THE NATURE OF EXTREME EMISSION LINE GALAXIES AT<i>z</i>= 1-2: KINEMATICS AND METALLICITIES FROM NEAR-INFRARED SPECTROSCOPY

Maseda, Michael V.; Wel, Arjen van der; Rix, Hans─Walter; Cunha, Elisabete da; Pacifici, Camilla; Momcheva, Ivelina; Brammer, Gabriel; Meidt, Sharon E.; Franx, Marijn; Dokkum, Pieter van; Fumagalli, M.; Bell, Eric F.; Ferguson, Henry C.; Förster-Schreiber, N. M.; Koekemoer, Anton M.; Koo, David C.; Lundgren, Britt; Marchesini, Danilo; Nelson, Erica J.; Patel, Shannon G.; Skelton, Rosalind E.; Straughn, Amber N.; Trump, Jonathan R.; Whitaker, Katherine E.

doi:10.1088/0004-637x/791/1/17

Cited by 126 publications

(184 citation statements)

References 92 publications

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“…where Re is the effective radius (assumed here to be the virial radius), σv is the velocity dispersion (e.g., Rhoads et al 2014;Maseda et al 2014). In general, it is well known that the coefficient C is weakly dependent on the density profile when the velocity dispersion is measuread over large apertures (in principle, over all the object), and independent of orbital anisotropy (e.g., see Ciotti 1991Ciotti , 1994.…”

Section: Dynamical Mass Of Id11mentioning

confidence: 99%

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Paving the way for the JWST: witnessing globular cluster formation at z > 3

Vanzella¹,

Calura²,

Meneghetti³

et al. 2017

Monthly Notices of the Royal Astronomical Society

175

215

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We report on five compact, extremely young (< 10 Myr) and blue (β U V < −2.5, F λ = λ β ) objects observed with VLT/MUSE at redshift 3.1169, 3.235, in addition to three objects at z = 6.145. These sources are magnified by the Hubble Frontier Field galaxy clusters MACS J0416 and AS1063. Their de-lensed half light radii (R e ) are between 16 to 140 pc, the stellar masses are 1 − 20 × 10 6 M , the magnitudes are m U V = 28.8 − 31.4 (−17 < M U V < −15) and specific star formation rates can be as large as ∼ 800 Gyr −1 . Multiple images of these systems are widely separated in the sky (up to 50 ) and individually magnified by factors 3-40. Remarkably, the inferred physical properties of two objects are similar to those expected in some globular cluster formation scenarios, representing the best candidate proto-globular clusters (proto-GC) discovered so far. Rest-frame optical high dispersion spectroscopy of one of them at z = 3.1169 yields a velocity dispersion σ v 20 km s −1 , implying a dynamical mass dominated by the stellar mass. Another object at z = 6.145, with de-lensed31.4), shows a stellar mass and a star-formation rate surface density consistent with the values expected from popular GC formation scenarios. An additional star-forming region at z = 6.145, with de-lensed m U V 32, a stellar mass of 0.5 ×10 6 M and a star formation rate of 0.06 M yr −1 is also identified. These objects currently represent the faintest spectroscopically confirmed star-forming systems at z > 3, elusive even in the deepest blank fields. We discuss how proto-GCs might contribute to the ionization budget of the universe and augment Lyα visibility during reionization. This work underlines the crucial role of JWST in characterizing the restframe optical and near-infrared properties of such low-luminosity high−z objects.

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Section: Dynamical Mass Of Id11mentioning

confidence: 99%

“…Assuming the above relation applies to ID11 and adopting C = 4 as for the Green Pea galaxies (Maseda et al 2014;Erb et al 2014), the comparison with the stellar mass gives M dyn /M 1. Given the uncertainties in the estimation of Re and the stellar mass, the ratio is fully consistent with a value of ∼ 1.…”

Section: Dynamical Mass Of Id11mentioning

confidence: 99%

Paving the way for the JWST: witnessing globular cluster formation at z > 3

Vanzella¹,

Calura²,

Meneghetti³

et al. 2017

Monthly Notices of the Royal Astronomical Society

175

215

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“…An alternative selection criterion based on other strong emission lines would have the drawback that we could only select a smaller number of galaxies over a smaller redshift range, e.g., Hα emitters can be selected at z < ∼ 0.5. Finally, the choice of a sample of strong [O iii] emitters has also been motivated by the aim of collecting a representative and statistically significant sample of star-forming galaxies that would be easily detectable at higher redshifts (z ∼ 2−3) in deep wide-field NIR surveys (e.g., van der Wel et al 2011;Atek et al 2011;Xia et al 2012;Guaita et al 2013;Maseda et al 2013Maseda et al , 2014. Since they would be affected by similar biases, our sample is intended to offer a valuable benchmark for future direct comparison with other probes of strong emission-line galaxies at higher redshifts.…”

Section: The Eelg Sample Selectionmentioning

confidence: 99%

“…In this context, recent deep multiwavelength surveys have offered a new avenue for studying chemical enrichment and starburst activity and its associated feedback processes in strongly star-forming EELGs out to z ∼ 1 and beyond (see, e.g., Hoyos et al 2005;van der Wel et al 2011;Atek et al 2011;Trump et al 2011;Xia et al 2012;Henry et al 2013;Ly et al 2014;Amorín et al 2014a,b;Masters et al 2014;Maseda et al 2014). This is the case of the COSMOS survey ) and one of its spectroscopic follow-ups, the zCOSMOS 20k bright survey (Lilly et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Extreme emission-line galaxies out toz~ 1 in zCOSMOS

Amorín

Pérez-Montero

Contini

et al. 2015

A&A

113

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Context. The study of large and representative samples of low-metallicity star-forming galaxies at different cosmic epochs is of great interest to the detailed understanding of the assembly history and evolution of low-mass galaxies. Aims. We present a thorough characterization of a large sample of 183 extreme emission-line galaxies (EELGs) at redshift 0.11 ≤ z ≤ 0.93 selected from the 20k zCOSMOS bright survey because of their unusually large emission line equivalent widths. Methods. We use multiwavelength COSMOS photometry, HST-ACS I-band imaging, and optical zCOSMOS spectroscopy to derive the main global properties of star-forming EELGs, such as sizes, stellar masses, star formation rates (SFR), and reliable oxygen abundances using both "direct" and "strong-line" methods. Results. The EELGs are extremely compact (r 50 ∼ 1.3 kpc), low-mass (M * ∼ 10 7 −10 10 M ) galaxies forming stars at unusually high specific star formation rates (sSFR ≡ SFR/M up to 10 −7 yr −1 ) compared to main sequence star-forming galaxies of the same stellar mass and redshift. At rest-frame UV wavelengths, the EELGs are luminous and show high surface brightness and include strong Lyα emitters, as revealed by GALEX spectroscopy. We show that zCOSMOS EELGs are high-ionization, low-metallicity systems, with median 12+ log(O/H) = 8.16 ± 0.21 (0.2 Z ) including a handful of extremely metal-deficient (<0.1 Z ) EELGs. While ∼80% of the EELGs show non-axisymmetric morphologies, including clumpy and cometary or tadpole galaxies, we find that ∼29% of them show additional low-surface-brightness features, which strongly suggests recent or ongoing interactions. As star-forming dwarfs in the local Universe, EELGs are most often found in relative isolation. While only very few EELGs belong to compact groups, almost one third of them are found in spectroscopically confirmed loose pairs or triplets. Conclusions. The zCOSMOS EELGs are galaxies caught in a transient and probably early period of their evolution, where they are efficiently building up a significant fraction of their present-day stellar mass in an ongoing, galaxy-wide starburst. Therefore, the EELGs constitute an ideal benchmark for comparison studies between low-and high-redshift low-mass star-forming galaxies.

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“…This makes them easier to identify even beyond the local Universe in current spectroscopic surveys. Throughout this paper, we refer to this kind of faint galaxy with and have more extreme properties; for example, higher surface densities, lower starburst ages, and lower gas metallicities than the average population of star-forming dwarfs (Kniazev et al 2004;Cardamone et al 2009;Amorín et al 2010Amorín et al , 2012Amorín et al , 2014Amorín et al , 2015Atek et al 2011;van der Wel et al 2011;Maseda et al 2014). While the population of EELGs itself constitutes an ideal laboratory for studying star formation and chemical enrichment under extreme physical conditions, it also appears to contain environments that most closely resemble "typical" galaxies at very high redshifts (z > ∼ 3−4, e.g., Smit et al 2014;Stark et al 2017).…”

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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THE NATURE OF EXTREME EMISSION LINE GALAXIES ATz= 1-2: KINEMATICS AND METALLICITIES FROM NEAR-INFRARED SPECTROSCOPY

Cited by 126 publications

References 92 publications

Paving the way for the JWST: witnessing globular cluster formation at z > 3

Paving the way for the JWST: witnessing globular cluster formation at z > 3

Extreme emission-line galaxies out toz~ 1 in zCOSMOS

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

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