scholarly journals Stellar migrations and metal flows – Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy

2020 ◽  
Vol 496 (1) ◽  
pp. 80-94 ◽  
Author(s):  
Fiorenzo Vincenzo ◽  
Chiaki Kobayashi
Keyword(s):  
Galaxy Formation ◽  
Milky Way ◽  
Formation Rate ◽  
Age Distribution ◽  
Radial Dependence ◽  
Radial Gradient ◽  
Thin Disc ◽  
Galaxy Formation And Evolution ◽  
Age Relation ◽  
Formation And Evolution

ABSTRACT In order to understand the roles of metal flows in galaxy formation and evolution, we analyse our self-consistent cosmological chemodynamical simulation of a Milky Way like galaxy during its thin-disc phase. Our simulated galaxy disc qualitatively reproduces the variation of the dichotomy in [α/Fe]–[Fe/H] at different Galactocentric distances as derived by APOGEE-DR16, as well as the stellar age distribution in [α/Fe]–[Fe/H] from APOKASC-2. The disc grows from the inside out, with a radial gradient in the star-formation rate during the entire phase. Despite the radial dependence, the outflow-to-infall ratio of metals in our simulated halo shows a time-independent profile scaling with the disc growth. The simulated disc undergoes two modes of gas inflow: (i) an infall of metal-poor and relatively low-[α/Fe] gas, and (ii) a radial flow where already chemically enriched gas moves inwards with an average velocity of ∼0.7 km s−1. Moreover, we find that stellar migrations mostly happen outwards, on typical time-scales of ∼5 Gyr. Our predicted radial metallicity gradients agree with the observations from APOGEE-DR16, and the main effect of stellar migrations is to flatten the radial metallicity profiles by 0.05 dex/kpc in the slopes. We also show that the effect of migrations can appear more important in [α/Fe] than in the [Fe/H]–age relation of thin-disc stars.

scholarly journals The volumetric star formation law in the Milky Way

2019 ◽  
Vol 632 ◽  
pp. A127 ◽  
Author(s):  
C. Bacchini ◽  
F. Fraternali ◽  
G. Pezzulli ◽  
A. Marasco ◽  
G. Iorio ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Milky Way ◽  
Formation Rate ◽  
Scale Height ◽  
Hydrostatic Equilibrium ◽  
Open Questions ◽  
Classical Cepheids ◽  
Galaxy Formation And Evolution ◽  
Disc Galaxies

Several open questions on galaxy formation and evolution have their roots in the lack of a universal star formation law that could univocally link the gas properties, such as its density, to the star formation rate (SFR) density. In a recent paper we used a sample of nearby disc galaxies to infer the volumetric star formation (VSF) law, a tight correlation between the gas and the SFR volume densities derived under the assumption of hydrostatic equilibrium for the gas disc. However, due to the dearth of information about the vertical distribution of the SFR in these galaxies, we could not find a unique slope for the VSF law, but two alternative values. In this paper, we use the scale height of the SFR density distribution in our Galaxy adopting classical Cepheids (age ≲200 Myr) as tracers of star formation. We show that this latter is fully compatible with the flaring scale height expected from gas in hydrostatic equilibrium. These scale heights allowed us to convert the observed surface densities of gas and SFR into the corresponding volume densities. Our results indicate that the VSF law ρSFR ∝ ραgas with α ≈ 2 is valid in the Milky Way as well as in nearby disc galaxies.

scholarly journals Characterisation of the Galactic thick disk

2013 ◽  
Vol 9 (S298) ◽  
pp. 17-27
Author(s):  
Thomas Bensby
Keyword(s):  
Galaxy Formation ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Thin Disk ◽  
Thick Disk ◽  
Host Galaxy ◽  
Galaxy Formation And Evolution ◽  
Formation History ◽  
History Of ◽  
Formation And Evolution

AbstractThick disks appear to be common in external large spiral galaxies and our own Milky Way also hosts one. The existence of a thick disk is possibly directly linked to the formation history of the host galaxy and if its properties is known it can constrain models of galaxy formation and help us to better understand galaxy formation and evolution. This brief review attempts to highlight some of the characteristics of the Galactic thick disk and how it relates to other stellar populations such as the thin disk and the Galactic bulge. Focus has been put on results from high-resolution spectroscopic data obtained during the last 10 to 15 years.

scholarly journals Dust reddening in star-forming galaxies

2012 ◽  
Vol 8 (S292) ◽  
pp. 291-291
Author(s):  
Ting Xiao ◽  
Tinggui Wang ◽  
Huiyuan Wang ◽  
Hongyan Zhou ◽  
Honglin Lu ◽  
...  
Keyword(s):  
Star Formation ◽  
Gas Phase ◽  
Galaxy Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Analytical Models ◽  
Star Forming ◽  
Crucial Component ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution

AbstractDust is a crucial component of galaxies in modifying the observed properties of galaxies. Previous studies have suggested that dust reddening in star-forming galaxies is correlated with star formation rate (SFR), luminosity, gas-phase metallicity (Z), stellar mass (M*) and inclination. In this work we investigate the fundamental relations between dust reddening and physical properties of galaxies, and obtain a well-defined empirical recipe for dust reddening. The empirical formulae can be incorporated into semi-analytical models of galaxy formation and evolution to estimate the dust reddening and facilitate comparison with observations.

scholarly journals The Stellar Population of the Thin Disk

2009 ◽  
Vol 5 (S265) ◽  
pp. 304-312
Author(s):  
Carlos Allende Prieto
Keyword(s):  
Galaxy Formation ◽  
Stellar Population ◽  
Milky Way ◽  
Galactic Disk ◽  
Symmetry Plane ◽  
Thin Disk ◽  
Solar Neighborhood ◽  
Galaxy Formation And Evolution ◽  
The Galaxy ◽  
Formation And Evolution

AbstractWe discuss recent observations of stars located close to the symmetry plane of the Milky Way, and examine them in the context of theories of Galaxy formation and evolution. The kinematics, ages, and compositions of thin disk stars in the solar neighborhood display complex patterns, and interesting correlations. The Galactic disk does not seem to pose any unsurmountable obstacles to hierarchical galaxy formation theories, but a model of the Milky Way able to reproduce the complexity found in the data will likely require a meticulous study of a significant fraction of the stars in the Galaxy. Making such an observational effort seems necessary in order to make a physics laboratory out of our own galaxy, and ultimately ensure that the most relevant processes are properly understood.

scholarly journals Dwarf Cosmology with the Stromlo Missing Satellites Survey

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Helmut Jerjen
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Milky Way ◽  
Primary Objective ◽  
Sloan Digital Sky Survey ◽  
Galaxy Formation And Evolution ◽  
National University ◽  
Formation And Evolution ◽  
Satellite Galaxies

The standard Lambda Cold Dark Matter model is considered to be a triumph of theoretical astrophysics but observations of the Milky Way and its system of satellite galaxies irresistibly signal that theory is incomplete on galactic and subgalactic scales. The Stromlo Missing Satellites (SMS) Survey is a critical endeavor to investigate at what level predictions of CDM cosmology are consistent with the observed matter distribution in the Milky Way halo. It will be the deepest, most extended search for optically elusive satellite galaxies to date, covering 20 000 square degrees of sky. The international SMS Survey collaboration will exploit 150 TB of CCD images in six filters acquired by the new SkyMapper telescope of the Australian National University over the next five years, expecting on completion photometric limits 0.5–1.0 mag fainter than the Sloan Digital Sky Survey. The primary objective of the program is to characterise the baryonic and dark matter components of a complete sample of MW satellites in the Southern hemisphere to provide stringent observational constraints for improving our understanding of how the Milky Way formed and what physical processes governed galaxy formation and evolution in general.

Searching for Ultra-diffuse galaxies in the low-density environment around NGC 3115

2019 ◽  
Vol 15 (S359) ◽  
pp. 257-259
Author(s):  
Marco Canossa-Gosteinski ◽  
Ana L. Chies-Santos ◽  
Cristina Furlanetto ◽  
Rodrigo F. Freitas ◽  
William Schoenell
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Visual Inspection ◽  
Milky Way ◽  
Structural Parameters ◽  
Low Density ◽  
Massive Galaxies ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution

AbstractUltra-diffuse galaxies (UDGs) are extremely low luminosity galaxies and some of them seem to have a lack of dark matter. Therefore, they can offer important clues to better understand galaxy formation and evolution. Little is known about UDGs in less dense environments, as most of the known UDGs have been found in very dense regions, in the outskirts of massive galaxies in galaxy clusters. In this work, we present the properties of UDGs candidates identified through visual inspection around the low-density environment of NGC 3115, the closest S0 galaxy from the Milky Way. We have measured the structural parameters of 41 UDGs candidates using images obtained with the Dark Energy Camera at the Blanco Telescope. Such structural parameters will be used to characterise and select the best UDG candidates, that will have their properties traced for future follow-up campaigns.

scholarly journals The star-formation history of the Milky Way Galaxy

2008 ◽  
Vol 4 (S258) ◽  
pp. 11-22 ◽  
Author(s):  
Rosemary F. G. Wyse
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
Milky Way ◽  
Star Formation History ◽  
Milky Way Galaxy ◽  
Galaxy Formation And Evolution ◽  
History Of ◽  
Formation And Evolution ◽  
Star Formation Histories

AbstractThe star-formation histories of the main stellar components of the Milky Way constrain critical aspects of galaxy formation and evolution. I discuss recent determinations of such histories, together with their interpretation in terms of theories of disk galaxy evolution.

scholarly journals A New Catalog of Isolated Galaxies

2009 ◽  
Vol 5 (S267) ◽  
pp. 464-464
Author(s):  
J. A. Vázquez-Mata ◽  
H. M. Hernández-Toledo ◽  
Changbom Park ◽  
Yun-Young Choi
Keyword(s):  
Galaxy Formation ◽  
Environmental Effects ◽  
Comparative Studies ◽  
Sloan Digital Sky Survey ◽  
Selection Algorithm ◽  
Isolated Galaxies ◽  
Galaxy Formation And Evolution ◽  
Sky Survey ◽  
Data Release ◽  
Formation And Evolution

We present a new catalog of isolated galaxies (coined as UNAM–KIAS) obtained through an automated systematic search. The 1520 isolated galaxies were found in ~ 1.4 steradians of the sky in the Sloan Digital Sky Survey Data Release 5 (SDSS DR5) photometry. The selection algorithm was implemented from a variation of the criteria developed by Karachentseva (1973), with full redshift information. This new catalog is aimed to carry out comparative studies of environmental effects and constraining the currently competing scenarios of galaxy formation and evolution.

scholarly journals The Role of Radio Loud Phase of Nuclear Activity in Galaxy Formation and Evolution

2013 ◽  
Vol 9 (S304) ◽  
pp. 419-420
Author(s):  
Gabriel A. Ohanian
Keyword(s):  
Galaxy Formation ◽  
Subsequent Development ◽  
Nuclear Activity ◽  
Evolution Of Galaxies ◽  
Galaxy Formation And Evolution ◽  
Formation And Evolution ◽  
Key Questions

AbstractKey questions, which arise when one tries to clear up a problem of formation and evolution of galaxies, is the question of energy: what is the energetic budget of AGN owing to form galaxies and provide its subsequent development? Hence, for understanding the formation and evolution of galaxies, it is important to estimate the energetic budget of AGN which we try to do involving radio loud phase of nuclear activity.

scholarly journals The Structure of the Stellar Hosts in Blue Compact Dwarf Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 300-300
Author(s):  
R.O. Amorín ◽  
J.A.L. Aguerri ◽  
L.M. Cairós ◽  
N. Caon ◽  
C. Muñoz-Tuñón
Keyword(s):  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Structural Parameters ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Galaxy Formation And Evolution ◽  
Radial Profiles ◽  
Low Surface Brightness ◽  
Formation And Evolution

AbstractBlue compact dwarf (BCD) galaxies are gas-rich, low-luminosity (Mb≳-18 mag) and compact systems, currently undergoing violent star-formation burst (Sargent & Searle 1970). While it was initially hypothesized that they were very young galaxies (e.g. Sargent & Searle 1970, et al. 1988), the subsecuent detection of an extended, redder stellar host galaxy showed that the vast majority of them are old systems (e.g. Gil de Paz et al. 2003,2005). BCDs play an important role for understanding the process of galaxy formation and evolution.The structural properties of the low surface brightness stellar host in BCDs are often studied by fitting r1/n models to the outer regions of their radial profiles. The limitations imposed by the presence of a large starburst emission overlapping the underlying component makes this kind of analysis a difficult task.We propose a two-dimensional fitting methodology in order to improve the extraction of the structural parameters of the LSB host Amorín et al. 2006, submitted). A set of ideal simulations are presented in order to test the reliability of the method and to determine its robustness and flexibility. We present the different steps of the method discussing its advantages and weaknesses. We compare the results for a sample of eight objects with those already obtained using a one-dimensional technique (Caon et al. 2005).We fit a PSF convolved Sérsic model to the BVR images with the GALFIT publicly software (Peng et al. 2002). We restrict the fit to the stellar host by masking out the starburst region and take special care to minimize the sky-subtraction uncertainties. Consistency checks are performed to assess the reliability and accuracy of the derived structural parameters.We obtain robust fits for all the sample galaxies, all of which, except one, show low Sérsic indices n—very close to 1—with good agreement in the three bands. These findings suggest that the stellar hosts in BCDs have near-exponential profiles. Since the Sérsic index n of host galaxies is important in the context of the possible structural and evolutionary connections among the different types of dwarf galaxies, we are currently extending the study to a larger sample of objects. This kind of studies will help us to understand the mechanisms that form and shape BCD galaxies, and how they relate to the other dwarf galaxy classes.

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