scholarly journals Origin of giant stellar clumps in high-redshift galaxies

2020 ◽  
Vol 494 (1) ◽  
pp. 1263-1275 ◽  
Author(s):  
Xi Meng ◽  
Oleg Y Gnedin
Keyword(s):  
Galaxy Formation ◽  
Compact Star ◽  
High Redshift ◽  
Emission Measure ◽  
Young Stars ◽  
High Redshift Galaxies ◽  
Order Of Magnitude ◽  
The Masses ◽  
Stellar Masses ◽  
Redshift Galaxies

ABSTRACT We examine the nature of kpc-scale clumps seen in high-redshift galaxies using a suite of cosmological simulations of galaxy formation. We identify rest-frame UV clumps in mock HST images smoothed to 500 pc resolution, and compare them with the intrinsic 3D clumps of young stars identified in the simulations with 100 pc resolution. According to this comparison for the progenitors of Milky Way-sized galaxies probed by our simulations, we expect that the stellar masses of the observed clumps are overestimated by as much as an order of magnitude, and that the sizes of these clumps are also overestimated by factor of several, due to a combination of spatial resolution and projection. The masses of young stars contributing most of the UV emission can also be overestimated by factor of a few. We find that most clumps of young stars present in a simulation at one time dissolve on a timescale shorter than ∼150 Myr. Some clumps with dense cores can last longer but eventually disperse. Most of the clumps are not bound structures, with virial parameter αvir > 1. We find similar results for clumps identified in mock maps of H α emission measure. We examine the predictions for effective clump sizes from the linear theory of gravitational perturbations and conclude that they are inconsistent with being formed by global disc instabilities. Instead, the observed clumps represent random projections of multiple compact star-forming regions.

scholarly journals New methods for identifying Lyman continuum leakers and reionization-epoch analogues

2020 ◽  
Vol 498 (1) ◽  
pp. 164-180 ◽  
Author(s):  
Harley Katz ◽  
Dominika Ďurovčíková ◽  
Taysun Kimm ◽  
Joki Rosdahl ◽  
Jeremy Blaizot ◽  
...  
Keyword(s):  
Emission Line ◽  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
High Redshift ◽  
Indirect Methods ◽  
High Redshift Galaxies ◽  
Lyman Continuum ◽  
The Universe ◽  
Ionization Parameter ◽  
Redshift Galaxies

ABSTRACT Identifying low-redshift galaxies that emit Lyman continuum radiation (LyC leakers) is one of the primary, indirect methods of studying galaxy formation in the epoch of reionization. However, not only has it proved challenging to identify such systems, it also remains uncertain whether the low-redshift LyC leakers are truly ‘analogues’ of the sources that reionized the Universe. Here, we use high-resolution cosmological radiation hydrodynamics simulations to examine whether simulated galaxies in the epoch of reionization share similar emission line properties to observed LyC leakers at z ∼ 3 and z ∼ 0. We find that the simulated galaxies with high LyC escape fractions (fesc) often exhibit high O32 and populate the same regions of the R23–O32 plane as z ∼ 3 LyC leakers. However, we show that viewing angle, metallicity, and ionization parameter can all impact where a galaxy resides on the O32–fesc plane. Based on emission line diagnostics and how they correlate with fesc, lower metallicity LyC leakers at z ∼ 3 appear to be good analogues of reionization-era galaxies. In contrast, local [S ii]-deficient galaxies do not overlap with the simulated high-redshift LyC leakers on the S ii Baldwin–Phillips–Terlevich (BPT) diagram; however, this diagnostic may still be useful for identifying leakers. We use our simulated galaxies to develop multiple new diagnostics to identify LyC leakers using infrared and nebular emission lines. We show that our model using only [C ii]158 μm and [O iii]88 μm can identify potential leakers from non-leakers from the local Dwarf Galaxy Survey. Finally, we apply this diagnostic to known high-redshift galaxies and find that MACS 1149_JD1 at z = 9.1 is the most likely galaxy to be actively contributing to the reionization of the Universe.

Constraining Galaxy Formation Epoch

2005 ◽  
Vol 201 ◽  
pp. 536-537
Author(s):  
Sukyoung. Yi ◽  
T. Brown ◽  
S. Heap ◽  
I. Hubeny ◽  
W. Landsman ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Population Synthesis ◽  
High Redshift Galaxies ◽  
The Galaxy ◽  
The Difference ◽  
Age Estimates ◽  
Good Agreement ◽  
Redshift Galaxies

Pinning down the ages of high redshift galaxies is the most direct way of constraining the galaxy formation epoch. There has been a debate on the age of LBDS 53W091, a red galaxy at z=1.5. The discrepancy in the age estimates of various groups is due to the difference in the population synthesis model. However, there is generally a good agreement among popular models. Polishing the models and assessing their internal uncertainties are crucial in the analysis of high redshift galaxies.

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 Dark-ages reionization and galaxy-formation simulation – VII. The sizes of high-redshift galaxies

2016 ◽  
Vol 465 (3) ◽  
pp. 3134-3142 ◽  
Author(s):  
Chuanwu Liu ◽  
Simon J. Mutch ◽  
Gregory B. Poole ◽  
P. W. Angel ◽  
Alan R. Duffy ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Dark Ages ◽  
Redshift Galaxies

scholarly journals Stellar Masses of High-Redshift Galaxies

2003 ◽  
pp. 296-301
Author(s):  
Casey Papovich ◽  
Mark Dickinson ◽  
Henry C. Ferguson
Keyword(s):  
High Redshift ◽  
High Redshift Galaxies ◽  
Stellar Masses ◽  
Redshift Galaxies

scholarly journals Photometric estimates of stellar masses in high-redshift galaxies

2004 ◽  
Vol 418 (3) ◽  
pp. 913-926 ◽  
Author(s):  
S. Berta ◽  
J. Fritz ◽  
A. Franceschini ◽  
A. Bressan ◽  
C. Lonsdale
Keyword(s):  
High Redshift ◽  
High Redshift Galaxies ◽  
Stellar Masses ◽  
Redshift Galaxies

scholarly journals Damped Lyα systems as probes of chemical evolution over cosmological timescales

2008 ◽  
Vol 4 (S255) ◽  
pp. 121-128
Author(s):  
Miroslava Dessauges-Zavadsky
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Large Contribution ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Current State ◽  
Galaxy Population ◽  
Stellar Masses ◽  
Star Formation Histories ◽  
Redshift Galaxies

AbstractWe review the current state of knowledge of damped Lyα systems (DLAs) selected in absorption on quasar sightlines. These objects are extremely useful to study the interstellar medium of high-redshift galaxies and the nucleosynthesis in the early Universe. The characteristics of this galaxy population has been investigated for years and slowly we are getting information on their puzzling nature. Imaging atz<1 shows that DLAs are associated with a mixing bag of galaxies with no especially large contribution from dwarf galaxies. Evidence for a mild evolution of the cosmic mean metallicity with time is observed. The star formation histories of these high-redshift galaxies begin to be accessible and indicate that DLAs tend to be young, gas-dominated galaxies with low star formation rates per unit area. Finally, indirect estimation of the DLA stellar masses from the mass-metallicity relations observed for emission-selected star-forming galaxies atz= 2−3 points to intermediate-mass galaxies withM*< 109M⊙.

scholarly journals Dark-ages reionization and galaxy formation simulation – IV. UV luminosity functions of high-redshift galaxies

2016 ◽  
Vol 462 (1) ◽  
pp. 235-249 ◽  
Author(s):  
Chuanwu Liu ◽  
Simon J. Mutch ◽  
P. W. Angel ◽  
Alan R. Duffy ◽  
Paul M. Geil ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Dark Ages ◽  
Luminosity Functions ◽  
Redshift Galaxies

scholarly journals Dark-ages Reionization and Galaxy formation simulation – I. The dynamical lives of high-redshift galaxies

2016 ◽  
Vol 459 (3) ◽  
pp. 3025-3039 ◽  
Author(s):  
Gregory B. Poole ◽  
Paul W. Angel ◽  
Simon J. Mutch ◽  
Chris Power ◽  
Alan R. Duffy ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Dark Ages ◽  
Redshift Galaxies

The Epoch of Galaxy Formation

1990 ◽  
Vol 43 (2) ◽  
pp. 135 ◽  
Author(s):  
PJ Quinn
Keyword(s):  
Galaxy Formation ◽  
Stellar Population ◽  
High Redshift ◽  
Active Galaxies ◽  
High Redshift Galaxies ◽  
Ongoing Process ◽  
Redshift Galaxies

Observations of merging and active galaxies at red shifts less than one suggest that galaxy formation is an ongoing process. Cosmological N�body models and analytiC estimates of the collapse times of large galaxies suggest that the first systems to form .probably did so at redshifts less than 4. The theoretical picture that leads to these estimates of the beginning of the formation epoch may be seriously in error if new observations of high redshift galaxies reveal a pre�existing old stellar population.

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