Recovering the star formation history of galaxies through spectral fitting: Current challenges

2019 ◽  
Vol 15 (S359) ◽  
pp. 386-390
Author(s):  
Lucimara P. Martins
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Stellar Spectra ◽  
Spectral Fitting ◽  
Formation History ◽  
History Of ◽  
Nearby Galaxies ◽  
Extract Information

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.

scholarly journals Dissecting 30 Doradus: Optical and Near Infrared Star Formation History of the starburst cluster NGC2070 from the Hubble Tarantula Treasury Project

2015 ◽  
Vol 12 (S316) ◽  
pp. 77-83
Author(s):  
Michele Cignoni ◽  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Near Infrared ◽  
Mass Function ◽  
Large Magellanic Cloud ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Formation History ◽  
History Of ◽  
30 Doradus

AbstractI will present new results on the star formation history of 30 Doradus in the Large Magellanic Cloud based on the panchromatic imaging survey Hubble Tarantula Treasury Project (HTTP). Here the focus is on the starburst cluster NGC2070. The star formation history is derived by comparing the deepest ever optical and NIR color-magnitude diagrams (CMDs) with state-of-the-art synthetic CMDs generated with the latest PARSEC models, which include all stellar phases from pre-main sequence to post-main sequence. For the first time in this region we are able to measure the star formation using intermediate and low mass stars simultaneously. Our results suggest that NGC2070 experienced a prolonged activity. I will discuss the detailed star formation history, initial mass function and reddening distribution.

scholarly journals Star formation history of the solar neighbourhood as told by Gaia

2020 ◽  
Vol 501 (1) ◽  
pp. 302-328
Author(s):  
Jairo A Alzate ◽  
Gustavo Bruzual ◽  
Daniel J Díaz-González
Keyword(s):  
Star Formation ◽  
Binary Stars ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Solar Neighbourhood ◽  
Data Set ◽  
Formation History ◽  
Solar Metallicity ◽  
History Of

ABSTRACT The Gaia data release 2 (DR2) catalogue is the best source of stellar astrometric and photometric data available today. The history of the Milky Way galaxy is written in stone in this data set. Parallaxes and photometry tell us where the stars are today, when were they formed, and with what chemical content, that is, their star formation history (SFH). We develop a Bayesian hierarchical model suited to reconstruct the SFH of a resolved stellar population. We study the stars brighter than $G\, =\, 15$ within 100 pc of the Sun in Gaia DR2 and derive an SFH of the solar neighbourhood in agreement with previous determinations and improving upon them because we detect chemical enrichment. Our results show a maximum of star formation activity about 10 Gyr ago, producing large numbers of stars with slightly below solar metallicity (Z  =  0.014), followed by a decrease in star formation up to a minimum level occurring around 8 Gyr ago. After a quiet period, star formation rises to a maximum at about 5 Gyr ago, forming stars of solar metallicity (Z  =  0.017). Finally, star formation has been decreasing until the present, forming stars of Z  =  0.03 at a residual level. We test the effects introduced in the inferred SFH by ignoring the presence of unresolved binary stars in the sample, reducing the apparent limiting magnitude, and modifying the stellar initial mass function.

scholarly journals The star-formation history of the Universe from the stellar populations of nearby galaxies

Nature ◽  
2004 ◽  
Vol 428 (6983) ◽  
pp. 625-627 ◽  
Author(s):  
Alan Heavens ◽  
Benjamin Panter ◽  
Raul Jimenez ◽  
James Dunlop
Keyword(s):  
Star Formation ◽  
Stellar Populations ◽  
Star Formation History ◽  
Formation History ◽  
History Of ◽  
Nearby Galaxies ◽  
The Universe

scholarly journals Comment on “An excess of massive stars in the local 30 Doradus starburst”

Science ◽  
2018 ◽  
Vol 361 (6400) ◽  
pp. eaat6506 ◽  
Author(s):  
Will M. Farr ◽  
Ilya Mandel
Keyword(s):  
Star Formation ◽  
Power Law ◽  
Ad Hoc ◽  
Massive Stars ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Formation History ◽  
Power Law Exponent ◽  
Stellar Initial Mass Function

Schneider et al. (Reports, 5 January 2018, p. 69) used an ad hoc statistical method in their calculation of the stellar initial mass function. Adopting an improved approach, we reanalyze their data and determine a power-law exponent of 2.05−0.13+0.14. Alternative assumptions regarding dataset completeness and the star formation history model can shift the inferred exponent to 2.11−0.17+0.19 and 2.15−0.13+0.13, respectively.

scholarly journals PROBING THE STAR FORMATION HISTORY AND INITIAL MASS FUNCTION OF THEz∼ 2.5 LENSED GALAXY SMM J163554.2+661225 WITHHERSCHEL

2011 ◽  
Vol 742 (2) ◽  
pp. 108 ◽  
Author(s):  
Keely D. Finkelstein ◽  
Casey Papovich ◽  
Steven L. Finkelstein ◽  
Christopher N. A. Willmer ◽  
Jane R. Rigby ◽  
...  
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Initial Mass ◽  
Formation History

scholarly journals Unravelling the origin of the counter-rotating core in IC 1459 with KMOS and MUSE

2019 ◽  
Vol 488 (2) ◽  
pp. 1679-1694 ◽  
Author(s):  
Laura J Prichard ◽  
Sam P Vaughan ◽  
Roger L Davies
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Large Data ◽  
Major Axis ◽  
Stellar Populations ◽  
Mass Function ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Spectral Fitting ◽  
Field Unit

ABSTRACT The massive early-type galaxy IC 1459 is a slowly rotating galaxy that exhibits a rapidly counter-rotating kinematically decoupled core (KDC, RKDC ≈ 5 arcsec ≈ 0.1Re). To investigate the origin of its KDC, we coupled large data mosaics from the near-infrared and optical integral field unit instruments K-band Multi-Object Spectrograph (KMOS) and Multi-Unit Spectroscopic Explorer (MUSE), respectively. We studied IC 1459’s stellar populations and, for the first time for a KDC, the spatially resolved initial mass function (IMF). We used full-spectral-fitting to fit the stellar populations and IMF simultaneously, and an alternative spectral-fitting method that does not assume a star formation history (SFH; although does not constrain the IMF) for comparison. When no SFH is assumed, we derived a negative metallicity gradient for IC 1459 that could be driven by a distinct metal-poor population in the outer regions of the galaxy, and a radially constant old stellar age. We found a radially constant bottom-heavy IMF out to ${\sim }\frac {1}{3}R_{\rm e}$. The radially flat IMF and age extend beyond the counter-rotating core. We detected high-velocity dispersion along the galaxy’s major axis. Our results potentially add weight to findings from orbital modelling of other KDCs that the core is not a distinct population of stars but in fact two smooth co-spatial counter-rotating populations. No clear picture of formation explains the observational results of IC 1459, but we propose it could have included a gas-rich intense period of star formation at early times, perhaps with counter-rotating accreting cold streams, followed by dry and gas-rich mergers through to the present day.

Sign in / Sign up

Export Citation Format

Share Document