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Showing 1-14 of about 14 results.
The MOSDEF Survey: Environmental Dependence of the Gas-phase Metallicity of Galaxies at 1.4 ≤ z ≤ 2.6Chartab, NimaMobasher, BahramShapley, Alice E.Shivaei, IreneSanders, Ryan L.Coil, Alison L.Kriek, MariskaReddy, Naveen A.Siana, BrianFreeman, William R.Azadi, MojeganBarro, GuillermoFetherolf, TaraLeung, GenePrice, Sedona H.Zick, TomDOI: info:10.3847/1538-4357/abd71fv. 908120
Chartab, Nima, Mobasher, Bahram, Shapley, Alice E., Shivaei, Irene, Sanders, Ryan L., Coil, Alison L., Kriek, Mariska, Reddy, Naveen A., Siana, Brian, Freeman, William R., Azadi, Mojegan, Barro, Guillermo, Fetherolf, Tara, Leung, Gene, Price, Sedona H., and Zick, Tom. 2021. "The MOSDEF Survey: Environmental Dependence of the Gas-phase Metallicity of Galaxies at 1.4 ≤ z ≤ 2.6." The Astrophysical Journal 908:120. https://doi.org/10.3847/1538-4357/abd71f
ID: 159617
Type: article
Authors: Chartab, Nima; Mobasher, Bahram; Shapley, Alice E.; Shivaei, Irene; Sanders, Ryan L.; Coil, Alison L.; Kriek, Mariska; Reddy, Naveen A.; Siana, Brian; Freeman, William R.; Azadi, Mojegan; Barro, Guillermo; Fetherolf, Tara; Leung, Gene; Price, Sedona H.; Zick, Tom
Abstract: Using the near-IR spectroscopy of the MOSFIRE Deep Evolution Field survey, we investigate the role of the local environment in the gas-phase metallicity of galaxies. The local environment measurements are derived from accurate and uniformly calculated photometric redshifts with well-calibrated probability distributions. Based on rest-frame optical emission lines, [N II]λ6584 and Hα, we measure gas-phase oxygen abundances of 167 galaxies at 1.37 ≤ z ≤ 1.7 and 303 galaxies at 2.09 ≤ z ≤ 2.61, located in diverse environments. We find that at z ∼ 1.5, the average metallicity of galaxies in overdensities with M* ∼ 109.8 M, 1010.2 M⊙, and 1010.8 M is higher relative to their field counterparts by 0.094 ± 0.051, 0.068 ± 0.028, and 0.052 ± 0.043 dex, respectively. However, this metallicity enhancement does not exist at higher redshift, z ∼ 2.3, where, compared to the field galaxies, we find 0.056 ± 0.043, 0.056 ± 0.028, and 0.096 ± 0.034 dex lower metallicity for galaxies in overdense environments with M* ∼ 109.8 M, 1010.2 M and 1010.7 M, respectively. Our results suggest that, at 1.37 ≤ z ≤ 2.61, the variation of mass-metallicity relation with local environment is small (, respectively. Our results suggest that, at 1.37 ≤ z ≤ 2.61, the variation of mass-metallicity relation with local environment is small (* Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation.
The MOSDEF survey: a comprehensive analysis of the rest-optical emission-line properties of z ∼ 2.3 star-forming galaxiesRunco, Jordan N.Shapley, Alice E.Sanders, Ryan L.Topping, Michael W.Kriek, MariskaReddy, Naveen A.Coil, Alison L.Mobasher, BahramSiana, BrianFreeman, William R.Shivaei, IreneAzadi, MojeganPrice, Sedona H.Leung, Gene C. K.Fetherolf, Tarade Groot, LauraZick, TomFornasini, Francesca M.Barro, GuillermoDOI: info:10.1093/mnras/stab119v. 5022600–2614
Runco, Jordan N., Shapley, Alice E., Sanders, Ryan L., Topping, Michael W., Kriek, Mariska, Reddy, Naveen A., Coil, Alison L., Mobasher, Bahram, Siana, Brian, Freeman, William R., Shivaei, Irene, Azadi, Mojegan, Price, Sedona H., Leung, Gene C. K., Fetherolf, Tara, de Groot, Laura, Zick, Tom, Fornasini, Francesca M., and Barro, Guillermo. 2021. "The MOSDEF survey: a comprehensive analysis of the rest-optical emission-line properties of z ∼ 2.3 star-forming galaxies." Monthly Notices of the Royal Astronomical Society 502:2600– 2614. https://doi.org/10.1093/mnras/stab119
ID: 159267
Type: article
Authors: Runco, Jordan N.; Shapley, Alice E.; Sanders, Ryan L.; Topping, Michael W.; Kriek, Mariska; Reddy, Naveen A.; Coil, Alison L.; Mobasher, Bahram; Siana, Brian; Freeman, William R.; Shivaei, Irene; Azadi, Mojegan; Price, Sedona H.; Leung, Gene C. K.; Fetherolf, Tara; de Groot, Laura; Zick, Tom; Fornasini, Francesca M.; Barro, Guillermo
Abstract: We analyse the rest-optical emission-line spectra of z ∼ 2.3 star-forming galaxies in the complete MOSFIRE Deep Evolution Field (MOSDEF) survey. In investigating the origin of the well-known offset between the sequences of high-redshift and local galaxies in the [O III]λ5008/Hβ versus [N II]λ6585/Hα ('[N II] BPT') diagram, we define two populations of z ∼ 2.3 MOSDEF galaxies. These include the high population that is offset towards higher [O III]λ5008/Hβ and/or [N II]λ6585/Hα with respect to the local SDSS sequence and the low population that overlaps the SDSS sequence. These two groups are also segregated within the [O III]λ5008/Hβ versus [S II]λλ6718,6733/Hα and the [O III]λλ4960,5008/[O II ]λλ3727,3730 (O32) versus ([O III]λλ4960,5008+[O II]λλ3727,3730)/Hβ (R23) diagrams, which suggests qualitatively that star-forming regions in the more offset galaxies are characterized by harder ionizing spectra at fixed nebular oxygen abundance. We also investigate many galaxy properties of the split sample and find that the high sample is on average smaller in size and less massive, but has higher specific star formation rate (SFR) and SFR surface density values and is slightly younger compared to the low population. From Cloudy+BPASS photoionization models, we estimate that the high population has a lower stellar metallicity (i.e. harder ionizing spectrum) but slightly higher nebular metallicity and higher ionization parameter compared to the low population. While the high population is more α-enhanced (i.e. higher α/Fe) than the low population, both samples are significantly more α-enhanced compared to local star-forming galaxies with similar rest-optical line ratios. These differences must be accounted for in all high-redshift star-forming galaxies - not only those 'offset' from local excitation sequences.
The MOSDEF survey: an improved Voronoi binning technique on spatially resolved stellar populations at z ∼ 2Fetherolf, TaraReddy, Naveen A.Shapley, Alice E.Kriek, MariskaSiana, BrianCoil, Alison L.Mobasher, BahramFreeman, William R.Sanders, Ryan L.Price, Sedona H.Shivaei, IreneAzadi, Mojegande Groot, LauraLeung, Gene C. K.Zick, Tom O.DOI: info:10.1093/mnras/staa2775v. 4985009–5029
Fetherolf, Tara, Reddy, Naveen A., Shapley, Alice E., Kriek, Mariska, Siana, Brian, Coil, Alison L., Mobasher, Bahram, Freeman, William R., Sanders, Ryan L., Price, Sedona H., Shivaei, Irene, Azadi, Mojegan, de Groot, Laura, Leung, Gene C. K., and Zick, Tom O. 2020. "The MOSDEF survey: an improved Voronoi binning technique on spatially resolved stellar populations at z ∼ 2." Monthly Notices of the Royal Astronomical Society 498:5009– 5029. https://doi.org/10.1093/mnras/staa2775
ID: 157643
Type: article
Authors: Fetherolf, Tara; Reddy, Naveen A.; Shapley, Alice E.; Kriek, Mariska; Siana, Brian; Coil, Alison L.; Mobasher, Bahram; Freeman, William R.; Sanders, Ryan L.; Price, Sedona H.; Shivaei, Irene; Azadi, Mojegan; de Groot, Laura; Leung, Gene C. K.; Zick, Tom O.
Abstract: We use a sample of 350 star-forming galaxies at 1.25 160-band alone, we introduce a modified Voronoi binning method that additionally incorporates the S/N distribution of several resolved filters. The spectral energy distribution (SED)-derived resolved E(B - V)stars, stellar population ages, star-formation rates (SFRs), and stellar masses that are inferred from the Voronoi bins constructed from multiple filters are generally consistent with the properties inferred from the integrated photometry within the uncertainties, with the exception of the inferred E(B - V)stars from our z ∼ 1.5 sample due to their UV slopes being unconstrained by the resolved photometry. The results from our multifilter Voronoi binning technique are compared to those derived from a 'traditional' single-filter Voronoi binning approach. We find that single-filter binning produces inferred E(B - V)stars that are systematically redder by 0.02 mag, on average, but could differ by up to 0.20 mag and could be attributed to poorly constrained resolved photometry covering the UV slope. Overall, we advocate that our methodology produces more reliable SED-derived parameters due to the best-fitting resolved SEDs being better constrained at all resolved wavelengths - particularly those covering the UV slope.
The MOSDEF Survey: Neon as a Probe of ISM Physical Conditions at High RedshiftJeong, Moon-SeongShapley, Alice E.Sanders, Ryan L.Runco, Jordan N.Topping, Michael W.Reddy, Naveen A.Kriek, MariskaCoil, Alison L.Mobasher, BahramSiana, BrianShivaei, IreneFreeman, William R.Azadi, MojeganPrice, Sedona H.Leung, Gene C. K.Fetherolf, Tarade Groot, LauraZick, TomFornasini, Francesca M.Barro, GuillermoDOI: info:10.3847/2041-8213/abba7av. 902L16
Jeong, Moon-Seong, Shapley, Alice E., Sanders, Ryan L., Runco, Jordan N., Topping, Michael W., Reddy, Naveen A., Kriek, Mariska, Coil, Alison L., Mobasher, Bahram, Siana, Brian, Shivaei, Irene, Freeman, William R., Azadi, Mojegan, Price, Sedona H., Leung, Gene C. K., Fetherolf, Tara, de Groot, Laura, Zick, Tom, Fornasini, Francesca M., and Barro, Guillermo. 2020. "The MOSDEF Survey: Neon as a Probe of ISM Physical Conditions at High Redshift." The Astrophysical Journal 902:L16. https://doi.org/10.3847/2041-8213/abba7a
ID: 157586
Type: article
Authors: Jeong, Moon-Seong; Shapley, Alice E.; Sanders, Ryan L.; Runco, Jordan N.; Topping, Michael W.; Reddy, Naveen A.; Kriek, Mariska; Coil, Alison L.; Mobasher, Bahram; Siana, Brian; Shivaei, Irene; Freeman, William R.; Azadi, Mojegan; Price, Sedona H.; Leung, Gene C. K.; Fetherolf, Tara; de Groot, Laura; Zick, Tom; Fornasini, Francesca M.; Barro, Guillermo
Abstract: We present results on the properties of neon emission in z ∼ 2 star-forming galaxies drawn from the MOSFIRE Deep Evolution Field (MOSDEF) survey. Doubly ionized neon ([Ne III]λ3869) is detected at ≥3σ in 61 galaxies, representing ∼25% of the MOSDEF sample with Hα, Hβ, and [O III]λ5007 detections at similar redshifts. We consider the neon emission-line properties of both individual galaxies with [Ne III]λ3869 detections and composite z ∼ 2 spectra binned by stellar mass. With no requirement of [Ne III]λ3869 detection, the latter provide a more representative picture of neon emission-line properties in the MOSDEF sample. The [Ne III]λ3869/[O II]λ3727 ratio (Ne3O2) is anticorrelated with stellar mass in z ∼ 2 galaxies, as expected based on the mass-metallicity relation. It is also positively correlated with the [O III]λ5007/[O II]λ3727 ratio (O32), but z ∼ 2 line ratios are offset toward higher Ne3O2 at fixed O32, compared with both local star-forming galaxies and individual H II regions. Despite the offset toward higher Ne3O2 at fixed O32 at z ∼ 2, biases in inferred Ne3O2-based metallicity are small. Accordingly, Ne3O2 may serve as an important metallicity indicator deep into the reionization epoch. Analyzing additional rest-optical line ratios including [Ne III]λ3869/[O III]λ5007 (Ne3O3) and [O III]λ5007/Hβ (O3Hβ), we conclude that the nebular emission-line ratios of z ∼ 2 star-forming galaxies suggest a harder ionizing spectrum (lower stellar metallicity, i.e., Fe/H) at fixed gas-phase oxygen abundance, compared to systems at z ∼ 0. These new results based on neon lend support to the physical picture painted by oxygen, nitrogen, hydrogen, and sulfur emission of an ionized interstellar medium in high-redshift star-forming galaxies irradiated by chemically young, α-enhanced massive stars. * Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.
The MOSDEF Survey: Kinematic and Structural Evolution of Star-forming Galaxies at 1.4 ≤ z ≤ 3.8Price, Sedona H.Kriek, MariskaBarro, GuillermoShapley, Alice E.Reddy, Naveen A.Freeman, William R.Coil, Alison L.Shivaei, IreneAzadi, Mojegande Groot, LauraSiana, BrianMobasher, BahramSanders, Ryan L.Leung, Gene C. K.Fetherolf, TaraZick, Tom O.Übler, HannahFörster Schreiber, Natascha M.DOI: info:10.3847/1538-4357/ab7990v. 89491
Price, Sedona H., Kriek, Mariska, Barro, Guillermo, Shapley, Alice E., Reddy, Naveen A., Freeman, William R., Coil, Alison L., Shivaei, Irene, Azadi, Mojegan, de Groot, Laura, Siana, Brian, Mobasher, Bahram, Sanders, Ryan L., Leung, Gene C. K., Fetherolf, Tara, Zick, Tom O., Übler, Hannah, and Förster Schreiber, Natascha M. 2020. "The MOSDEF Survey: Kinematic and Structural Evolution of Star-forming Galaxies at 1.4 ≤ z ≤ 3.8." The Astrophysical Journal 894:91. https://doi.org/10.3847/1538-4357/ab7990
ID: 156967
Type: article
Authors: Price, Sedona H.; Kriek, Mariska; Barro, Guillermo; Shapley, Alice E.; Reddy, Naveen A.; Freeman, William R.; Coil, Alison L.; Shivaei, Irene; Azadi, Mojegan; de Groot, Laura; Siana, Brian; Mobasher, Bahram; Sanders, Ryan L.; Leung, Gene C. K.; Fetherolf, Tara; Zick, Tom O.; Übler, Hannah; Förster Schreiber, Natascha M.
Abstract: We present ionized gas kinematics for 681 galaxies at $z\sim 1.4\mbox{--}3.8$ from the MOSFIRE Deep Evolution Field survey, measured using models that account for random galaxy-slit misalignments together with structural parameters derived from CANDELS Hubble Space Telescope (HST) imaging. Kinematics and sizes are used to derive dynamical masses. Baryonic masses are estimated from stellar masses and inferred gas masses from dust-corrected star formation rates (SFRs) and the Kennicutt-Schmidt relation. We measure resolved rotation for 105 galaxies. For the remaining 576 galaxies we use models based on HST imaging structural parameters together with integrated velocity dispersions and baryonic masses to statistically constrain the median ratio of intrinsic ordered to disordered motion, $V/{\sigma }_{V,0}$ . We find that $V/{\sigma }_{V,0}$ increases with increasing stellar mass and decreasing specific SFR (sSFR). These trends may reflect marginal disk stability, where systems with higher gas fractions have thicker disks. For galaxies with detected rotation we assess trends between their kinematics and mass, sSFR, and baryon surface density ( ${{\rm{\Sigma }}}_{\mathrm{bar},e}$). Intrinsic dispersion correlates most with ${{\rm{\Sigma }}}_{\mathrm{bar},e}$ , and velocity correlates most with mass. By comparing dynamical and baryonic masses, we find that galaxies at $z\sim 1.4\mbox{--}3.8$ are baryon dominated within their effective radii ( ${R}_{E}$), with ${M}_{\mathrm{dyn}}$ / ${M}_{\mathrm{baryon}}$ increasing over time. The inferred baryon fractions within ${R}_{E}$ , ${f}_{\mathrm{bar}}$ , decrease over time, even at fixed mass, size, or surface density. At fixed redshift, ${f}_{\mathrm{bar}}$ does not appear to vary with stellar mass but increases with decreasing ${R}_{E}$ and increasing ${{\rm{\Sigma }}}_{\mathrm{bar},e}$ . For galaxies at $z\gtrsim 2$ , the median inferred baryon fractions generally exceed 100%. We discuss possible explanations and future avenues to resolve this tension.
The MOSDEF Survey: The First Direct Measurements of the Nebular Dust Attenuation Curve at High RedshiftReddy, Naveen A.Shapley, Alice E.Kriek, MariskaSteidel, Charles C.Shivaei, IreneSanders, Ryan L.Mobasher, BahramCoil, Alison L.Siana, BrianFreeman, William R.Azadi, MojeganFetherolf, TaraLeung, GenePrice, Sedona H.Zick, TomDOI: info:10.3847/1538-4357/abb674v. 902123
Reddy, Naveen A., Shapley, Alice E., Kriek, Mariska, Steidel, Charles C., Shivaei, Irene, Sanders, Ryan L., Mobasher, Bahram, Coil, Alison L., Siana, Brian, Freeman, William R., Azadi, Mojegan, Fetherolf, Tara, Leung, Gene, Price, Sedona H., and Zick, Tom. 2020. "The MOSDEF Survey: The First Direct Measurements of the Nebular Dust Attenuation Curve at High Redshift." The Astrophysical Journal 902:123. https://doi.org/10.3847/1538-4357/abb674
ID: 158818
Type: article
Authors: Reddy, Naveen A.; Shapley, Alice E.; Kriek, Mariska; Steidel, Charles C.; Shivaei, Irene; Sanders, Ryan L.; Mobasher, Bahram; Coil, Alison L.; Siana, Brian; Freeman, William R.; Azadi, Mojegan; Fetherolf, Tara; Leung, Gene; Price, Sedona H.; Zick, Tom
Abstract: We use a sample of 532 star-forming galaxies at redshifts z ? 1.4-2.6 with deep rest-frame optical spectra from the MOSFIRE Deep Evolution Field (MOSDEF) survey to place the first constraints on the nebular attenuation curve at high redshift. Based on the first five low-order Balmer emission lines detected in the composite spectra of these galaxies (Ha through ${\rm{H}}\epsilon $ ), we derive a nebular attenuation curve that is similar in shape to that of the Galactic extinction curve, suggesting that the dust covering fraction and absorption/scattering properties along the lines of sight to massive stars at high redshift are similar to those of the average Milky Way sight line. The curve derived here implies nebular reddening values that are, on average, systematically larger than those derived for the stellar continuum. In the context of stellar population synthesis models that include the effects of stellar multiplicity, the difference in reddening of the nebular lines and stellar continuum may imply molecular cloud crossing timescales that are a factor of $\gtrsim 3\times $ longer than those inferred for local molecular clouds, star formation rates that are constant or increasing with time such that newly formed and dustier OB associations always dominate the ionizing flux, and/or that the dust responsible for reddening the nebular emission may be associated with nonmolecular (i.e., ionized and neutral) phases of the interstellar medium. Our analysis points to a variety of investigations of the nebular attenuation curve that will be enabled with the next generation of ground- and space-based facilities. * Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA and was made possible by the generous financial support of the W.M. Keck Foundation.
The MOSDEF Survey: [S III] as a New Probe of Evolving Interstellar Medium ConditionsSanders, Ryan L.Jones, TuckerShapley, Alice E.Reddy, Naveen A.Kriek, MariskaCoil, Alison L.Siana, BrianMobasher, BahramShivaei, IrenePrice, Sedona H.Freeman, William R.Azadi, MojeganLeung, Gene C. K.Fetherolf, TaraZick, Tom O.de Groot, LauraBarro, GuillermoFornasini, Francesca M.DOI: info:10.3847/2041-8213/ab5d40v. 888L11
Sanders, Ryan L., Jones, Tucker, Shapley, Alice E., Reddy, Naveen A., Kriek, Mariska, Coil, Alison L., Siana, Brian, Mobasher, Bahram, Shivaei, Irene, Price, Sedona H., Freeman, William R., Azadi, Mojegan, Leung, Gene C. K., Fetherolf, Tara, Zick, Tom O., de Groot, Laura, Barro, Guillermo, and Fornasini, Francesca M. 2020. "The MOSDEF Survey: [S III] as a New Probe of Evolving Interstellar Medium Conditions." The Astrophysical Journal 888:L11. https://doi.org/10.3847/2041-8213/ab5d40
ID: 155688
Type: article
Authors: Sanders, Ryan L.; Jones, Tucker; Shapley, Alice E.; Reddy, Naveen A.; Kriek, Mariska; Coil, Alison L.; Siana, Brian; Mobasher, Bahram; Shivaei, Irene; Price, Sedona H.; Freeman, William R.; Azadi, Mojegan; Leung, Gene C. K.; Fetherolf, Tara; Zick, Tom O.; de Groot, Laura; Barro, Guillermo; Fornasini, Francesca M.
Abstract: We present measurements of [S III]λλ9069,9531 for a sample of z ∼ 1.5 star-forming galaxies, the first representative sample with measurements of these lines at z ≳ 0.1. We employ the line ratio S 32 ≡ [S III]λλ9069,9531/[S II]λλ6716,6731 as a novel probe of evolving interstellar medium (ISM) conditions. Since this ratio includes the low- ionization line [S II], it is crucial that the effects of diffuse ionized gas (DIG) on emission-line ratios be accounted for in z ∼ 0 galaxy spectra, or else that comparisons be made to samples of local H II regions in which DIG emission is not present. We find that S 32 decreases with increasing stellar mass at both z ∼ 1.5 and z ∼ 0, but with a shallow slope suggesting S 32 has a weak dependence on metallicity, in contrast with [O III]/[O II] that displays a strong metallicity dependence. As a result, S 32 only mildly evolves with redshift at fixed stellar mass. The z ∼ 1.5 sample is systematically offset toward lower S 32 and higher [S II]/Hα at fixed [O III]/Hβ relative to z = 0 H II regions. We find that such trends can be explained by a scenario in which the ionizing spectrum is harder at fixed O/H with increasing redshift, but are inconsistent with an increase in ionization parameter at fixed O/H. This analysis demonstrates the advantages of expanding beyond the strongest rest-optical lines for evolutionary studies, and the particular utility of [S III] for characterizing evolving ISM conditions and stellar compositions. These measurements provide a basis for estimating [S III] line strengths for high-redshift galaxies, a line that the James Webb Space Telescope will measure out to z ∼ 5.5. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation.
The MOSDEF survey: direct-method metallicities and ISM conditions at z ∼ 1.5-3.5Sanders, Ryan L.Shapley, Alice E.Reddy, Naveen A.Kriek, MariskaSiana, BrianCoil, Alison L.Mobasher, BahramShivaei, IreneFreeman, William R.Azadi, MojeganPrice, Sedona H.Leung, GeneFetherolf, Tarade Groot, LauraZick, TomFornasini, Francesca M.Barro, GuillermoDOI: info:10.1093/mnras/stz3032v. 4911427–1455
Sanders, Ryan L., Shapley, Alice E., Reddy, Naveen A., Kriek, Mariska, Siana, Brian, Coil, Alison L., Mobasher, Bahram, Shivaei, Irene, Freeman, William R., Azadi, Mojegan, Price, Sedona H., Leung, Gene, Fetherolf, Tara, de Groot, Laura, Zick, Tom, Fornasini, Francesca M., and Barro, Guillermo. 2020. "The MOSDEF survey: direct-method metallicities and ISM conditions at z ∼ 1.5-3.5." Monthly Notices of the Royal Astronomical Society 491:1427– 1455. https://doi.org/10.1093/mnras/stz3032
ID: 155679
Type: article
Authors: Sanders, Ryan L.; Shapley, Alice E.; Reddy, Naveen A.; Kriek, Mariska; Siana, Brian; Coil, Alison L.; Mobasher, Bahram; Shivaei, Irene; Freeman, William R.; Azadi, Mojegan; Price, Sedona H.; Leung, Gene; Fetherolf, Tara; de Groot, Laura; Zick, Tom; Fornasini, Francesca M.; Barro, Guillermo
Abstract: We present detections of [O III] λ4363 and direct-method metallicities for star-forming galaxies at z = 1.7-3.6. We combine new measurements from the MOSFIRE Deep Evolution Field (MOSDEF) survey with literature sources to construct a sample of 18 galaxies with direct-method metallicities at z > 1, spanning 7.5 */M) = 7-10. We find that strong-line calibrations based on local analogues of high-redshift galaxies reliably reproduce the metallicity of the z > 1 sample on average. We construct the first mass-metallicity relation at z > 1 based purely on direct-method O/H, finding a slope that is consistent with strong- line results. Direct-method O/H evolves by ≲0.1 dex at fixed M* and star formation rate from z ∼ 0 to 2.2. We employ photoionization models to constrain the ionization parameter and ionizing spectrum in the high-redshift sample. Stellar models with supersolar O/Fe and binary evolution of massive stars are required to reproduce the observed strong-line ratios. We find that the z > 1 sample falls on the z ∼ 0 relation between ionization parameter and O/H, suggesting no evolution of this relation from z ∼ 0 to z ∼ 2. These results suggest that the offset of the strong-line ratios of this sample from local excitation sequences is driven primarily by a harder ionizing spectrum at fixed nebular metallicity compared to what is typical at z ∼ 0, naturally explained by supersolar O/Fe at high redshift caused by rapid formation time-scales. Given the extreme nature of our z > 1 sample, the implications for representative z ∼ 2 galaxy samples at ∼1010 M are unclear, but similarities to z > 6 galaxies suggest that these conclusions can be extended to galaxies in the epoch of reionization.
The MOSDEF Survey: The Variation of the Dust Attenuation Curve with MetallicityShivaei, IreneReddy, NaveenRieke, GeorgeShapley, AliceKriek, MariskaBattisti, AndrewMobasher, BahramSanders, RyanFetherolf, TaraAzadi, MojeganCoil, Alison L.Freeman, William R.de Groot, LauraLeung, GenePrice, Sedona H.Siana, BrianZick, TomDOI: info:10.3847/1538-4357/aba35ev. 899117
Shivaei, Irene, Reddy, Naveen, Rieke, George, Shapley, Alice, Kriek, Mariska, Battisti, Andrew, Mobasher, Bahram, Sanders, Ryan, Fetherolf, Tara, Azadi, Mojegan, Coil, Alison L., Freeman, William R., de Groot, Laura, Leung, Gene, Price, Sedona H., Siana, Brian, and Zick, Tom. 2020. "The MOSDEF Survey: The Variation of the Dust Attenuation Curve with Metallicity." The Astrophysical Journal 899:117. https://doi.org/10.3847/1538-4357/aba35e
ID: 157644
Type: article
Authors: Shivaei, Irene; Reddy, Naveen; Rieke, George; Shapley, Alice; Kriek, Mariska; Battisti, Andrew; Mobasher, Bahram; Sanders, Ryan; Fetherolf, Tara; Azadi, Mojegan; Coil, Alison L.; Freeman, William R.; de Groot, Laura; Leung, Gene; Price, Sedona H.; Siana, Brian; Zick, Tom
Abstract: We derive a UV-optical stellar dust attenuation curve of galaxies at z = 1.4-2.6 as a function of gas-phase metallicity. We use a sample of 218 star-forming galaxies, excluding those with very young or heavily obscured star formation, from the MOSFIRE Deep Evolution Field survey with Hα, Hβ, and [N II]λ 6585 spectroscopic measurements. We constrain the shape of the attenuation curve by comparing the average flux densities of galaxies sorted into bins of dust obscuration using Balmer decrements, i.e., Hα-to-Hβ luminosities. The average attenuation curve for the high-metallicity sample ( $12+\mathrm{log}({\rm{O}}/{\rm{H}})\gt 8.5$ , corresponding to ${M}_{* }\gtrsim {10}^{10.4}$ ${M}_{\odot }$ ) has a shallow slope, identical to that of the Calzetti local starburst curve, and a significant UV 2175 Å extinction bump that is ∼0.5× the strength of the Milky Way bump. On the other hand, the average attenuation curve of the low-metallicity sample ( $12+\mathrm{log}({\rm{O}}/{\rm{H}})\sim 8.2-8.5$ ) has a steeper slope similar to that of the SMC curve, only consistent with the Calzetti slope at the 3σ level. The UV bump is not detected in the low-metallicity curve, indicating the relative lack of the small dust grains causing the bump at low metallicities. Furthermore, we find that on average the nebular reddening (E(B - V)) is a factor of 2 times larger than that of the stellar continuum for galaxies with low metallicities, while the nebular and stellar reddening are similar for galaxies with higher metallicities. The latter is likely due to a high surface density of dusty clouds embedding the star-forming regions but also reddening the continuum in the high-metallicity galaxies.
Infrared Contributions of X-Ray Selected Active Galactic Nuclei in Dusty Star-forming GalaxiesBrown, AriannaNayyeri, HooshangCooray, AsanthaMa, JingzheHickox, Ryan C.Azadi, MojeganDOI: info:10.3847/1538-4357/aaf73bv. 87187
Brown, Arianna, Nayyeri, Hooshang, Cooray, Asantha, Ma, Jingzhe, Hickox, Ryan C., and Azadi, Mojegan. 2019. "Infrared Contributions of X-Ray Selected Active Galactic Nuclei in Dusty Star-forming Galaxies." The Astrophysical Journal 871:87. https://doi.org/10.3847/1538-4357/aaf73b
ID: 150437
Type: article
Authors: Brown, Arianna; Nayyeri, Hooshang; Cooray, Asantha; Ma, Jingzhe; Hickox, Ryan C.; Azadi, Mojegan
Abstract: We investigate the infrared (IR) contribution from supermassive black hole activity versus host galaxy emission in the mid- to far-IR spectrum for a large sample of X-ray bright active galactic nuclei (AGN) residing in dusty, star-forming host galaxies. We select 703 AGN with {L}{{X}}={10}42{--}{10}46 erg s‑1 at 0.1 at 0.1 at 0.1 X in bins of star-forming activity for AGN at low redshifts. We estimate an average dust covering factor (CF) of 33% based on IR SEDs and bolometric AGN luminosity, corresponding to a Type 2 AGN population of roughly a third. We also see a population of AGN that challenge the inclination-based unification model with individual dust CFs that contradict the nuclear obscuration expected from observed X-ray hardness ratios. We see no strong connection between AGN fractions in the IR and corresponding total IR, 24 μm, or X-ray luminosities. The average rest-frame AGN contribution as a function of IR wavelength shows significant (∼80%) contributions in the mid-IR that trail off at λ > 30 μm. Additionally, we provide a relation between observed L X and pure AGN IR output for high-z AGN, allowing future studies to estimate AGN IR contribution using only observed X-ray flux density estimates.
The MOSDEF Survey: The Metallicity Dependence of X-Ray Binary Populations at z ̃ 2Fornasini, Francesca M.Kriek, MariskaSanders, Ryan L.Shivaei, IreneCivano, FrancescaReddy, Naveen A.Shapley, Alice E.Coil, Alison L.Mobasher, BahramSiana, BrianAird, JamesAzadi, MojeganFreeman, William R.Leung, Gene C. K.Price, Sedona H.Fetherolf, TaraZick, TomBarro, GuillermoDOI: info:10.3847/1538-4357/ab4653v. 88565
Fornasini, Francesca M., Kriek, Mariska, Sanders, Ryan L., Shivaei, Irene, Civano, Francesca, Reddy, Naveen A., Shapley, Alice E., Coil, Alison L., Mobasher, Bahram, Siana, Brian, Aird, James, Azadi, Mojegan, Freeman, William R., Leung, Gene C. K., Price, Sedona H., Fetherolf, Tara, Zick, Tom, and Barro, Guillermo. 2019. "The MOSDEF Survey: The Metallicity Dependence of X-Ray Binary Populations at z ̃ 2." The Astrophysical Journal 885:65. https://doi.org/10.3847/1538-4357/ab4653
ID: 154601
Type: article
Authors: Fornasini, Francesca M.; Kriek, Mariska; Sanders, Ryan L.; Shivaei, Irene; Civano, Francesca; Reddy, Naveen A.; Shapley, Alice E.; Coil, Alison L.; Mobasher, Bahram; Siana, Brian; Aird, James; Azadi, Mojegan; Freeman, William R.; Leung, Gene C. K.; Price, Sedona H.; Fetherolf, Tara; Zick, Tom; Barro, Guillermo
Abstract: Population synthesis models predict that high-mass X-ray binary (HMXB) populations produced in low-metallicity environments should be more X-ray luminous, a trend supported by studies of nearby galaxies. This trend may be responsible for the observed increase of the X-ray luminosity (L X) per star formation rate (SFR) with redshift due to the decrease of metallicity (Z) at fixed stellar mass as a function of redshift. To test this hypothesis, we use a sample of 79 z ̃ 2 star-forming galaxies with oxygen abundance measurements from the MOSDEF survey, which obtained rest-frame optical spectra for ̃1500 galaxies in the CANDELS fields at 1.37 ) per star formation rate (SFR) with redshift due to the decrease of metallicity (Z) at fixed stellar mass as a function of redshift. To test this hypothesis, we use a sample of 79 z ̃ 2 star-forming galaxies with oxygen abundance measurements from the MOSDEF survey, which obtained rest-frame optical spectra for ̃1500 galaxies in the CANDELS fields at 1.37 ) per star formation rate (SFR) with redshift due to the decrease of metallicity (Z) at fixed stellar mass as a function of redshift. To test this hypothesis, we use a sample of 79 z ̃ 2 star-forming galaxies with oxygen abundance measurements from the MOSDEF survey, which obtained rest-frame optical spectra for ̃1500 galaxies in the CANDELS fields at 1.37 X/SFR of our z ̃ 2 galaxy sample is enhanced by ≈0.4-0.8 dex relative to local HMXB L X-SFR scaling relations. Splitting our sample by Z, we find that L X/SFR and Z are anticorrelated with 97% confidence. This observed Z dependence for HMXB-dominated galaxies is consistent with both the local L X-SFR-Z relation and a subset of population synthesis models. Although the statistical significance of the observed trends is weak owing to the low X-ray statistics, these results constitute the first direct evidence connecting the redshift evolution of L X/SFR and the Z dependence of HMXBs.
The MOSDEF Survey: A Census of AGN-driven Ionized Outflows at z = 1.4─3.8Leung, Gene C. K.Coil, Alison L.Aird, JamesAzadi, MojeganKriek, MariskaMobasher, BahramReddy, NaveenShapley, AliceSiana, BrianFetherolf, TaraFornasini, Francesca M.Freeman, William R.Price, Sedona H.Sanders, Ryan L.Shivaei, IreneZick, TomDOI: info:10.3847/1538-4357/ab4a7cv. 88611
Leung, Gene C. K., Coil, Alison L., Aird, James, Azadi, Mojegan, Kriek, Mariska, Mobasher, Bahram, Reddy, Naveen, Shapley, Alice, Siana, Brian, Fetherolf, Tara, Fornasini, Francesca M., Freeman, William R., Price, Sedona H., Sanders, Ryan L., Shivaei, Irene, and Zick, Tom. 2019. "The MOSDEF Survey: A Census of AGN-driven Ionized Outflows at z = 1.4─3.8." The Astrophysical Journal 886:11. https://doi.org/10.3847/1538-4357/ab4a7c
ID: 154572
Type: article
Authors: Leung, Gene C. K.; Coil, Alison L.; Aird, James; Azadi, Mojegan; Kriek, Mariska; Mobasher, Bahram; Reddy, Naveen; Shapley, Alice; Siana, Brian; Fetherolf, Tara; Fornasini, Francesca M.; Freeman, William R.; Price, Sedona H.; Sanders, Ryan L.; Shivaei, Irene; Zick, Tom
Abstract: Using data from the MOSFIRE Deep Evolution Field (MOSDEF) survey, we present a census of active galactic nucleus (AGN)─driven ionized outflows in a sample of 159 AGNs at 1.4 ≤ z ≤ 3.8. The sample spans AGN bolometric luminosities of 1044─47 erg s−1 and includes both quiescent and star-forming galaxies extending across 3 orders of magnitude in stellar mass. We identify and characterize outflows from the Hβ, [O III], Hα, and [N II] emission line spectra. We detect outflows in 17% of the AGNs, seven times more often than in a mass-matched sample of inactive galaxies in MOSDEF. The outflows are fast and galaxy-wide, with velocities of ∼400─3500 km s {}-1 and spatial extents of 0.3─11.0 kpc. The incidence of outflows among AGNs is independent of the stellar mass of the host galaxy, with outflows detected in both star-forming and quiescent galaxies. This suggests that outflows exist across different phases in galaxy evolution. We investigate relations between outflow kinematic, spatial, and energetic properties and both AGN and host galaxy properties. Our results show that AGN-driven outflows are widespread in galaxies along the star-forming main sequence. The mass-loading factors of the outflows are typically 0.1─1 and increase with AGN luminosity, capable of exceeding unity at {L}AGN}≳ {10}46 {erg} {{{s}}}-1. In these more luminous sources, the ionized outflow alone is likely sufficient to regulate star formation and, when combined with outflowing neutral and molecular gas, may be able to quench star formation in their host galaxies.
The MOSDEF Survey: Sulfur Emission-line Ratios Provide New Insights into Evolving Interstellar Medium Conditions at High RedshiftShapley, Alice E.Sanders, Ryan L.Shao, PengReddy, Naveen A.Kriek, MariskaCoil, Alison L.Mobasher, BahramSiana, BrianShivaei, IreneFreeman, William R.Azadi, MojeganPrice, Sedona H.Leung, Gene C. K.Fetherolf, Tarade Groot, LauraZick, TomFornasini, Francesca M.Barro, GuillermoDOI: info:10.3847/2041-8213/ab385av. 881L35
Shapley, Alice E., Sanders, Ryan L., Shao, Peng, Reddy, Naveen A., Kriek, Mariska, Coil, Alison L., Mobasher, Bahram, Siana, Brian, Shivaei, Irene, Freeman, William R., Azadi, Mojegan, Price, Sedona H., Leung, Gene C. K., Fetherolf, Tara, de Groot, Laura, Zick, Tom, Fornasini, Francesca M., and Barro, Guillermo. 2019. "The MOSDEF Survey: Sulfur Emission-line Ratios Provide New Insights into Evolving Interstellar Medium Conditions at High Redshift." The Astrophysical Journal 881:L35. https://doi.org/10.3847/2041-8213/ab385a
ID: 154252
Type: article
Authors: Shapley, Alice E.; Sanders, Ryan L.; Shao, Peng; Reddy, Naveen A.; Kriek, Mariska; Coil, Alison L.; Mobasher, Bahram; Siana, Brian; Shivaei, Irene; Freeman, William R.; Azadi, Mojegan; Price, Sedona H.; Leung, Gene C. K.; Fetherolf, Tara; de Groot, Laura; Zick, Tom; Fornasini, Francesca M.; Barro, Guillermo
Abstract: We present results on the emission-line properties of 1.3 ≤ z ≤ 2.7 galaxies drawn from the complete the MOSFIRE Deep Evolution Field (MOSDEF) survey. Specifically, we use observations of the emission-line diagnostic diagram of [O III]λ 5007/Hβ versus [S II]λλ6717,6731/Hα, i.e., the "[S II] BPT diagram," to gain insight into the physical properties of high-redshift star-forming regions. High-redshift MOSDEF galaxies are offset toward lower [S II]λλ6717,6731/Hα at fixed [OIII]λ5007/Hβ, relative to local galaxies from the Sloan Digital Sky Survey (SDSS). Furthermore, at fixed [O III]λ5007/Hβ, local SDSS galaxies follow a trend of decreasing [S II]λλ6717,6731/Hα as the surface density of star formation (ΣSFR) increases. We explain this trend in terms of the decreasing fractional contribution from diffuse ionized gas (f DIG) as ΣSFR increases in galaxies, which causes galaxy-integrated line ratios to shift toward the locus of pure H II-region emission. The z ̃ 0 relationship between f DIG and ΣSFR implies that high-redshift galaxies have lower f DIG values than typical local systems, given their significantly higher typical ΣSFR. When an appropriate low-redshift benchmark with zero or minimal f DIG is used, high-redshift MOSDEF galaxies appear offset toward higher [SII]λλ6717,6731/Hα and/or [O III]λ 5007/Hβ. The joint shifts of high-redshift galaxies in the [S II] and [N II] BPT diagrams are best explained in terms of the harder spectra ionizing their star-forming regions at fixed nebular oxygen abundance (expected for chemically young galaxies), as opposed to large variations in N/O ratios or higher ionization parameters. The evolving mixture of H II regions and diffuse ionized gas is an essential ingredient of our description of the interstellar medium over cosmic time. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.
The MOSDEF Survey: No Significant Enhancement in Star Formation or Deficit in Metallicity in Merging Galaxy Pairs at 1.5 ≲ z ≲ 3.5Wilson, Tim J.Shapley, Alice E.Sanders, Ryan L.Reddy, Naveen A.Freeman, William R.Kriek, MariskaShivaei, IreneCoil, Alison L.Siana, BrianMobasher, BahramPrice, Sedona H.Azadi, MojeganBarro, Guillermode Groot, LauraFetherolf, TaraFornasini, Francesca M.Leung, Gene C. K.Zick, Tom O.DOI: info:10.3847/1538-4357/ab06eev. 87418
Wilson, Tim J., Shapley, Alice E., Sanders, Ryan L., Reddy, Naveen A., Freeman, William R., Kriek, Mariska, Shivaei, Irene, Coil, Alison L., Siana, Brian, Mobasher, Bahram, Price, Sedona H., Azadi, Mojegan, Barro, Guillermo, de Groot, Laura, Fetherolf, Tara, Fornasini, Francesca M., Leung, Gene C. K., and Zick, Tom O. 2019. "The MOSDEF Survey: No Significant Enhancement in Star Formation or Deficit in Metallicity in Merging Galaxy Pairs at 1.5 ≲ z ≲ 3.5." The Astrophysical Journal 874:18. https://doi.org/10.3847/1538-4357/ab06ee
ID: 155439
Type: article
Authors: Wilson, Tim J.; Shapley, Alice E.; Sanders, Ryan L.; Reddy, Naveen A.; Freeman, William R.; Kriek, Mariska; Shivaei, Irene; Coil, Alison L.; Siana, Brian; Mobasher, Bahram; Price, Sedona H.; Azadi, Mojegan; Barro, Guillermo; de Groot, Laura; Fetherolf, Tara; Fornasini, Francesca M.; Leung, Gene C. K.; Zick, Tom O.
Abstract: We study the properties of 30 spectroscopically identified pairs of galaxies observed during the peak epoch of star formation in the universe. These systems are drawn from the MOSFIRE Deep Evolution Field (MOSDEF) Survey at 1.4 ≤ z ≤ 3.8, and are interpreted as early-stage galaxy mergers. Galaxy pairs in our sample are identified as two objects whose spectra were collected on the same Keck/MOSFIRE spectroscopic slit. Accordingly, all pairs in the sample have projected separations R proj ≤ 60 kpc. The velocity separation for pairs was required to be ∆v ≤ 500 km s-1, which is a standard threshold for defining interacting galaxy pairs at low redshift. Stellar mass ratios in our sample range from 1.1 to 550, with 12 ratios closer than or equal to 3:1, the common definition of a "major merger." Studies of merging pairs in the local universe indicate an enhancement in star formation activity and deficit in gas-phase oxygen abundance relative to isolated galaxies of the same mass. We compare the MOSDEF pairs sample to a control sample of isolated galaxies at the same redshift, finding no measurable SFR enhancement or metallicity deficit at fixed stellar mass for the pairs sample. The lack of significant difference between the average properties of pairs and control samples appears in contrast to results from low-redshift studies, although the small sample size and lower signal-to-noise of the high-redshift data limit definitive conclusions on redshift evolution. These results are consistent with some theoretical works, suggesting a reduced differential effect of precoalescence mergers on galaxy properties at high redshift-specifically that precoalescence mergers do not drive strong starbursts. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.