Related papers: Further constraints on white dwarf galactic halos
There is wide agreement that Type Ia supernovae (used as standard candles for cosmology) are associated with the thermonuclear explosions of white dwarf stars. The nuclear runaway that leads to the explosion could start in a white dwarf…
Oxygen to iron abundance ratios of metal-poor stars provide information on nucleosynthesis yields from massive stars which end in Type II supernova explosions. Using a standard model of chemical evolution of the Galaxy we have reproduced…
We present a general phenomenological model for the metallicity distribution (MD) in terms of [Fe/H] for dwarf spheroidal galaxies (dSphs). These galaxies appear to have stopped accreting gas from the intergalactic medium and are fossilized…
Standard analytical chemical evolution modelling of galaxies has been assuming the stellar initial mass function (IMF) to be invariant and fully sampled allowing fractions of massive stars to contribute even in dwarf galaxies with very low…
Type Ia supernovae, sparked off by exploding white dwarfs of mass close to Chandrasekhar limit, play the key role to understand the expansion rate of universe. However, recent observations of several peculiar type Ia supernovae argue for…
The cold dark matter halo mass function is much steeper than the galaxy stellar mass function on galactic and subgalactic scales. This difference is usually reconciled by assuming that the galaxy formation efficiency drops sharply with…
We review recent determinations of the present day and initial mass functions in various components of the Galaxy, disk, spheroid, young and globular clusters. As a general feature, the IMF is well described by a power-law form for $m\ga 1…
The stellar initial mass function (IMF) is expressed by $\phi(m) \propto m^{-\alpha}$ with the slope $\alpha$, and known as the poorly-constrained but very important function in studies of star and galaxy formation. There are no sensible…
We test whether the universal initial mass function (UIMF) or the integrated galaxial IMF (IGIMF) can be employed to explain the metallicity distribution (MD) of giants in the Galactic bulge. We make use of a single-zone chemical evolution…
Although it a very narrow angle survey, the depth of the HDF results in its sampling a significant volume of the halo of our galaxy. Thus it is useful for the purposes of detecting (or placing upper limits on the distribution of)…
We review Galactic halo formation theories and supporting evidence, in particular kinematics and detailed chemical abundances of stars in some relevant globular clusters as well as Local Group dwarf galaxies. Outer halo red HB clusters tend…
Recent estimates point to abundances of z > 4 sub-millimeter (sub-mm) galaxies far above model predictions. The matter is still debated. According to some analyses the excess may be substantially lower than initially thought and perhaps…
(abridged) The case can be made for a rather universal stellar IMF form that can be approximated by a two-part power-law function in the stellar regime. However, there exists a possible hint for a systematic variation with metallicity. A…
Three component models of the IMF are made to consider possible origins for the observed relative variations in the numbers of brown dwarfs, solar-to-intermediate mass stars, and high mass stars. Three distinct physical processes are noted.…
We present results from general relativistic calculations of nuclear ignition in white dwarf stars triggered by near encounters with rotating intermediate mass black holes with different spin and alignment parameters. These encounters…
The interpretation of microlensing results towards the Large Magellanic Cloud (LMC) still remains controversial. White dwarfs have been proposed to explain these results and, hence, to contribute significantly to the mass budget of our…
Recent studies of white dwarfs in open clusters have provided new constraints on the initial - final mass relationship (IFMR) for main sequence stars with masses in the range 2.5 - 6.5 Mo. We re-evaluate the ensemble of data that determines…
If massive black holes constitute the dark matter in the halo surrounding the Milky Way, the existence of low mass globular clusters in the halo suggests an upper limit to their mass, $M_{_{BH}}$. We use a combination of the impulse…
We explore the effects on nucleosynthesis in Type II supernovae of various parameters (mass cut, neutron excess, explosion energy, progenitor mass) in order to explain the observed trends of the iron-peak element abundance ratios ([Cr/Fe],…
In this study, we modify the semi-analytic model Galacticus in order to accurately reproduce the observed properties of dwarf galaxies in the Milky Way. We find that reproducing observational determinations of the halo occupation fraction…