M. Muccino

M. Muccino
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M. Muccino

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High Energy Astrophysical Phenomena (26)
Cosmology and Nongalactic Astrophysics (11)
Solar and Stellar Astrophysics (2)
General Relativity and Quantum Cosmology (1)

Publications Authored By M. Muccino

Theoretical and observational evidences have been recently gained for a two-fold classification of short bursts: 1) short gamma-ray flashes (S-GRFs), with isotropic energy $E_{iso}<10^{52}$~erg and no black hole (BH) formation, and 2) the authentic short gamma-ray bursts (S-GRBs), with isotropic energy $E_{iso}>10^{52}$~erg evidencing a BH formation in the binary neutron star merging process. The signature for the BH formation consists in the on-set of the high energy ($0.1$--$100$~GeV) emission, coeval to the prompt emission, in all S-GRBs. Read More

The long lasting attempt to identify the nature of X-ray flares, observed by Swift after the prompt emission of some long gamma ray bursts (GRBs), is here addressed within the context of a special subclass of long GRBs with isotropic energy $E_{iso} > 10^{52}$~erg, recently indicated as binary-driven hypernovae (BdHNe). Such BdHNe have as progenitor a tight binary system composed of a carbon-oxygen core (CO$_\mathrm{core}$) and a neutron star (NS) undergoing an induced gravitational collapse (IGC) to a black hole (BH) triggered by the CO$_\mathrm{core}$ explosion as a supernova (SN). Only in the case of such BdHNe, when analysed in the rest frame of the sources, the time of occurrence, the temporal duration, the X-ray luminosity and the total energy of the flares correlate with the $E_{iso}$. Read More

It has previously been discovered that there is a universal power law behavior exhibited by the late X-ray emission (LXRE) of a "golden sample" (GS) of six long energetic GRBs, when observed in the rest-frame of the source. This remarkable feature, independent of the different isotropic energy (E_iso) of each GRB, has been used to estimate the cosmological redshift of some long GRBs. This analysis is extended here to a new class of 161 long GRBs, all with E_iso > 10^52 erg. Read More

In a new classification of merging binary neutron stars (NSs) we separate short gamma-ray bursts (GRBs) in two sub-classes. The ones with $E_{iso}\lesssim10^{52}$ erg coalesce to form a massive NS and are indicated as short gamma-ray flashes (S-GRFs). The hardest, with $E_{iso}\gtrsim10^{52}$ erg, coalesce to form a black hole (BH) and are indicated as genuine short-GRBs (S-GRBs). Read More

We investigate theoretical and observational constraints on the mass-radius relations for neutron stars. For that purpose we consider the model of neutron stars taking into considerations strong, weak, electromagnetic and gravitational interactions in the equation of state and integrate the structure equations within the Hartle-Thorne formalism for rotating configurations. On the basis of the theoretical restrictions imposed by general relativity, mass-shedding and axisymmetric secular instabilities we calculate the upper and lower bounds for the parameters of neutron stars. Read More

We investigate the kilohertz quasi-periodic oscillations of low-mass X-ray binaries within the Hartle-Thorne spacetime. On the basis the relativistic precession model we extract the total mass $M$, angular momentum $J$, and quadrupole moment $Q$ of a compact object in a low-mass X-ray binary by analyzing the data of the Z -source GX 5-1. In view of the recent neutron star model we compute the radius, angular velocity and other parameters of this source by imposing the observational and theoretical constraints on the mass-radius relation. Read More

GRBs, traditionally classified as "long" and "short", have been often assumed, till recently, to originate from a single black hole (BH) with an ultrarelativistic jetted emission. There is evidence that both long and short bursts have as progenitors merging and/or accreting binaries, each composed by a different combination of carbon-oxygen cores (CO$_{\rm core}$), neutron stars (NSs), BHs and white dwarfs (WDs). Consequently, the traditional long bursts have been sub-classified as (I) X-ray flashes (XRFs), (II) binary-driven hypernovae (BdHNe), and (III) BH-supernovae (BH-SNe). Read More

There is mounting evidence for the binary nature of the progenitors of gamma-ray bursts (GRBs). For a long GRB, the induced gravitational collapse (IGC) paradigm proposes as progenitor, or "in-state", a tight binary system composed of a carbon-oxygen core (CO$_{core}$) undergoing a supernova (SN) explosion which triggers hypercritical accretion onto a neutron star (NS) companion. For a short GRB, a NS-NS merger is traditionally adopted as the progenitor. Read More

Context: Data from cosmic microwave background radiation (CMB), baryon acoustic oscillations (BAO), and supernovae Ia (SNe-Ia) support a constant dark energy equation of state with $w_0 \sim -1$. Measuring the evolution of $w$ along the redshift is one of the most demanding challenges for observational cosmology. Aims: We discuss the existence of a close relation for GRBs, named Combo-relation, based on characteristic parameters of GRB phenomenology such as the prompt intrinsic peak energy $E_{p,i}$, the X-ray afterglow, the initial luminosity of the shallow phase $L_0$, the rest-frame duration $\tau$ of the shallow phase, and the index of the late power-law decay $\alpha_X$. Read More

In light of the relativistic precession model, we present here detailed analyses, extending the ones performed in the Schwarzschild and Kerr spacetimes. We consider the kilohertz quasi-periodic oscillations in the Hartle-Thorne spacetime, which describes the gravitational field of a rotating and deformed object. We derive the analytic formulas for the epicyclic frequencies in the Hartel-Thorne spacetime and by means of these frequencies we interpret the kilohertz quasi-periodic oscillations of low-mass X-ray binaries of the atoll and Z - sources, on the basis of the relativistic precession model. Read More

We show the existence of two families of short GRBs, both originating from the merger of binary neutron stars (NSs): family-1 with $E_{iso}<10^{52}$ erg, leading to a massive NS as the merged core, and family-2 with $E_{iso}>10^{52}$ erg, leading to a black hole (BH). Following the identification of the prototype GRB 090227B, we present the details of a new example of family-2 short burst: GRB 140619B. From the spectral analysis of the early $\sim0. Read More

Context: Observations suggest that the major fraction of long duration gamma-ray bursts (GRBs) are connected with broad-lines supernovae Ib/c, (SNe-Ibc). The presence of GRB-SNe is revealed by rebrightenings emerging from the optical GRB afterglow $10$--$15$ days, in the rest-frame of the source, after the prompt GRB emission. Aims: \textit{Fermi}-GBM has a field of view (FoV) which is about 6. Read More

We have performed our data analysis of the observations by Swift and Fermi satellites in order to probe the induced gravitational collapse (IGC) paradigm for GRBs associated with supernovae (SNe), in the "terra incognita" of GRB 130427A. We compare and contrast our data analysis with those in the literature. We have verified that the GRB 130427A conforms to the IGC paradigm by examining the power law behavior of the luminosity in the early $10^4$ s of the Swift-XRT observations. Read More

Context: The induced gravitational collapse (IGC) paradigm addresses the very energetic (10^{52}-10^{54}erg) long gamma-ray bursts (GRBs) associated to supernovae (SNe). Unlike the traditional "collapsar" model, an evolved FeCO core with a companion neutron star (NS) in a tight binary system is considered as the progenitor. This special class of sources, here named "binary driven hypernovae" (BdHNe), presents a composite sequence composed of four different episodes [. Read More

CONTEXT: The induced gravitational collapse (IGC) scenario has been introduced in order to explain the most energetic gamma ray bursts (GRBs), Eiso=10^{52}-10^{54}erg, associated with type Ib/c supernovae (SNe). It has led to the concept of binary-driven hypernovae (BdHNe) originating in a tight binary system composed by a FeCO core on the verge of a SN explosion and a companion neutron star (NS). Their evolution is characterized by a rapid sequence of events: [. Read More

Following the recently established "Binary-driven HyperNova" (BdHN) paradigm, we here interpret GRB 970828 in terms of the four episodes typical of such a model. The "Episode 1", up to 40 s after the trigger time t_0, with a time varying thermal emission and a total energy of E_{iso,1st} = 2.60 x 10^{53} erg, is interpreted as due to the onset of an hyper-critical accretion process onto a companion neutron star, triggered by the companion star, an FeCO core approaching a SN explosion. Read More

It has been proposed that the temporal coincidence of a gamma-ray burst (GRB) and a type Ib/c supernova (SN) can be explained with the concept of induced gravitational collapse (IGC), induced by the matter ejected from an SN Ib/c accreting onto a neutron star (NS). We found a standard luminosity light curve behavior in the late-time X-ray emission of this subclass of GRBs. We interpret this as the result of a common physical mechanism in this particular phase of the X-ray emission, possibly related to the creation of the NS from the SN process. Read More

GRB 090510, observed both by Fermi and AGILE satellites, is the first bright short-hard Gamma-Ray Burst (GRB) with an emission from the keV up to the GeV energy range. Within the Fireshell model, we interpret the faint precursor in the light curve as the emission at the transparency of the expanding e+e- plasma: the Proper-GRB (P-GRB). From the observed isotropic energy we assume a total energy Ee+e-=(1. Read More

Context. It has been proposed that the temporal coincidence of a gamma-ray burst (GRB) and a type Ib/c supernova (SN) can be explained with the concept of induced gravitational collapse (IGC), induced by the matter ejected from an SN Ib/c accreting onto a neutron star (NS). The NS is expected to reach the critical mass necessary for it to collapse to a black hole (BH) and emit a GRB. Read More

Context: GRB110709B is the first source for which Swift BAT triggered twice, with a time separation of ~10 min. The first emission (Ep. 1) goes from 40s before the 1{\deg} trigger up to 60s after it. Read More

The possibility to divide GRBs in different subclasses allow to understand better the physics underlying their emission mechanisms and progenitors. The induced gravitational collapse scenario proposes a binary progenitor to explain the time-sequence in GRBs-SNe. We show the existence of a common behavior of the late decay of the X-ray afterglow emission of this subclass of GRBs, pointing to a common physical mechanism of their late emission, consistent with the IGC picture. Read More

The time-resolved spectral analysis of GRB090227B, made possible by the Fermi-GBM data, allows to identify in this source the missing link between the genuine short and long GRBs. Within the Fireshell model [.. Read More

Following the recent theoretical interpretation of GRB 090618 and GRB 101023, we here interpret GRB 970828 in terms of a double episode emission: the first episode, observed in the first 40 s of the emission, is interpreted as the proto-black-hole emission; the second episode, observed after t$_0$+50 s, as a canonical gamma ray burst. The transition between the two episodes marks the black hole formation. The characteristics of the real GRB, in the second episode, are an energy of $E_{tot}^{e^+e^-} = 1. Read More

We present the results of the analysis of GRB 101023 in the fireshell scenario. Its redshift has not been determined due to the lack of data in the optical band, so we tried to infer it from the Amati Relation, obtaining z=0.9. Read More

GRB 090618 offered an unprecedented opportunity to have coordinated data, by the best of the X and Gamma Ray observatories, of the nearest (z = 0.54) energetic source (10$^{54}$ erg). Using the Fermi-GBM observations of this GRB, we have analyzed this source to explore the possibility of having components yet to be observed in other sources. Read More

Semi-classical states for the Wheeler-DeWitt equation of a Bianchi type I model in the presence of a scalar field are analyzed. It is outlined how this scheme can effectively describe more general situations, where the curvature of the Bianchi type IX model and a proper potential term for the scalar field are present. The introduction of a cosmological constant term accounts for the quasi-isotropization mechanism which bridges the proposed framework with a late isotropic phase. Read More