Revealing New Physical Structures in the Supernova Remnant N63A through Chandra Imaging Spectroscopy

We present Chandra X-ray observations of the supernova remnant (SNR) N63A in the Large Magellanic Cloud (LMC). N63A, one of the brightest LMC remnants, is embedded in an H II region and probably associated with an OB association. The optical remnant consists of three lobes of emission contained within the approximately three times larger X-ray remnant. Our Chandra data reveal a number of new physical structures in N63A. The most striking of these are the several ``crescent''-shaped structures located beyond the main shell that resemble similar features seen in the Vela SNR. In Vela, these have been interpreted as arising from high speed clumps of supernova ejecta interacting with the ambient medium. Another distinct feature of the remnant is a roughly triangular ``hole'' in the X-ray emission near the location of the optical lobes and the brightest radio emission. X-ray spectral analysis shows that this deficit of emission is a result of absorption by an intervening dense cloud with a mass of ~450 M_sun that is currently being engulfed by the remnant's blast wave. We also find that the rim of the remnant, as well as the crescent-shaped features, have considerably softer X-ray spectra than the interior. Limits on hard X-ray emission rule out a young, energetic pulsar in N63A, but the presence of an older or less active one, powering a wind nebula with a luminosity less than ~4e10^34 erg/s, is allowed.Comment: 18 pages, 5 figures (2 color), accepted for publication in Ap

Association of CD69 Up-Regulation on CD4+ CLA+ T cells versus patch test, strip patch test and clinical history in nickel sensitization

<p>Abstract</p> <p>Objective</p> <p>The patch test (PT) with its modification - the strip patch test (SPT) - is the standard in vivo procedure to diagnose an allergic contact dermatitis (ACD). To date, none of the in vitro tests for the diagnosis of ACD fulfils the requirements of an easy, valid and reliable test. To investigate the prediction ability of a flow cytometric assay of CD69 up-regulation on CD4+ CLA+ T cells in nickel-sensitive and non-nickel-sensitive patients.</p> <p>Methods</p> <p>In a prospective, investigator-blinded, clinical study a total of 85 nickel-sensitive (n = 44; 51.8%) and non-nickel-sensitive patients (n = 41; 48.2%) were enrolled. The association between CD69 up-regulation on CD4+ CLA+ T cells on the one hand and PT, SPT, and clinical history on the other hand was measured. Association is expressed with c statistic values (receiver operating characteristic analysis) and corresponding 95% CIs.</p> <p>Results</p> <p>The associations were c = 0.57 (95% CI: 0.42-0.72) between CD69 up-regulation and PT, c = 0.49 (95% CI: 0.36-0.62) between CD69 up-regulation and SPT, and c = 0.51 (95% CI: 0.37-0.64) between CD69 up-regulation and clinical history.</p> <p>Conclusions</p> <p>CD69 up-regulation on CD4+ CLA+ T cells in vitro could not predict neither a positive PT or SPT result nor a positive clinical history to nickel sulfate. The combination of clinical history and patch testing still remains the basis for diagnosing ACD.</p

Discovery of Radio/X-ray/Optical Resolved Supernova Remnants in the Center of the Andromeda Galaxy

We have detected a spatially resolved supernova remnant (SNR) in the center of the Andromeda Galaxy, in radio, X-ray, and optical wavelengths. These observations provide the highest spatial resolution imaging of a radio/X-ray/optical SNR in that galaxy to date. The multi-wavelength morphology, radio spectral index, X-ray colors, and narrow-band optical imaging are consistent with a shell-type SNR. A second SNR is also seen resolved in both radio and X-ray. By comparing the morphological sturcture of the SNRs in different wavelengths and with that in our own Galaxy, we can study the shock morphologies of SNRs in the Andromeda Galaxy. The proximity of the SNRs to the core suggests high interstellar medium density in the vicinity of the SNRs in the center of the Andromeda Galaxy.Comment: 5 pages, 3 figures, accepted for publication in ApJ

In which shell-type SNRs should we look for gamma-rays and neutrinos from p-p collisions?

We present a simple analytic model for the various contributions to the non-thermal emission from shell type SNRs, and show that this model's results reproduce well the results of previous detailed calculations. We show that the \geq 1 TeV gamma ray emission from the shell type SNRs RX J1713.7-3946 and RX J0852.0-4622 is dominated by inverse-Compton scattering of CMB photons (and possibly infra-red ambient photons) by accelerated electrons. Pion decay (due to proton-proton collisions) is shown to account for only a small fraction, \lesssim10^-2, of the observed flux, as assuming a larger fractional contribution would imply nonthermal radio and X-ray synchrotron emission and thermal X-ray Bremsstrahlung emission that far exceed the observed radio and X-ray fluxes. Models where pion decay dominates the \geq 1 TeV flux avoid the implied excessive synchrotron emission (but not the implied excessive thermal X-ray Bremsstrahlung emission) by assuming an extremely low efficiency of electron acceleration, K_ep \lesssim 10^-4 (K_ep is the ratio of the number of accelerated electrons and the number of accelerated protons at a given energy). We argue that observations of SNRs in nearby galaxies imply a lower limit of K_ep \gtrsim 10^-3, and thus rule out K_ep values \lesssim 10^-4 (assuming that SNRs share a common typical value of K_ep). It is suggested that SNRs with strong thermal X-ray emission, rather than strong non-thermal X-ray emission, are more suitable candidates for searches of gamma rays and neutrinos resulting from proton-proton collisions. In particular, it is shown that the neutrino flux from the SNRs above is probably too low to be detected by current and planned neutrino observatories (Abridged).Comment: 13 pages, 1 figure, accepted for publication in JCAP, minor revision

Structure of W3(OH) from Very High Spectral Resolution Observations of 5 Centimeter OH Masers

Recent studies of methanol and ground-state OH masers at very high spectral resolution have shed new light on small-scale maser processes. The nearby source W3(OH), which contains numerous bright masers in several different transitions, provides an excellent laboratory for high spectral resolution techniques. We present a model of W3(OH) based on EVN observations of the rotationally-excited 6030 and 6035 MHz OH masers taken at 0.024 km/s spectral resolution. The 6.0 GHz masers are becoming brighter with time and show evidence for tangential proper motions. We confirm the existence of a region of magnetic field oriented toward the observer to the southeast and find another such region to the northeast in W3(OH), near the champagne flow. The 6.0 GHz masers trace the inner edge of a counterclockwise rotating torus feature. Masers at 6030 MHz are usually a factor of a few weaker than at 6035 MHz but trace the same material. Velocity gradients of nearby Zeeman components are much more closely correlated than in the ground state, likely due to the smaller spatial separation between Zeeman components. Hydroxyl maser peaks at very long baseline interferometric resolution appear to have structure on scales both smaller than that resolvable as well as on larger scales.Comment: 21 pages using emulateapj.cls including 16 figures and 2 tables, accepted to Ap

On the Origin of Asymmetries in Bilateral Supernova Remnants

AIMS: We investigate whether the morphology of bilateral supernova remnants (BSNRs) observed in the radio band is determined mainly either by a non-uniform interstellar medium (ISM) or by a non-uniform ambient magnetic field. METHODS: We perform 3-D MHD simulations of a spherical SNR shock propagating through a magnetized ISM. Two cases of shock propagation are considered: 1) through a gradient of ambient density with a uniform ambient magnetic field; 2) through a homogeneous medium with a gradient of ambient magnetic field strength. From the simulations, we synthesize the synchrotron radio emission, making different assumptions about the details of acceleration and injection of relativistic electrons. RESULTS: We find that asymmetric BSNRs are produced if the line-of-sight is not aligned with the gradient of ambient plasma density or with the gradient of ambient magnetic field strength. We derive useful parameters to quantify the degree of asymmetry of the remnants that may provide a powerful diagnostic of the microphysics of strong shock waves through the comparison between models and observations. CONCLUSIONS: BSNRs with two radio limbs of different brightness can be explained if a gradient of ambient density or, most likely, of ambient magnetic field strength is perpendicular to the radio limbs. BSNRs with converging similar radio arcs can be explained if the gradient runs between the two arcs.Comment: 14 pages, 8 Figures; paper accepted for publication in A&A; the paper with high-resolution figures can be downloaded at http://www.astropa.unipa.it/~orlando/PAPERS/sorlando_6045.pd

An X-Ray Study of Supernova Remnant N49 and Soft Gamma-Ray Repeater 0526-66 in the Large Magellanic Cloud

We report on the results from our deep Chandra observation (120 ks) of the supernova remnant (SNR) N49 and soft Gamma-ray repeater (SGR) 0526-66 in the Large Magellanic Cloud. We firmly establish the detection of an ejecta "bullet" beyond the southwestern boundary of N49. The X-ray spectrum of the bullet is distinguished from that of the main SNR shell, showing significantly enhanced Si and S abundances. We also detect an ejecta feature in the eastern shell, which shows metal overabundances similar to those of the bullet. If N49 was produced by a core-collapse explosion of a massive star, the detected Si-rich ejecta may represent explosive O-burning or incomplete Si-burning products from deep interior of the supernova. On the other hand, the observed Si/S abundance ratio in the ejecta may favor Type Ia origin for N49. We refine the Sedov age of N49, tau_Sed ~ 4800 yr, with the explosion energy E_0 ~ 1.8 x 10^51 erg. Our blackbody (BB) + power law (PL) model for the quiescent X-ray emission from SGR 0526-66 indicates that the PL photon index (Gamma ~ 2.5) is identical to that of PSR 1E1048.1-5937, the well-known candidate transition object between anomalous X-ray pulsars and SGRs. Alternatively, the two-component BB model implies X-ray emission from a small (R ~ 1 km) hot spot(s) (kT ~ 1 keV) in addition to emission from the neutron star's cooler surface (R ~ 10 km, kT ~ 0.4 keV). There is a considerable discrepancy in the estimated column toward 0526-66 between BB+PL and BB+BB model fits. Discriminating these spectral models would be crucial to test the long-debated physical association between N49 and 0526-66.Comment: Accepted by ApJ, 27 pages in total (aastex preprint format) including 5 figures (4 in color) and 5 table

Effects of non-uniform interstellar magnetic field on synchrotron X-ray and inverse-Compton gamma-ray morphology of SNRs

Observations of SNRs in X-ray and gamma-ray bands promise to contribute with important information in our understanding on the nature of galactic cosmic rays. The analysis of SNRs images collected in different energy bands requires the support of theoretical modeling of synchrotron and inverse Compton (IC) emission. We develop a numerical code (REMLIGHT) to synthesize, from MHD simulations, the synchrotron radio, X-ray and IC gamma-ray emission from SNRs expanding in non-uniform interstellar medium (ISM) and/or non-uniform interstellar magnetic field (ISMF). As a first application, the code is used to investigate the effects of non-uniform ISMF on the SNR morphology in the non-thermal X-ray and gamma-ray bands. We perform 3D MHD simulations of a spherical SNR shock expanding through a magnetized ISM with a gradient of ambient magnetic field strength. The model includes an approximate treatment of upstream magnetic field amplification and the effect of shock modification due to back reaction of accelerated cosmic rays. From the simulations, we synthesize the synchrotron radio, X-ray and IC gamma-ray emission with REMLIGHT, making different assumptions about the details of acceleration and injection of relativistic electrons. A gradient of the ambient magnetic field strength induces asymmetric morphologies in radio, X-ray and gamma-ray bands independently from the model of electron injection if the gradient has a component perpendicular to the line-of-sight. The degree of asymmetry of the remnant morphology depends on the details of the electron injection and acceleration and is different in the radio, X-ray, and gamma-ray bands. The non-thermal X-ray morphology is the most sensitive to the gradient, showing the highest degree of asymmetry. The IC gamma-ray emission is weakly sensitive to the non-uniform ISMF, the degree of asymmetry of the SNR morphology being the lowest in this band.Comment: 16 pages, 13 Figures; accepted for publication on A&A. Version with full resolution images can be found at http://www.astropa.unipa.it/~orlando/PREPRINTS/sorlando_15505.pd

Wooden breast e white striping : ocorrência em três empresas avícolas

To increase the amount of meat produced, researchers have promoted intensive genetic selection for growth rate and muscling and have improved nutrition and management conditions. However, there has been an increase in the number of reports of breast muscle myopathies observed in poultry processing plants, including white striping (WS) and wooden breast (WB). This study aimed to evaluate and to compare the occurrence of WS and WB myopathies in three poultry processing plants and to perform an anatomopathological characterization, including macroscopic and microscopic analyses. A total of 408,334 carcasses were condemned or downgraded due to the presence of WB or WS, which represents 0.73% of the total number of slaughtered animals during the evaluated period. WB was more frequent than WS, but the occurrence of each myopathy varied significantly according to each establishment. WB was more frequent in the establishment which includes only male flocks, an average age of 45 days, and an average live weight of 2775g (B). WS was more frequent in establishment with male, female and mixed flocks, average ages ranging from 41 to 44 days, and average live weight 1731g-2830g (A). It is probably related with specific condition of each poultry company, including genetics, age, nutrition and management conditions. Macroscopically, WB and WS lesions are characterized by hypertrophy and stiffness of the pectoralis major muscle. Under microscopy, the myopathies showed similarities regarding the detected histological abnormalities, characterized by a process of myodegeneration, although the connective tissue infiltrate was more severe in the breasts with WB than in those with WS myopathy. The results found in this study demonstrate that the rates of condemnation for these myopathies are high, vary significantly among the analyzed companies and may cause major economic losses for the productive sector in the region.Para melhorar a quantidadede carne produzida, os pesquisadores têm promovido ao longo dos anos uma seleção genética intensiva para a taxa de crescimento e desenvolvimento de músculos, além de melhorias nas condições nutricionais, sanitárias e de manejo. No entanto, houve um aumento no número de relatos de miopatias dos músculos do peito observados em abatedouros-frigoríficos de aves, incluindo white striping (WS) e wooden breast (WB). O objetivo deste estudo foi avaliar a ocorrência de WB e WS em três abatedouros-frigoríficos de aves e realizar uma caracterização anatomopatológica, incluindo análises macroscópicas e microscópicas. Um total de 408.334 carcaças foi condenado (total ou parcialmente) devido à presença WB ou WS, o que representou 0,73% do número total de animais abatidos durante o período avaliado. Apesar de a ocorrência de WB ter sido maior do que a de WS, a frequência de cada uma variou significativamente de acordo com o estabelecimento. WB foi mais frequente no estabelecimento que incluía apenas lotes de machos, com média de 45 dias de idade e peso médio ao abate de 2775g (B). WS foi mais frequente no estabelecimento com lotes de machos, fêmeas e mistos, com idade entre 41 e 44 dias e peso médio ao abate entre 1731g-2830g (A). Isto pode ser justificado por condições específicas de cada empresa, incluindo genética, idade das aves, nutrição e condições de manejo. Macroscopicamente, as lesões de WB e de WS foram caracterizadas principalmente por hipertrofia e rigidez do músculo pectoralis major. À microscopia, ambas as miopatias mostraram semelhanças em relação às anormalidades histológicas detectadas, caracterizadas principalmente por um processo de miodegeneração. Nos músculos apresentando WB, o infiltrado de tecido conjuntivo foi mais intenso quando comparado àqueles com WS. Os resultados encontrados neste trabalho demonstram que os índices de condenação por essas miopatias são altos, variam significativamente entre as empresas analisadas e podem causar grandes perdas econômicas para o setor produtivo da região

The Cygnus X region XXII. A probable HAeBe star with a giant bipolar outflow in DR 16

From medium-resolution radio images, DR 16 was suspected to be a large cometary nebula. To test this suggestion we obtained a higher resolution (15\arcsec) VLA continuum map. We also analyzed data from the Canadian Galactic Plane Survey in continuum, H I line, and IR. These data were supplemented by published near-infrared (J, H, K) stellar photometric results and MSX 8.28 micrometer data. We suggest that DR 16 is the diffuse H II region of an ongoing star formation site at a distance of about 3 kpc. The complicated radio picture arises from the superposition of diffuse H II with the remains of a giant bipolar outflow. The outflow was generated by a probable Herbig AeBe star, and the lobes are the remnants of its working surfaces. Additional ring-like features are discussed. DR 16 is part of a larger volume of space in the local spiral arm where star formation is an ongoing process.Comment: 15 pages, 14 figures, accepted by A&