* Astronomy

Members Login
Post Info TOPIC: GRB110328A


L

Posts: 130245
Date:
RE: GRB110328A
Permalink  
 


This new class of GRB-like events was first discovered through the detection of GRB 110328A by the Swift Gamma-Ray Burst Mission on 28 March 2011.
Read more



__________________


L

Posts: 130245
Date:
Permalink  
 

Title: On the origin of the radio emission of Sw 1644+57
Authors: Rodolfo Barniol Duran, Tsvi Piran

We apply relativistic equipartition synchrotron arguments to the radio emission of the tidal disruption event candidate Sw 1644+57. We find that, regardless of the details of the equipartition scenario considered, the energy required to produce the observed radio (i.e., energy in the magnetic field and radio emitting electrons) must increase by a factor of ~20 during the first 200 days. It then saturates. This energy increase cannot be alleviated by a varying geometry of the system. The radio data can be explained by: (i) An afterglow like emission of the X-ray emitting narrow relativistic jet. The additional energy can arise here from a slower moving material ejected in the first few days that gradually catches up with the slowing down blast wave (Berger et al. 2012). However, this requires at least ~4x10^{53} erg in the slower moving outflow. This is much more than the energy of the fast moving outflow that produced the early X-rays and it severely constrains the overall energy budget. (ii) Alternatively, the radio may arise from a mildly relativistic outflow. Here, the energy for the radio emission increases with time to at least ~10^{51} erg after 200 days. This scenario requires, however, a second X-ray emitting narrow relativistic component. Given these results, it is worthwhile to consider models in which the energy of the magnetic field and/or of the radio emitting electrons increases with time without a continuous energy supply to the blast wave. This can happen, for example, if the energy is injected initially mostly in one form (Poynting flux or baryonic) and it is gradually converted to the other form, leading to a time-varying deviation from equipartition. Another intriguing possibility is that a gradually decreasing Inverse Compton cooling modifies the synchrotron emission and leads to an increase of the available energy in the radio emitting electrons (Kumar et al. 2013).

Read more (459kb, PDF)



__________________


L

Posts: 130245
Date:
GRB 110328A
Permalink  
 


Flaring black holes may solve cosmic ray puzzle

Gamma-ray bursts are usually created by exploding stars, which produce neutrinos. So last April, when the IceCube neutrino detector in Antarctica saw no neutrinos accompanying high-energy cosmic rays, astronomers favoured galaxies with active supermassive black holes at their cores as the source of the rays. But a more recent study found that only one galaxy was powerful enough to have produced cosmic rays with such high energies. The rest appear to come from galaxies that seem too weak.
Read more



__________________


L

Posts: 130245
Date:
Sw 1644+57
Permalink  
 


Gamma ray bursts are stellar death cries

The Visible Universe, in partnership with NASA's Swift telescope and massive stars throughout the galaxy, is proud to present the premiere of a terrifying extragalactic murder mystery.
Prepare for thrills and chills in this awesome display of cosmic savagery. Astronomers call it Sw 1644+57.

Read more



__________________


L

Posts: 130245
Date:
RE: GRB110328A
Permalink  
 


Killer black hole devours star in a flash

One of the biggest and brightest bangs ever recorded by astronomers came from a massive black hole at the centre of a distant galaxy. The black hole appears to have ripped apart a star that wandered too close, creating a powerful beam of energy that crossed the 3.8 billion light years to Earth.
The observations, published in the journal Science, were carried out by an international team including STFC-funded astronomers from the universities of Warwick, Leicester and Hertfordshire. They used an array of space and ground based facilities including the Hubble, UKIRT (UK Infrared Telescope) and Gemini telescopes to witness this catastrophic event.

 Read more 



__________________


L

Posts: 130245
Date:
Swift J164449.3+57345
Permalink  
 


Powerful cosmic blast as black hole shreds star

Astronomers have spied a star's swan song as it is shredded by a black hole.
Researchers suspect that the star wandered too close to the black hole and got sucked in by the huge gravitational forces.
The star's final moments sent a flash of radiation hurtling towards Earth.

Read more 



__________________


L

Posts: 130245
Date:
GRB 110328A
Permalink  
 


Black hole kills star and blasts 3.8 billion light year beam at Earth

Observations led by astronomers at the University of Warwick have shown that the flash from one of the biggest and brightest bangs yet recorded by astronomers comes from a massive black hole at the centre of a distant galaxy. The black hole appears to have ripped apart a star that wandered too close, creating a powerful beam of energy that crossed the 3.8 billion light years to Earth.
Their research is published today 16th June, in the Journal Science, in a paper entitled "An Extremely Luminous Panchromatic Outburst from the Nucleus of a Distant Galaxy".
The high energy X-rays and gamma-rays persisted at an extremely bright level for weeks after the event, with bright flares arising when further chunks of the star apparently fell into the black hole, while at optical and infrared wavelengths it is as bright as a hundred billion suns. The extreme brightness of this event comes from the fact that it created a powerful beam of energy pointing a jet of light towards the Milky Way and thus concentrated into only a small fraction of the sky and which was detected at Earth 3.8 billion years after the star was ripped apart.

Read more 



__________________


L

Posts: 130245
Date:
Swift J164449.3+57345
Permalink  
 


Black hole eats star, producing bright gamma-ray flash

A bright flash of gamma rays observed March 28 by the Swift satellite may have been the death rattle of a star falling into a massive black hole and being ripped apart, according to a team of astronomers led by the University of California, Berkeley.
When the Swift Gamma Burst Mission spacecraft first detected the flash within the constellation Draco, astronomers thought it was a gamma-ray burst from a collapsing star and designated it GRB 110328A. On March 31, however, UC Berkeley's Joshua Bloom sent out an email circular suggesting that it wasn't a typical gamma-ray burst at all, but a high-energy jet produced as a star about the size of our sun was shredded by a black hole a million times more massive.

Read more 



__________________


L

Posts: 130245
Date:
RE: GRB110328A
Permalink  
 


Title: Quark-Novae in Low-Mass X-ray Binaries as a model for G87-7 and for GRB 110328A
Authors: Rachid Ouyed (1), Jan E. Staff (2), Prashanth Jaikumar (3 and 4) ((1) Physics&Astronomy, University of Calgary, AB, Canada, (2) Physics&Astronomy, Louisiana State University, LA, USA, (3) Physics&Astronomy, California State University Long Beach, CA, USA, (4) Institute of Mathematical Sciences, India)

We propose a simple model explaining two outstanding astrophysical problems related to compact objects: (1) that of stars such as G87-7 (alias EG 50) that constitute a class of relatively low-mass white dwarfs which nevertheless fall away from the C/O composition and (2) that of GRB 110328A/Swift J164449.3+57345 which showed spectacularly long-lived strong X-ray flaring, posing a challenge to standard GRB models. We argue that both these observations may have an explanation within the unified framework of a Quark-Nova occurring in a low-mass X-ray binary (neutron star-white dwarf). For LMXBs where the binary separation is sufficiently tight, ejecta from the Neutron Star triggers nuclear burning in the white dwarf on impact, leading to alpha-rich and Fe-rich composition compact white dwarfs reminiscent of G87-7. Under slightly different conditions, the white dwarf is ablated and its ashes raining down on the Quark star leads to accretion-driven X-ray luminosity with energetics and duration reminiscent of GRB 110328A. We predict additional flaring activity towards the end of the accretion phase if the Quark star turns into a Black Hole.

Read more  (26kb, PDF)



__________________


L

Posts: 130245
Date:
GRB 110328A
Permalink  
 


Title: Superlong GRB 110328A: generation in the collapsing star cluster
Authors: V.I. Dokuchaev, Yu.N. Eroshenko

We interpret the recently observed super-long cosmic gamma-ray burst GRB 110328A in the model of collapsing galactic nucleus. The neutron stars and stellar-mass black holes can form evolutionary a compact self-gravitating subsystem in galactic center. Merges of these star remnants during the avalanche contraction and collapse of the cluster can explain the bright peaks in the light-curve of GRB 110328A, while numerous smaller peaks and quasi-steady radiation can arise from the gravitational lensing and accretion of gas onto the forming supermassive black hole.

Read more  (8kb, PDF)



__________________
1 2  >  Last»  | Page of 2  sorted by
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard