PHYSICAL PROPERTIES OF EMISSION-LINE GALAXIES AT<i>z</i>∼ 2 FROM NEAR-INFRARED SPECTROSCOPY WITH MAGELLAN FIRE

Masters, D. C.; McCarthy, Patrick J.; Siana, Brian; Malkan, Matthew A.; Mobasher, Bahram; Atek, Hakim; Henry, Alaina; Martin, Crystal L.; Rafelski, Marc; Hathi, N. P.; Scarlata, Claudia; Ross, Nathaniel; Bunker, Andrew J.; Blanc, Guillermo A.; Bedregal, A. G.; Domínguez, A.; Colbert, James; Teplitz, Harry I.; Dressler, Alan

doi:10.1088/0004-637x/785/2/153

Cited by 209 publications

(321 citation statements)

References 92 publications

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“…As figure 19 demonstrates, the two components of the neighbouring source are broadly consistent with a star-formation driven spectrum, although both lie above the local mean in [O III]/Hβ (a trait also often seen in high redshift star forming galaxies, e.g. Masters et al 2014;. While component A has measured line ratios consistent with a 'composite' spectrum, large errors on the measured values permit a purely star forming spectrum.…”

Section: The Host and Environment Of Grb 080517mentioning

confidence: 65%

GRB 080517: a local, low-luminosity gamma-ray burst in a dusty galaxy at z = 0.09

Stanway¹,

Levan²,

Tanvir³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We present an analysis of the photometry and spectroscopy of the host galaxy of Swift-detected GRB 080517. From our optical spectroscopy, we identify a redshift of z = 0.089 ± 0.003, based on strong emission lines, making this a rare example of a very local, low luminosity, long gamma ray burst. The galaxy is detected in the radio with a flux density of S 4.5 GHz =0.22±0.04 mJy -one of relatively few known GRB hosts with a securely measured radio flux. Both optical emission lines and a strong detection at 22µm suggest that the host galaxy is forming stars rapidly, with an inferred star formation rate ∼ 16 M ⊙ yr −1 and a high dust obscuration (E(B − V ) > 1, based on sight-lines to the nebular emission regions). The presence of a companion galaxy within a projected distance of 25 kpc, and almost identical in redshift, suggests that star formation may have been triggered by galaxy-galaxy interaction. However, fitting of the remarkably flat spectral energy distribution from the ultraviolet through to the infrared suggests that an older, 500 Myr post-starburst stellar population is present along with the ongoing star formation. We conclude that the host galaxy of GRB 080517 is a valuable addition to the still very small sample of well-studied local gamma-ray burst hosts.

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Section: The Host and Environment Of Grb 080517mentioning

confidence: 65%

GRB 080517: a local, low-luminosity gamma-ray burst in a dusty galaxy at z = 0.09

Stanway¹,

Levan²,

Tanvir³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…Local SFGs make a tight relation in the BPT diagram, which is caused by the anticorrelation between the oxygen abundance, 12+log(O/H), and the ionization parameter, qion (Dopita & Evans 1986;Dopita et al 2000Dopita et al , 2006a. Recent studies have revealed that z ∼ 2 galaxies have [N II] λ6584/Hα (N2) values higher than those of the local SFGs for a given [O III] λ5007/Hβ (O3) on average (Shapley et al 2005;Erb et al 2006;Brinchmann et al 2008;Liu et al 2008;Kewley et al 2013b;Steidel et al 2014;Masters et al 2014;Yabe et al 2014;Hayashi et al 2015;Shapley et al 2015;Sanders et al 2016;Kashino et al 2017). The z = 2 galaxies observed in the Keck Baryonic Structure Survey (KBSS; Steidel et al 2014) show the average of ∼ 0.4 dex excesses in [N II] λ6584/Hα.…”

Section: Introductionmentioning

confidence: 99%

“…For the explanation of the N/O redshift evolution, Queyrel et al (2009), Masters et al (2014), and Yabe et al (2015) have estimated N/O ratios at z ∼ 2, and have claimed the increase of N/O at fixed O/H. The excessive N/O ratios at fixed O/H may be caused by the decrease of O/H due to the pristine gas inflow into galaxies with rich nitrogen gas produced by the secondary nucleosynthesis, while Wolf-Rayet (WR) stars can produce the nitrogen in a time scale shorter than the oxygen production time scale in supernovae (Andrews & Martini 2013).…”

Section: Introductionmentioning

confidence: 99%

“…This N2S2 index is calibrated by and Amorín et al (2010). Masters et al (2014) derive the N/O ratio, assuming that the electron temperature (Te) is 10,000 K. However, with local SDSS galaxies, the strong line method gives N/O values systematically higher than the reliable direct temperature (Te) method (see Section 5 for more details). Moreover, there remain possible systematics in applying this z ∼ 0 empirical N2S2 relation to z ∼ 2 SFGs whose ISM properties should be different from z ∼ 0 galaxies.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of N/O abundance ratios and ionization parameters from z ∼ 0 to 2 investigated by the direct temperature method

Kojima

Ouchi

Nakajima

et al. 2017

Publications of the Astronomical Society of Japan

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We present N/O abundance ratios, ionization parameters q ion , and oxygen abundance O/H for a total of 41 galaxies (11 individual galaxies and a 30-galaxy stack) including Lyα emitters and Lyman break galaxies at z ∼ 2, and investigate galaxy evolution from z ∼ 0 to 2 in conjunction with 208,529 local SDSS galaxies and 9 green pea galaxies (GPs). In contrast with most of the recent studies, we obtain the N/O ratio, q ion , and O/H measurements by direct T e methods with [O III] λ4363 and O III] λ1665 lines. Based on these reliable measurements, we find that there exist z ∼ 2 galaxies with an excess of N/O falling beyond the local average of N/O-O/H relation, while the majority of the z ∼ 2 galaxies have the N/O ratios nearly comparable with z ∼ 0 galaxies in the N/O-stellar mass relation. Our galaxies place the upper limit of N/O ratio log(N/O) ≤ −1.26 on average, suggesting that the N/O ratio evolves, if at all, by < 0.17 dex. Exploiting our reliable measurements free from the N/O-q ion -O/H degeneracies, we identify, for the first time, that z ∼ 2 galaxies with offsets in the BPT diagram indicate either 1) only an N/O excess, 2) only a q ion excess, or 3) both N/O and q ion excesses. We argue that the BPT offsets at z ∼ 2 are not made by one of 1)-3) galaxy populations alone, but the composite of 1)-3) populations. We confirm that these 1)-3) populations also exist at z ∼ 0, such as GPs and SDSS low-mass and high-SFR galaxies (LMHSs).

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“…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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PHYSICAL PROPERTIES OF EMISSION-LINE GALAXIES ATz∼ 2 FROM NEAR-INFRARED SPECTROSCOPY WITH MAGELLAN FIRE

Cited by 209 publications

References 92 publications

GRB 080517: a local, low-luminosity gamma-ray burst in a dusty galaxy at z = 0.09

GRB 080517: a local, low-luminosity gamma-ray burst in a dusty galaxy at z = 0.09

Evolution of N/O abundance ratios and ionization parameters from z ∼ 0 to 2 investigated by the direct temperature method

Extreme emission-line galaxies out toz~ 1 in zCOSMOS

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