Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433

SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.

Developing a supportive and palliative care intervention for patients with allogeneic stem cell transplantation: protocol of a multicentre mixed-methods study (allo-PaS)

INTRODUCTION

Although allogeneic stem cell transplantation (allo-SCT) is a curative treatment for many haematological malignancies, it is often associated with a high morbidity and mortality. Yet, little is known about the needs for supportive and palliative care among allo-SCT recipients. Moreover, targeted interventions that reduce symptom burden and suffering are still lacking. The present study aims to inform a supportive-palliative care intervention for patients with allo-SCT and their informal carers by exploring their experience and assessing their needs, especially their existential concerns, regarding four research topics: symptom burden and quality of life; coexistence of a chance for cure and a relevant risk of dying; change in goals of care; dying phase.

METHODS AND ANALYSIS

This is a descriptive mixed-methods study in progress with a convergent parallel design. Data on the four research topics will be collected and analysed separately in three steps: (1) qualitative semi-structured interviews among 20 patients, 20 informal carers and 12 healthcare providers (HCPs) and focus groups among 12-24 HCPs; (2) a quantitative cross-sectional survey with validated questionnaires and self-developed questions among 100 patients, 100 informal carers and 50 HCPs; (3) a retrospective case analysis of all deceased patients who underwent an allo-SCT between 2010 and 2019, with collection of quantitative and qualitative data. The qualitative and quantitative data sets will be finally merged for comparison and interpretation. Results will serve to develop a supportive-palliative care intervention.

ETHICS AND DISSEMINATION

The Ethics Commission of the Faculty of Medicine of the University of Cologne approved this study (20-1370_2). The study results will be published in peer-review journals, be presented at congresses and will be translated into clinical practice through the development of the palliative-supportive care intervention.

TRIAL REGISTRATION NUMBER

DRKS00027290 (German Clinical Trials Register).

Angular Correlations in the β Decay of ^{8}B: First Tensor-Current Limits from a Mirror-Nucleus Pair

We present the first measurement of the α-β-ν angular correlation in the Gamow-Teller β^{+} decay of ^{8}B. This was accomplished using the Beta-decay Paul Trap, expanding on our previous work on the β^{-} decay of ^{8}Li. The ^{8}B result is consistent with the V-A electroweak interaction of the standard model and, on its own, provides a limit on the exotic right-handed tensor current relative to the axial-vector current of |C_{T}/C_{A}|^{2}<0.013 at the 95.5% confidence level. This represents the first high-precision angular correlation measurements in mirror decays and was made possible through the use of an ion trap. By combining this ^{8}B result with our previous ^{8}Li results, we demonstrate a new pathway for increased precision in searches for exotic currents.

Scaling up conservation agriculture: An exploration of challenges and opportunities through a stakeholder engagement process

Increasing the resilience of agricultural landscapes requires fundamental changes to the dominant commodity production model, including incorporating practices such as reduced tillage, cover cropping, and extended rotations that reduce soil disturbance while increasing biological diversity. Increasing farmer adoption of these conservation systems offers the potential to transform agriculture to a more vibrant, resilient system that protects soil, air, and water quality. Adoption of these resilience practices is not without significant challenges. This paper presents findings from a participatory effort to better understand these challenges and to develop solutions to help producers overcome them. Through repeated, facilitated discussions with farmers and agricultural and conservation professionals across the U.S. state of Michigan, we confronted the policy, economic, and structural barriers that are inhibiting broader adoption of conservation systems, as well as identified policies, programs, and markets that can support their adoption. What emerged was a complex picture and dynamic set of challenges at multiple spatial scales and across multiple domains. The primary themes emerging from these discussions were barriers and opportunities, including markets, social networks, human capital, and conservation programs. Exacerbating the technical, agronomic, and economic challenges farmers face at the farm level, there are a host of community constraints, market access and availability problems, climatic and environmental changes, and policies (governmental and corporate) that cross-pressure farmers when it comes to making conservation decisions. Understanding these constraints is critical to developing programs, policies, and state and national investments that can drive adoption of conservation agriculture.

How does stress affect maternal and paternal perceptions of relationship strain after a preterm birth? Results of a retrospective survey study

AIM

Strain on couple relationships is associated with a lower well-being. As premature birth is known to pose stress to parents, this study explores whether interparental relationship strain comes to pass within mothers and fathers during their infant's stay in a neonatal intensive care unit.

METHODS

A retrospective cross-sectional survey was conducted with parents who experienced a preterm birth (September to December 2020). Linear regression was used to analyse associations between stress and relationship strain.

RESULTS

The study included 437 mothers and 301 fathers. Fathers experienced lower relationship strain (M = 2.49, SD = 1.00) than mothers (M = 3.37, SD = 1.04). Overall, a significant association between relationship strain and stress due to the infant's behaviour and appearance was found for mothers (β = 0.16, p = 0.02) and fathers, with a significantly higher association for fathers (β = 0.27, p ≤ 0.002). With regard to parental role alterations, only mothers showed a significant association (β = 0.21, p ≤ 0.001).

CONCLUSION

Although mothers showed higher levels of stress and relationship strain, stress may also have an impact on fathers. Therefore, research should focus on stress prevention measures to meet both maternal and paternal needs.

A German study on the impact of stress on interparental relationship strain after preterm birth

Background

Relationship satisfaction is an important predictor of well-being. Few studies address the effects of stress on interparental relationships of parents with preterm infants. However, the experience of a preterm birth represents an extreme, stressful event and therefore may place a strain on a relationship. Our aim is to examine the impact of postnatal stress on maternal and paternal perceptions of relationship strain.

Methods

As part of the Neo-CamCare project, a retrospective cross-sectional study was conducted targeting parents with infants with a birth weight below 1,500 g. Linear regression was used to analyse the influence of stress on relationship strain.

Results

437 mothers and 301 fathers participated. Data indicate that interparental relationship strain experienced by fathers (M = 2.61, SD = 1.46) is lower than strain experienced by mothers (M = 3.43, SD = 1.7). The stress level due to the infant's behaviour and appearance is lower in fathers (M = 2.53, SD = 0.95) than in mothers (M = 2.98, SD = 1.05). Stress due to parental role change is higher in mothers (M = 3.37, p = 1.04) than in fathers (M = 2.49, SD = 0.99). Regression analyses show that stress due to behaviour and appearance, as well as parental role change, can be associated with relationship strain in mothers. For fathers, only stress experienced due to the behaviour and appearance can be associated with relationship strain, whereas parental role change is not significant.

Conclusions

Our data illustrate that relationship strain can result from stress in mothers and fathers, indicating the need for stress prevention measures for both. Only mothers show relationship strain due to stress in their parental role. Although it is unclear what mechanisms underlie these findings, we assume that the maternal role is still primarily associated with child care. One way to relieve maternal stress could be to increase psychological support and the promotion paternal involvement in the postnatal period.

Key messages

Search for Dark Matter Annihilation Signals in the H.E.S.S. Inner Galaxy Survey

The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented γ-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (≳100  GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant γ-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section ⟨σv⟩. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach ⟨σv⟩ values of 3.7×10^{-26}  cm^{3} s^{-1} for 1.5 TeV DM mass in the W^{+}W^{-} annihilation channel, and 1.2×10^{-26}  cm^{3} s^{-1} for 0.7 TeV DM mass in the τ^{+}τ^{-} annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based γ-ray observations thus probe ⟨σv⟩ values expected from thermal-relic annihilating TeV DM particles.

Parental preference for webcams in neonatal intensive care units: an indicator of lacking trust?

Background

Some neonatal intensive care units offer parents webcam systems for times when they cannot be in the ward. Leaving an infant in the ward can be challenging for parents, and trust in the neonatal healthcare professionals mitigates parents’ worries of not knowing how their infant is doing while they are away. If parents lack trust in the neonatal healthcare professionals, they may attempt to compensate by using webcams. In this work, we examine whether an association exists between the parental preference to use a webcam and low trust in physicians and nursing staff.

Methods

In a nationwide, retrospective cross-sectional study, parents of infants with a birth weight below 1500 g were surveyed six to 18 months after their infant’s birth. Parents who were not offered a webcam system in the ward were asked whether they would have opted for it. Trust was measured by the Trust in Physician and Trust in Nursing Staff scales.

Results

Of the parents who were not offered a webcam, 69% would have chosen to use a webcam if they had been granted the opportunity. The decision for or against a webcam was not significantly associated with either trust in physicians (OR = 0.654, 95% CI = 0.456, 0.937, p = .124) or trust in nursing staff (OR = 1.064, 95% CI = 0.783, 1.446, p = .932).

Conclusions

While the majority of parents surveyed would opt for webcam usage, this preference should not be interpreted as an indicator of lacking trust in neonatal healthcare professionals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03456-2.

Driving new technologies in hospitals: association of organizational and personal factors with the readiness of neonatal intensive care unit staff toward webcam implementation

Background

The use of webcam technology in neonatal intensive care units (NICUs) enables parents to see their child when the parents cannot be present at the NICU. The webcam’s use has been gaining increasing attention. Lead physicians and lead nursing staff play a key role in the decision of whether to implement webcams. This study investigates factors that are associated with the readiness for the implementation of a webcam system among lead NICU staff.

Methods

A postal survey was conducted among all lead physicians and lead nursing staff in all German NICUs between December 2020 and April 2021 (total N = 416, one lead physician and one lead nursing staff per NICU, N = 208). On the basis of normalization process theory, personal (technology acceptance) and organizational (innovation climate) attributes were chosen to determine their association with the readiness for the implementation of a webcam system. The association of these factors was determined using multiple linear regression models for both lead physicians and lead nurses.

Results

Overall, a response rate of 66.59% (n = 277) was achieved. Technology acceptance proved to be a significant factor associated with the readiness for the implementation of a webcam system among lead physicians. Furthermore, staff already working with webcams in their NICUs indicated a significantly higher level of technology acceptance than staff without webcam experience and without any desire to use a webcam in the future. No significant association was found between innovation climate and the readiness for the implementation of a webcam system.

Conclusions

Technology acceptance was identified as a factor associated with the readiness for the implementation of a webcam system. The insights from this study can be used to manage potential barriers regarding the readiness for implementation of webcams in NICUs.

Trial registration

The Neo-CamCare study is registered at the German Clinical Trials Register. DRKS-ID: DRKS00017755. Date of Registration in DRKS: 25-09-2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08072-5.

Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE, [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to a month after its 2021 outburst, observed using the High Energy Stereoscopic System. The VHE emission has a similar temporal profile to lower-energy GeV emission, indicating a common origin, with a two-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic-rays to very high energies.

Trust in medical professionals and its influence on the stress experience of parents of premature infants

AIM

To examine parents' perceptions of stress and their trust in physicians and nursing staff and to investigate whether trust influences the parental perceptions of potential stressors resulting from their infant's hospitalisation in a neonatal intensive care unit.

METHODS

Parents of very and extremely low birth weight infants were surveyed in a nationwide retrospective cross-sectional study 6-18 months after their child's birth. Parental stress was measured utilising the PSS:NICU_German/2-scales, and trust was measured by the scales Trust in Physicians and Trust in Nursing Staff. In addition to descriptive analyses, multiple linear regression models were conducted.

RESULTS

The change in parents' anticipated roles was assessed as more stressful than their infant's appearance and behaviour. Trust in nursing staff significantly influenced the parental stress level. Although the level of trust in physicians was rated higher than trust in nursing staff, trust in physicians did not yield a significant effect on the parental stress experience.

CONCLUSION

Efforts to foster parental trust in nursing staff may reduce the parental stress level and hence enable parents to better cope with the situation. The parental resources unleashed in this way can be employed to enhance parenting.

Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera-electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

Natural history of growth and anaemia in children with epidermolysis bullosa: a retrospective cohort study

BACKGROUND

Impaired growth and anaemia are major extracutaneous complications of epidermolysis bullosa (EB), but data on their development are lacking.

OBJECTIVES

To determine the clinical course of growth and anaemia in children with EB and clarify the impact of nutritional compromise, inflammation and genetic factors.

METHODS

A retrospective study was conducted of 200 children, 157 with recessive dystrophic EB (RDEB) and 43 with junctional EB (JEB)-generalized intermediate, followed at the main referral centre in Germany. Growth charts were calculated using the modified LMS method and were correlated with parameters of anaemia, nutrition, inflammation and the molecular defect in a linear model.

RESULTS

In our cohort of patients with RDEB, weight impairment started at 12-18 months old; by the age of 10 years, 50% showed wasting. The predicted median weight at age 20 years was 35·2 kg for men and 40·1 kg for women. In JEB, growth resembled that of healthy children. Anaemia was present from the second year of life onwards in RDEB and JEB. Low levels of haemoglobin, iron, vitamin D, zinc and albumin, high levels of C-reactive protein, and absence of collagen VII correlated significantly with low weight in RDEB. No correlation was observed in JEB.

CONCLUSIONS

The results highlight that nutritional compromise occurs early in children with RDEB and therefore may require interventions as of the first year or two of life. What's already known about this topic? Children with epidermolysis bullosa (EB) suffer from failure to thrive and anaemia as major extracutaneous complications. The course of growth and the development of anaemia in EB are poorly characterized. What does this study add? A molecularly well characterized cohort of 200 children with EB was followed with regard to anthropometrics, anaemia and inflammation. We demonstrate early onset of growth failure and anaemia, most pronounced in the subset of recessive dystrophic EB. Awareness of early growth delay and nutritional deficiencies will improve EB care in daily practice.

Unresolved Gamma-Ray Sky through its Angular Power Spectrum

The gamma-ray sky has been observed with unprecedented accuracy in the last decade by the Fermi -large area telescope (LAT), allowing us to resolve and understand the high-energy Universe. The nature of the remaining unresolved emission [unresolved gamma-ray background (UGRB)] below the LAT source detection threshold can be uncovered by characterizing the amplitude and angular scale of the UGRB fluctuation field. This Letter presents a measurement of the UGRB autocorrelation angular power spectrum based on eight years of Fermi-LAT Pass 8 data products. The analysis is designed to be robust against contamination from resolved sources and noise systematics. The sensitivity to subthreshold sources is greatly enhanced with respect to previous measurements. We find evidence (with ∼3.7σ significance) that the scenario in which two classes of sources contribute to the UGRB signal is favored over a single class. A double power law with exponential cutoff can explain the anisotropy energy spectrum well, with photon indices of the two populations being 2.55±0.23 and 1.86±0.15.

Search for γ-Ray Line Signals from Dark Matter Annihilations in the Inner Galactic Halo from 10 Years of Observations with H.E.S.S

Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy γ rays. The central region of the Milky Way halo is one of the most promising targets given its large amount of DM and proximity to Earth. We report on a search for a monoenergetic spectral line from self-annihilations of DM particles in the energy range from 300 GeV to 70 TeV using a two-dimensional maximum likelihood method taking advantage of both the spectral and spatial features of the signal versus background. The analysis makes use of Galactic center observations accumulated over ten years (2004-2014) with the H.E.S.S. array of ground-based Cherenkov telescopes. No significant γ-ray excess above the background is found. We derive upper limits on the annihilation cross section ⟨σv⟩ for monoenergetic DM lines at the level of 4×10^{-28}  cm^{3} s^{-1} at 1 TeV, assuming an Einasto DM profile for the Milky Way halo. For a DM mass of 1 TeV, they improve over the previous ones by a factor of 6. The present constraints are the strongest obtained so far for DM particles in the mass range 300 GeV-70 TeV. Ground-based γ-ray observations have reached sufficient sensitivity to explore relevant velocity-averaged cross sections for DM annihilation into two γ-ray photons at the level expected from the thermal relic density for TeV DM particles.

Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data

The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival directions of cosmic-ray electrons or positrons could be a signature of the presence of nearby sources. We use almost seven years of data with energies above 42 GeV processed with the Pass 8 reconstruction. The present data sample can probe dipole anisotropies down to a level of 10^{-3}. We take into account systematic effects that could mimic true anisotropies at this level. We present a detailed study of the event selection optimization of the cosmic-ray electrons and positrons to be used for anisotropy searches. Since no significant anisotropies have been detected on any angular scale, we present upper limits on the dipole anisotropy. The present constraints are among the strongest to date probing the presence of nearby young and middle-aged sources.

H.E.S.S. Limits on Linelike Dark Matter Signatures in the 100 GeV to 2 TeV Energy Range Close to the Galactic Center

A search for dark matter linelike signals iss performed in the vicinity of the Galactic Center by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis iss developed to improve the sensitivity to linelike signals. The upgraded analysis along with newer data extend the energy coverage of the previous measurement down to 100 GeV. The 18 h of data collected with the H.E.S.S. array allow one to rule out at 95% C.L. the presence of a 130 GeV line (at l=-1.5°, b=0° and for a dark matter profile centered at this location) previously reported in Fermi-LAT data. This new analysis overlaps significantly in energy with previous Fermi-LAT and H.E.S.S.

RESULTS

No significant excess associated with dark matter annihilations was found in the energy range of 100 GeV to 2 TeV and upper limits on the gamma-ray flux and the velocity weighted annihilation cross section are derived adopting an Einasto dark matter halo profile. Expected limits for present and future large statistics H.E.S.S. observations are also given.

Search for Dark Matter Annihilations towards the Inner Galactic Halo from 10 Years of Observations with H.E.S.S

The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using γ-ray observations towards the inner 300 pc of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic Center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant γ-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section ⟨σv⟩. These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach ⟨σv⟩ values of 6×10^{-26}  cm^{3} s^{-1} in the W^{+}W^{-} channel for a DM particle mass of 1.5 TeV, and 2×10^{-26}  cm^{3} s^{-1} in the τ^{+}τ^{-} channel for a 1 TeV mass. For the first time, ground-based γ-ray observations have reached sufficient sensitivity to probe ⟨σv⟩ values expected from the thermal relic density for TeV DM particles.

How to assess diabetes distress: comparison of the Problem Areas in Diabetes Scale (PAID) and the Diabetes Distress Scale (DDS)

AIMS

To compare the properties of the two most commonly used assessment tools for diabetes distress, the Problem Areas in Diabetes Scale (PAID) and the Diabetes Distress Scale (DDS), in order to discriminate their psychometric capabilities and functions.

METHODS

Six hundred and twenty-eight people with diabetes (67% Type 1, 33% Type 2) were cross-sectionally assessed with the PAID, the DDS and further self-report scales regarding coping, quality of life, depressive symptoms and self-care, and medical data were gained. We analysed the PAID and DDS for areas of contentual/psychometric divergence in assessing diabetes distress and compared their associations with criteria of interest.

RESULTS

Content analysis: The PAID covers a greater variety of emotional concerns and shows a stronger focus on food-related problems and complications. The DDS is more reflective of physician-related distress and problems concerning diabetes self-management. Psychometric analysis: Exploratory factor analyses revealed four-factor structures of both scales, explaining 60% (PAID) and 67% (DDS) of variance. Confirmatory factor analyses confirmed that single-factor and four-factor models fit the data. Total scales proved high and subscales mostly satisfactory reliability. Associations with criteria of interest: The PAID was significantly more strongly associated with dysfunctional coping styles, quality of life and depressive symptoms. The DDS showed significantly stronger associations with diabetes self-care and metabolic outcomes.

CONCLUSION

Our results support both PAID and DDS as good self-report measures of diabetes distress. The observed contentual/psychometric differences suggest that a justified choice with regard to the intended clinical or scientific purpose can improve the acquisition of the required data.

Use of Whole Genome Sequencing and Patient Interviews To Link a Case of Sporadic Listeriosis to Consumption of Prepackaged Lettuce

We report on a case of listeriosis in a patient who probably consumed a prepackaged romaine lettuce-containing product recalled for Listeria monocytogenes contamination. Although definitive epidemiological information demonstrating exposure to the specific recalled product was lacking, the patient reported consumption of a prepackaged romaine lettuce-containing product of either the recalled brand or a different brand. A multinational investigation found that patient and food isolates from the recalled product were indistinguishable by pulsed-field gel electrophoresis and were highly related by whole genome sequencing, differing by four alleles by whole genome multilocus sequence typing and by five high-quality single nucleotide polymorphisms, suggesting a common source. To our knowledge, this is the first time prepackaged lettuce has been identified as a likely source for listeriosis. This investigation highlights the power of whole genome sequencing, as well as the continued need for timely and thorough epidemiological exposure data to identify sources of foodborne infections.

Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope

We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10^{-12}  GeV^{-1} for ALP masses 0.5≲m_{a}≲5  neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

Resolving the Extragalactic γ-Ray Background above 50 GeV with the Fermi Large Area Telescope

The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, dN/dS, of extragalactic γ-ray sources at E>50  GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (∼8×10^{-12}  ph cm^{-2} s^{-1}). We employ a one-point photon fluctuation analysis to constrain the behavior of dN/dS below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, S_{b}, in the range [8×10^{-12},1.5×10^{-11}]  ph cm^{-2} s^{-1} and power-law indices below and above the break of α_{2}∈[1.60,1.75] and α_{1}=2.49±0.12, respectively. Integration of dN/dS shows that point sources account for at least 86_{-14}^{+16}% of the total extragalactic γ-ray background. The simple form of the derived source count distribution is consistent with a single population (i.e., blazars) dominating the source counts to the minimum flux explored by this analysis. We estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.

Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data

The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ≲100  GeV annihilating via quark and τ-lepton channels.