scholarly journals Star formation history, double degenerates and Type Ia supernovae in the thin disc

2011 ◽  
Vol 417 (2) ◽  
pp. 1392-1401 ◽  
Author(s):  
Shenghua Yu ◽  
C. Simon Jeffery
2009 ◽  
Author(s):  
L. Greggio ◽  
E. Cappellaro ◽  
Giuliana Giobbi ◽  
Amedeo Tornambe ◽  
Gabriella Raimondo ◽  
...  

2004 ◽  
Vol 21 (2) ◽  
pp. 157-160
Author(s):  
Simone Recchi

AbstractWe study the effect of different star formation regimes on the dynamical and chemical evolution of IZw18, the most metal-poor dwarf galaxy locally known. To do that we adopt a two-dimensional hydrocode coupled with detailed chemical yields originating from Type II and Type Ia supernovae and from intermediate-mass stars. Particular emphasis is devoted to the problem of mixing of metals. We conclude that, under particular conditions, cooling of metals occurs with a timescale of the order of 10 Myr, thus confirming the hypothesis of instantaneous mixing adopted in chemical evolution models. We try to draw conclusions about the star formation history and the age of the last burst in IZw18.


2009 ◽  
Vol 5 (S262) ◽  
pp. 358-361
Author(s):  
Yutaka Ihara ◽  
Mamoru Doi ◽  
Tomoki Morokuma ◽  
Raynald Pain ◽  
Naohiro Takanashi ◽  
...  

AbstractWe present a measurement of the rate of high-z Type Ia supernovae (SNe Ia) using multi-epoch observations of Subaru/XMM-Newton Deep Field (SXDF) with Suprime-Cam on the Subaru Telescope. Although SNe Ia are regarded as a standard candle, progenitor systems of SNe Ia have not been resolved yet. One of the key parameters to show the progenitor systems by observations is the delay time distribution between the binary system formation and subsequent SN explosion. Recently, a wide range of delay time is studied by SN Ia rates compared with an assumed cosmic star formation history. If SNe Ia with short delay time are dominant, the cosmic SN Ia rate evolution should closely trace that of the cosmic star formation. In order to detect a lot of high-z SNe Ia and measure SN Ia rates, we repeatedly carried out wide and deep imaging observations in the í-band with Suprime-Cam in 2002 (FoV~1 deg2, mi < 25.5 mag). We obtained detailed light curves of the variable objects, and 50 objects are classified as SNe Ia using the light curve fitting method at the redshift range of 0.2 < z < 1.3. In order to check the completeness and contamination of the light curve classification method, we performed Monte Carlo simulations and generated ~100,000 light curves of SNe Ia and II from templates. The control time and detection efficiency of the SN survey are also calculated using the artificial light curves. We derived an increasing trend of rates at around z ~ 1.2. Our results are almost consistent with other SN Ia rate results from low-z to high-z. Our results are the first results of high-z SN Ia rates with large statistics using light curves obtained by ground based telescopes, and give us visions of the SN rate studies for the future.


Author(s):  
Silvia Pellegrini ◽  
Andrea Negri ◽  
Luca Ciotti

AbstractEarly-type galaxies (ETGs) host a hot ISM produced mainly by stellar winds, and heated by Type Ia supernovae and the thermalization of stellar motions. High resolution 2D hydrodynamical simulations showed that ordered rotation in the stellar component results in the formation of a centrifugally supported cold equatorial disc. In a recent numerical investigation we found that subsequent generations of stars are formed in this cold disc; this process consumes most of the cold gas, leaving at the present epoch cold masses comparable to those observed. Most of the new stellar mass formed a few Gyrs ago, and resides in a disc.


2004 ◽  
Vol 21 (2) ◽  
pp. 171-174 ◽  
Author(s):  
Naohito Nakasato

AbstractWe have computed full hydrochemodynamical evolution for 150 initial models of protogalaxies with our chemodynamical SPH code named GENSO. Various parameters for all models are identical except for a seed for a random number generator. In other words, all models have similar global properties but have the different merging history that leads to a different evolution in each model. Results of the series of computations have two main applications. Firstly, we have an initial model catalogue for subsequent modelling of galaxy evolution. Since the resulting evolution depends strongly on the initial phase of the particle distribution, it is crucial to find a suitable initial model when we model a specific real galaxy in the Universe, notably the Milky Way in our case. We will make a precise chemical and dynamical model of the Milky Way out of 150 models in our initial model catalogue. Secondly, we can obtain a large variety of global histories of physical values such as star formation, metallicity in the ISM and stellar components, and Type II and Ia supernova rates. For example, the resulting total star formation history shows the peak at a high redshift z ∼ 6 and the peak value is ∼280 M⊙ yr–1 Mpc–3. Also, the Type Ia rate obtained has a peak at z ∼ 3.5. All of our results and model catalogue are publicly available from our website for those who wish to model galaxy evolution.


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