The Star Formation History of Elliptical Galaxies

1996 ◽  
pp. 37-46 ◽  
Author(s):  
Roger L. Davies

1996 ◽  
Vol 171 ◽  
pp. 37-45
Author(s):  
Roger L. Davies

There is a growing body of evidence indicating young ages, 8 ± 3 Gyrs, for elliptical galaxies and significant age gradients with a younger population residing at the centre. The data appear to be consistent with a scenario where elliptical galaxies are assembled hierarchically with low luminosity galaxies forming first. Late star formation, associated with the last merging event and usually involving only a small fraction of the galaxy mass, could then account for the low age estimates of some luminous galaxies.



2007 ◽  
Vol 24 ◽  
pp. 73-76
Author(s):  
S.K. Yi ◽  
S. Kaviraj ◽  
K. Schawinski ◽  
S. Khochfar ◽  






1999 ◽  
Vol 118 (5) ◽  
pp. 2245-2261 ◽  
Author(s):  
Carme Gallart ◽  
Wendy L. Freedman ◽  
Antonio Aparicio ◽  
Giampaolo Bertelli ◽  
Cesare Chiosi


Author(s):  
M. Cignoni ◽  
S. Degl'Innocenti ◽  
P. G. Prada Moroni ◽  
S. N. Shore


2020 ◽  
Vol 501 (2) ◽  
pp. 1803-1822
Author(s):  
Seunghwan Lim ◽  
Douglas Scott ◽  
Arif Babul ◽  
David J Barnes ◽  
Scott T Kay ◽  
...  

ABSTRACT As progenitors of the most massive objects, protoclusters are key to tracing the evolution and star formation history of the Universe, and are responsible for ${\gtrsim }\, 20$ per cent of the cosmic star formation at $z\, {\gt }\, 2$. Using a combination of state-of-the-art hydrodynamical simulations and empirical models, we show that current galaxy formation models do not produce enough star formation in protoclusters to match observations. We find that the star formation rates (SFRs) predicted from the models are an order of magnitude lower than what is seen in observations, despite the relatively good agreement found for their mass-accretion histories, specifically that they lie on an evolutionary path to become Coma-like clusters at $z\, {\simeq }\, 0$. Using a well-studied protocluster core at $z\, {=}\, 4.3$ as a test case, we find that star formation efficiency of protocluster galaxies is higher than predicted by the models. We show that a large part of the discrepancy can be attributed to a dependence of SFR on the numerical resolution of the simulations, with a roughly factor of 3 drop in SFR when the spatial resolution decreases by a factor of 4. We also present predictions up to $z\, {\simeq }\, 7$. Compared to lower redshifts, we find that centrals (the most massive member galaxies) are more distinct from the other galaxies, while protocluster galaxies are less distinct from field galaxies. All these results suggest that, as a rare and extreme population at high z, protoclusters can help constrain galaxy formation models tuned to match the average population at $z\, {\simeq }\, 0$.



2019 ◽  
Vol 15 (S359) ◽  
pp. 386-390
Author(s):  
Lucimara P. Martins

AbstractWith the exception of some nearby galaxies, we cannot resolve stars individually. To recover the galaxies star formation history (SFH), the challenge is to extract information from their integrated spectrum. A widely used tool is the full spectral fitting technique. This consists of combining simple stellar populations (SSPs) of different ages and metallicities to match the integrated spectrum. This technique works well for optical spectra, for metallicities near solar and chemical histories not much different from our Galaxy. For everything else there is room for improvement. With telescopes being able to explore further and further away, and beyond the optical, the improvement of this type of tool is crucial. SSPs use as ingredients isochrones, an initial mass function, and a library of stellar spectra. My focus are the stellar libraries, key ingredient for SSPs. Here I talk about the latest developments of stellar libraries, how they influence the SSPs and how to improve them.



Sign in / Sign up

Export Citation Format

Share Document