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.
Aims.
Gamma-ray burst (GRB) 190829A (
z
= 0.0785) was detected by
Fermi
and
Swift
and also at very high energy (VHE) by the High-Energy Stereoscopic System (H.E.S.S.) telescopes. The prompt emission ...displayed two emission episodes separated by a quiescent gap of ∼40 s. We present the 10.4 m Gran Telescopio Canarias (GTC) observations of the afterglow of GRB 190829A and its underlying supernova. We also compare GRB 190829A to GRB 180728A, a GRB with similar behaviour, and discuss the implications on underlying physical mechanisms producing these two GRBs.
Methods.
We present multi-band photometric data along with spectroscopic follow-up observations taken with the 10.4 m GTC telescope. Together with the data from the prompt emission, the 10.4 m GTC data are used to understand the emission mechanisms and possible progenitor.
Results.
A detailed analysis of the multi-band observations of the afterglow requires the cooling frequency to pass between the optical and X-ray bands at early epochs. The afterglow then transitions to the underlying supernova (SN) 2019oyw, which dominates later on.
Conclusions.
Although the prompt emission temporal properties of GRB 190829A and GRB 180728A are similar, the two pulses are different in the spectral domain. We find that SN 2019oyw associated with GRB 190829A is powered by Ni decay and is a Type Ic-BL SN. The spectroscopic and photometric properties of this SN are consistent with those observed for SN 1998bw, but evolved earlier.
Since the 1995 discovery of the broad iron K-line emission from the Seyfert galaxy MCG-6-30-15 (ref. 1), broad iron K lines have been found in emission from several other Seyfert galaxies, from ...accreting stellar-mass black holes and even from accreting neutron stars. The iron K line is prominent in the reflection spectrum created by the hard-X-ray continuum irradiating dense accreting matter. Relativistic distortion of the line makes it sensitive to the strong gravity and spin of the black hole. The accompanying iron L-line emission should be detectable when the iron abundance is high. Here we report the presence of both iron K and iron L emission in the spectrum of the narrow-line Seyfert 1 galaxy 1H 0707-495. The bright iron L emission has enabled us to detect a reverberation lag of about 30 s between the direct X-ray continuum and its reflection from matter falling into the black hole. The observed reverberation timescale is comparable to the light-crossing time of the innermost radii around a supermassive black hole. The combination of spectral and timing data on 1H 0707-495 provides strong evidence that we are witnessing emission from matter within a gravitational radius, or a fraction of a light minute, from the event horizon of a rapidly spinning, massive black hole.
Several active galactic nuclei show correlated variations in the UV/optical range, with time delays increasing at longer wavelengths. Thermal reprocessing of the X-rays illuminating the accretion ...disk has been proposed as a viable explanation. In this scenario, the variable X-ray flux irradiating the accretion disk is partially reflected in X-rays and partially absorbed, thermalized, and reemitted with some delay by the accretion disk at longer wavelengths. We investigate this scenario assuming an X-ray pointlike source illuminating a standard Novikov-Thorne accretion disk around a rotating black hole. We consider all special and general relativistic effects to determine the incident X-ray flux on the disk and in propagating light from the source to the disk and to the observer. We also compute the disk reflection flux, taking into consideration the disk ionization. We investigate the dependence of the disk response function and time lags on various physical parameters, such as the black hole mass and spin; X-ray corona height, luminosity, and photon index; accretion rate; inclination; and inner/outer disk radii. We find it is important to consider relativistic effects and the disk ionization in estimating the disk response. We also find a strong nonlinearity between the X-ray luminosity and the disk response. We present an analytic function for the time-lag dependence on wavelength, which can be used to fit observed time-lag spectra. We also estimate the fraction of the reverberation signal with respect to the total flux, and we suggest possible explanations for the lack of X-ray-UV/optical correlated variations in a few sources.
Abstract
We present a detailed prompt emission and early optical afterglow analysis of the two very-high-energy (VHE) detected bursts GRB 201015A and GRB 201216C, and their comparison with a subset ...of similar bursts. Time-resolved spectral analysis of multistructured GRB 201216C using the Bayesian binning algorithm revealed that during the entire duration of the burst, the low-energy spectral index (
α
pt
) remained below the limit of the synchrotron line of death. However, statistically some of the bins supported the additional thermal component. Additionally, the evolution of spectral parameters showed that both the peak energy (
E
p
) and
α
pt
tracked the flux. These results were further strengthened using the values of the physical parameters obtained by synchrotron modeling of the data. Our earliest optical observations of both bursts using the F/Photometric Robotic Atmospheric Monitor Observatorio del Roque de los Muchachos and Burst Observer and Optical Transient Exploring System robotic telescopes displayed a smooth bump in their early optical light curves, consistent with the onset of the afterglow due to synchrotron emission from an external forward shock. Using the observed optical peak, we constrained the initial bulk Lorentz factors of GRB 201015A and GRB 201216C to Γ
0
= 204 and Γ
0
= 310, respectively. The present early optical observations are the earliest known observations constraining outflow parameters and our analysis indicate that VHE detected bursts could have a diverse range of observed luminosity within the detectable redshift range of present VHE facilities.
We apply a reflection-based model to the best available XMM–Newton spectra of X-ray bright ultraluminous X-ray sources (NGC 1313 X–1, NGC 1313 X–2, M 81 X–6, Holmberg IX X–1, NGC 5408 X–1 and ...Holmberg II X–1). A spectral drop is apparent in the data of all the sources at energies 6–7 keV. The drop is interpreted here in terms of relativistically blurred ionized reflection from the accretion disc. A soft excess is also detected from these sources as usually found in the spectra of active galactic nuclei (AGN), with emission from O K and Fe L, in the case of NGC 5408 X–1 and Holmberg II X–1, which can be understood as features arising from reflection of the disc. Remarkably, ionized disc reflection and the associated power-law continuum provide a good description of the broad-band spectrum, including the soft excess. There is no requirement for thermal emission from the inner disc in the description of the spectra. The black holes of these systems must then be highly spinning, with a spin close to the maximum rate of a maximal spinning black hole. The results require the action of strong light bending in these sources. We suggest that they could be strongly accreting black holes in which most of the energy is extracted from the flow magnetically and released above the disc thereby avoiding the conventional Eddington limit.
ABSTRACT
We present the results from an X-ray variability study of IRAS 13224-3809. This is probably the best source for X-ray reverberation studies since it is X-ray bright, extremely variable, and ...it has been extensively observed with XMM–Newton. We used all the archival XMM–Newton data from the three EPIC cameras (to increase the signal to noise) and, given the many observations of the source, we were able to compute the time lags spectra in three different flux levels/periods. We fitted the time lags and energy spectra, simultaneously, using a new X-ray reverberation code that computes the time-dependent reflection spectra of the disc as a response to an X-ray flash from a point source located on the axis of the black hole (BH) accretion disc (lamp-post geometry). To the best of our knowledge, this is the first time for active galactic nuclei that both time lags and energy spectra are fitted by a model simultaneously in different flux periods. The model fits in the case when the BH is rapidly rotating are significantly better than the model fits in the case of a Schwarzschild BH. This result strongly favours the hypothesis of a rotating central BH in this source. We also detect significant variations in the height of the X-ray corona. The X-ray height appears to increase from ∼3–5 gravitational radii when the X-ray luminosity is of the order of ∼1.5–3 per cent of the Eddington limit, up to ∼10 gravitational radii, when the luminosity doubles.
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (greater than two seconds) duration are produced by the core-collapse of massive ...stars
, and those of short (less than two seconds) duration by the merger of compact objects, such as two neutron stars
. A third class of events with hybrid high-energy properties was identified
, but never conclusively linked to a stellar progenitor. The lack of bright supernovae rules out typical core-collapse explosions
, but their distance scales prevent sensitive searches for direct signatures of a progenitor system. Only tentative evidence for a kilonova has been presented
. Here we report observations of the exceptionally bright GRB 211211A, which classify it as a hybrid event and constrain its distance scale to only 346 megaparsecs. Our measurements indicate that its lower-energy (from ultraviolet to near-infrared) counterpart is powered by a luminous (approximately 10
erg per second) kilonova possibly formed in the ejecta of a compact object merger.
Background Systemic mast cell activation disorders (MCADs) are characterized by severe and systemic mast cell (MC) mediators–related symptoms frequently associated with increased serum baseline ...tryptase (sBt). Objective To analyze the clinical, biological, and molecular characteristics of adult patients presenting with systemic MC activation symptoms/anaphylaxis in the absence of skin mastocytosis who showed clonal (c) versus nonclonal (nc) MCs and to provide indication criteria for bone marrow (BM) studies. Methods Eighty-three patients were studied. Patients showing clonal BM MCs were grouped into indolent systemic mastocytosis without skin lesions (ISMs- ; n = 48) and other c-MCADs (n = 3)—both with CD25++ BM MCs and either positive mast/stem cell growth factor receptor gene ( KIT ) mutation or clonal human androgen receptor assay (HUMARA) tests—and nc-MCAD (CD25-negative BM MCs in the absence of KIT mutation; n = 32) and compared for their clinical, biological, and molecular characteristics. Results Most clonal patients (48/51; 94%) met the World Health Organization criteria for systemic mastocytosis and were classified as ISMs- , whereas the other 3 c-MCAD and all nc-MCAD patients did not. In addition, although both patients with ISMs- and patients with nc-MCAD presented with idiopathic and allergen-induced anaphylaxis, the former showed a higher frequency of men, cardiovascular symptoms, and insect bite as a trigger, together with greater sBt. Based on a multivariate analysis, a highly efficient model to predict clonality before BM sampling was built that includes male sex ( P = .01), presyncopal and/or syncopal episodes ( P = .009) in the absence of urticaria and angioedema ( P = .003), and sBt >25 μg/L ( P = .006) as independent predictive factors. Conclusions Patients with c-MCAD and ISMs- display unique clinical and laboratory features different from nc-MCAD patients. A significant percentage of c-MCAD patients can be considered as true ISMs- diagnosed at early phases of the disease.
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