Tuberculous meningitis (TBM) is a frequent cause of meningitis in individuals with human immunodeficiency virus (HIV) infection, resulting in death in approximately 40% of affected patients. A severe ...complication of antiretroviral therapy (ART) in these patients is neurological tuberculosis–immune reconstitution inflammatory syndrome (IRIS), but its underlying cause remains poorly understood. To investigate the pathogenesis of TBM-IRIS, we performed longitudinal whole-blood microarray analysis of HIV-infected patients with TBM and reflected the findings at the protein level. Patients in whom TBM-IRIS eventually developed had significantly more abundant neutrophil-associated transcripts, from before development of TBM-IRIS through IRIS symptom onset. After ART initiation, a significantly higher abundance of transcripts associated with canonical and noncanonical inflammasomes was detected in patients with TBM-IRIS than in non-IRIS controls. Whole-blood transcriptome findings complement protein measurement from the site of disease, which together suggest a dominant role for the innate immune system in the pathogenesis of TBM-IRIS.
Context.
Long gamma-ray bursts (GRBs) are produced during the dramatic deaths of massive stars with very short lifetimes, meaning that they explode close to the birth place of their progenitors. Over ...a short period they become the most luminous objects observable in the Universe, being perfect beacons to study high-redshift star-forming regions.
Aims.
We aim to use the afterglow of GRB 161023A at a redshift
z
= 2.710 as a background source to study the environment of the explosion and the intervening systems along its line of sight.
Methods.
For the first time, we complement ultraviolet (UV), optical and near-infrared (NIR) spectroscopy with millimetre spectroscopy using the Atacama Large Millimeter Array (ALMA), which allows us to probe the molecular content of the host galaxy. The X-shooter spectrum shows a plethora of absorption features including fine-structure and metastable transitions of Fe, Ni, Si, C, and O. We present photometry ranging from 43 s to over 500 days after the burst.
Results.
We infer a host-galaxy metallicity of Zn/H = −1.11 ± 0.07, which, corrected for dust depletion, results in X/H = −0.94 ± 0.08. We do not detect molecular features in the ALMA data, but we derive limits on the molecular content of log(
N
CO
/cm
−2
) < 15.7 and log(
N
HCO
+
/cm
−-12
, which are consistent with those that we obtain from the optical spectra, log(
N
H
2
/cm
−2
)< 15.2 and log(
N
CO
/cm
−2
) < 14.5. Within the host galaxy, we detect three velocity systems through UV, optical and NIR absorption spectroscopy, all with levels that were excited by the GRB afterglow. We determine the distance from these systems to the GRB to be in the range between 0.7 and 1.0 kpc. The sight line to GRB 161023A shows nine independent intervening systems, most of them with multiple components.
Conclusions.
Although no molecular absorption was detected for GRB 161023A, we show that GRB millimetre spectroscopy is now feasible and is opening a new window on the study of molecular gas within star-forming galaxies at all redshifts. The most favoured lines of sight for this purpose will be those with high metallicity and dust.
Shell-type supernova remnants (SNRs) are considered prime candidates for the acceleration of Galactic cosmic rays (CRs) up to the knee of the CR spectrum at E ≈ 3 × 1015 eV. Our Milky Way galaxy ...hosts more than 350 SNRs discovered at radio wavelengths and at high energies, of which 220 fall into the H.E.S.S. Galactic Plane Survey (HGPS) region. Of those, only 50 SNRs are coincident with a H.E.S.S source and in 8 cases the very high-energy (VHE) emission is firmly identified as an SNR. The H.E.S.S. GPS provides us with a legacy for SNR population study in VHE γ-rays and we use this rich data set to extract VHE flux upper limits from all undetected SNRs. Overall, the derived flux upper limits are not in contradiction with the canonical CR paradigm. Assuming this paradigm holds true, we can constrain typical ambient density values around shell-type SNRs to n ≤ 7 cm−3 and electron-to-proton energy fractions above 10 TeV to ϵep ≤ 5 × 10−3. Furthermore, comparisons of VHE with radio luminosities in non-interacting SNRs reveal a behaviour that is in agreement with the theory of magnetic field amplification at shell-type SNRs.
We search for high-energy gamma-ray emission from the binary neutron star merger GW170817 with the H.E.S.S. Imaging Air Cherenkov Telescopes. The observations presented here have been obtained ...starting only 5.3 hr after GW170817. The H.E.S.S. target selection identified regions of high probability to find a counterpart of the gravitational-wave event. The first of these regions contained the counterpart SSS17a that has been identified in the optical range several hours after our observations. We can therefore present the first data obtained by a ground-based pointing instrument on this object. A subsequent monitoring campaign with the H.E.S.S. telescopes extended over several days, covering timescales from 0.22 to 5.2 days and energy ranges between to . No significant gamma-ray emission has been found. The derived upper limits on the very-high-energy gamma-ray flux for the first time constrain non-thermal, high-energy emission following the merger of a confirmed binary neutron star system.
ABSTRACT
Studies using the Energetic Gamma‐Ray Experiment Telescope (EGRET) revealed that blazars flat‐spectrum radio quasars (FSRQs) and BL Lac objects emit most of their luminosity in the ...high‐energy gamma‐ray (E > 100 MeV) range. From the 271 sources observed by EGRET, 131 are still unidentified. A systematic search is conducted to identify possible high‐energy gamma‐ray blazars among the unidentified EGRET population. Based upon multiwavelength emission properties, 13 extragalactic radio sources were selected in the EGRET error boxes for further investigation. From the above‐mentioned sample, results of a multiwavelength follow‐up of two EGRET sources, 3EG J0821−5814 and 3EG J0706−3837, are presented. These sources are associated with their radio counterparts PKS J0820−5705 and PMN J0710−3850, respectively. Spectroscopic observations utilizing the SOAR/Goodman spectrograph at the Cerro Tololo Inter‐American Observatory in Chile reveal a spectrum of PKS J0820−5705 that corresponds to that of a radio‐loud active galactic nucleus (FSRQ) with redshift z = 0.06 ± 0.01, while the visibility of wide and narrow emission lines in the spectrum of PMN J0710−3850 resembles that of a low‐ionization nuclear emission‐line region (LINER) or type 1 Seyfert galaxy at z = 0.129 ± 0.001. The observed Ca ii K&H lines depression ratio at 4000 Å showed a shallow depression of 8.8 ± 2.5 per cent for PKS J0820−5705 and 80 ± 1 per cent for PMN J0710−3850, suggesting the presence of a strong non‐thermal optical contribution in PKS J0820−5705, which clearly distinguishes its spectrum from that of a radio galaxy. The weaker optical non‐thermal contribution for PMN J0710−3850 is in accordance with that expected of a LINER. For PMN J0710−3850 the line flux ratios O iii λ5007/Hβ < 3 and N ii λ6583/Hα > 0.6 which are in agreement with the expected ratios of LINERs. However, the absence of O ii λ3727 implies an anomalously low O ii/O iii < 0.5 ratio for a LINER, and agrees more with the ratio observed in type 1 Seyfert galaxies. The average velocities inferred from the Balmer lines range between 2300 and 4300 km s−1, while O i and O iii velocities range between 420 and 490 km s−1, consistent with both LINERs and type 1 Seyfert galaxies. The X‐ray luminosities of these two sources are LX ∼ 9 × 1043 erg s−1 (PKS J0820−5705) and LX ∼ 9 × 1042 erg s−1 (PMN J0710−3850), respectively. The X‐ray luminosity of PMN J0710−3850 is an order of magnitude higher than the upper limit detected from LINERs, and correlates well with the typical X‐ray luminosities observed in type 1 Seyfert galaxies. The X‐ray luminosity of PKS J0820−5705 is consistent with the observed luminosity of FSRQs. Optical photometry carried out with the South African Astronomical Observatory 1.0‐m telescope displayed 1–2 mag variability in the B and R bands for PKS J0821−5705, on time‐scales of hours, while a 5σ variability of the average R‐band magnitude could be discerned over a 3 d time span. A smaller 0.5 mag variability is visible in the B band for PMN J0710−3850 on time‐scales of hours. No variability was detected in the R band for this source.
The Galactic neutron star X-ray binary Her X-1 displays a well-known 35-day superorbital modulation in its X-ray and optical light curves. Detected across a broad energy range, the modulation is ...prevalent in X-rays, cycling between low and high states. The 35-day modulation is believed to be the result of the periodic occultation of the neutron star by a warped precessing accretion disc. Using optical observations of Her X-1 during both the anomalous low state (ALS) and the normal high state, it is shown that the orbital light curve of Her X-1 varies systematically over the 35-day precession cycle. The 35-day precessional profile is remarkably consistent between the ALS and normal high state of Her X-1, suggesting only a very slight change in the form of the disc warp between the two states. Comparison of optical and X-ray light curves suggests that a significant component of the X-ray flux during the ALS originates from the companion star.
Aims.
We study
γ
-ray emission from the shell-type supernova remnant (SNR) RX J0852.0−4622 to better characterize its spectral properties and its distribution over the SNR.
Methods.
The analysis of ...an extended High Energy Spectroscopic System (H.E.S.S.) data set at very high energies (
E
> 100 GeV) permits detailed studies, as well as spatially resolved spectroscopy, of the morphology and spectrum of the whole RX J0852.0−4622 region. The H.E.S.S. data are combined with archival data from other wavebands and interpreted in the framework of leptonic and hadronic models. The joint
Fermi
-LAT-H.E.S.S. spectrum allows the direct determination of the spectral characteristics of the parent particle population in leptonic and hadronic scenarios using only GeV-TeV data.
Results.
An updated analysis of the H.E.S.S. data shows that the spectrum of the entire SNR connects smoothly to the high-energy spectrum measured by
Fermi
-LAT. The increased data set makes it possible to demonstrate that the H.E.S.S. spectrum deviates significantly from a power law and is well described by both a curved power law and a power law with an exponential cutoff at an energy of
E
cut
= (6.7 ± 1.2
stat
± 1.2
syst
) TeV. The joint
Fermi
-LAT-H.E.S.S. spectrum allows the unambiguous identification of the spectral shape as a power law with an exponential cutoff. No significant evidence is found for a variation of the spectral parameters across the SNR, suggesting similar conditions of particle acceleration across the remnant. A simple modeling using one particle population to model the SNR emission demonstrates that both leptonic and hadronic emission scenarios remain plausible. It is also shown that at least a part of the shell emission is likely due to the presence of a pulsar wind nebula around PSR J0855−4644.
CAL 83 is the prototypical close binary supersoft X-ray source in the Large Magellanic Cloud, has a 1 d orbital period, and is believed to consist of a white dwarf (WD) primary accreting from an ...evolved donor. Based on published WD model atmosphere fits to X-ray data, the WD has a mass of ∼1.3 M, just below the Chandrasekhar limit. From a systematic search through archival XMM-Newton data for periodic emission from CAL 83 down to the shortest possible period just above the WD break-up period, we report the discovery of an ∼67 s supersoft X-ray modulation, which we interpret as the rotation period of a highly spun-up WD. Such a short period can be explained within the framework of a high mass accretion history, where accretion disc torques could have spun up the WD over time-scales comparable to the thermal time-scale. The presence of carbon, oxygen and nitrogen in published optical and ultraviolet spectra may suggest CNO cycling in the envelope of a secondary star that is oversized for its inferred mass, suggesting that the secondary star shed a significant fraction of its envelope during a high mass-transfer history, resulting in a highly spun-up WD. The reported 67 s period shows an approximately ±3 s drift from the median value in single runs, which we interpret as a hydrogen burning gas envelope surrounding the WD, with a period not quite synchronized with the WD rotation period.
The blazar Mrk 501 (z = 0.034) was observed at very-high-energy (VHE, E 100 GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23-24 (MJD 56832) with the H.E.S.S. phase-II ...array of Cherenkov telescopes. Data taken that night by H.E.S.S. at large zenith angle reveal an exceptional number of gamma-ray photons at multi-TeV energies, with rapid flux variability and an energy coverage extending significantly up to 20 TeV. This data set is used to constrain Lorentz invariance violation (LIV) using two independent channels: a temporal approach considers the possibility of an energy dependence in the arrival time of gamma-rays, whereas a spectral approach considers the possibility of modifications to the interaction of VHE gamma-rays with extragalactic background light (EBL) photons. The non-detection of energy-dependent time delays and the non-observation of deviations between the measured spectrum and that of a supposed power-law intrinsic spectrum with standard EBL attenuation are used independently to derive strong constraints on the energy scale of LIV (EQG) in the subluminal scenario for linear and quadratic perturbations in the dispersion relation of photons. For the case of linear perturbations, the 95% confidence level limits obtained are EQG,1 > 3.6 × 1017 GeV using the temporal approach and EQG,1 > 2.6 × 1019 GeV using the spectral approach. For the case of quadratic perturbations, the limits obtained are EQG,2 > 8.5 × 1010 GeV using the temporal approach and EQG,2 > 7.8 × 1011 GeV using the spectral approach.
Few studies from Africa have described the clinical impact of co-infections on SARS-CoV-2 infection. Here, we investigate the presentation and outcome of SARS-CoV-2 infection in an African setting of ...high HIV-1 and tuberculosis prevalence by an observational case cohort of SARS-CoV-2 patients. A comparator group of non SARS-CoV-2 participants is included. The study includes 104 adults with SARS-CoV-2 infection of whom 29.8% are HIV-1 co-infected. Two or more co-morbidities are present in 57.7% of participants, including HIV-1 (30%) and active tuberculosis (14%). Amongst patients dually infected by tuberculosis and SARS-CoV-2, clinical features can be typical of either SARS-CoV-2 or tuberculosis: lymphopenia is exacerbated, and some markers of inflammation (D-dimer and ferritin) are further elevated (p < 0.05). Amongst HIV-1 co-infected participants those with low CD4 percentage strata exhibit reduced total, but not neutralising, anti-SARS-CoV-2 antibodies. SARS-CoV-2 specific CD8 T cell responses are present in 35.8% participants overall but undetectable in combined HIV-1 and tuberculosis. Death occurred in 30/104 (29%) of all COVID-19 patients and in 6/15 (40%) of patients with coincident SARS-CoV-2 and tuberculosis. This shows that in a high incidence setting, tuberculosis is a common co-morbidity in patients admitted to hospital with COVID-19. The immune response to SARS-CoV-2 is adversely affected by co-existent HIV-1 and tuberculosis.
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