scholarly journals Evolution of dwarf galaxy observable parameters

2020 ◽  
Vol 493 (1) ◽  
pp. 638-650
Author(s):  
Eimantas Ledinauskas ◽  
Kastytis Zubovas
Keyword(s):  
Galaxy Evolution ◽  
Dwarf Galaxies ◽  
Background Radiation ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Stellar Mass ◽  
Local Universe ◽  
Isolated Galaxies ◽  
Mass Assembly ◽  
Hubble Time

ABSTRACT We present a semi-analytic model of isolated dwarf galaxy evolution and use it to study the build-up of observed correlations between dwarf galaxy properties. We analyse the evolution using models with averaged and individual halo mass assembly histories in order to determine the importance of stochasticity on the present-day properties of dwarf galaxies. The model has a few free parameters, but when these are calibrated using the halo mass–stellar mass and stellar mass–metallicity relations, the results agree with other observed dwarf galaxy properties remarkably well. Redshift evolution shows that even isolated galaxies change significantly over the Hubble time and that ‘fossil dwarf galaxies’ with properties equivalent to those of high-redshift analogues should be extremely rare, or non-existent, in the local Universe. A break in most galaxy property correlations develops over time, at a stellar mass $M_* \simeq 10^7 \, {\rm M_{\odot }}$. It is caused predominantly by the ionizing background radiation and can therefore in principle be used to constrain the properties of reionization.

Dwarf galaxies at low and high redshift

2018 ◽  
Vol 14 (S344) ◽  
pp. 437-445
Author(s):  
Xu Kong ◽  
Jianhui Lian ◽  
Yulong Gao ◽  
Zuyi Chen ◽  
Guangwen Chen ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Formation Rate ◽  
Mass Star ◽  
Chemical Enrichment ◽  
Galaxy Sample

AbstractThe overwhelming majority of galaxies in the Universe are dwarf galaxies. But although they are important components in understanding galaxy evolution, these systems are typically too faint to be observed at high redshifts. However, we are able to obtain an unobscured view of early star formation and chemical enrichment in these galaxies at low redshift and low-redshift analogs at high redshift. In this talk, I will review the mass-metallicity relation, the mass-star formation rate relation of galaxies, the classifications of dwarf galaxies, and the importance of dwarf galaxies for both astronomy and physics. Then I will introduce some work in our group on connections among between different types of dwarf galaxies,the mass-metallicity relations and the main sequence relations of dwarf galaxies, using the deep optical and near infrared images and spectra of large dwarf galaxy sample. At the end, I will talk about some projects of dwarf galaxies we are working on, including the spectroscopic survey for compact dwarf galaxies using the LAMOST.

scholarly journals The Evolution of the Baryonic Tully-Fisher Relation over the past 6 Gyr

2010 ◽  
Vol 6 (S277) ◽  
pp. 138-141 ◽  
Author(s):  
M. Puech ◽  
F. Hammer ◽  
H. Flores ◽  
R. Delgado-Serrano ◽  
M. Rodrigues ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Zero Point ◽  
Stellar Mass ◽  
Local Universe ◽  
The Past ◽  
Spatially Resolved ◽  
Fisher Relation ◽  
First Time ◽  
Gas Fractions

AbstractScaling relations are salient ingredients of galaxy evolution and formation models. I summarize results from the IMAGES survey, which combines spatially-resolved kinematics from FLAMES/GIRAFFE with imaging from HST/ACS and other facilities. Specifically, I will focus on the evolution of the stellar mass and baryonic Tully-Fisher Relations (TFR) from z = 0.6 down to z = 0. We found a significant evolution in zero point and scatter of the stellar mass TFR compared to the local Universe. Combined with gas fractions derived by inverting the Schmidt-Kennicutt relation, we derived for the first time a baryonic TFR at high redshift. Conversely to the stellar mass TFR, the baryonic relation does not appear to evolve in zero point, which suggests that most of the reservoir of gas converted into stars over the past 6 Gyr was already gravitationally bound to galaxies at z = 0.6.

scholarly journals The MOSDEF survey: differences in SFR and metallicity for morphologically selected mergers at z ∼ 2

2020 ◽  
Vol 501 (1) ◽  
pp. 137-145
Author(s):  
Katelyn Horstman ◽  
Alice E Shapley ◽  
Ryan L Sanders ◽  
Bahram Mobasher ◽  
Naveen A Reddy ◽  
...  
Keyword(s):  
High Redshift ◽  
Statistical Significance ◽  
Formation Rate ◽  
Control Sample ◽  
Stellar Mass ◽  
Mass Star ◽  
Local Universe ◽  
Galaxy Interactions ◽  
Isolated Galaxies ◽  
Future Work

ABSTRACT We study the properties of 55 morphologically-identified merging galaxy systems at z ∼ 2. These systems are flagged as mergers based on features such as tidal tails, double nuclei, and asymmetry. Our sample is drawn from the MOSFIRE Deep Evolution Field (MOSDEF) survey, along with a control sample of isolated galaxies at the same redshift. We consider the relationships between stellar mass, star formation rate (SFR), and gas-phase metallicity for both merging and non-merging systems. In the local universe, merging systems are characterized by an elevated SFR and depressed metallicity compared to isolated systems at a given mass. Our results indicate SFR enhancement and metallicity deficit for merging systems relative to non-merging systems for a fixed stellar mass at z ∼ 2, though larger samples are required to establish these preliminary results with higher statistical significance. In future work, it will be important to establish if the enhanced SFR and depressed metallicity in high-redshift mergers deviate from the ‘fundamental metallicity relation,’ as is observed in mergers in the local universe, and therefore shed light on gas flows during galaxy interactions.

scholarly journals The role of mergers and interactions in driving the evolution of dwarf galaxies over cosmic time

2020 ◽  
Vol 500 (4) ◽  
pp. 4937-4957 ◽  
Author(s):  
G Martin ◽  
R A Jackson ◽  
S Kaviraj ◽  
H Choi ◽  
J E G Devriendt ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Large Fraction ◽  
Structural Evolution ◽  
Cosmic Time ◽  
Stellar Mass ◽  
High Mass ◽  
Key Drivers ◽  
Mass Assembly

ABSTRACT Dwarf galaxies (M⋆ < 109 M⊙) are key drivers of mass assembly in high-mass galaxies, but relatively little is understood about the assembly of dwarf galaxies themselves. Using the NewHorizon cosmological simulation (∼40 pc spatial resolution), we investigate how mergers and fly-bys drive the mass assembly and structural evolution of around 1000 field and group dwarfs up to z = 0.5. We find that, while dwarf galaxies often exhibit disturbed morphologies (5 and 20 per cent are disturbed at z = 1 and z = 3 respectively), only a small proportion of the morphological disturbances seen in dwarf galaxies are driven by mergers at any redshift (for 109 M⊙, mergers drive under 20 per cent morphological disturbances). They are instead primarily the result of interactions that do not end in a merger (e.g. fly-bys). Given the large fraction of apparently morphologically disturbed dwarf galaxies which are not, in fact, merging, this finding is particularly important to future studies identifying dwarf mergers and post-mergers morphologically at intermediate and high redshifts. Dwarfs typically undergo one major and one minor merger between z = 5 and z = 0.5, accounting for 10 per cent of their total stellar mass. Mergers can also drive moderate star formation enhancements at lower redshifts (3 or 4 times at z = 1), but this accounts for only a few per cent of stellar mass in the dwarf regime given their infrequency. Non-merger interactions drive significantly smaller star formation enhancements (around two times), but their preponderance relative to mergers means they account for around 10 per cent of stellar mass formed in the dwarf regime.

scholarly journals Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions

2021 ◽  
Vol 502 (2) ◽  
pp. 1785-1796
Author(s):  
R A Jackson ◽  
S Kaviraj ◽  
G Martin ◽  
J E G Devriendt ◽  
A Slyz ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Evolution ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Stellar Mass ◽  
Matter Content ◽  
Mass Relation ◽  
Potential Wells ◽  
Tidal Interactions ◽  
New Interactions

ABSTRACT In the standard ΛCDM (Lambda cold dark matter) paradigm, dwarf galaxies are expected to be dark matter-rich, as baryonic feedback is thought to quickly drive gas out of their shallow potential wells and quench star formation at early epochs. Recent observations of local dwarfs with extremely low dark matter content appear to contradict this picture, potentially bringing the validity of the standard model into question. We use NewHorizon, a high-resolution cosmological simulation, to demonstrate that sustained stripping of dark matter, in tidal interactions between a massive galaxy and a dwarf satellite, naturally produces dwarfs that are dark matter-deficient, even though their initial dark matter fractions are normal. The process of dark matter stripping is responsible for the large scatter in the halo-to-stellar mass relation in the dwarf regime. The degree of stripping is driven by the closeness of the orbit of the dwarf around its massive companion and, in extreme cases, produces dwarfs with halo-to-stellar mass ratios as low as unity, consistent with the findings of recent observational studies. ∼30 per cent of dwarfs show some deviation from normal dark matter fractions due to dark matter stripping, with 10 per cent showing high levels of dark matter deficiency (Mhalo/M⋆ < 10). Given their close orbits, a significant fraction of dark matter-deficient dwarfs merge with their massive companions (e.g. ∼70 per cent merge over time-scales of ∼3.5 Gyr), with the dark matter-deficient population being constantly replenished by new interactions between dwarfs and massive companions. The creation of these galaxies is therefore a natural by-product of galaxy evolution and their existence is not in tension with the standard paradigm.

scholarly journals Delayed Stellar Mass Assembly in the Low Surface Brightness Dwarf Galaxy KDG 215

2018 ◽  
Vol 864 (1) ◽  
pp. L14 ◽  
Author(s):  
John M. Cannon ◽  
Zili Shen ◽  
Kristen B. W. McQuinn ◽  
Joshua Bartz ◽  
Lilly Bralts-Kelly ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxy ◽  
Stellar Mass ◽  
Low Surface Brightness ◽  
Mass Assembly

scholarly journals Dark-ages reionization and galaxy formation simulation – XVII. Sizes, angular momenta, and morphologies of high-redshift galaxies

2019 ◽  
Vol 488 (2) ◽  
pp. 1941-1959 ◽  
Author(s):  
Madeline A Marshall ◽  
Simon J Mutch ◽  
Yuxiang Qin ◽  
Gregory B Poole ◽  
J Stuart B Wyithe
Keyword(s):  
Angular Momentum ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Stellar Mass ◽  
Galaxy Mergers ◽  
High Redshift Galaxies ◽  
Massive Galaxies ◽  
Angular Momenta ◽  
Redshift Galaxies

Abstract We study the sizes, angular momenta, and morphologies of high-redshift galaxies, using an update of the meraxes semi-analytic galaxy evolution model. Our model successfully reproduces a range of observations from redshifts z = 0–10. We find that the effective radius of a galaxy disc scales with ultraviolet (UV) luminosity as $R_\mathrm{ e}\propto L_{\textrm{UV}}^{0.33}$ at z = 5–10, and with stellar mass as $R_e\propto M_\ast ^{0.24}$ at z = 5 but with a slope that increases at higher redshifts. Our model predicts that the median galaxy size scales with redshift as Re ∝ (1 + z)−m, where m = 1.98 ± 0.07 for galaxies with (0.3–1)$L^\ast _{z=3}$ and m = 2.15 ± 0.05 for galaxies with (0.12–0.3)$L^\ast _{z=3}$. We find that the ratio between stellar and halo specific angular momentum is typically less than 1 and decreases with halo and stellar mass. This relation shows no redshift dependence, while the relation between specific angular momentum and stellar mass decreases by ∼0.5 dex from z = 7 to z = 2. Our model reproduces the distribution of local galaxy morphologies, with bulges formed predominantly through galaxy mergers for low-mass galaxies, disc-instabilities for galaxies with M* ≃ 1010–$10^{11.5}\, \mathrm{M}_\odot$, and major mergers for the most massive galaxies. At high redshifts, we find galaxy morphologies that are predominantly bulge-dominated.

scholarly journals From peculiar morphologies to Hubble-type spirals: the relation between galaxy dynamics and morphology in star-forming galaxies at z ∼ 1.5

2019 ◽  
Vol 492 (1) ◽  
pp. 1492-1512
Author(s):  
S Gillman ◽  
A L Tiley ◽  
A M Swinbank ◽  
C M Harrison ◽  
Ian Smail ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Galaxy Evolution ◽  
Surface Density ◽  
Rest Frame ◽  
Star Formation Rate ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Star Forming

ABSTRACT We present an analysis of the gas dynamics of star-forming galaxies at z ∼ 1.5 using data from the KMOS Galaxy Evolution Survey. We quantify the morphology of the galaxies using HSTcandels imaging parametrically and non-parametrically. We combine the H α dynamics from KMOS with the high-resolution imaging to derive the relation between stellar mass (M*) and stellar specific angular momentum (j*). We show that high-redshift star-forming galaxies at z ∼ 1.5 follow a power-law trend in specific stellar angular momentum with stellar mass similar to that of local late-type galaxies of the form j*  ∝  M$_*^{0.53\, \pm \, 0.10}$. The highest specific angular momentum galaxies are mostly disc-like, although generally both peculiar morphologies and disc-like systems are found across the sequence of specific angular momentum at a fixed stellar mass. We explore the scatter within the j* – M* plane and its correlation with both the integrated dynamical properties of a galaxy (e.g. velocity dispersion, Toomre Qg, H α star formation rate surface density ΣSFR) and its parametrized rest-frame UV / optical morphology (e.g. Sérsic index, bulge to total ratio, clumpiness, asymmetry, and concentration). We establish that the position in the j* – M* plane is strongly correlated with the star-formation surface density and the clumpiness of the stellar light distribution. Galaxies with peculiar rest-frame UV / optical morphologies have comparable specific angular momentum to disc- dominated galaxies of the same stellar mass, but are clumpier and have higher star formation rate surface densities. We propose that the peculiar morphologies in high-redshift systems are driven by higher star formation rate surface densities and higher gas fractions leading to a more clumpy interstellar medium.

scholarly journals The elephant in the bathtub: when the physics of star formation regulate the baryon cycle of galaxies

2020 ◽  
Vol 500 (2) ◽  
pp. 2000-2011
Author(s):  
Jindra Gensior ◽  
J M Diederik Kruijssen
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Formation Rate ◽  
Cosmic Time ◽  
Free Fall ◽  
Isolated Galaxies ◽  
The Galaxy ◽  
Galaxy Masses

ABSTRACT In simple models of galaxy formation and evolution, star formation is solely regulated by the amount of gas present in the galaxy. However, it has recently been shown that star formation can be suppressed by galactic dynamics in galaxies that contain a dominant spheroidal component and a low gas fraction. This ‘dynamical suppression’ is hypothesized to also contribute to quenching gas-rich galaxies at high redshift, but its impact on the galaxy population at large remains unclear. In this paper, we assess the importance of dynamical suppression in the context of gas regulator models of galaxy evolution through hydrodynamic simulations of isolated galaxies, with gas-to-stellar mass ratios of 0.01–0.20 and a range of galactic gravitational potentials from disc-dominated to spheroidal. Star formation is modelled using a dynamics-dependent efficiency per free-fall time, which depends on the virial parameter of the gas. We find that dynamical suppression becomes more effective at lower gas fractions and quantify its impact on the star formation rate as a function of gas fraction and stellar spheroid mass surface density. We combine the results of our simulations with observed scaling relations that describe the change of galaxy properties across cosmic time, and determine the galaxy mass and redshift range where dynamical suppression may affect the baryon cycle. We predict that the physics of star formation can limit and regulate the baryon cycle at low redshifts (z ≲ 1.4) and high galaxy masses (M* ≳ 3 × 1010 M⊙), where dynamical suppression can drive galaxies off the star formation main sequence.

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