The pulvinar sign refers to exclusive T1WI hyperintensity of the lateral pulvinar. Long considered a common sign of Fabry disease, the pulvinar sign has been reported in many pathologic conditions. ...The exact incidence of the pulvinar sign has never been tested in representative cohorts of patients with Fabry disease. The aim of this study was to assess the prevalence of the pulvinar sign in Fabry disease by analyzing T1WI in a large Fabry disease cohort, determining whether relaxometry changes could be detected in this region independent of the pulvinar sign positivity.
We retrospectively analyzed brain MR imaging of 133 patients with Fabry disease recruited through specialized care clinics. A subgroup of 26 patients underwent a scan including 2 FLASH sequences for relaxometry that were compared with MRI scans of 34 healthy controls.
The pulvinar sign was detected in 4 of 133 patients with Fabry disease (3.0%). These 4 subjects were all adult men (4 of 53, 7.5% of the entire male population) with renal failure and under enzyme replacement therapy. When we tested for discrepancies between Fabry disease and healthy controls in quantitative susceptibility mapping and relaxometry maps, no significant difference emerged for any of the tested variables.
The pulvinar sign has a significantly lower incidence in Fabry disease than previously described. This finding, coupled with a lack of significant differences in quantitative MR imaging, allows hypothesizing that selective involvement of the pulvinar is a rare neuroradiologic sign of Fabry disease.
Context. The ~1700 year old PSR B0540−69 in the Large Magellanic Clouds (LMC) is considered the twin of the Crab pulsar because of its similar spin parameters, magnetic field, and energetics. ...PSR B0540−69 (V ~ 22.5) is also one of the very few pulsars for which both optical pulsations and polarised emission have been measured. Its optical spectrum is fit by a power-law, ascribed to synchrotron radiation, like for the young Crab and Vela pulsars. At variance with them, however, a double break is required to join the X-ray and optical power-law spectra, with the first one possibly occurring in the near ultraviolet (nUV). Aims. Near-infrared (nIR) observations, never performed for PSR B0540−69, are crucial to determine whether the optical power-law spectrum extends to longer wavelengths or a new break occurs, like it happens for both the Crab and Vela pulsars in the mid-infrared (mIR), hinting at an even more complex particle energy and density distribution in the pulsar magnetosphere. Methods. We observed PSR B0540−69 in the J, H, and KS bands with the Very Large Telescope (VLT) to detect it, for the first time, in the nIR and characterise its optical-to-nIR spectrum. To disentangle the pulsar emission from that of its pulsar wind nebula (PWN), we obtained high-spatial resolution adaptive optics images with the NAOS-CONICA instrument (NACO). Results. We could clearly identify PSR B0540−69 in our J, H, and KS-band images and measure its flux (J = 20.14, H = 19.33, KS = 18.55, with an overall error of ± 0.1 mag in each band). The joint fit to the available optical and nIR photometry with a power-law spectrum Fν ∝ ν−α gives a spectral index α = 0.70 ± 0.04, slightly more precise than measured in the optical only. This clearly implies that there is no spectral break between the optical and the nIR. We also detected, for the first time, the PSR B0540−69 PWN in the nIR. The comparison between our NACO images and Hubble Space Telescope (HST) optical ones does not reveal any apparent difference in the PWN morphology as a function of wavelength. The PWN optical-to-nIR spectrum is also fit by a single power-law, with spectral index α = 0.56 ± 0.03, slightly flatter than the pulsar’s. Conclusions. Using NACO at the VLT, we obtained the first detection of PSR B0540−69 and its PWN in the nIR. Due to the small angular scale of the PWN (~4″) only the spatial resolution of the James Webb Space Telescope (JWST) will make it possible to extend the study of the pulsar and PWN spectrum towards the mid-IR.
Context. Optical polarisation measurements are key tests for different models of the pulsar magnetosphere. Furthermore, comparing the relative orientation of the phase-averaged linear polarisation ...direction and the pulsar proper motion vector may unveil a peculiar alignment, clearly seen in the Crab pulsar. Aims. Our goal is to obtain the first measurement of the phase-averaged optical linear polarisation of the fifth brightest optical pulsar, PSR B0656+14, which also has a precisely measured proper motion, and to verify a possible alignment between the polarisation direction and the proper motion vector. Methods. We carried out observations with the Very Large Telescope (VLT) to measure the phase-averaged optical polarisation degree (PD) and position angle (PA) of PSR B0656+14. Results. We measured a PD of 11.9% ± 5.5% and a PA of 125.8° ± 13.2°, measured east of north. Albeit of marginal significance, this is the first measurement of the phase-averaged optical PD for this pulsar. Moreover, we found that the PA of the phase-averaged polarisation vector is close to that of the pulsar proper motion (93.12° ± 0.38°). Conclusions. Deeper observations are needed to confirm our polarisation measurement of PSR B0656+14, whereas polarisation measurements for more pulsars will better assess possible correlations of the polarisation degree with the pulsar parameters.
In August 2002, XMM-Newton devoted two full orbits to the observation of 1E 1207.4–5209, making this isolated neutron star the most deeply scrutinized galactic target of the mission. Thanks to the ...high throughput of the EPIC instrument, ~360 000 photons were collected from the source, allowing a very sensitive study of the temporal and spectral behaviour of this object. The spectral data, both time-averaged and phase-resolved, yield one compelling interpretation of the observed features: cyclotron absorption from one fundamental (~0.7 keV) and three harmonics, at ~1.4, ~2.1 and ~2.8 keV. Possible physical consequences are discussed, also on the basis of the obvious phase variations of the features' shapes and depths. We also present deep VLT optical data which we have used to search for a counterpart, with negative results down to $V\sim27$.
Abstract
We present the results of deep optical imaging of the radio/γ-ray pulsar PSR J2043+2740, obtained with the Large Binocular Telescope (LBT). With a characteristic age of 1.2 Myr, PSR ...J2043+2740 is one of the oldest (non-recycled) pulsars detected in γ-rays, although with still a quite high rotational energy reservoir ($\dot{E}_{\rm rot} = 5.6 \times 10^{34}$ erg s−1). The presumably close distance (a few hundred pc), suggested by the hydrogen column density (NH ≲ 3.6 × 1020 cm−2), would make it a viable target for deep optical observations, never attempted until now. We observed the pulsar with the Large Binocular Camera of the LBT. The only object (V = 25.44 ± 0.05) detected within ∼3 arcsec from the pulsar radio coordinates is unrelated to it. PSR J2043+2740 is, thus, undetected down to V ∼ 26.6 (3σ), the deepest limit on its optical emission. We discuss the implications of this result on the pulsar emission properties.
PSR J0205+6449 is a young (∼5400 yr), Crab-like pulsar detected in radio and at X-ray and γ-ray energies and has the third largest spin-down flux among known rotation-powered pulsars. It also powers ...a bright synchrotron nebula detected in the optical and X-rays. At a distance of ∼3.2 kpc and with an extinction comparable to the Crab, PSR J0205+6449 is an obvious target for optical observations. We observed PSR J0205+6449 with several optical facilities, including 8 m class ground-based telescopes, such as the Gemini and the Gran Telescopio Canarias. We detected a point source, at a significance of 5.5σ, of magnitude i
′ ∼ 25.5, at the centre of the optical synchrotron nebula, coincident with the very accurate Chandra and radio positions of the pulsar. Thus, we discovered a candidate optical counterpart to PSR J0205+6449. The pulsar candidate counterpart is also detected in the g
′ (∼27.4) band and weakly in the r
′ (∼26.2) band. Its optical spectrum is fitted by a power law with photon index ΓO = 1.9 ± 0.5, proving that the optical emission, if of non-thermal origin, is as expected for a young pulsar. The optical photon index is similar to the X-ray one (ΓX = 1.77 ± 0.03), although the optical fluxes are below the extrapolation of the X-ray power spectrum. This would indicate the presence of a double spectral break between the X-ray and optical energy range, at variance with what is observed for the Crab and Vela pulsars, but similar to the Large Magellanic Cloud pulsar PSR B0540−69.
Fabry disease (FD) is an X-linked lysosomal storage disorder caused by a deficiency of the lysosomal hydrolase α-galactosidase A (α-GalA) that leads to the intra-lysosomal accumulation of ...globotriaosylceramide (Gb3) in various organ systems. As a consequence, a multisystems disorder develops, culminating in stroke, progressive renal and cardiac dysfunction. Enzyme replacement therapy (ERT) offers a specific treatment for patients affected by FD, though the monitoring of treatment is hindered by a lack of surrogate markers of response. Remarkably, due to the high heterogeneity of the Fabry phenotype, both diagnostic testing and treatment decisions are more challenging in females than in males; thus, reliable biomarkers for Fabry disease are needed, particularly for female patients. Here, we use a proteomic approach for the identification of disease-associated markers that can be used for the early diagnosis of FD as well as for monitoring the effectiveness of ERT. Our data show that the urinary proteome of Fabry naïve patients is different from that of normal subjects. In addition, biological pathways mainly affected by FD are related to immune response, inflammation, and energetic metabolism. In particular, the up-regulation of uromodulin, prostaglandin H2 d-isomerase and prosaposin in the urine of FD patients was demonstrated; these proteins might be involved in kidney damage at the tubular level, inflammation and immune response. Furthermore, comparing the expression of these proteins in Fabry patients before and after ERT treatment, a decrease of their concentration was observed, thus demonstrating the correlation between the identified markers and the effectiveness of the pharmacological treatment.
The identification of the stellar companions to binary pulsars is key to studying the evolution of the binary system and how this is influenced by the interactions between the two stars. For only a ...fraction of the known binary pulsars, the stellar companions have been identified. Here, we used 11 source catalogues available from multiwavelength (ultraviolet, optical, infrared) imaging sky surveys to search for the stellar companions of a sample of 144 field binary pulsars (i.e. not in globular clusters) selected from the Australia Telescope National Facility data base (version 1.48) and from the public list of γ-ray pulsars detected by Fermi. We found positional associations in at least one source catalogue for 22 pulsars, of which 10 are detected in γ-rays by Fermi, including 15 millisecond pulsars. For six pulsars in our compilation, we confirm their identifications. For another seven pulsars that had yet not been identified, we examine potential identifications. In particular, we identified a likely companion star candidate to PSR J2317+1439, whereas for both PSR B1953+29 and PSR J1935+1726 the companion star identification is more uncertain. Follow-up observations of these three pulsars are needed to settle the proposed identifications. For the remaining nine pulsars that had been already identified, we provide additional spectral information in at least one of the surveys’ spectral bands, which we will use to better constrain the stars’ spectral energy distributions.
The First Detection of a Pulsar with ALMA Mignani, R. P.; Paladino, R.; Rudak, B. ...
Astrophysical journal. Letters,
12/2017, Letnik:
851, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Although there is a general consensus on the fact that pulsars' radio emission is coherent in nature, whereas the emission from the optical to high-energy γ-rays is due to incoherent processes, it ...has not been established yet at which wavelengths the transition occurs, which is key information for all emission models of pulsar magnetospheres. Of course, to address this issue, covering the spectral region between the GHz radio frequencies and the mid-infrared (IR) is crucial. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the Vela pulsar (PSR B0833−45), one of the very few observed in radio and from the mid-IR up to the very high-energy γ-rays. We detected Vela at frequencies of 97.5, 145, 233, and 343.5 GHz, which makes it the first pulsar ever detected with ALMA. Its energy density spectrum follows a power law of spectral index = −0.93 0.16. This corresponds to very high brightness temperatures-from 1017 to 1015 K-suggesting that a coherent radiative process still contributes to the millimeter/submillimeter emission. Therefore, this is the first indication of coherent emission in pulsars extending to the submillmeter range. At the same time, we identified an extended structure, preliminarily detected in ground-based near-IR observations, at a distance of ∼1 4 from the pulsar, possibly interpreted as a counter-jet protruding from the pulsar.
Abstract
G315.4−2.3 is a young Galactic supernova remnant (SNR) whose identification as the remains of a Type II supernova (SN) explosion has been debated for a long time. In particular, recent ...multiwavelength observations suggest that it is the result of a Type Ia SN, based on spectroscopy of the SNR shell and the lack of a compact stellar remnant. However, two X-ray sources, one detected by Einstein and ROSAT (Source V) and the other by Chandra (Source N), have been proposed as possible isolated neutron star candidates. In both cases, no clear optical identification was available and, therefore, we performed an optical and X-ray study to determine the nature of these two sources. Based on Chandra astrometry, Source V is associated with a bright V ∼ 14 star, which has been suggested based on the less accurate ROSAT position. Similarly, from Very Large Telescope archival observations, we found that Source N is associated with a relatively bright star (V = 20.14). These likely identifications suggest that both X-ray sources cannot be isolated neutron stars.
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