LONG GAMMA RAY BURSTS TO INVESTIGATE THE STAR FORMATION IN DARK MATTER HALOS

These two false-color images compare the distribution of normal matter (red, left) with dark matter (blue, right) in the universe. The brightness of clumps corresponds to the density of mass. The comparison will provide insight on how structure formed in the evolving universe under the relentless pull of gravity. Credit: NASA, ESA, CalTech

Gamma-ray bursts (GRBs) are the most luminous explosive events in the cosmos, which can be detected even out to the edge of the Universe and they can be used to probe the properties of the high-z Universe, including high-z star formation history.

Long (>2 seconds) gamma-ray bursts (LGRBs) are powered by the core collapse of massive stars, so the cosmic GRB rate should in principle trace the cosmic star formation rate. It is important to note that stars can only form in structures that are suitably dense: the star formation occurs only if the mass of the dark matter halo of the collapsed structures is greater than the minimum value M_{min}.
Structures with masses smaller than M_{min} are considered as part of the intergalactic medium and do not take part in the star formation process.
The connection of LGRBs with the collapse of massive stars has provided a good opportunity for probing star formation in dark matter halos. The value M_{min} can be constrained by directly comparing the observed and expected redshift distributions of LGRBs.
In a recent paper (Wei et al. 2016), the authors used the latest Swift GRB data to obtain a value for the minimum mass of 10^{7.7} < M_{min} < 10^{10.7} solar masses. Below this limit the star formation process should not take place.

Read more >>
http://arxiv.org/pdf/1511.04483v1.pdf
http://www.sciencedirect.com/science/article/pii/S2214404815000658

Comments

SUPERNOVAE FROM WD-WD DIRECT COLLISIONS

Image: Supernova remnant N 63A. Credit: NASA/ESA/HEIC and The Hubble Heritage Team (STScI/AURA) Models for supernovae (SNe) related to thermonuclear explosions of white dwarfs (WDs) have been extensively studied over the last few decades, mostly focusing on single degenerate (accretion of material of a WD) and double degenerate (WD-WD merger) scenarios.

Scientists detect comets outside our solar system

An artist’s conception of a view from within the Exocomet system KIC 3542116. Credit: Danielle Futselaar Team of professional and citizen scientists identifies tails of comets streaking past a distant star Jennifer Chu | MIT News Office Scientists from MIT and other institutions, working closely with amateur astronomers, have spotted the dusty tails of six exocomets — comets outside our solar system — orbiting a faint star 800 light years from Earth. These cosmic balls of ice and dust, which were about the size of Halley’s Comet and traveled about 100,000 miles per hour before they ultimately vaporized, are some of the smallest objects yet found outside our own solar system. The discovery marks the first time that an object as small as a comet has been detected using transit photometry, a technique by which astronomers observe a star’s light for telltale dips in intensity. Such dips signal potential transits, or crossings of planets or other objects in front of a star, ...

ABOUT THE FORMATION OF THE COLD CLASSICAL KUIPER BELT

Image: The Kuiper Belt. Credit: NASA . The Kuiper belt is a circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt (the circumstellar disc located roughly between the orbits of the planets Mars and Jupiter), but it is far larger-20 times as wide and 20 to 200 times as massive.

SpaceTime

Search This Blog