Multi-wavelength observations of the energetic GRB 080810: detailed mapping of the broadband spectral evolution

GRB 080810 was one of the first bursts to trigger both Swift and the Fermi Gamma-ray Space Telescope. It was subsequently monitored over the X-ray and UV/optical bands by Swift, in the optical by ROTSE and a host of other telescopes and was detected in the radio by the VLA. The redshift of z= 3.355 +/- 0.005 was determined by Keck/HIRES and confirmed by RTT150 and NOT. The prompt gamma/X-ray emission, detected over 0.3-10^3 keV, systematically softens over time, with E_peak moving from ~600 keV at the start to ~40 keV around 100 s after the trigger; alternatively, this spectral evolution could be identified with the blackbody temperature of a quasithermal model shifting from ~60 keV to ~3 keV over the same time interval. The first optical detection was made at 38 s, but the smooth, featureless profile of the full optical coverage implies that this originated from the afterglow component, not the pulsed/flaring prompt emission. Broadband optical and X-ray coverage of the afterglow at the start of the final X-ray decay (~8 ks) reveals a spectral break between the optical and X-ray bands in the range 10^15 - 2x10^16 Hz. The decay profiles of the X-ray and optical bands show that this break initially migrates blueward to this frequency and then subsequently drifts redward to below the optical band by ~3x10^5 s. GRB 080810 was very energetic, with an isotropic energy output for the prompt component of 3x10^53 erg and 1.6x10^52 erg for the afterglow; there is no evidence for a jet break in the afterglow up to six days following the burst.Comment: 15 pages, 9 figures, 4 in colour. Accepted for publication in MNRA

Spectroscopic identification of r-process nucleosynthesis in a double neutron-star merger.

The merger of two neutron stars is predicted to give rise to three major detectable phenomena: a short burst of γ-rays, a gravitational-wave signal, and a transient optical-near-infrared source powered by the synthesis of large amounts of very heavy elements via rapid neutron capture (the r-process). Such transients, named 'macronovae' or 'kilonovae', are believed to be centres of production of rare elements such as gold and platinum. The most compelling evidence so far for a kilonova was a very faint near-infrared rebrightening in the afterglow of a short γ-ray burst at redshift z = 0.356, although findings indicating bluer events have been reported. Here we report the spectral identification and describe the physical properties of a bright kilonova associated with the gravitational-wave source GW170817 and γ-ray burst GRB 170817A associated with a galaxy at a distance of 40 megaparsecs from Earth. Using a series of spectra from ground-based observatories covering the wavelength range from the ultraviolet to the near-infrared, we find that the kilonova is characterized by rapidly expanding ejecta with spectral features similar to those predicted by current models. The ejecta is optically thick early on, with a velocity of about 0.2 times light speed, and reaches a radius of about 50 astronomical units in only 1.5 days. As the ejecta expands, broad absorption-like lines appear on the spectral continuum, indicating atomic species produced by nucleosynthesis that occurs in the post-merger fast-moving dynamical ejecta and in two slower (0.05 times light speed) wind regions. Comparison with spectral models suggests that the merger ejected 0.03 to 0.05 solar masses of material, including high-opacity lanthanides

Mechanism of eIF6 release from the nascent 60S ribosomal subunit.

SBDS protein (deficient in the inherited leukemia-predisposition disorder Shwachman-Diamond syndrome) and the GTPase EFL1 (an EF-G homolog) activate nascent 60S ribosomal subunits for translation by catalyzing eviction of the antiassociation factor eIF6 from nascent 60S ribosomal subunits. However, the mechanism is completely unknown. Here, we present cryo-EM structures of human SBDS and SBDS-EFL1 bound to Dictyostelium discoideum 60S ribosomal subunits with and without endogenous eIF6. SBDS assesses the integrity of the peptidyl (P) site, bridging uL16 (mutated in T-cell acute lymphoblastic leukemia) with uL11 at the P-stalk base and the sarcin-ricin loop. Upon EFL1 binding, SBDS is repositioned around helix 69, thus facilitating a conformational switch in EFL1 that displaces eIF6 by competing for an overlapping binding site on the 60S ribosomal subunit. Our data reveal the conserved mechanism of eIF6 release, which is corrupted in both inherited and sporadic leukemias.Supported by a Federation of European Biochemical Societies Long term Fellowship (to FW), Specialist Programme from Bloodwise [12048] (AJW), the Medical Research Council [MC_U105161083] (AJW) and [U105115237] (RRK), Wellcome Trust strategic award to the Cambridge Institute for Medal Research [100140], Tesni Parry Trust (AJW), Ted’s Gang (AJW) and the Cambridge NIHR Biomedical Research Centre.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/nsmb.311

NleG Type 3 Effectors from Enterohaemorrhagic Escherichia coli Are U-Box E3 Ubiquitin Ligases

NleG homologues constitute the largest family of type 3 effectors delivered by pathogenic E. coli, with fourteen members in the enterohaemorrhagic (EHEC) O157:H7 strain alone. Identified recently as part of the non-LEE-encoded (Nle) effector set, this family remained uncharacterised and shared no sequence homology to other proteins including those of known function. The C-terminal domain of NleG2-3 (residues 90 to 191) is the most conserved region in NleG proteins and was solved by NMR. Structural analysis of this structure revealed the presence of a RING finger/U-box motif. Functional assays demonstrated that NleG2-3 as well as NleG5-1, NleG6-2 and NleG9′ family members exhibited a strong autoubiquitination activity in vitro; a characteristic usually expressed by eukaryotic ubiquitin E3 ligases. When screened for activity against a panel of 30 human E2 enzymes, the NleG2-3 and NleG5-1 homologues showed an identical profile with only UBE2E2, UBE2E3 and UBE2D2 enzymes supporting NleG activity. Fluorescence polarization analysis yielded a binding affinity constant of 56±2 µM for the UBE2D2/NleG5-1 interaction, a value comparable with previous studies on E2/E3 affinities. The UBE2D2 interaction interface on NleG2-3 defined by NMR chemical shift perturbation and mutagenesis was shown to be generally similar to that characterised for human RING finger ubiquitin ligases. The alanine substitutions of UBE2D2 residues Arg5 and Lys63, critical for activation of eukaryotic E3 ligases, also significantly decreased both NleG binding and autoubiquitination activity. These results demonstrate that bacteria-encoded NleG effectors are E3 ubiquitin ligases analogous to RING finger and U-box enzymes in eukaryotes

The transverse momentum dependence of charged kaon Bose-Einstein correlations in the SELEX experiment

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOWe report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/c σ-, π- and 540GeV/c p beams from the SELEX (E781) experiment at the Fermilab Tevatron. K±K± correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, λ, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types. © 2015 The Authors.We report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/c σ-, π- and 540GeV/c p beams from the SELEX (E781) experiment at the Fermilab Tevatron. K±K± correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, λ, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types.753458464CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOSem informaçãoSem informaçãoRuss, J.S., Akchurin, N., Andreev, V.A., First charm hadroproduction results from SELEX (1998) ICHEP'98 Proc. Int. Conf. on High Energy Physics II, p. 1259. , arxiv:hep-ex/9812031Goldhaber, G., Fowler, W.B., Goldhaber, S., Hoang, T.F., Kalogeropoulos, T.E., Powell, W.M., Pion-pion correlations in antiproton annihilation events (1959) Phys. Rev. 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C, 83. , arxiv:1004.0925Engelfried, J., The SELEX phototube RICH detector (1999) Nucl. Instrum. Methods A, 431, pp. 53-69. , arxiv:hep-ex/9811001Engelfried, J., The E781 (SELEX) RICH detector (1998) Nucl. Instrum. Methods A, 409, pp. 439-442Sjöstrand, T., Mrenna, S., Skands, P., PYTHIA 6.4 physics and manual (2006) J. High Energy Phys., 5. , arxiv:hep-ph/0603175v2Chajȩcki, Z., Lisa, M., Global conservation laws and femtoscopy of small systems (2008) Phys. Rev. C, 78. , arxiv:0803.0022Lednický, R., Lyuboshitz, V.L., Erazmus, B., Nouais, D., How to measure which sort of particles was emitted earlier and which later (1996) Phys. Lett. B, 373, pp. 30-34Voloshin, S., Lednický, R., Panitkin, S., Xu, N., Relative space-time asymmetries in pion and nucleon production in noncentral nucleus-nucleus collisions at high-energies (1997) Phys. Rev. Lett., 79, pp. 4766-4769. , arxiv:nucl-th/9708044Pratt, S., Shapes and sizes from non-identical-particle correlations (2007) Braz. J. 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D, 87. , arxiv:1212.5958v2Khachatryan, V., Measurement of Bose-Einstein correlations in pp collisions at s = 0.9 and 7 TeV (2011) J. High Energy Phys., 5. , arxiv:1101.3518Akkelin, S.V., Sinyukov, Y.M., Deciphering nonfemtoscopic two-pion correlations in p+p collisions with simple analytical models (2012) Phys. Rev. D, 85. , arxiv:1106.5120Lednický, R., Progulova, T.B., Influence of resonances on Bose-Einstein correlations of identical pions (1992) Z. Phys. C, 55, pp. 295-305Lisa, M., Pratt, S., Soltz, R., Wiedemann, U., Femtoscopy in relativistic heavy ion collisions: two decades of progress (2005) Annu. Rev. Nucl. Part. Sci., 55, pp. 357-402. , arxiv:nucl-ex/0505014Pratt, S., Pion interferometry for exploding sources (1984) Phys. Rev. Lett., 53, pp. 1219-1221Abbiendi, G., Bose-Einstein study of position-momentum correlations of charged pions in hadronic Z0 decays (2007) Eur. Phys. J. C, 52, pp. 787-803. , arxiv:0708.1122Achard, P., Test of the τ-model of Bose-Einstein correlations and reconstruction of the source function in hadronic Z-boson decay at LEP (2011) Eur. Phys. J. C, 71, p. 1648. , arxiv:1105.4788Aamodt, K., Femtoscopy of pp collisions at s = 0.9 and 7 TeV at the LHC with two-pion Bose-Einstein correlations (2011) Phys. Rev. D, 84. , arxiv:1101.3665Wiedemann, U.A., Heinz, U.W., Resonance contributions to Hanbury-Brown-Twiss correlation radii (1997) Phys. Rev. C, 56, pp. 3265-3286. , arxiv:nucl-th/9611031Werner, K., Karpenko, I., Pierog, T., Bleicher, M., Mikhailov, K., Evidence for hydrodynamic evolution in proton-proton scattering at 900 GeV (2011) Phys. Rev. C, 83. , arxiv:1010.0400Humanic, T.J., Predictions for two-pion correlations for s=14TeV proton-proton collisions (2007) Phys. Rev. C, 76. , arxiv:nucl-th/0612098Alexopoulos, T., Study of source size in pp- collisions at s=1.8TeV using pion interferometry (1993) Phys. Rev. D, 48, pp. 1931-1942Csorgo, T., Kittel, W., Metzger, W.J., Novák, T., Parametrization of Bose-Einstein correlations and reconstruction of the space-time evolution of pion production in e+e- annihilation (2008) Phys. Lett. B, 663, pp. 214-216. , arxiv:0803.3528Bialas, A., Kucharczyk, M., Palka, H., Zalewski, K., Mass dependence of HBT correlations in e+e- annihilation (2000) Phys. Rev. D, 62. , arxiv:hep-ph/0006290Alexander, G., Open questions related to Bose-Einstein correlations in e+e- → hadrons (2004) Acta Phys. Pol. B, 35, pp. 69-76. , arxiv:hep-ph/0311114Alexander, G., Mass and transverse mass effects on the hadron emitter size (2001) Phys. Lett. B, 506, pp. 45-51. , arxiv:hep-ph/0101319The authors are indebted to the staff of Fermi National Accelerator Laboratory and for invaluable technical support from the staffs of collaborating institutions. This project was supported in part by Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie, Consejo Nacional de Ciencia y Tecnología (CONACyT), Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fondo de Apoyo a la Investigación (UASLP), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), the Israel Science Foundation founded by the Israel Academy of Sciences and Humanities, Istituto Nazionale di Fisica Nucleare (INFN), the International Science Foundation (ISF), the National Science Foundation, NATO, the Russian Academy of Sciences, the Russian Ministry of Science and Technology, the Russian Foundation for Basic Research (research project No. 11-02-01302-a), the Secretaría de Educación Pública (Mexico), the Turkish Scientific and Technological Research Board (TÜBİTAK), and the U.S. Department of Energy. We thank ITEP and National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) for providing computing powers and support for data analysis and simulations. The authors also would like to thank Prof. Michael Lisa and Prof. Richard Lednický for helpful comments and fruitful discussions

Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state

The very high energy (VHE ¿ 100 GeV) -ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ¿ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and ¿-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy ¿-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL). © ESO 2018.The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015-71662-C2-2-P, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ. IA acknowledges support by a Ramón y Cajal grant of the Ministerio de Economía, Industria y Competitividad (MINECO) of Spain. The research at the IAA–CSIC was supported in part by the MINECO through grants AYA2016–80889–P, AYA2013–40825–P, and AYA2010–14844, and by the regional government of Andalucía through grant P09–FQM–4784.Peer Reviewe

A detailed study of the very-high-energy Crab pulsar emission with the LST-1

Context: There are currently three pulsars firmly detected by imaging atmospheric Cherenkov telescopes (IACTs), two of them reaching TeV energies, challenging models of very-high-energy (VHE) emission in pulsars. More precise observations are needed to better characterize pulsar emission at these energies. The LST-1 is the prototype of the Large-Sized Telescope, that will be part of the Cherenkov Telescope Array Observatory (CTAO). Its improved performance over previous IACTs makes it well suited for studying pulsars. Aims: To study the Crab pulsar emission with the LST-1, improving and complementing the results from other telescopes. These observations can also be used to characterize the potential of the LST-1 to study other pulsars and detect new ones. Methods: We analyzed a total of $\sim$103 hours of gamma-ray observations of the Crab pulsar conducted with the LST-1 in the period from September 2020 to January 2023. The observations were carried out at zenith angles less than 50 degrees. A new analysis of the Fermi-LAT data was also performed, including $\sim$14 years of observations. Results: The Crab pulsar phaseogram, long-term light-curve, and phase-resolved spectra are reconstructed with the LST-1 from 20 GeV to 450 GeV for P1 and up to 700 GeV for P2. The pulsed emission is detected with a significance of 15.2$σ$. The two characteristic emission peaks of the Crab pulsar are clearly detected (&gt;10$σ$), as well as the so-called bridge emission (5.7$σ$). We find that both peaks are well described by power laws, with spectral indices of $\sim$3.44 and $\sim$3.03 respectively. The joint analysis of Fermi-LAT and LST-1 data shows a good agreement between both instruments in the overlapping energy range. The detailed results obtained in the first observations of the Crab pulsar with LST-1 show the potential that CTAO will have to study this type of sources

Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)

This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands

Localization and broadband follow-up of the gravitational-wave transient GW150914

© 2016. The American Astronomical Society. All rights reserved. A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams