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.

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.

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.

Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A

Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera–electron volts. Its arrival direction was consistent with the location of a known γ-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength campaign followed, ranging from radio frequencies to γ-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy γ-rays. This observation of a neutrino in spatial coincidence with a γ-ray–emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos.

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.

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.

Generation of lymphoma-type variant hamster polyomavirus genomes in hamsters susceptible to lymphoma induction

The hamster polyomavirus (HaPV) induces either hair follicle epitheliomas or lymphomas in either Z3 or HaP respectively. Syrian hamsters. In the lymphomas specifically deleted "lymphoma-type" (lt) HaPV genomes are accumulated. In the present study the temporal pattern of generation of HaPV (lt) DNA was investigated in context of the development of lymphomas in neonatally infected HaP hamsters. The generation of HaPV (lt) DNA was first detectable during the postnatal phase of high level replication of viral DNA in hemopoietic organs (at 7 days post infection), thus clearly preceding the development of overt lymphoma. A variety of HaPV (lt) DNA species is generated in lymphoid cells, but usually only one of them is accumulated to high amounts in lymphoma cells. Furthermore, the pattern of HaPV (lt) and wild-type (wt) DNA was studied in normal and tumor tissues of tumor-bearing hamsters as well as in tumor-free hamsters. In tumor-bearing hamsters predominantly HaPV (lt) DNA species were found in the infected tissues, while HaPV (wt) DNA was detected rarely and only in tumor-free tissues. In contrast, in tissues of tumor-free hamsters HaPV (wt) DNA prevailed over HaPV (lt) DNA species.

In vivo replication of hamster polyomavirus DNA displays lymphotropism in hamsters susceptible to lymphoma induction

Using the whole body section hybridization technique, we monitored the organ- and age-specific pattern of replication of hamster polyomavirus (HaPV) DNA in a colony of Syrian hamsters, which are susceptible to lymphoma induction. Three phases of viral infection and replication could be distinguished: first, a phase of acute infection characterized by high levels of replication of HaPV DNA in the haemopoietic organs and the liver. This culminated 5 to 7 days post-infection (p.i.); second, at 10 days p.i., a phase of viral clearance became evident; and finally, a third phase reflected both the restriction of HaPV replication in adult hamsters and the accumulation of HaPV DNA at sites of tumour development. A remarkable conformity was observed between the tissue specificity of viral replication and the induced tumour profile: high levels of replication of HaPV DNA were restricted to cells of the haemopoietic system and lymphoid tumours were induced. As shown by in situ hybridization, the viral infection in non-haemopoietic organs was due to the dissemination of HaPV-infected blood cells.

Hamster polyomavirus-encoded proteins: gene cloning, heterologous expression and immunoreactivity

The hamster polyomavirus (HaPV) is associated with spontaneously appearing skin epithelioma of the Syrian hamster Z3 strain. Virus particles prepared from the skin epithelioma cause lymphoma and leukemia when injected into newborn hamsters from a distinct Syrian hamster colony (HaP); in contrast to the skin epithelioma the hemopoietic tumors are virus free but accumulate viral DNA. To study the humoral immune response of HaPV-infected Z3 hamsters we produced recombinant HaPV proteins in Escherichia coli as beta-galactosidase-, TrpE- and dihydrofolate reductase-fusion proteins or as non-fused proteins. Recombinant plasmids carried segments of all putative early and late HaPV proteins. The recombinant proteins were detected in stained SDS polyacrylamide gels and in Western blots using monoclonal anti-TrpE and anti-beta-galactosidase antibodies and sera of HaPV-infected hamsters. Sera from HaPV-infected Z3 hamsters and crude lysates of all clones were applied to Western blots to characterize the humoral immune response in the animals. HaPV-specific antibodies were found to be directed against early protein segments translated from the first common exon and from the second unique exon of LT and MT, resp., as well as against the late proteins VP1 and VP2/3. The almost complete VP2 was recognized by all sera whereas VP1 was detected only by a half of the sera. Our data suggest the presence of at least 2 immunodominant regions in VP2, one in the C-terminal VP1 and at least 4 in early proteins.

Linkage analysis in German breast cancer families with early onset of the disease, using highly polymorphic markers from the chromosome 17q11-q24 region

Linkage analysis in German breast cancer families with early onset of the disease by using six markers on chromosome 17q11-q24 has been carried out. In the region between markers D17S250 and GH, three markers showed positive LOD scores at an estimated distance of zero. Evidence for linkage is greatest for D17S250, with a LOD score of 2.42.

Comparison of different in situ hybridization techniques for the detection of human papillomavirus DNA in cervical smears

Different hybridization methods were used for detection of human papillomavirus (HPV) DNA in cervical smears. The results obtained by filter in situ hybridization (FISH) are consistent with most of the reports recently published. To overcome the unsatisfactory limitations of this method, especially the difficulties to distinguish clearly between positive and negative signals, we developed an in situ hybridization protocol using a cytospin and 35S-labelled as well as biotinylated DNA-probes. For direct comparison of different methods, the samples were obtained from two groups of patients. One group were women with reiterated Papanicolaou smears III, IV; the other were women with reiterated Pap III, IV and additional histological scoring. In all cases but one, the different methods used have shown the same results. In one case the hybridization on slides using 35S-labelled as well as biotinylated probes gave a negative result, whereas the FISH method using a 32P-labelled probe allowed to detect of HPV 16 and 18 DNA only when more than 1 x 10(6) cells were present per filter. Our data demonstrate that in situ hybridization on slides is a specific and sensitive technique, which enables a clear distinction between positive and negative results using a small number of cells and which, especially with biotinylated probes, is suitable for application in routine work.

Oncogenic and nononcogenic human genital papillomaviruses generate the E7 mRNA by different mechanisms

A new promoter located within E6 was mapped in human papillomavirus type 6b (HPV6b)- and HPV11-containing benign genital condylomata (genital warts). The RNA transcribed from this promoter represented the major RNA species colinear with open reading frames E6 and E7 and can encode the E7 protein. No equivalent promoter was active in HPV16-containing cancers and cancer-derived cell lines. In those, the major transcripts contained one of two different introns within E6 and the RNAs could encode two different E6 proteins and E7.

Studies on the SV40-like papovavirus SV40-GBM. III. Propagation at low multiplicities of infection in various human cell lines

At low multiplicity several human cell lines supported the lytic infection with SV40-GBM better than that with the wild type SV40. The efficiency of viral DNA replication differed in the cell lines used suggesting that specific host cell factors may determine the rate of viral DNA synthesis. Furthermore, the emergence of different DNA defects during propagation of the virus indicates that host cell factors in question might also influence the composition of the viral DNA population.

Studies on the SV40-like papovavirus SV40-GBM. I. Genomic analysis by restriction endonucleases and electron microscopy after propagation in CV-1 monkey cells

Infection of CV-1 monkey cells with SV40-GBM, a papovavirus isolated from a human glioblastoma multiforme, resulted in the appearance of defective viral DNA molecules. In contrast to SV40 wild-type, two main types of variant DNA molecules could be found after three viral passages at multiplicities of infection of about 10. The molecules of one variant DNA (GBM3-L) were about 19% shorter than the GBM3-H DNA molecules and the DNA of the original GBM isolate, as demonstrated by electron microscopy. Restriction enzyme analysis revealed that GBM3-L DNA had lost both the EcoRI and the HpaII cleavage sites which are located in the late viral genome region. Furthermore, SV40 GBM3-L did not possess the two PvuII sites which are located in the late genome region, and a portion of the GBM3-H and GBM3-L DNA molecules had lost the unique KpnI site. Heteroduplex analysis verified that the rearrangements in the GBM3-L DNA are located only in the late region of this DNA. The possible differences between SV40 wild-type and SV40-GBM are discussed on the basis of these results.

[Effect of heparin, spermidine and Be2+ ions on the phosphatase and RNAse activity of rat liver cell nuclei]

Effects of heparin, spermidine, and Be2+ ions on the ATPase and beta-glycerophosphatase and RNA-ase activities of the rat liver cell nuclei were studied. Be2+ was shown to inhibit the ATPase activity and, to a lesser extent, beta-glycerophosphatase activities. Physiological concentrations of heparin and spermidine also lowered the mentioned two activities, as well as the RNAase activity of the nuclei. Evidence is presented for the inhibitory effect of heparin and spermidine on endonucleases.