ABSTRACT
We report on a search for persistent radio emission from the one-off fast radio burst (FRB) 20190714A, as well as from two repeating FRBs, 20190711A and 20171019A, using the MeerKAT radio ...telescope. For FRB 20171019A, we also conducted simultaneous observations with the High-Energy Stereoscopic System (H.E.S.S.) in very high-energy gamma rays and searched for signals in the ultraviolet, optical, and X-ray bands. For this FRB, we obtain a UV flux upper limit of $1.39 \times 10^{-16}~{\rm erg\, cm^{-2}\, s^{-1}}$Å−1, X-ray limit of $\sim 6.6 \times 10^{-14}~{\rm erg\, cm^{-2}\, s^{-1}}$ and a limit on the very high energy gamma-ray flux $\Phi (E\gt 120\, {\rm GeV}) \lt 1.7\times 10^{-12}\, \mathrm{erg\, cm^{-2}\, s^{-1}}$. We obtain a radio upper limit of ∼15 $\mu$Jy beam−1 for persistent emission at the locations of both FRBs 20190711A and 20171019A with MeerKAT. However, we detected an almost unresolved (ratio of integrated flux to peak flux is ∼1.7 beam) radio emission, where the synthesized beam size was ∼ 8 arcsec size with a peak brightness of $\sim 53\, \mu$Jy beam−1 at MeerKAT and $\sim 86\, \mu$Jy beam−1 at e-MERLIN, possibly associated with FRB 20190714A at z = 0.2365. This represents the first detection of persistent continuum radio emission potentially associated with a (as-yet) non-repeating FRB. If the association is confirmed, one of the strongest remaining distinction between repeaters and non-repeaters would no longer be applicable. A parallel search for repeat bursts from these FRBs revealed no new detections down to a fluence of 0.08 Jy ms for a 1 ms duration burst.
Context . HESS J1813–178 is a very-high-energy γ -ray source spatially coincident with the young and energetic pulsar PSR J1813–1749 and thought to be associated with its pulsar wind nebula (PWN). ...Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813–178 region, taking advantage of improved analysis methods and an extended dataset. Aims . Using data taken by the High Energy Stereoscopic System (H.E.S.S.) experiment and the Fermi -LAT, we aim to describe the γ -ray emission in the region with a consistent model, to provide insights into its origin. Methods . We performed a likelihood-based analysis on 32 hours of H.E.S.S. data and 12 yr of Fermi -LAT data and we fitted a spectro-morphological model to the combined datasets. These results allowed us to develop a physical model for the origin of the observed γ -ray emission in the region. Results . In addition to the compact very-high-energy γ -ray emission centred on the pulsar, we find a significant yet previously undetected component along the Galactic plane. With Fermi -LAT data, we confirm extended high-energy emission consistent with the position and elongation of the extended emission observed with H.E.S.S. These results establish a consistent description of the emission in the region from GeV energies to several tens of TeV. Conclusions . This study suggests that HESS J1813–178 is associated with a γ -ray PWN powered by PSR J1813–1749. A possible origin of the extended emission component is inverse Compton emission from electrons and positrons that have escaped the confines of the pulsar and form a halo around the PWN.
Abstract
Cosmological
N
-body simulations show that Milky Way–sized galaxies harbor a population of unmerged dark matter (DM) subhalos. These subhalos could shine in gamma-rays and eventually be ...detected in gamma-ray surveys as unidentified sources. We performed a thorough selection among unidentified Fermi-Large Area Telescope Objects (UFOs) to identify them as possible tera-electron-volt-scale DM subhalo candidates. We search for very-high-energy (E ≳ 100 GeV) gamma-ray emissions using H.E.S.S. observations toward four selected UFOs. Since no significant very-high-energy gamma-ray emission is detected in any data set of the four observed UFOs or in the combined UFO data set, strong constraints are derived on the product of the velocity-weighted annihilation cross section 〈
σ
v
〉 by the
J
factor for the DM models. The 95% confidence level observed upper limits derived from combined H.E.S.S. observations reach 〈
σ
v
〉
J
values of 3.7 × 10
−5
and 8.1 × 10
−6
GeV
2
cm
−2
s
−1
in the
W
+
W
−
and
τ
+
τ
−
channels, respectively, for a 1 TeV DM mass. Focusing on thermal weakly interacting massive particles, the H.E.S.S. constraints restrict the
J
factors to lie in the range 6.1 × 10
19
–2.0 × 10
21
GeV
2
cm
−5
and the masses to lie between 0.2 and 6 TeV in the
W
+
W
−
channel. For the
τ
+
τ
−
channel, the
J
factors lie in the range 7.0 × 10
19
–7.1 × 10
20
GeV
2
cm
−5
and the masses lie between 0.2 and 0.5 TeV. Assuming model-dependent predictions from cosmological
N
-body simulations on the
J
-factor distribution for Milky Way–sized galaxies, the DM models with masses >0.3 TeV for the UFO emissions can be ruled out at high confidence level.
Abstract
We report on the observations of four well-localized binary black hole (BBH) mergers by the High Energy Stereoscopic System (H.E.S.S.) during the second and third observing runs of Advanced ...LIGO and Advanced Virgo, O2 and O3. H.E.S.S. can observe 20 deg
2
of the sky at a time and follows up gravitational-wave (GW) events by “tiling” localization regions to maximize the covered localization probability. During O2 and O3, H.E.S.S. observed large portions of the localization regions, between 35% and 75%, for four BBH mergers (GW170814, GW190512_180714, GW190728_064510, and S200224ca). For these four GW events, we find no significant signal from a pointlike source in any of the observations, and we set upper limits on the very high energy (>100 GeV)
γ
-ray emission. The 1–10 TeV isotropic luminosity of these GW events is below 10
45
erg s
−1
at the times of the H.E.S.S. observations, around the level of the low-luminosity GRB 190829A. Assuming no changes are made to how follow-up observations are conducted, H.E.S.S. can expect to observe over 60 GW events per year in the fourth GW observing run, O4, of which eight would be observable with minimal latency.
Abstract
Magnetar hyperflares are the most plausible explanation for fast radio bursts (FRBs)—enigmatic powerful radio pulses with durations of several milliseconds and high brightness temperatures. ...The first observational evidence for this scenario was obtained in 2020 April when an FRB was detected from the direction of the Galactic magnetar and soft gamma-ray repeater SGR 1935+2154. The FRB was preceded by two gamma-ray outburst alerts by the BAT instrument aboard the Swift satellite, which triggered follow-up observations by the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observed SGR 1935+2154 for 2 hr on 2020 April 28. The observations are coincident with X-ray bursts from the magnetar detected by INTEGRAL and Fermi-GBM, thus providing the first very high energy gamma-ray observations of a magnetar in a flaring state. High-quality data acquired during these follow-up observations allow us to perform a search for short-time transients. No significant signal at energies
E
> 0.6 TeV is found, and upper limits on the persistent and transient emission are derived. We here present the analysis of these observations and discuss the obtained results and prospects of the H.E.S.S. follow-up program for soft gamma-ray repeaters.
Abstract
In 2021 July,
PKS 1510−089
exhibited a significant flux drop in the high-energy
γ
-ray (by a factor 10) and optical (by a factor 5) bands and remained in this low state throughout 2022. ...Similarly, the optical polarization in the source vanished, resulting in the optical spectrum being fully explained through the steady flux of the accretion disk and the broad-line region. Unlike the aforementioned bands, the very-high-energy
γ
-ray and X-ray fluxes did not exhibit a significant flux drop from year to year. This suggests that the steady-state very-high-energy
γ
-ray and X-ray fluxes originate from a different emission region than the vanished parts of the high-energy
γ
-ray and optical jet fluxes. The latter component has disappeared through either a swing of the jet away from the line of sight or a significant drop in the photon production efficiency of the jet close to the black hole. Either change could become visible in high-resolution radio images.
Electrocoagulation with aluminum and stainless steel electrodes was investigated. Electrocoagulation tests were performed to treat synthetic wastewater containing heavy metallic ions (Cu
2+
), with ...concentrations ranging from 100 to 600 ppm. Concentrations of the remaining copper and coagulant (Al
3+
), generated by electrochemical oxidation of the anode, were optimized by an experimental design methodology. The study was conducted using a Doehlert matrix. The factors considered are: the initial concentration of copper (
C
Cu0
); the stirring speed (
N
); the current density (
J
); and the electrolysis time (
t
). As for the response functions measured by atomic absorption, they imply the final concentration of the metallic ions of copper (
Y
1
) and of the metallic ions of aluminum accumulated in the wastewater after electrocoagulation treatment (
Y
2
). The isoresponse curves and the optimum path study of the two retained responses showed that the two optima were found to be opposite. In order to minimize the two responses and determine the conditions of electrocoagulation that satisfy the requirements of the Tunisian standard for effluent discharges NT-106-02 (≤1 ppm for copper and ≤ 10 ppm for aluminum), multicriteria optimization using the desirability function was achieved. In so doing, the determined optimal operating conditions for the process of electrocoagulation were:
C
Cu0
= 421.43 ppm,
N
= 44.19 rpm,
J
= 656.41 mA dm
−2
and
t
= 65.12 min, while the corresponding estimated response values were 0.25 ppm and 3.38 ppm for cooper and coagulant (Al
3+
), respectively. The removal efficiency over 98% was reached for copper. In addition, the results of the study demonstrate that a simultaneous increase of the current density and the stirring speed notably reduces not only the concentration of the remaining copper but also the treatment duration, without inducing a strong increase of the sludge.
Clean Intermittent Catheterization (CIC) is the method of choice for bladder emptying in patients having bladder emptying disorders, acquired or pharmacologically induced, whether it is ...neurologically related or not. The aim of this study is to assess the theoretical and practical knowledge of general practitioners (GP) on CIC.
Observational prospective study (anonymous online questionnaire) was conducted with 224 GP between March and April 2020. Each physician had to complete a questionnaire about the definition of CIC, its indications and usage, the indications of urine culture, antibiotic therapy, and the complications of this method of drainage.
Only 18.3% of GP that took part in the study gave an exact definition of CIC. As to the importance of it, 67.9% responded that it protects the upper urinary tract and 37.1% that it prevents urinary tract infections (UTI). Fifty-two per cent of physicians were unaware of the regular frequency at which it should carry out a day. Fifty eight percent prescribed sterile gloves and 57.1% an antiseptic. UTI was considered as the main complication of CIC by 87.1% of physicians and 35.7% requested a systematic urine culture for patients under CIC. For patients with an asymptomatic bacteriuria, 65.6% of GP prescribed antibiotic therapy.
GP need to improve their knowledge of SIP, its framework, indications, modalities, and the way to deal with colonization or urinary tract infection. This will improve the management of impacted patients.
During 2017 and 2018, from June to October, leaf galls were observed for the first time on Sonchus oleraceus L. (Asteraceae), sow thistle, in Akouda‐Sousse, Tunisia. Leaves with galls were collected ...and brought to the laboratory. After a few days, adults emerged from the leaf galls. Morphological identification showed the emerged gall midges to be Cystiphora sonchi (Vallot, 1827) (Diptera: Cecidomyiidae). This is the first record of this species in Tunisia and Africa.
Cystiphora sonchi (Vallot, 1827) (Diptera: Cecidomyiidae), premier signalement en Tunisie et en Afrique
En 2017 et 2018, de juin à octobre, des galles ont été observées pour la première fois sur des feuilles de Sonchus oleraceus L. (Asteraceae), aussi appelé laiteron, dans la région d'Akouda (Sousse, Tunisie). Des feuilles à galles ont été collectées et mises en élevage en laboratoire. Après quelques jours, des moucherons adultes ont émergés lesquels ont été identifiés comme appartenant à l’espèce Cystiphora sonchi (Vallot, 1827) (Diptera: Cecidomyiidae). Il s’agit du premier signalement de cette espèce en Tunisie et en Afrique.
Cystiphora sonchi (Vallot, 1827 год) (Diptera: Cecidomyiidae), первое сообщение для Туниса и Африки
С июня по октябрь 2017 и 2018 годов в Акуда‐Суссе, в Тунисе, на листьях осота Sonchus oleraceus L. (Asteraceae) впервые были обнаружены галлы. Листья с галлами были собраны и привезены в лабораторию. Через несколько дней из галлов отродились взрослые особи. Морфологическая идентификация показала, что отродившиеся галлицы были Cystiphora sonchi (Vallot, 1827) (Diptera: Cecidomyiidae). Это первое сообщение об этом виде в Тунисе и Африке.
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