Spectral properties of gamma‐ray bursts observed by COMPTEL

During the first year of operation, the COMPTEL instrument on board the Compton Gamma Ray Observatory detected 22 γ‐ray bursts within its field of view. Spectra and time histories for the strongest 7 of these bursts have been obtained from both the main instrument (0.75–30 MeV) and the burst modules (0.1–10 MeV). The deconvolved photon spectra for the majority of bursts are fit by a single power law model with spectral index between −1.6 and −2.8. One strong burst, GRB 910814, exhibited significant curvature and could not be fit by a single power law model. A broken power law model with a break in slope at ∼2 MeV is a good fit to the time averaged spectrum of this burst. There is evidence, at the 2.8σ level, for a change in the break energy of GRB 910814, from above 2 MeV to below 1 MeV during the first 9 s of the burst

Search for gamma‐ray emission from AGN with COMPTEL

The COMPTEL data (∼0.7–30 MeV) were searched for emission from AGN. Four sources have been detected so far: the quasars 3C 273, 3C 279, PKS 0528+134, and the radio galaxy Centaurus A. 3C 273 and 3C 279 were detected in CGRO observation period 3 with quite different spectral shapes. There is also evidence for 3C 273 at a weak flux level in observation period 11. The quasar PKS 0528+134 was detected above 3 MeV as part of a search for AGN already observed by EGRET. Cen A was seen up to 3 MeV by combining data from different observation periods

COMPTEL observations of the inner galaxy

This paper presents a first global study of COMPTEL observations of the inner Galaxy in the energy range 0.75–10 MeV. Preliminary findings demonstrate COMPTEL’s capabilities for mapping the observed gamma radiation and disentangling the contributions from point sources and diffuse emission

Gamma‐ray burst studies by COMPTEL during its first year of operation

During the first year of Compton GRO operations, more than 20 cosmic gamma‐ray burst‐detected by the BATSE instrument ‐ occurred inside the 1 sr field of view of the imaging gamma‐ray telescope COMPTEL. Using COMPTEL’s primary mode of operation (the telescope mode) direct images (with ∼1° GRB location accuracy) and event spectra (0.7 MeV – 30 MeV) with spectral resolution better than 10% FWHM have been obtained. In its secondary mode of burst operations, COMPTEL has recorded time resolved spectra (0.1 MeV – 10 MeV) from its large NaI detectors. This paper summarises the results on cosmic GRB sources obtained by COMPTEL during its first year of operation

The ATHENA X-ray Integral Field Unit (X-IFU)

The X-ray Integral Field Unit (X-IFU) on board the Advanced Telescope for High-ENergy Astrophysics (Athena) will provide spatially resolved high-resolution X-ray spectroscopy from 0.2 to 12 keV, with 5" pixels over a eld of view of 5 arc minute equivalent diameter and a spectral resolution of 2.5 eV up to 7 keV. In this paper, we rst review the core scienti c objectives of Athena, driving the main performance parameters of the X-IFU, namely the spectral resolution, the eld of view, the e ective area, the count rate capabilities, the instrumental background. We also illustrate the breakthrough potential of the X-IFU for some observatory science goals. Then we brie y describe the X-IFU design as de ned at the time of the mission consolidation review concluded in May 2016, and report on its predicted performance. Finally, we discuss some options to improve the instrument performance while not increasing its complexity and resource demands (e.g. count rate capability, spectral resolution)

COMPTEL images locations of gamma‐ray bursts

The γ‐ray telescope COMPTEL onboard GRO has so far located 6 gamma‐ray bursts which occurred in its ∼1 sr field of view. The positions of the sources were derived by the maximum‐entropy method. Systematic and statistical uncertainties for the four strongest bursts are approximately 1° to 2° and can be reduced in future analysis

Initial results from COMPTEL—an overview

COMPTEL is presently completing the first full sky survey in MeV gamma‐ray astronomy (0.7 to 30 MeV). An overview of initial results from the survey is given: among these are the observations of the Crab and Vela pulsars with unprecedented accuracy, the observation of the black hole candidates Cyg X‐1 and Nova Persei 1992, an analysis of the diffuse Galactic continuum emission from the Galactic center region, the broad scale distribution of the 1.8 MeV line from radioactive 2 6Al, upper limits on gamma‐ray line emission from SN 1991T, observations of the three quasars 3C273, 3C279 and PKS 0528+134 and the radio galaxy Cen A, measurements of energy spectra, time histories and locations of a number of cosmic gamma‐ray bursts, and gamma‐ray and neutron emission from solar flares

The elemental abundances in the intracluster medium as observed with XMM-Newton

XMM-Newton observations of 19 galaxy clusters are used to measure the elemental abundances and their spatial distributions in the intracluster medium. The sample mainly consists of X-ray bright and relaxed clusters with a cD galaxy. Along with detailed Si, S and Fe radial abundance distributions within 300-700 kpc in radius, the O abundances are accurately derived in the central region of the clusters. The Fe abundance maxima towards the cluster center, possibly due to the metals from the cD galaxy,are spatially resolved. The Si and S abundances also exhibit central increases in general, resulting in uniform Fe-Si-S ratios within the cluster. In contrast, the O abundances are in general uniform over the cluster. The mean O to Fe ratio within the cluster core is sub-solar, while that of the cluster scale is larger than the solar ratio. These measurements indicate that most of the Fe-Si-S and O in the intracluster medium have different origins, presumably in supernovae Ia and II, respectively. The obtained Fe and O mass are also used to discuss the past star formation history in clusters.Comment: Accepted for publication in Astronomy and Astrophysic

Midgut neuroendocrine tumor patients have a depleted gut microbiome with a discriminative signature

Rationale: When compared to other types of cancer, the prevalence of midgut neuroendocrine tumors (NET) has disproportionally increased over the past decades. To date, there has been very little progress in discovering (epi)genetic drivers and treatment options for these tumors. Recent microbiome research has revealed that enteroendocrine cells communicate with the intestinal microbiome and has provided novel treatment targets for various other cancer types. Hence, our aim was to analyze the role of the gut microbiome in midgut NET patients. Methods: Fecal samples, prospectively collected from patients and control subjects, were analyzed with next generation 16S sequencing. Patients with neuroendocrine carcinomas and recent antibiotics use were excluded. Relevant variables were extracted from questionnaires and electronic health records. Microbial composition was compared between patients and controls as well as between groups within the patient cohort. Results: 87 midgut NET patients and 95 controls were included. Midgut NET patients had a less rich and diverse gut microbiome than controls (p &lt; 0.001). Moreover, we identified 31 differentially abundant species and a gut microbial signature consisting of 17 species that was predictive of midgut NET presence with an area under the receiver operating characteristic curve of 0.863. Gut microbial composition was not directly associated with the presence of the carcinoid syndrome, tumor grade or multifocality. Nonetheless, we did observe a potential link between microbial diversity and the presence of carcinoid syndrome symptoms within the subset of patients with elevated 5-hydroxyindolacetic acid levels. Conclusion: Midgut NET patients have an altered gut microbiome which suggests a role in NET development and could provide novel targets for microbiome-based diagnostics and therapeutics.</p

COMPTEL observations of cosmic gamma‐ray bursts

The imaging γ‐ray telescope COMPTEL on board NASA’s Compton Gamma‐Ray Observatory (GRO) has observed many cosmic gamma‐ray bursts during the early mission phase of GRO. COMPTEL records time‐resolved burst spectra over 0.1 MeV to 10 MeV energies, and, for the first time, produces direct single‐telescope gamma‐ray images (0.8–30 MeV) of cosmic gamma‐ray bursts occurring in its 1 sr field of field