The Stellar Population of High Redshift Galaxies

2006 ◽  
pp. 335-338
Author(s):  
Dörte Mehlert ◽  
Stefan Noll ◽  
Immo Appenzeller ◽  
the FDF team
Keyword(s):  
Stellar Population ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Was the Milky Way Bulge Formed from the Buckling Disk Instability, Hierarchical Collapse, Accretion of Clumps, or All of the Above?

2017 ◽  
Vol 34 ◽  
Author(s):  
David M. Nataf
Keyword(s):  
Stellar Population ◽  
Milky Way ◽  
Velocity Dispersion ◽  
High Redshift ◽  
Rapid Development ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Thin And Thick Disks ◽  
Bulge Formation ◽  
Redshift Galaxies

AbstractThe assembly of the Milky Way bulge is an old topic in astronomy, one now in a period of renewed and rapid development. That is due to tremendous advances in observations of bulge stars, motivating observations of both local and high-redshift galaxies, and increasingly sophisticated simulations. The dominant scenario for bulge formation is that of the Milky Way as a nearly pure disk galaxy, with the inner disk having formed a bar and buckled. This can potentially explain virtually all bulge stars with [Fe/H] ≳ −1.0, which comprise 95% of the stellar population. The evidence is the incredible success in N-body models of this type in making non-trivial, non-generic predictions, such as the rotation curve and velocity dispersion measured from radial velocities, and the spatial morphologies of the peanut/X-shape and the long bar. The classical bulge scenario, whereby the bulge formed from early dissipative collapse and mergers, remains viable for stars with [Fe/H] ≲ −1.0 and potentially a minority of the other stars. A classical bulge is expected from Λ-CDM cosmological simulations, can accentuate the properties of an existing bar in a hybrid system, and is most consistent with the bulge abundance trends such as [Mg/Fe], which are elevated relative to both the thin and thick disks. Finally, the clumpy-galaxy scenario is considered, as it is the correct description of most Milky Way precursors given observations of high-redshift galaxies. Simulations predict that these star-forming clumps will sometimes migrate to the centres of galaxies where they may form a bulge, and galaxies often include a bulge clump as well. They will possibly form a bar with properties consistent with those of the Milky Way, such as the exponential profile and metallicity gradient. Given the relative successes of these scenarios, the Milky Way bulge is plausibly of composite origin, with a classical bulge and/or inner halo numerically dominant for stars with [Fe/H] ≲ −1.0, a buckling thick disk for stars with − 1.0 ≲ [Fe/H]] ≲ -0.50 perhaps descended from the clumpy-galaxy phase, and a buckling thin disk for stars with [Fe/H] ≳ −0.50. Overlaps from these scenarios are uncertain throughout.

scholarly journals THE ESTIMATION OF STAR FORMATION RATES AND STELLAR POPULATION AGES OF HIGH-REDSHIFT GALAXIES FROM BROADBAND PHOTOMETRY

2010 ◽  
Vol 725 (2) ◽  
pp. 1644-1651 ◽  
Author(s):  
Seong-Kook Lee ◽  
Henry C. Ferguson ◽  
Rachel S. Somerville ◽  
Tommy Wiklind ◽  
Mauro Giavalisco
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
High Redshift ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Evidence for TP‐AGB Stars in High‐Redshift Galaxies, and Their Effect on Deriving Stellar Population Parameters

2006 ◽  
Vol 652 (1) ◽  
pp. 85-96 ◽  
Author(s):  
C. Maraston ◽  
E. Daddi ◽  
A. Renzini ◽  
A. Cimatti ◽  
M. Dickinson ◽  
...  
Keyword(s):  
Stellar Population ◽  
High Redshift ◽  
Agb Stars ◽  
Population Parameters ◽  
High Redshift Galaxies ◽  
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.

scholarly journals TRACING THE EVOLUTION OF HIGH-REDSHIFT GALAXIES USING STELLAR ABUNDANCES

2016 ◽  
Vol 820 (1) ◽  
pp. 71 ◽  
Author(s):  
Brian D. Crosby ◽  
Brian W. O’Shea ◽  
Timothy C. Beers ◽  
Jason Tumlinson
Keyword(s):  
High Redshift ◽  
Stellar Abundances ◽  
High Redshift Galaxies ◽  
Redshift Galaxies

scholarly journals Self-consistent proto-globular cluster formation in cosmological simulations of high-redshift galaxies

2020 ◽  
Vol 493 (3) ◽  
pp. 4315-4332 ◽  
Author(s):  
Xiangcheng Ma ◽  
Michael Y Grudić ◽  
Eliot Quataert ◽  
Philip F Hopkins ◽  
Claude-André Faucher-Giguère ◽  
...  
Keyword(s):  
High Pressure ◽  
Star Formation ◽  
High Redshift ◽  
Cluster Formation ◽  
Mass Function ◽  
Cosmological Simulations ◽  
High Redshift Galaxies ◽  
Cluster Mass ◽  
Formation Efficiency ◽  
Redshift Galaxies

ABSTRACT We report the formation of bound star clusters in a sample of high-resolution cosmological zoom-in simulations of z ≥ 5 galaxies from the Feedback In Realistic Environments project. We find that bound clusters preferentially form in high-pressure clouds with gas surface densities over $10^4\, \mathrm{ M}_{\odot }\, {\rm pc}^{-2}$, where the cloud-scale star formation efficiency is near unity and young stars born in these regions are gravitationally bound at birth. These high-pressure clouds are compressed by feedback-driven winds and/or collisions of smaller clouds/gas streams in highly gas-rich, turbulent environments. The newly formed clusters follow a power-law mass function of dN/dM ∼ M−2. The cluster formation efficiency is similar across galaxies with stellar masses of ∼107–$10^{10}\, \mathrm{ M}_{\odot }$ at z ≥ 5. The age spread of cluster stars is typically a few Myr and increases with cluster mass. The metallicity dispersion of cluster members is ∼0.08 dex in $\rm [Z/H]$ and does not depend on cluster mass significantly. Our findings support the scenario that present-day old globular clusters (GCs) were formed during relatively normal star formation in high-redshift galaxies. Simulations with a stricter/looser star formation model form a factor of a few more/fewer bound clusters per stellar mass formed, while the shape of the mass function is unchanged. Simulations with a lower local star formation efficiency form more stars in bound clusters. The simulated clusters are larger than observed GCs due to finite resolution. Our simulations are among the first cosmological simulations that form bound clusters self-consistently in a wide range of high-redshift galaxies.

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.

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