Early X-Ray Flares in GRBs Ruffini, R.; Wang, Y.; Aimuratov, Y. ...
Astrophysical journal/The Astrophysical journal,
01/2018, Volume:
852, Issue:
1
Journal Article
Peer reviewed
Open access
We analyze the early X-ray flares in the GRB "flare-plateau-afterglow" (FPA) phase observed by Swift-XRT. The FPA occurs only in one of the seven GRB subclasses: the binary-driven hypernovae (BdHNe). ...This subclass consists of long GRBs with a carbon-oxygen core and a neutron star (NS) binary companion as progenitors. The hypercritical accretion of the supernova (SN) ejecta onto the NS can lead to the gravitational collapse of the NS into a black hole. Consequently, one can observe a GRB emission with isotropic energy erg, as well as the associated GeV emission and the FPA phase. Previous work had shown that gamma-ray spikes in the prompt emission occur at cm with Lorentz Gamma factors . Using a novel data analysis, we show that the time of occurrence, duration, luminosity, and total energy of the X-ray flares correlate with Eiso. A crucial feature is the observation of thermal emission in the X-ray flares that we show occurs at radii ∼1012 cm with . These model-independent observations cannot be explained by the "fireball" model, which postulates synchrotron and inverse-Compton radiation from a single ultrarelativistic jetted emission extending from the prompt to the late afterglow and GeV emission phases. We show that in BdHNe a collision between the GRB and the SN ejecta occurs at 1010 cm, reaching transparency at ∼1012 cm with . The agreement between the thermal emission observations and these theoretically derived values validates our model and opens the possibility of testing each BdHN episode with the corresponding Lorentz Gamma factor.
We analyze GRB 151027A within the binary-driven hypernova approach, with a progenitor of a carbon-oxygen core on the verge of a supernova (SN) explosion and a binary companion neutron star (NS). The ...hypercritical accretion of the SN ejecta onto the NS leads to its gravitational collapse into a black hole (BH), to the emission of the gamma-ray burst (GRB), and to a copious e+e− plasma. The impact of this e+e− plasma on the SN ejecta explains the early soft X-ray flare observed in long GRBs. Here, we apply this approach to the ultra-relativistic prompt emission (UPE) and to the hard X-ray flares. We use GRB 151027A as a prototype. From the time-integrated and the time-resolved analysis, we identify a double component in the UPE and confirm its ultra-relativistic nature. We confirm the mildly relativistic nature of the soft X-ray flare, of the hard X-ray flare, and of the extended thermal emission (ETE). We show that the ETE identifies the transition from an SN to a hypernova (HN). We then address the theoretical justification of these observations by integrating the hydrodynamical propagation equations of the e+e− into the SN ejecta, with the latter independently obtained from 3D smoothed particle hydrodynamics simulations. We conclude that the UPE, the hard X-ray flare, and the soft X-ray flare do not form a causally connected sequence. Within our model, they are the manifestation of the same physical process of the BH formation as seen through different viewing angles, implied by the morphology and the ∼300 s rotation period of the HN ejecta.
Theoretical and observational evidences for a two-fold classification of short bursts have been recently obtained: (1) short gamma-ray flashes (S-GRFs), with isotropic energy E iso < 10 52 erg and no ...black hole (BH) formation, and (2) authentic short gamma-ray bursts (S-GRBs), with isotropic energy E iso > 10 52 erg showing evidence of BH formation in the binary neutron star merging process. The signature for BH formation is the onset of high-energy (0.1-100 GeV) emission, coeval to the prompt emission, in all S-GRBs. No GeV emission is expected nor observed in S-GRFs. In this paper, we present two S-GRBs, GRB 081024B and GRB 140402A, in addition to the already identified S-GRBs, GRB 090227B, GRB 090510, and GRB 140619B. We also return to the absence of GeV emission in the S-GRB 090227B, at an angle of 71 ° from the Fermi-LAT boresight. All of the correctly identified S-GRBs correlate with high-energy emission, implying no significant presence of beaming in GeV emission. The existence of a common power-law behavior in the GeV luminosities, following the BH formation, when measured in the source rest frame, points to a commonality in the mass and spin of the newly formed BHs in all S-GRBs.
A genetic perspective of human history in Europe was derived from 22 binary markers of the nonrecombining Y chromosome (NRY). Ten lineages account for >95% of the 1007 European Y chromosomes studied. ...Geographic distribution and age estimates of alleles are compatible with two Paleolithic and one Neolithic migratory episode that have contributed to the modern European gene pool. A significant correlation between the NRY haplotype data and principal components based on 95 protein markers was observed, indicating the effectiveness of NRY binary polymorphisms in the characterization of human population composition and history.
The aim of this study was to analyze the association of different clinical contributors of hypoxic-ischemic encephalopathy with NOS3 gene polymorphisms. A total of 110 children with hypoxic-ischemic ...encephalopathy and 128 control children were selected for this study. Association of gender, gestational age, birth weight, Apgar score, cranial ultrasonography, and magnetic resonance imaging findings with genotypic data of six haplotype-tagging single nucleotide polymorphisms and the most commonly investigated rs1800779 and rs2070744 polymorphisms was analyzed. The TGT haplotype of rs1800783, rs1800779, and rs2070744 polymorphisms was associated with hypoxic-ischemic encephalopathy. Children with the TGT haplotype were infants below 32 weeks of gestation and they had the most severe brain damage. Increased incidence of the TT genotype of the NOS3 rs1808593 SNP was found in the group of hypoxic-ischemic encephalopathy patients with medium and severe brain damage. The probability of brain damage was twice as high in children with the TT genotype than in children with the TG genotype of the same polymorphism. Furthermore, the T allele of the same polymorphism was twice as frequent in children with lower Apgar scores. This study strongly suggests associations of NOS3 gene polymorphism with intensity of brain damage and severity of the clinical picture in affected children.
In a series of recent publications, scientists from ICRANet, led by professor Remo Ruffini, have reached a novel comprehensive picture of gamma-ray bursts (GRBs) thanks to their development of a ...series of new theoretical approaches. Among those, the induced gravitational collapse (IGC) paradigm explains a class of energetic, long-duration GRBs associated with Ib/c supernovae (SN), recently named binary-driven hypernovae (BdHNe).
BdHNe have a well defined set of observational features which allow to identify them. Among them, the main two are: 1) long duration of the GRB explosion, namely larger than 2 s in the rest frame; 2) a total energy, released in all directions by the GRB explosion, larger than 10
52
ergs.
A striking result is the observation, in the BdHNe sources, of a universal late time power-law decay in the X-rays luminosity after 10
4
s, with typical decaying slope of ~ 1.5. This leads to the possible establishment of a new distance indicator having redshift up to z ~ 8.
Thanks to this novel theoretical and observational understanding, it was possible for ICRANet scientists to build the firstst BdHNe catalog, composed by the 345 BdHNe identified up to the end of 2016.
In this work we study a role of baryon load and interstellarmediumdensity to explain the nature of peaks in the ultra-relativistic prompt emission (UPE) phase of Gamma-ray Bursts (GRBs). We study the ...behavior of their Γ Lorenz factor fromthe moment of transparency all the way up to interstellarmedium. We finally study the characteristic of equitemporal surfaces in the UPE phase.
Long gamma-ray burst GRB 151027A was observed by all three detectors onboard the
Swift
spacecraft, and many more, including MAXI,
Konus
-Wind and
Fermi
GBM/LAT instruments. This revealed a complex ...structure of the prompt and afterglow emission, consisting of a double-peak gammaray prompt with a quiescent period and a HRF/SXF within the X-ray afterglow, together with multiple BB components seen within the time-resolved spectral analysis. These features, within the fireshell model, are interpreted as the manifestation of the same physical process viewed at different angles with respect to the HN ejecta. Here we present the time-resolved and time-integrated spectral analysis used to determine the energy of the
e
−
e
+
plasma
E
tot
and the baryon load B. These quantities describe the dynamics of the fireshell up to the transparency point. We proceed with the light-curve simulation from which CBM density values and its inhomogeneities are deduced. We also investigate the properties of GRB 140206A, whose prompt emission exhibits a similar structure.
This study illuminates the intra-nuclear fate of COL1A1 RNA in osteogenesis imperfecta (OI) Type I. Patient fibroblasts were shown to carry a heterozygous defect in splicing of intron 26, blocking ...mRNA export. Both the normal and mutant allele associated with a nuclear RNA track, a localized accumulation of posttranscriptional RNA emanating to one side of the gene. Both tracks had slightly elongated or globular morphology, but mutant tracks were cytologically distinct in that they lacked the normal polar distribution of intron 26. Normal COL1A1 RNA tracks distribute throughout an SC-35 domain, from the gene at the periphery. Normally, almost all 50 COL1A1 introns are spliced at or adjacent to the gene, before mRNA transits thru the domain. Normal COL1A1 transcripts may undergo maturation needed for export within the domain such as removal of a slow-splicing intron (shown for intron 24), after which they may disperse. Splice-defective transcripts still distribute thru the SC-35 domain, moving ∼1-3 μm from the gene. However, microfluorimetric analyses demonstrate mutant transcripts accumulate to abnormal levels within the track and domain. Hence, mutant transcripts initiate transport from the gene, but are impeded in exit from the SC-35 domain. This identifies a previously undefined step in mRNA export, involving movement through an SC-35 domain. A model is presented in which maturation and release for export of COL1A1 mRNA is linked to rapid cycling of metabolic complexes within the splicing factor domain, adjacent to the gene. This paradigm may apply to SC-35 domains more generally, which we suggest may be nucleated at sites of high demand and comprise factors being actively used to facilitate expression of associated loci.
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