Alfalfa Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. Iii. An Extremely Metal Deficient Galaxy

Skillman, Evan D.; Salzer, John J.; Berg, Danielle A.; Pogge, Richard W.; Haurberg, Nathalie C.; Cannon, John; Aver, Erik; Olive, Keith A.; Giovanelli, Riccardo; Haynes, Martha P.; Adams, Elizabeth A. K.; McQuinn, Kristen B. W.; Rhode, Katherine L.

doi:10.1088/0004-6256/146/1/3

Cited by 127 publications

(197 citation statements)

References 125 publications

(196 reference statements)

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“…The most-metal deficient BCDs I Zw 18, SBS 0335-052W, and SBS 0335-052E are shown with filled blue triangles and are labelled. One of the most metal-poor dwarf galaxies, Leo P from Skillman et al (2013) is plotted with a large open black square. For comparison, the "standard" L-Z relation for emission-line galaxies (SDSS and star-forming galaxies from Izotov et al 2006a; are shown in black dots with the linear regression to these data (solid line).…”

Section: Resultsmentioning

confidence: 99%

New candidates for extremely metal-poor emission-line galaxies in the SDSS/BOSS DR10

Гусева

Izotov

Fricke

et al. 2015

A&A

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We present a spectroscopic study of eight extremely low-metallicity candidate emission-line galaxies with oxygen abundances possibly below 12 + log O/H = 7.35. These galaxies were selected from data release 10 of the Sloan Digital Sky Survey/Baryon Oscillation Spectroscopic Survey (SDSS/BOSS DR10). We will call these extremely metal-deficient (XMD) galaxies. The electron temperaturesensitive emission line [O iii] λ4363 is detected in three galaxies and marginally detected in two galaxies, allowing for abundance determination by a "direct" method. Because of large uncertainties in the [O iii]λ4363 Å line fluxes, we also calculated oxygen abundance in these galaxies together with the remaining three galaxies using a strong-line semi-empirical method. This method gives oxygen abundances higher than 7.35 for three galaxies with detected [O iii]λ4363 Å line and lower than 7.35 for the remaining five objects of the sample. The newly-discovered galaxies represent excellent targets for follow-up spectroscopic observations with the largest telescopes to improve the oxygen abundance determination and to increase the number of these very rare low-metallicity objects. The extreme location of the most massive and luminous XMD galaxies and XMD candidates in the stellar mass-metallicity diagram implies that these galaxies may be genuine young objects. With stellar masses of up to ∼10 7 -10 8 M , the galaxies are not chemically enriched and strongly deviate to lower metallicity as compared to the relation obtained for a large sample of low-redshift, star-forming galaxies.

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Section: Resultsmentioning

confidence: 99%

New candidates for extremely metal-poor emission-line galaxies in the SDSS/BOSS DR10

Гусева

Izotov

Fricke

et al. 2015

A&A

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“…The lines represent fits described in the text and Table 6. Tremonti et al 2004;Salzer et al 2005b;Lee et al 2006;van Zee & Haynes 2006;Berg et al 2012;Haurberg et al 2013;Skillman et al 2013). The underlying cause of this relationship is not fully understood, but it is believed to trace a more fundamental M-Z relationship, where luminosity is representative of stellar mass.…”

Section: Discussionmentioning

confidence: 99%

“…This method has already led to the discovery of several XMD galaxies (Skillman et al 1989a(Skillman et al , 1989bvan Zee 2000;Pustilnik et al 2005Pustilnik et al , 2011Berg et al 2012;Skillman et al 2013). Despite the fact that there should be large numbers of low-luminosity galaxies according to the galaxy luminosity function, searching for these systems is very difficult as they tend to be very low surface brightness and difficult to detect optically.…”

Section: Introductionmentioning

confidence: 99%

Oxygen Abundance Measurements of Shield Galaxies

Haurberg

Salzer

Cannon

et al. 2015

ApJ

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We have derived oxygen abundances for eight galaxies from the Survey for H i in Extremely Low-mass Dwarfs (SHIELD). The SHIELD survey is an ongoing study of very-low-mass galaxies, with M H i between 10 6.5 and 10 7.5 M , that were detected by the Arecibo Legacy Fast ALFA survey. Hα images from the WIYN 3.5 m telescope show that these eight SHIELD galaxies each possess one or two active star-forming regions, which were targeted with long-slit spectral observations using the Mayall 4 m telescope at Kitt Peak National Observatory. We obtained a direct measurement of the electron temperature by detection of the weak [O iii] λ4363 line in two of the H ii regions. Oxygen abundances for the other H ii regions were estimated using a strong-line method. When the SHIELD galaxies are plotted on a B-band L-Z diagram, they appear to suggest a slightly shallower slope to the relationship than normally seen. However, that offset is systematically reduced when the near-infrared luminosity is used instead. This indicates a different mass-to-light ratio for the galaxies in this sample and we suggest that this may be indicative of differing star formation histories in the lowest luminosity and surface brightness dwarf irregulars.

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“…As discussed in Berg et al (2012) and Skillman et al (2013), the number of "extremely metal deficient" galaxies ("XMDs;" systems with 12 + log(O/H) 7.65 or Z 9% Z using the solar oxygen abundance of 12 + log(O/H) = 8.69 ± 0.05 from Asplund et al 2009) remains small. Here we compare the neutral gas properties of Leo P with those of the other systems studied in the Berg et al (2012) sample.…”

Section: Leo P Compared To Other Extremely Metal Deficient Galaxiesmentioning

confidence: 99%

“…To date, none of these systems has been the subject of a detailed mass distribution analysis. McQuinn et al (2013) 12+log(O/H) 7.17 ± 0.04 Skillman et al (2013) M V (mag) −9.37 +0.15 −0.50…”

Section: Introductionmentioning

confidence: 99%

Alfalfa Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. V. Neutral Gas Dynamics and Kinematics

Bernstein-Cooper

Cannon

Elson

et al. 2014

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We present new H i spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H i images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H i morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V c =15 ± 5 km s −1 . Within the H i radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is 15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s −1 and 10.1 ± 1.2 km s −1 , corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H i component is unresolved at a physical resolution of 200 pc. The highest H i surface densities are observed in close physical proximity to the single H ii region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

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Alfalfa Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. Iii. An Extremely Metal Deficient Galaxy

Cited by 127 publications

References 125 publications

New candidates for extremely metal-poor emission-line galaxies in the SDSS/BOSS DR10

New candidates for extremely metal-poor emission-line galaxies in the SDSS/BOSS DR10

Oxygen Abundance Measurements of Shield Galaxies

Alfalfa Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. V. Neutral Gas Dynamics and Kinematics

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