We report the early discovery of the optical afterglow of gamma-ray burst (GRB) 140801A in the 137 deg... 3-... error-box of the Fermi Gamma-ray Burst Monitor (GBM). MASTER is the only observatory ...that automatically reacts to all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart was discovered solely from its GBM localization. The optical afterglow of GRB 140801A was found by MASTER Global Robotic Net 53 s after receiving the alert, making it the fastest optical detection of a GRB from a GBM error-box. Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m Big Telescope Alt-azimuth of the Special Astrophysical Observatory of the Russian Academy of Sciences reveals a redshift of z = 1.32. We performed optical and near-infrared photometry of GRB 140801A using different telescopes with apertures ranging from 0.4 to 10.4 m. GRB 140801A is a typical burst in many ways. The rest-frame bolometric isotropic energy release and peak energy of the burst are ... erg and ..., respectively, which is consistent with the Amati relation. The absence of a jet break in the optical light curve provides a lower limit on the half-opening angle of the ... The observed ... is consistent with the limit derived from the Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis show that GRB 140801A could belong to the class of intermediate duration. The rapid detection of the optical counterpart of GRB 140801A is especially important regarding the upcoming experiments with large coordinate error-box areas. (ProQuest: ... denotes formulae/symbols omitted.)
The Afterglow and Kilonova of the Short GRB 160821B Troja, E.; Castro-Tirado, A. J.; Gonzalez, J Becerra ...
Monthly notices of the Royal Astronomical Society,
08/2019, Letnik:
489, Številka:
2
Journal Article
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GRB 160821B is a short duration gamma-ray burst (GRB) detected and localized by the Neil Gehrels Swift Observatory in the outskirts of a spiral galaxy at z = 0.1613, at a projected physical offset of ...16 kpc from the galaxy’s center. We present X-ray, optical/nIR, and radio observations of its counterpart and model them with two distinct components of emission: a standard afterglow, arising from the interaction of the relativistic jet with the surrounding medium, and a kilonova, powered by the radioactive decay of the sub-relativistic ejecta. Broadband modelling of the afterglow data reveals a weak reverse shock propagating backward into the jet, and a likely jet-break at 3.5 d. This is consistent with a structured jet seen slightly off-axis (θview ∼ θcore) while expanding into a low-density medium (n ≈ 10−3 cm−3). Analysis of the kilonova properties suggests a rapid evolution towards red colours, similar toAT2017gfo, and a low-nIR luminosity, possibly due to the presence of a long-lived neutron star. The global properties of the environment, the inferred low mass (Mej <~ 0.006 Msun) and velocities (vej >~ 0.05c) of lanthanide-rich ejecta are consistent with a binary neutron star merger progenitor.
ABSTRACT
We examine the prospects of the high-redshift long gamma-ray bursts (LGRBs) Hubble diagram as a test of the basic cosmological principles. Analysis of the Hubble diagram allows us to test ...several fundamental cosmological principles using the directly observed flux–distance–redshift relation. Modern LGRBs data together with the correlation between the spectral peak energy and the isotropic equivalent radiated energy (the so-called Amati relation) can be used for construction of the Hubble diagram at the model-independent level. We emphasize observational selection effects, which inevitably exist and distort the theoretically predicted relations. An example is the weak and strong gravitational lensing bias effect for high-redshift LGRB in the presence of limited observational sensitivity (Malmquist bias). After bias correction, there is a tendency to vacuum-dominated models with $\Omega _\Lambda \rightarrow 0.9$, Ωm → 0.1. Forthcoming gamma-ray observations by the Transient High-Energy Sky and Early Universe Surveyor (THESEUS) space mission together with ground- and space-based multimessenger facilities will allow us to improve essentially the restrictions on alternative basic principles of cosmological models.
Abstract
The picturesque and high conservation value thermal landscapes of the Valley of Geysers feature endothermal (heated by endogenous fluids) soils which support endangered and unique species. ...However, such soils have not been distinguished as a separate taxon within most classification systems. In this study, we described the soil morphology at macro-, meso- and micro-scales, chemistry, mineralogy and vegetation of these landscapes as they are affected by the steam-heated acid-sulfate waters. The studied catenary sequence from exothermal (non-heated) to endothermal soils was characterized by decreasing contents of soil organic carbon, sand fraction, essential nutrients (Ca, K, Mg, Mn and Si), increasing soil acidity, amounts of fine particle-size fractions and contents of trace elements (Al, As, Co, Cr, Cu, Fe, Pb, Ti and V) as well as the development of sodium-sulfate salinity, kaolinization and ferrugination. In phytocenoses supported by endothermal soils, species of order
Rosales
and
Asparagales
were overrepresented among obligate and facultative thermophytes respectively, and species of order
Poales
were underrepresented among facultative thermophytes in relation to the flora of the Valley of Geysers. Phytocenoses on the non-heated Andosols were enriched in
Polypodiopsida
species. The results of our comparative analysis of the thermally-induced variability in the soils and vegetation contribute to the general understanding of mineralogical, bio-abiotic and biological systems affected by steam-heated acid-sulfate waters. We hope that our findings will provide a basis for future transdisciplinary studies of the influence of steam-heated waters of a hot spring on the thermal landscapes.
This paper presents data on the simultaneous and complementary observations of the gamma-ray burst (GRB) GRB 161017A for optical, X-ray, and gamma wavelengths obtained by the Russian multi-messenger ...Lomonosov space observatory and supplemented by additional data from the Swift satellite as well as the ground-based MASTER Global Robotic Net and the 10 m Gran Telescopio Canarias. Multifrequency spectra of this very powerful explosion indicate that it originated at a distance of 10 billion light years from Earth. Here, we present the results of the prompt, early, and afterglow optical observations. The light curves and spectra suggest that the prompt optical and high-energy emissions occur in the same region near the GRB source.
Lactoferrin is a non-heme iron-binding glycoprotein with multiple health-beneficial functions including antimicrobial, antioxidant, anticarcinogenic, and immunomodulatory effects. There is emerging ...evidence that neutrophils may serve as targets of lactoferrin in vivo, and here we show how recombinant human lactoferrin (rhLf) can contribute to this regulation. Indeed, our results demonstrate that rhLf binds efficiently to human neutrophils and induces a variety of early cellular responses such as mobilization of intracellular Ca2+, remodeling of actin cytoskeleton, and degranulation (release of lysozyme and myeloperoxidase). In addition, rhLf facilitates lectin-induced H2O2 production and stabilization of lectin-induced cellular aggregates. The role of calcium signaling seems to be essential for rhLf-induced activation of neutrophils, as Ca2+-chelators inhibit degranulation response while lectin-induced H2O2 production correlates significantly with cytoplasmic Ca2+ elevation. Taken together, our findings justify that rhLf can activate neutrophil functions in a calcium-dependent manner and hence, can potentiate innate immune responses.
We present photometry and spectroscopy of the Type IIP supernova (SN IIP) 2009bw in UGC 2890 from a few days after the outburst to 241 d. The light curve of SN 2009bw during the photospheric phase is ...similar to that of normal SNe IIP but with a brighter peak and plateau (
mag,
mag). The luminosity drop from the photospheric to the nebular phase is one of the fastest ever observed, ∼2.2 mag in about 13 d. The radioactive tail of the bolometric light curve indicates that the amount of ejected 56Ni is ≈0.022 M⊙. The photospheric spectra reveal high-velocity lines of Hα and Hβ until about 105 d after the shock breakout, suggesting a possible early interaction between the SN ejecta and pre-existent circumstellar material, and the presence of CNO elements. By modelling the bolometric light curve, ejecta expansion velocity and photospheric temperature, we estimate a total ejected mass of ∼8-12 M⊙, a kinetic energy of ∼0.3 foe and an initial radius of ∼3.6-7 × 1013 cm.
We present the low-resolution spectroscopic and UBVRI broad-band photometric investigations of the Type IIb supernova (SN) 2011fu, discovered in UGC 01626. The photometric follow-up of this event was ...initiated a few days after the explosion and covers a period of about 175 d. The early-phase light curve shows a rise, followed by steep decay in all bands, and shares properties very similar to that seen for SN 1993J, with a possible detection of the adiabatic cooling phase. Modelling of the quasi-bolometric light curve suggests that the progenitor had an extended (∼1 × 1013 cm), low-mass (∼0.1 M) H-rich envelope on top of a dense, compact (∼2 × 1011 cm), more massive (∼1.1 M) He-rich core. The nickel mass synthesized during the explosion was found to be ∼0.21 M, slightly larger than that seen for other Type IIb SNe. The spectral modelling performed with synow suggests that the early-phase line velocities for H and Fe ii features were ∼16 000 and ∼14 000 km s−1, respectively. Then, the velocities declined up to day +40 and became nearly constant at later epochs.
The pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involves dysregulations of iron metabolism, and although the mechanism of this pathology is not yet fully ...understood, correction of iron metabolism pathways seems a promising pharmacological target. The previously observed effect of inhibiting SARS-CoV-2 infection by ferristatin II, an inducer of transferrin receptor 1 (TfR1) degradation, prompted the study of competition between Spike protein and TfR1 ligands, especially lactoferrin (Lf) and transferrin (Tf). We hypothesized molecular mimicry of Spike protein as cross-reactivity of Spike-specific antibodies with Tf and Lf. Thus, strong positive correlations (R
2
> 0.95) were found between the level of Spike-specific IgG antibodies present in serum samples of COVID-19-recovered and Sputnik V-vaccinated individuals and their Tf-binding activity assayed with peroxidase-labeled anti-Tf. In addition, we observed cross-reactivity of Lf-specific murine monoclonal antibody (mAb) towards the SARS-CoV-2 Spike protein. On the other hand, the interaction of mAbs produced to the receptor-binding domain (RBD) of the Spike protein with recombinant RBD protein was disrupted by Tf, Lf, soluble TfR1, anti-TfR1 aptamer, as well as by peptides RGD and GHAIYPRH. Furthermore, direct interaction of RBD protein with Lf, but not Tf, was observed, with affinity of binding estimated by K
D
to be 23 nM and 16 nM for apo-Lf and holo-Lf, respectively. Treatment of Vero E6 cells with apo-Lf and holo-Lf (1–4 mg/mL) significantly inhibited SARS-CoV-2 replication of both Wuhan and Delta lineages. Protective effects of Lf on different arms of SARS-CoV-2-induced pathogenesis and possible consequences of cross-reactivity of Spike-specific antibodies are discussed.
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