arXiv subjects

C. Yozin

Publications and source records attributed to C. Yozin.

4 recordsLinked to original sources

arXiv2018

Formation of the active star forming region LHA 120-N 44 triggered by tidally-driven colliding HI flows

N44 is the second active site of high mass star formation next to R136 in the Large Magellanic Cloud (LMC). We carried out a detailed analysis of HI at 60 arcsec resolution by using the ATCA & Parkes data. We presented decomposition of the HI emission into two velocity components (the L- and D-components) with the velocity separation of 60 km s$^{-1}$. In addition, we newly defined the I-component whose velocity is intermediate between the L- and D-components. The D-component was used to derive the rotation curve of the LMC disk, which is consistent with the stellar rotation curve (Alves et al. 2000). Toward the active cluster forming region of LHA 120-N 44, the three velocity components of HI gas show signatures of dynamical interaction including bridges and complementary spatial distributions. We hypothesize that the L- and D-components have been colliding with each other since 5 Myrs ago and the interaction triggered formation of the O and early B stars ionizing N44. In the hypothesis the I-component is interpreted as decelerated gas in terms of momentum exchange in the collisional interaction of the L- and D-components. In the N44 region the Planck sub-mm dust optical depth is correlated with the HI intensity, which is well approximated by a linear regression. We found that the N44 region shows a significantly steeper regression line than in the Bar region indicating less dust abundance in the N44 region, which is ascribed to the tidal interaction between the LMC with the SMC 0.2 Gyrs ago.

astro-ph.GA↗

arXiv2015

Local ultra faint dwarves as a product of Galactic processing during a Magellanic group infall

The recent discoveries of ultra-faint dwarf (UFD) galaxies in the vicinity of the Magellanic system supports the expectation from cosmological models that such faint objects exist and are numerous. By developing a mass model of the Local Group and backwards integrating the Magellanic Clouds' present kinematics, we find that the locations of these UFDs are consistent with those predicted if previously associated with the Large MC as part of a loose association. We further demonstrate how these satellites are likely to have been processed by the Galactic hot halo upon accretion, with the implication that ongoing detections of extremely gas-rich objects on the periphery of the Galaxy and without clear stellar counterparts are analogous to the progenitors of the gas-deficient UFDs. Our model allows us predict the locations of other putative Magellanic satellites, and propose how their distribution/kinematics provide a novel constraint on the dynamical properties of the Galaxy. We also predict that the stripped metal-poor HI, previously associated with these UFDs, lies coincident with but distinguishable from the extensive Magellanic Stream.

astro-ph.GA↗

arXiv2015

The quenching and survival of ultra-diffuse galaxies in the Coma cluster

We conduct the first self-consistent numerical simulations of a recently discovered population of 47 large, faint (ultra-diffuse) galaxies, speculated to lie in the Coma cluster. With structural properties consistent with very large low surface brightness systems (i.e. $μ$(g,0)$<24$ mag arcsec$^{\rm -2}$, r$_{\rm eff}$ comparable to the Galaxy), the red colour ($\langle$g-r$\rangle$$\sim$0.8) and assumed low metallicity of these objects compels us to consider a scenario in which these are underdeveloped galaxies whose early ($z$$\simeq$2) accretion to an overdense environment quenched further growth. Our simulations demonstrate the efficacy of this scenario, with respect to available observational constraints, using progenitor galaxy models derived from scaling relations, and idealised tidal/hydrodynamical models of the Coma cluster. The apparent ubiquity of these objects in Coma implies they constitute an important galaxy population, we accordingly discuss their properties with respect to a $Λ$CDM cosmology, classical LSBs, and the role of baryonic physics in their early formation.

astro-ph.GA↗

arXiv2012

The Fornax dwarf galaxy as a remnant of recent dwarf-dwarf merging in the Local Group

We present results from the first numerical analysis to support the hypothesis, first proposed in Coleman et al. (2004), that the Fornax dwarf galaxy was formed from the minor merging of two dwarfs about 2 Gyr ago. Using orbits for the Fornax dwarf that are consistent with the latest proper motion measurements, our dynamical evolution models show that the observed asymmetric shell-like substructures can be formed from the remnant of a smaller dwarf during minor merging. These models also predict the formation of diffuse stellar streams. We discuss how these stellar substructures depend on model parameters of dwarf-dwarf merging, and how the intermediate-age subpopulations found in the vicinity of these substructures may be formed from gas accretion in the past merger events. We also suggest that one of Fornax's GCs originates from a merged dwarf companion, and demonstrate where as yet undetected tidal streams or HI gas formed from the dwarf merging may be found in the outer halo of the Galaxy.

astro-ph.GA↗