Periodic bursts of star formation in irregular galaxies

Pelupessy, F. I.; Werf, P. P. van der; Icke, Vincent

doi:10.1051/0004-6361:20047071

Cited by 81 publications

(116 citation statements)

References 69 publications

(79 reference statements)

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“…It seems to be a free parameter that can play a role in the periodic bursts of star formation recently suggested by Pelupessy et al (2004) or may play a role in the dwarf evolving in an orbit where the SFR can be activated by strong tidal interactions. As we can see from Fig.…”

Section: The Evolution With the Star Formation Processesmentioning

confidence: 96%

“…Pelupessy et al 2004;Slyz et al 2005;de Avillez & Breitschwerdt 2005). Given the small dynamical mass inferred for dwarf galaxies, it is surprising that the ISM can remain bound long enough to permit star formation episodes that last for a few Gyr (as found by, e.g., Babusiaux et al 2005;Carney & Seitzer 1986;Dolphin 2002;Mateo 1998;Grebel et al 2003) giving a typical baryonic matter 1 binding energy of ∼10 53 erg with a total expected number of SN events of 10 3 ÷ 10 4 .…”

Section: Introductionmentioning

confidence: 98%

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Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

Pasetto

Grebel²,

Berczik

et al. 2010

A&A

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The chemodynamical evolution of spherical multi-component self-gravitating models for isolated dwarf galaxies is studied. We compared their evolution with and without feedback effects from star formation processes. We found that initially cuspy dark matter profiles flatten with time without any special tuning conditions as a result of star formation. Thus the seemingly flattened profiles found in many dwarfs do not contradict the cuspy profiles predicted by cosmological models. We also calculated the chemical evolution of stars and gas, to permit comparisons with observational data.

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Section: The Evolution With the Star Formation Processesmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 98%

Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

Pasetto

Grebel²,

Berczik

et al. 2010

A&A

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show abstract

“…Differently from high-mass (M * > 10 9 M ) galaxies, which show a continuous rate of star formation (SF), the most common scenario for dwarf galaxies is the cyclic bursty mode, as pointed out by theoretical models (e.g., Hopkins et al 2014;Sparre et al 2017) and observations (Guo et al 2016b). Intense SF episodes produce stellar feedback through strong winds and supernova, which heat and expel the surrounding gas in outflows, eventually resulting in a temporary quenching of SF on timescales of tens of Myr (e.g., Olmo-Garcia et al 2017;Pelupessy et al 2004). Then, the metal-enriched gas may be accreted back to the galaxy triggering new SF episodes.…”

Section: Introductionmentioning

confidence: 99%

Characterization of star-forming dwarf galaxies at 0.1 ≲z ≲ 0.9 in VUDS: probing the low-mass end of the mass-metallicity relation

Calabró

Amorín

Fontana

et al. 2017

A&A

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Context. The study of statistically significant samples of star-forming dwarf galaxies (SFDGs) at different cosmic epochs is essential for the detailed understanding of galaxy assembly and chemical evolution. However, the main properties of this large population of galaxies at intermediate redshift are still poorly known. Aims. We present the discovery and spectrophotometric characterization of a large sample of 164 faint (i AB ∼ 23-25 mag) SFDGs at redshift 0.13 ≤ z ≤ 0.88 selected by the presence of bright optical emission lines in the VIMOS Ultra Deep Survey (VUDS). We investigate their integrated physical properties and ionization conditions, which are used to discuss the low-mass end of the mass-metallicity relation (MZR) and other key scaling relations. Methods. We use optical VUDS spectra in the COSMOS, VVDS-02h, and ECDF-S fields, as well as deep multi-wavelength photometry that includes HST-ACS F814W imaging, to derive stellar masses, extinction-corrected star-formation rates (SFR), and gas-phase metallicities of SFDGs. For the latter, we use the direct method and a T e -consistent approach based on the comparison of a set of observed emission lines ratios with the predictions of detailed photoionization models. Results. The VUDS SFDGs are compact (median r e ∼ 1.2 kpc), low-mass (M * ∼ 10 7 -10 9 M ) galaxies with a wide range of starformation rates (SFR(Hα) ∼ 10 −3 -10 1 M /yr) and morphologies. Overall, they show a broad range of subsolar metallicities (12 + log(O/H) = 7.26-8.7; 0.04 < ∼ Z/Z < ∼ 1). Nearly half of the sample are extreme emission-line galaxies (EELGs) characterized by high equivalent widths and emission line ratios indicative of higher excitation and ionization conditions. The MZR of SFDGs shows a flatter slope compared to previous studies of galaxies in the same mass range and redshift. We find the scatter of the MZR is partly explained in the low mass range by varying specific SFRs and gas fractions amongst the galaxies in our sample. In agreement with recent studies, we find the subclass of EELGs to be systematically offset to lower metallicity compared to SFDGs at a given stellar mass and SFR, suggesting a younger starburst phase. Compared with simple chemical evolution models we find that most SFDGs do not follow the predictions of a "closed-box" model, but those from a gas-regulating model in which gas flows are considered. While strong stellar feedback may produce large-scale outflows favoring the cessation of vigorous star formation and promoting the removal of metals, younger and more metal-poor dwarfs may have recently accreted large amounts of fresh, very metal-poor gas, that is used to fuel current star formation.

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“…ΛCDM simulations of ∼(1−2) × 10 10 M dark halos show the formation of dwarf galaxies with stellar masses between 5 × 10 7 M and 2 × 10 8 M (Pelupessy et al 2004;Stinson et al 2007;Governato et al 2010;Sawala et al 2011). Guo et al (2010) compared the abundance of dark haloes in the Millennium and Millennium-II Simulations to the observed abundances of galaxies as a function of the stellar mass obtained from SDSS DR-7 by Li & White (2009).…”

Section: Numerical Results and Discussionmentioning

confidence: 98%

Mass limits for dark clusters of degenerate fermions

Membrado

Pacheco

2013

A&A

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We calculate the range of possible masses for dark spheres of bound fully degenerate fermions as a function of the fermion mass. The cosmological constant is included in our calculations. We deduce that the minimum fermion mass that is able to give rise to degenerate fermion clusters is ∼0.02 g −1/4 eV, where g is the spin degeneracy parameter. We show that degenerate fermions of mc 2 ≈ (15−30) g −1/4 eV can build bound degenerate dark haloes that could reproduce the values of the rotation velocities of galaxies. The masses and radii derived for these degenerate dark haloes of typical galaxies, without considering any cosmological information, agree with the Jeans masses and radii of a cosmological background of ∼(20−30) g −1/4 eV degenerate fermions at redshift z ≈ 50. However, degenerate fermion objects of 10 15 M composed of these particles are too small to constitute the dark halo of galaxy clusters. We also derive degeneracy conditions for hot and cold dark matter fermions.

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Periodic bursts of star formation in irregular galaxies

Cited by 81 publications

References 69 publications

Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

Isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metalicity gradients

Characterization of star-forming dwarf galaxies at 0.1 ≲z ≲ 0.9 in VUDS: probing the low-mass end of the mass-metallicity relation

Mass limits for dark clusters of degenerate fermions

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