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Showing 1-14 of about 14 results.
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.
Connecting the metallicity dependence and redshift evolution of high-mass X-ray binariesFornasini, Francesca M.Civano, FrancescaSuh, HyewonDOI: info:10.1093/mnras/staa1211v. 495771–783
Fornasini, Francesca M., Civano, Francesca, and Suh, Hyewon. 2020. "Connecting the metallicity dependence and redshift evolution of high-mass X-ray binaries." Monthly Notices of the Royal Astronomical Society 495:771– 783. https://doi.org/10.1093/mnras/staa1211
ID: 156977
Type: article
Authors: Fornasini, Francesca M.; Civano, Francesca; Suh, Hyewon
Abstract: The integrated X-ray luminosity (LX) of high-mass X-ray binaries (HMXBs) in a galaxy is correlated with its star formation rate (SFR), and the normalization of this correlation increases with redshift. Population synthesis models suggest that the redshift evolution of LX/SFR is driven by the metallicity (Z) dependence of HMXBs, and the first direct evidence of this connection was recently presented using galaxies at z ∼ 2. To confirm this result with more robust measurements and better constrain the LX-SFR-Z relation, we have studied the Z dependence of LX/SFR at lower redshifts. Using samples of star-forming galaxies at z = 0.1-0.9 with optical spectra from the hCOSMOS and zCOSMOS surveys, we stacked Chandra data from the COSMOS Legacy survey to measure the average LX/SFR as a function of Z in three redshift ranges: z = 0.1-0.25, 0.25-0.4, and 0.5-0.9. We find no significant variation of the LX-SFR-Z relation with redshift. Our results provide further evidence that the Z dependence of HMXBs is responsible for the redshift evolution of LX/SFR. Combining all available z > 0 measurements together, we derive a best-fitting LX-SFR-Z relation and assess how different population synthesis models describe the data. These results provide the strongest constraints to date on the LX-SFR-Z relation in the range of 8.0 < 12 + log(O/H) < 9.0.
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: [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.
Chandra Observations of High-energy X-Ray Sources Discovered by INTEGRALTomsick, John A.Bodaghee, ArashChaty, SylvainClavel, MaïcaFornasini, Francesca M.Hare, JeremyKrivonos, RomanRahoui, FaridRodriguez, JeromeDOI: info:10.3847/1538-4357/ab5fd2v. 88953
Tomsick, John A., Bodaghee, Arash, Chaty, Sylvain, Clavel, Maïca, Fornasini, Francesca M., Hare, Jeremy, Krivonos, Roman, Rahoui, Farid, and Rodriguez, Jerome. 2020. "Chandra Observations of High-energy X-Ray Sources Discovered by INTEGRAL." The Astrophysical Journal 889:53. https://doi.org/10.3847/1538-4357/ab5fd2
ID: 155676
Type: article
Authors: Tomsick, John A.; Bodaghee, Arash; Chaty, Sylvain; Clavel, Maïca; Fornasini, Francesca M.; Hare, Jeremy; Krivonos, Roman; Rahoui, Farid; Rodriguez, Jerome
Abstract: The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has detected in excess of 1000 sources in the ∼20─100 keV band during its surveys of the sky over the past 17 years. We obtained 5 ks observations of 15 unclassified INTEGRAL Gamma-Ray (IGR) sources with the Chandra X-ray Observatory in order to localize them, to identify optical/IR counterparts, to measure their soft X-ray spectra, and to classify them. For 10 of the IGR sources, we detect Chandra sources that are likely (or in some cases certain) to be the counterparts. IGR J18007─4146 and IGR J15038─6021 both have Gaia parallax distances, placing them at ${2.5}_{-0.4}^{+0.5}$ and ${1.1}_{-0.4}^{+1.5}$ kpc, respectively. We tentatively classify both of them as intermediate polar-type cataclysmic variables. Also, IGR J17508─3219 is likely to be a Galactic source, but it is unclear if it is a Dwarf Nova or another type of transient. For IGR J17118─3155, we provide a Chandra localization, but it is unclear if the source is Galactic or extragalactic. Based on either near-IR/IR colors or the presence of extended near-IR emission, we classify four sources as active galactic nuclei (AGNs; IGR J16181─5407, IGR J16246─4556, IGR J17096─2527, and IGR J19294+1327), and IGR J20310+3835 and IGR J15541─5613 are AGN candidates. In addition, we identified an AGN in the INTEGRAL error circle of IGR J16120─3543 that is a possible counterpart.
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.
Neutron Stars and Black Holes in the Small Magellanic Cloud: The SMC NuSTAR Legacy SurveyLazzarini, M.Williams, B. F.Hornschemeier, A. E.Antoniou, ValliaVasilopoulos, G.Haberl, F.Vulic, N.Yukita, M.Zezas, AndreasBodaghee, A.Lehmer, B. D.Maccarone, T. J.Ptak, A.Wik, D.Fornasini, Francesca M.Hong, JaesubKennea, J. A.Tomsick, J. A.Venters, T.Udalski, A.Cassity, A.DOI: info:10.3847/1538-4357/ab3f32v. 8842
Lazzarini, M., Williams, B. F., Hornschemeier, A. E., Antoniou, Vallia, Vasilopoulos, G., Haberl, F., Vulic, N., Yukita, M., Zezas, Andreas, Bodaghee, A., Lehmer, B. D., Maccarone, T. J., Ptak, A., Wik, D., Fornasini, Francesca M., Hong, Jaesub, Kennea, J. A., Tomsick, J. A., Venters, T., Udalski, A., and Cassity, A. 2019. "Neutron Stars and Black Holes in the Small Magellanic Cloud: The SMC NuSTAR Legacy Survey." The Astrophysical Journal 884:2. https://doi.org/10.3847/1538-4357/ab3f32
ID: 154709
Type: article
Authors: Lazzarini, M.; Williams, B. F.; Hornschemeier, A. E.; Antoniou, Vallia; Vasilopoulos, G.; Haberl, F.; Vulic, N.; Yukita, M.; Zezas, Andreas; Bodaghee, A.; Lehmer, B. D.; Maccarone, T. J.; Ptak, A.; Wik, D.; Fornasini, Francesca M.; Hong, Jaesub; Kennea, J. A.; Tomsick, J. A.; Venters, T.; Udalski, A.; Cassity, A.
Abstract: We present a source catalog from the first deep hard X-ray (E > 10 keV) survey of the Small Magellanic Cloud (SMC), the Nuclear Spectroscopic Telescope Array (NuSTAR) Legacy Survey of the SMC. We observed three fields, for a total exposure time of 1 Ms, along the bar of this nearby star-forming galaxy. Fields were chosen for their young stellar and accreting binary populations. We detected 10 sources above a 3σ significance level (4-25 keV) and obtained upper limits on an additional 40 sources. We reached a 3σ limiting luminosity in the 4-25 keV band of ̃1035 erg s-1, allowing us to probe fainter X-ray binary (XRB) populations than has been possible with other extragalactic NuSTAR surveys. We used hard X-ray colors and luminosities to constrain the compact-object type, exploiting the spectral differences between accreting black holes and neutron stars at E > 10 keV. Several of our sources demonstrate variability consistent with previously observed behavior. We confirmed pulsations for seven pulsars in our 3σ sample. We present the first detection of pulsations from a Be-XRB, SXP 305 (CXO J005215.4-73191), with an X-ray pulse period of 305.69 ± 0.16 s and a likely orbital period of ̃1160-1180 days. Bright sources (≳5 × 1036 erg s-1) in our sample have compact-object classifications consistent with their previously reported types in the literature. Lower-luminosity sources (≲5 × 1036 erg s-1) have X-ray colors and luminosities consistent with multiple classifications. We raise questions about possible spectral differences at low luminosity between SMC pulsars and the Galactic pulsars used to create the diagnostic diagrams.
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.
Low-luminosity AGN and X-Ray Binary Populations in COSMOS Star-forming GalaxiesFornasini, Francesca M.Civano, FrancescaFabbiano, GiuseppinaElvis, MartinMarchesi, StefanoMiyaji, TakamitsuZezas, AndreasDOI: info:10.3847/1538-4357/aada4ev. 86543
Fornasini, Francesca M., Civano, Francesca, Fabbiano, Giuseppina, Elvis, Martin, Marchesi, Stefano, Miyaji, Takamitsu, and Zezas, Andreas. 2018. "Low-luminosity AGN and X-Ray Binary Populations in COSMOS Star-forming Galaxies." The Astrophysical Journal 865:43. https://doi.org/10.3847/1538-4357/aada4e
ID: 149160
Type: article
Authors: Fornasini, Francesca M.; Civano, Francesca; Fabbiano, Giuseppina; Elvis, Martin; Marchesi, Stefano; Miyaji, Takamitsu; Zezas, Andreas
Abstract: We present an X-ray stacking analysis of ∼75,000 star-forming galaxies between 0.1 40–1041 erg s‑1, a regime in which X-ray binaries (XRBs) can dominate the X-ray emission. Comparing the measured luminosities to established XRB scaling relations, we find that the redshift evolution of the luminosity per star formation rate (SFR) of XRBs depends sensitively on the assumed obscuration and may be weaker than previously found. The XRB scaling relation based on stacks from the Chandra Deep Field South overestimates the XRB contribution to the COSMOS high specific SFR stacks, possibly due to a bias affecting the CDF-S stacks because of their small galaxy samples. After subtracting the estimated XRB contribution from the stacks, we find that most stacks at z > 1.3 exhibit a significant X-ray excess indicating nuclear emission. The AGN emission is strongly correlated with stellar mass but does not exhibit an additional correlation with SFR. The hardness ratios of the high-redshift stacks indicate that the AGN are substantially obscured (N H ∼ 1023 cm‑2). These obscured AGN are not identified by IRAC color selection and have L X ∼ 1041–1043 erg s‑1, consistent with accretion at an Eddington rate of ∼10‑3 onto 107–108 M black holes. Combining our results with other X-ray studies suggests that AGN obscuration depends on stellar mass and an additional variable, possibly the Eddington rate.
The NuSTAR Extragalactic Surveys: Source Catalog and the Compton-thick Fraction in the UDS FieldMasini, A.Civano, FrancescaComastri, A.Fornasini, F.Ballantyne, D. R.Lansbury, G. B.Treister, E.Alexander, D. M.Boorman, P. G.Brandt, W. N.Farrah, D.Gandhi, P.Harrison, F. A.Hickox, R. C.Kocevski, D. D.Lanz, L.Marchesi, S.Puccetti, S.Ricci, C.Saez, C.Stern, D.Zappacosta, L.DOI: info:10.3847/1538-4365/aaa83dv. 23517
Masini, A., Civano, Francesca, Comastri, A., Fornasini, F., Ballantyne, D. R., Lansbury, G. B., Treister, E., Alexander, D. M., Boorman, P. G., Brandt, W. N., Farrah, D., Gandhi, P., Harrison, F. A., Hickox, R. C., Kocevski, D. D., Lanz, L., Marchesi, S., Puccetti, S., Ricci, C., Saez, C., Stern, D., and Zappacosta, L. 2018. "The NuSTAR Extragalactic Surveys: Source Catalog and the Compton-thick Fraction in the UDS Field." The Astrophysical Journal Supplement Series 235:17. https://doi.org/10.3847/1538-4365/aaa83d
ID: 146142
Type: article
Authors: Masini, A.; Civano, Francesca; Comastri, A.; Fornasini, F.; Ballantyne, D. R.; Lansbury, G. B.; Treister, E.; Alexander, D. M.; Boorman, P. G.; Brandt, W. N.; Farrah, D.; Gandhi, P.; Harrison, F. A.; Hickox, R. C.; Kocevski, D. D.; Lanz, L.; Marchesi, S.; Puccetti, S.; Ricci, C.; Saez, C.; Stern, D.; Zappacosta, L.
Abstract: We present the results and the source catalog of the NuSTAR survey in the UKIDSS Ultra Deep Survey (UDS) field, bridging the gap in depth and area between NuSTAR's ECDFS and COSMOS surveys. The survey covers a ∼0.6 deg2 area of the field for a total observing time of ∼1.75 Ms, to a half-area depth of ∼155 ks corrected for vignetting at 3–24 keV, and reaching sensitivity limits at half-area in the full (3–24 keV), soft (3–8 keV), and hard (8–24 keV) bands of 2.2 × 10‑14 erg cm‑2 s‑1, 1.0 × 10‑14 erg cm‑2 s‑1, and 2.7 × 10‑14 erg cm‑2 s‑1, respectively. A total of 67 sources are detected in at least one of the three bands, 56 of which have a robust optical redshift with a median of ∼ 1.1. Through a broadband (0.5–24 keV) spectral analysis of the whole sample combined with the NuSTAR hardness ratios, we compute the observed Compton-thick (CT; N H > 1024 cm‑2) fraction. Taking into account the uncertainties on each N H measurement, the final number of CT sources is 6.8 ± 1.2. This corresponds to an observed CT fraction of 11.5% ± 2.0%, providing a robust lower limit to the intrinsic fraction of CT active galactic nuclei and placing constraints on cosmic X-ray background synthesis models.
Black Holes and Neutron Stars in Nearby Galaxies: Insights from NuSTARVulic, N.Hornschemeier, A. E.Wik, D. R.Yukita, M.Zezas, A.Ptak, A. F.Lehmer, B. D.Antoniou, V.Maccarone, T. J.Williams, B. F.Fornasini, F. M.DOI: info:10.3847/1538-4357/aad500v. 864150
Vulic, N., Hornschemeier, A. E., Wik, D. R., Yukita, M., Zezas, A., Ptak, A. F., Lehmer, B. D., Antoniou, V., Maccarone, T. J., Williams, B. F., and Fornasini, F. M. 2018. "Black Holes and Neutron Stars in Nearby Galaxies: Insights from NuSTAR." The Astrophysical Journal 864:150. https://doi.org/10.3847/1538-4357/aad500
ID: 149169
Type: article
Authors: Vulic, N.; Hornschemeier, A. E.; Wik, D. R.; Yukita, M.; Zezas, A.; Ptak, A. F.; Lehmer, B. D.; Antoniou, V.; Maccarone, T. J.; Williams, B. F.; Fornasini, F. M.
Abstract: Nearby galaxy surveys have long classified X-ray binaries (XRBs) by the mass category of their donor stars (high-mass and low-mass). The NuSTAR observatory, which provides imaging data at E > 10 keV, has enabled the classification of extragalactic XRBs by their compact object type: neutron star (NS) or black hole (BH). We analyzed NuSTAR/Chandra/XMM-Newton observations from a NuSTAR-selected sample of 12 galaxies within 5 Mpc having stellar masses (M ) 107–11 M and star formation rates (SFRs) ≈ 0.01–15 M yr‑1. We detected 128 NuSTAR sources to a sensitivity of ≈1038 erg s‑1. Using NuSTAR color-intensity and color–color diagrams we classified 43 of these sources as candidate NSs and 47 as candidate BHs. We further subdivide BHs by accretion states (soft, intermediate, and hard) and NSs by weak (Z/Atoll) and strong (accreting pulsar) magnetic field. Using eight normal (Milky Way-type) galaxies in the sample, we confirm the relation between the SFR and galaxy X-ray point source luminosity in the 4–25 and 12–25 keV energy bands. We also constrained galaxy X-ray point source luminosity using the relation L X = α M + βSFR, finding agreement with previous work. The X-ray luminosity function (XLF) of all sources in the 4–25 and 12–25 keV energy bands matches the α = 1.6 slope for high-mass XRBs. We find that NS XLFs suggest a decline beginning at the Eddington limit for a 1.4 M NS, whereas the BH fraction shows an approximate monotonic increase in the 4–25 and 12–25 keV energy bands. We calculate the overall ratio of BH to NS to be ≈1 for 4–25 keV and ≈2 for 12–25 keV.