NEBULAR ATTENUATION IN Hα-SELECTED STAR-FORMING GALAXIES AT<i>z</i>= 0.8 FROM THE NewHα SURVEY

Momcheva, Ivelina; Lee, Janice; Ly, Chun; Salim, Samir; Dale, Daniel A.; Ouchi, Masami; Finn, Rose; Ono, Yoshiyasu

doi:10.1088/0004-6256/145/2/47

Cited by 65 publications

(63 citation statements)

References 113 publications

(197 reference statements)

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“…which is the average of our sample and is consistent with other emission-line galaxy samples (e.g., Ly et al 2012a;Domínguez et al 2013;Momcheva et al 2013). For Balmer decrements that imply negative reddening (six cases), we adopt -= E B V ( ) 0with measurement uncertainties based on Balmer decrement uncertainties.…”

Section: Dust Attenuation Correction From Balmer Decrementssupporting

confidence: 91%

Metal-Poor, Strongly Star-Forming Galaxies in the Deep2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

Rigby

Cooper

et al. 2015

ApJ

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We report on the discovery of 28 » z 0.8 metal-poor galaxies in DEEP2. These galaxies were selected for their detection of the weak [O III] λ4363 emission line, which provides a "direct" measure of the gas-phase metallicity. A primary goal for identifying these rare galaxies is to examine whether the fundamental metallicity relation (FMR) between stellar mass, gas metallicity, and star formation rate (SFR) holds for low stellar mass and high SFR galaxies. The FMR suggests that higher SFR galaxies have lower metallicity (at fixed stellar mass). To test this trend, we combine spectroscopic measurements of metallicity and dust-corrected SFR with stellar mass estimates from modeling the optical photometry. We find that these galaxies are 1.05 ± 0.61 dex above thez 1 stellar mass-SFR relation and 0.23 ± 0.23 dex below the local mass-metallicity relation. Relative to the FMR, the latter offset is reduced to 0.01 dex, but significant dispersion remains (0.29 dex with 0.16 dex due to measurement uncertainties). This dispersion suggests that gas accretion, star formation, and chemical enrichment have not reached equilibrium in these galaxies. This is evident by their short stellar mass doubling timescale of » -+ 100 75 310Myr, which suggests stochastic star formation. Combining our sample with otherz 1 metal-poor galaxies, we find a weak positive SFR-metallicity dependence (at fixed stellar mass) that is significant at 94.4% confidence. We interpret this positive correlation as recent star formation that has enriched the gas but has not had time to drive the metal-enriched gas out with feedback mechanisms.

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Section: Dust Attenuation Correction From Balmer Decrementssupporting

confidence: 91%

Metal-Poor, Strongly Star-Forming Galaxies in the Deep2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

Rigby

Cooper

et al. 2015

ApJ

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“…log 10 (Hα/Hβ) obs (Hα/Hβ) int (1) (see, e.g., Momcheva et al 2013, for a derivation of this equation). Given that in reality the reddening law is particular for any direction in the sky, the functional form of the attenuation curve is a matter of choice.…”

Section: Resultsmentioning

confidence: 99%

VLT/MUSE discovers a jet from the evolved B[e] star MWC 137

Mehner

Wit

Groh

et al. 2015

A&A

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Aims. Not all stars exhibiting the optical spectral characteristics of B [e] stars are in the same evolutionary stage. The Galactic B[e] star MWC 137 is a prime example of an object with uncertain classification, where previous work has suggested either a pre-or a postmain sequence classification. Our goal is to settle this debate and provide a reliable evolutionary classification. Methods. Integral field spectrograph observations with the Very Large Telescope Multi Unit Spectroscopic Explorer (VLT MUSE) of the cluster SH 2-266 are used to analyze the nature of MWC 137. Results. A collimated outflow is discovered that is geometrically centered on MWC 137. The central position of MWC 137 in the cluster SH 2-266 within the larger nebula suggests strongly that it is a member of this cluster and that it is the origin of both the nebula and the newly discovered jet. Comparison of the color-magnitude diagram of the brightest cluster stars with stellar evolutionary models results in a distance of about 5.2 ± 1.4 kpc. We estimate that the cluster is at least 3 Myr old. The jet emanates from MWC 137 at a position angle of 18-20• . The jet extends over 66 (1.7 pc) projected on the plane of the sky, shows several knots, and has electron densities of about 10 3 cm −1 and projected velocities of up to ±450 km s −1 . From the Balmer emission line decrement of the diffuse intracluster nebulosity, we determine E(B-V) = 1.4 mag for the inner 1 cluster region. The spectral energy distribution of the brightest cluster stars yields a slightly lower extinction of E(B-V) ∼ 1.2 mag for the inner region and E(B-V) ∼ 0.4-0.8 mag for the outer region. The extinction toward MWC 137 is estimated to be E(B-V) ∼ 1.8 mag (A V ∼ 5.6 mag). Conclusions. Our analysis of the optical and near-infrared color-magnitude and color-color diagrams suggests a post-main sequence stage for MWC 137. The existence of a jet in this object implies the presence of an accretion disk. Several possibilities for MWC 137's nature and the origin of its jet are discussed: e.g., the presence of a companion and a merger event.

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“…The nebular color excess E(B − V) of both regions A and B is reported in Table 1. The equation we use to calculate the color excess is obtained following the approach of Momcheva et al (2013) and using the extinction curve from Cardelli et al (1989). The theoretical Balmer decrement is fixed at Hα/Hβ = 2.86, corresponding to a temperature T = 10 4 K and an electron density n e = 10 2 cm −3 for Case B recombination (Osterbrock & Ferland 2006).…”

Section: Dust and Continuum Sourcesmentioning

confidence: 99%

Embedded star formation in the extended narrow line region of Centaurus A: Extreme mixing observed by MUSE

Santoro

Oonk

Morganti

et al. 2016

A&A

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We present a detailed study of the complex ionization structure in a small (∼250 pc) extended narrow line region (ENLR) cloud near Centaurus A using the Multi Unit Spectroscopic Explorer. This cloud is located in the so-called outer filament of ionized gas (about 15 kpc from the nucleus) where jet-induced star formation has been suggested to occur by different studies. We find that, despite the small size, a mixture of ionization mechanisms is operating, resulting in considerable complexity in the spatial ionization structure.The area includes two H ii regions where star formation is occurring and another location where star formation must have ceased very recently. Interestingly, the extreme Balmer decrement of one of the star forming regions (Hα/Hβ obs ∼ 6) indicates that it is still heavily embedded in its natal cocoon of gas and dust. At all three locations a continuum counterpart is found with spectra matching those of O/B stars local to Centaurus A. The H ii regions are embedded in a larger gas complex which is photoionized by the radiation of the central active galactic nucleus (AGN), but the O/B stars affect the spatial ionization pattern in the ENLR cloud very locally. In particular, in the surroundings of the youngest star forming region, we can isolate a tight mixing sequence in the diagnostic diagram going from gas with ionization due to a pure stellar continuum to gas only photoionized by the AGN. These results emphasize the complexity and the mixture of processes occurring in star forming regions under the influence of an AGN radiation. This is relevant for our understanding of AGN-induced star formation suggested to occur in a number of objects, including this region of Centaurus A. They also illustrate that these young stars influence the gas over only a limited region.

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NEBULAR ATTENUATION IN Hα-SELECTED STAR-FORMING GALAXIES ATz= 0.8 FROM THE NewHα SURVEY

Cited by 65 publications

References 113 publications

Metal-Poor, Strongly Star-Forming Galaxies in the Deep2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

Metal-Poor, Strongly Star-Forming Galaxies in the Deep2 Survey: The Relationship Between Stellar Mass, Temperature-Based Metallicity, and Star Formation Rate

VLT/MUSE discovers a jet from the evolved B[e] star MWC 137

Embedded star formation in the extended narrow line region of Centaurus A: Extreme mixing observed by MUSE

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