveal that: (i) only 20 pulsars exhibit significant fluctuations in their arrival times to be considered suitable for meaningful microglitch analyses; (ii) a phenomenal 299 microglitch events were identified in $\nu$ and/or $\dot{\nu}$: 266 of these events were found to be simultaneously significant in $\nu$ and $\dot{\nu}$, while 19 and 14 were noticeable only in $\nu$ and $\dot{\nu}$, respectively; (iii) irrespective of sign, the microglitches have fractional sizes which cover about 3 orders of magnitude in $\nu$ and $\dot{\nu}$ ($10^{-11} < |\Delta{\nu}/\nu| < 2.0\times10^{-8}$ and $5.0\times10^{-5} < |\Delta{\dot{\nu}}/\dot{\nu}| < 2.0\times10^{-2}$) with median values as $0.78\times10^{-9}$ and $0.36\times10^{-3}$, respectively.Comment: 12 pages, 3 figures, 2 Tables. Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa

The application of eDNA for monitoring of the great crested newt in the UK

Current ecological surveys for great crested newts are time-consuming and expensive and can only be carried out within a short survey window. Additional survey methods which would facilitate the detection of rare or protected species such as the great crested newt (Triturus cristatus) would be extremely advanta- geous. Environmental DNA (eDNA) analysis has been utilized for the detection of great crested newts in Denmark. Here, the same methodology has been applied to water samples taken from UK ponds concurrently with conventional field surveying techniques. Our eDNA analysis exhibited an 84% success rate with a kappa coefficient of agreement between field and eDNA surveys of 0.86. One pond determined to be negative for great crested newt by field survey was positive by eDNA analysis, revealing the potential for improved detection rates using this methodology. Analysis of water samples collected in late summer indicates that eDNA analysis could be used to detect great crested newt after the optimal survey window for current field techniques had passed. Conse- quently, eDNA analysis could augment currently stipulated techniques for great crested newt surveying as a relatively quick and inexpensive tool for collecting great crested newt presence and distribution data within the UK instead of or prior to full field surveys

Discovery of an Ultra-fast X-ray Pulsar in the Supernova Remnant N157B

We present the serendipitous discovery of 16 ms pulsed X-ray emission from the Crab-like supernova remnant N157B in the Large Magellanic Cloud. This is the fastest spinning pulsar associated with a supernova remnant (SNR). Observations with the Rossi X-ray Timing Explorer (RXTE), centered on the field containing SN1987A, reveal an X-ray pulsar with a narrow pulse profile. Archival ASCA X-ray data confirm this detection and locate the pulsar within 1' of the supernova remnant N157B, 14' from SN1987A. The pulsar manifests evidence for glitch(es) between the RXTE and ASCA observations which span 3.5 years; the mean linear spin-down rate is Pdot = 5.126 X 10E-14 s/s. The background subtracted pulsed emission is similar to other Crab-like pulsars with a power law of photon index of ~ 1.6. The characteristic spin-down age (~ 5000 years) is consistent with the previous age estimate of the SNR. The inferred B-field for a rotationally powered pulsar is ~ 1 X 10E12 Gauss. Our result confirms the Crab-like nature of N157B; the pulsar is likely associated with a compact X-ray source revealed by ROSAT HRI observations.Comment: 9 pages with 3 eps figure, LaTex (aas2pp2, psfig). Submitted to the Astrophysical Journal Letter

The application of eDNA for monitoring of the great crested newt in the UK

Current ecological surveys for great crested newts are time-consuming and expensive and can only be carried out within a short survey window. Additional survey methods which would facilitate the detection of rare or protected species such as the great crested newt (Triturus cristatus) would be extremely advanta- geous. Environmental DNA (eDNA) analysis has been utilized for the detection of great crested newts in Denmark. Here, the same methodology has been applied to water samples taken from UK ponds concurrently with conventional field surveying techniques. Our eDNA analysis exhibited an 84% success rate with a kappa coefficient of agreement between field and eDNA surveys of 0.86. One pond determined to be negative for great crested newt by field survey was positive by eDNA analysis, revealing the potential for improved detection rates using this methodology. Analysis of water samples collected in late summer indicates that eDNA analysis could be used to detect great crested newt after the optimal survey window for current field techniques had passed. Conse- quently, eDNA analysis could augment currently stipulated techniques for great crested newt surveying as a relatively quick and inexpensive tool for collecting great crested newt presence and distribution data within the UK instead of or prior to full field surveys