Extragalactic archaeology with the C, N, and O chemical abundances

We predict how the C, N, and O abundances within the interstellar medium of galaxies evolve as functions of the galaxy star formation history (SFH). We adopt a hydrodynamical cosmological simulation, focusing on three star-forming disc galaxies with different SFHs. By assuming failed supernovae, we can predict an increasing trend of the gas-phase N/O–O/H abundance diagram, which was not produced in our previous simulations without failed supernovae. At high redshifts, contrary to the predictions of classical chemical evolution models with instantaneous mixing approximation, we find almost flat trends in the N/O–O/H diagram, which are due to the contribution of intermediate-mass stars together with an inhomogeneous chemical enrichment. Finally, we also predict that the average N/O and C/O steadily increase as functions of time, while the average C/N decreases, due to the mass and metallicity dependence of the yields of asymptotic giant branch stars; such variations are more marked during more intense star formation episodes. Our predictions on the CNO abundance evolution can be used to study the SFH of disc galaxies with the James Webb Space Telescope.

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He abundances in disc galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935886 ◽

2019 ◽

Vol 630 ◽

pp. A125 ◽

Cited By ~ 3

Author(s):

F. Vincenzo ◽

A. Miglio ◽

C. Kobayashi ◽

J. T. Mackereth ◽

J. Montalban

Keyword(s):

Star Formation ◽

Gas Phase ◽

Galaxy Formation ◽

Asymptotic Giant Branch ◽

Star Formation History ◽

Asymptotic Giant Branch Stars ◽

Specific Chemical ◽

Chemical Enrichment ◽

Age Relations ◽

Disc Galaxies

We investigate how the stellar and gas-phase He abundances evolve as a function of time within simulated star-forming disc galaxies with different star formation histories. We make use of a cosmological chemodynamical simulation for galaxy formation and evolution, which includes star formation as well as energy and chemical enrichment feedback from asymptotic giant branch stars, core-collapse supernovae, and Type Ia supernovae. The predicted relations between the He mass fraction, Y, and the metallicity, Z, in the interstellar medium of our simulated disc galaxies depend on the galaxy star formation history. In particular, dY/dZ is not constant and evolves as a function of time, depending on the specific chemical element that we choose to trace Z; in particular, dY/dXO and dY/dXC increase as a function of time, whereas dY/dXN decreases. In the gas-phase, we find negative radial gradients of Y, due to the inside-out growth of our simulated galaxy discs as a function of time; this gives rise to longer chemical enrichment timescales in the outer galaxy regions, where we find lower average values for Y and Z. Finally, by means of chemical-evolution models, in the galactic bulge and inner disc, we predict steeper Y vs. age relations at high Z than in the outer galaxy regions. We conclude that for calibrating the assumed Y − Z relation in stellar models, C, N, and C+N are better proxies for the metallicity than O because they show steeper and less scattered relations.

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Recovering the Star Formation History of IC1613 Dwarf Galaxy Using Evolved Stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318006324 ◽

2018 ◽

Vol 14 (S344) ◽

pp. 77-80

Author(s):

Seyed Azim Hashemi ◽

Atefeh Javadi ◽

Jacco Th. van Loon

Keyword(s):

Star Formation ◽

Dwarf Galaxy ◽

Stellar Populations ◽

Asymptotic Giant Branch ◽

Star Formation History ◽

Evolved Stars ◽

Formation History ◽

The Galaxy ◽

Red Supergiants ◽

Period Variable

AbstractDetermining the star formation history (SFH) is key to understand the formation and evolution of dwarf galaxies. Recovering the SFH in resolved galaxies is mostly based on deep colour–magnitude diagrams (CMDs), which trace the signatures of multiple evolutionary stages of their stellar populations. In distant and unresolved galaxies, the integrated light of the galaxy can be decomposed, albeit made difficult by an age–metallicity degeneracy. Another solution to determine the SFH of resolved galaxies is based on evolved stars; these luminous stars are the most accessible tracers of the underlying stellar populations and can trace the entire SFH. Here we present a novel method based on long period variable (LPV) evolved asymptotic giant branch (AGB) stars and red supergiants (RSGs). We applied this method to reconstruct the SFH for IC1613, an irregular dwarf galaxy at a distance of 750 kpc. Our results provide an independent confirmation that no major episode of star formation occurred in IC1613 over the past 5 Gyr.

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The star formation history of galaxies in 3D: CALIFA perspective

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314009399 ◽

2014 ◽

Vol 10 (S309) ◽

pp. 99-104

Author(s):

R. M. González Delgado ◽

R. Cid Fernandes ◽

R. García-Benito ◽

E. Pérez ◽

A. L. de Amorim ◽

...

Keyword(s):

Star Formation ◽

Surface Density ◽

Spectral Synthesis ◽

Stellar Mass ◽

Star Formation History ◽

Chemical Enrichment ◽

Radial Profiles ◽

Formation History ◽

The Galaxy ◽

History Of

AbstractWe resolve spatially the star formation history of 300 nearby galaxies from the CALIFA integral field survey to investigate: a) the radial structure and gradients of the present stellar populations properties as a function of the Hubble type; and b) the role that plays the galaxy stellar mass and stellar mass surface density in governing the star formation history and metallicity enrichment of spheroids and the disks of galaxies. We apply the fossil record method based on spectral synthesis techniques to recover spatially and temporally resolved maps of stellar population properties of spheroids and spirals with galaxy mass from 109 to 7×1011 M⊙. The individual radial profiles of the stellar mass surface density (μ⋆), stellar extinction (AV), luminosity weighted ages (〈logage〉L), and mass weighted metallicity (〈log Z/Z⊙〉M) are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc and Sd). All these properties show negative gradients as a sight of the inside-out growth of massive galaxies. However, the gradients depend on the Hubble type in different ways. For the same galaxy mass, E and S0 galaxies show the largest inner gradients in μ⋆; and Andromeda-like galaxies (Sb with log M⋆ (M⊙) ∼ 11) show the largest inner age and metallicity gradients. In average, spiral galaxies have a stellar metallicity gradient ∼ −0.1 dex per half-light radius, in agreement with the value estimated for the ionized gas oxygen abundance gradient by CALIFA. A global (M⋆-driven) and local (μ⋆-driven) stellar metallicity relation are derived. We find that in disks, the stellar mass surface density regulates the stellar metallicity; in spheroids, the galaxy stellar mass dominates the physics of star formation and chemical enrichment.

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The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2015.38 ◽

2016 ◽

Vol 33 ◽

Cited By ~ 21

Author(s):

David M. Nataf

Keyword(s):

Star Formation ◽

Main Sequence ◽

Milky Way ◽

Central Star ◽

Asymptotic Giant Branch ◽

Star Formation History ◽

Asymptotic Giant Branch Stars ◽

Rr Lyrae ◽

Formation History ◽

Solar Metallicity

AbstractThe stellar population of the Milky Way bulge is thoroughly studied, with a plethora of measurements from virtually the full suite of instruments available to astronomers. It is thus perhaps surprising that alongside well-established results lies some substantial uncertainty in its star-formation history. Cosmological models predict the bulge to host the Galaxy's oldest stars for [Fe/H] ≲ −1, and this is demonstrated by RR Lyrae stars and globular cluster observations. There is consensus that bulge stars with [Fe/H] ≲ 0 are older than t ≈ 10 Gyr. However, at super-solar metallicity, there is a substantial unresolved discrepancy. Data from spectroscopic measurements of the main-sequence turnoff and subgiant branch, the abundances of asymptotic giant branch stars, the period distribution of Mira variables, the chemistry and central-star masses of planetary nebulae, all suggest a substantial intermediate-age population (t ≈ 3 Gyr). This is in conflict with predictions from cosmologically motivated chemical evolution models and photometric studies of the main-sequence turnoff region, which both suggest virtually no stars younger than t ≈ 8 Gyr. A possible resolution to this conflict is enhanced helium-enrichment, as this would shift nearly all of the age estimates in the direction of decreasing discrepancy.

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Field Studies, Luminosity Functions, and Star Formation History in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900039978 ◽

1984 ◽

Vol 108 ◽

pp. 79-87

Author(s):

L. L. Stryker

Keyword(s):

Star Formation ◽

Field Studies ◽

Magellanic Clouds ◽

Star Formation History ◽

General Question ◽

Star Forming ◽

Initial Epoch ◽

Luminosity Functions ◽

Formation History ◽

The Galaxy

One of the most fundamental questions we might ask about galaxies is, Do all galaxies have the same age? A less general question, and one which we can surely succeed in answering is, Are the Magellanic Clouds (MCs) the same age as the Galaxy? We must also make clear what is meant by the same age if, in fact, star forming activities in these systems have proceeded along different timescales. The age of a system can be masked if the strongest star-forming epoch was not coincident with the initial epoch. Deep colour-magnitude diagrams (CMDs) and luminosity functions (LFs) have had to wait until the advent of large southern telescopes, sensitive emulsions and detectors, and accurate methods of measuring crowded images.

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Asymptotic giant branch stars in NGC 6822: Probes of star formation history

The Astrophysical Journal ◽

10.1086/187298 ◽

1994 ◽

Vol 425 ◽

pp. L9 ◽

Cited By ~ 12

Author(s):

C. Gallart ◽

A. Aparicio ◽

C. Chiosi ◽

G. Bertelli ◽

J. M. Vilchez

Keyword(s):

Star Formation ◽

Asymptotic Giant Branch ◽

Star Formation History ◽

Asymptotic Giant Branch Stars ◽

Formation History ◽

Ngc 6822 ◽

Giant Branch Stars

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The Sagittarius Dwarf Galaxy Survey (SDGS): Constraints on the Star Formation History of the Sgr dSph

Symposium - International Astronomical Union ◽

10.1017/s0074180900204026 ◽

1999 ◽

Vol 192 ◽

pp. 121-128

Author(s):

M. Bellazzini ◽

F. R. Ferraro ◽

R. Buonanno

Keyword(s):

Star Formation ◽

Star Formation Rate ◽

Dwarf Galaxy ◽

Formation Rate ◽

Star Formation History ◽

Full Potential ◽

Chemical Enrichment ◽

Formation History ◽

The Galaxy ◽

History Of

The main characteristics of a wide photometric survey of the Sgr dwarf spheroidal galaxy are briefly presented. V and I photometry has been obtained for ~90000 stars toward Sgr and for ~9000 stars in a region devoid of Sgr stars (for decontamination purposes).The full potential of this large database is far from being completely explored. Here we present only preliminary results from the analysis of statistically decontaminated Color Magnitude Diagrams, trying to set a scheme of the Star Formation History of the Sgr Galaxy. A scenario is proposed in which star formation in Sgr began very early and lasted for several Gyr, with progressive chemical enrichment of the Inter-Stellar Medium (ISM). Nearly 8 Gyr ago the star formation rate abruptly decreased, perhaps in coincidence with the event that led to the gas depletion of the galaxy. A very small rate of star formation continued until relatively recent times (~ 1 Gyr ago).

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Chemo-dynamical simulations of galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310000827 ◽

2009 ◽

Vol 5 (S265) ◽

pp. 336-341

Author(s):

Chiaki Kobayashi

Keyword(s):

Star Formation ◽

Star Formation Rate ◽

Formation Rate ◽

Star Formation History ◽

Chemical Abundances ◽

Chemical Enrichment ◽

Formation History ◽

Dynamical Simulations ◽

Formation And Evolution ◽

Supernova Feedback

AbstractWe simulate the formation and evolution of galaxies with a self-consistent 3D hydrodynamical model including star formation, supernova feedback, and chemical enrichment. Hypernova feedback plays an essential role not only in solving the [Zn/Fe] problem, but also reproducing the cosmic star formation rate history and the mass-metallicity relations. In the Milky-Way type galaxy, the star formation history, and thus the kinematics and chemical abundances are different in bulge, disk, and thick disk.

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Quenching by gas compression and consumption

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834542 ◽

2019 ◽

Vol 624 ◽

pp. A81 ◽

Cited By ~ 4

Author(s):

Allison W. S. Man ◽

Matthew D. Lehnert ◽

Joël D. R. Vernet ◽

Carlos De Breuck ◽

Theresa Falkendal

Keyword(s):

Star Formation ◽

Formation Rate ◽

Relative Strength ◽

Star Formation History ◽

Molecular Gas ◽

Host Galaxies ◽

Massive Galaxies ◽

Star Forming ◽

Gas Compression ◽

Formation History

The objective of this work is to study how active galactic nuclei (AGN) influence star formation in host galaxies. We present a detailed investigation of the star-formation history and conditions of a z = 2.57 massive radio galaxy based on VLT/X-shooter and ALMA observations. The deep rest-frame ultraviolet spectrum contains photospheric absorption lines and wind features indicating the presence of OB-type stars. The most significantly detected photospheric features are used to characterize the recent star formation: neither instantaneous nor continuous star-formation history is consistent with the relative strength of the Si IIλ1485 and S Vλ1502 absorption. Rather, at least two bursts of star formation took place in the recent past, at 6+1-2 Myr and ≳20 Myr ago, respectively. We deduce a molecular H2 gas mass of (3.9 ± 1.0) × 1010 M⊙ based on ALMA observations of the [C I] 3P2−3P1 emission. The molecular gas mass is only 13% of its stellar mass. Combined with its high star-formation rate of (1020-170+190 M⊙ yr-1, this implies a high star-formation efficiency of (26 ± 8) Gyr−1 and a short depletion time of (38 ± 12) Myr. We attribute the efficient star formation to compressive gas motions in order to explain the modest velocity dispersions (⩽55 km s−1) of the photospheric lines and of the star-forming gas traced by [C I]. Because of the likely very young age of the radio source, our findings suggest that vigorous star formation consumes much of the gas and works in concert with the AGN to remove any residual molecular gas, and eventually quenching star formation in massive galaxies.

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