TY - JOUR
T1 - Nebular excitation in z ∼ 2 star-forming galaxies from the sins and luci surveys
T2 - The influence of shocks and active galactic nuclei
AU - Newman, Sarah F.
AU - Buschkamp, Peter
AU - Genzel, Reinhard
AU - Förster Schreiber, Natascha M.
AU - Kurk, Jaron
AU - Sternberg, Amiel
AU - Gnat, Orly
AU - Rosario, David
AU - Mancini, Chiara
AU - Lilly, Simon J.
AU - Renzini, Alvio
AU - Burkert, Andreas
AU - Carollo, C. Marcella
AU - Cresci, Giovanni
AU - Davies, Ric
AU - Eisenhauer, Frank
AU - Genel, Shy
AU - Shapiro Griffin, Kristen
AU - Hicks, Erin K.S.
AU - Lutz, Dieter
AU - Naab, Thorsten
AU - Peng, Yingjie
AU - Tacconi, Linda J.
AU - Wuyts, Stijn
AU - Zamorani, Gianni
AU - Vergani, Daniela
AU - Weiner, Benjamin J.
PY - 2014/1/20
Y1 - 2014/1/20
N2 - Based on high-resolution, spatially resolved data of 10 z ∼ 2 star-forming galaxies from the SINS/zC-SINF survey and LUCI data for 12 additional galaxies, we probe the excitation properties of high-z galaxies and the impact of active galactic nuclei (AGNs), shocks, and photoionization. We explore how these spatially resolved line ratios can inform our interpretation of integrated emission line ratios obtained at high redshift. Many of our galaxies fall in the "composite" region of the z ∼ 0 [N II]/Hα versus [O III]/Hβ diagnostic (BPT) diagram, between star-forming galaxies and those with AGNs. Based on our resolved measurements, we find that some of these galaxies likely host an AGN, while others appear to be affected by the presence of shocks possibly caused by an outflow or from an enhanced ionization parameter as compared with H II regions in normal, local star-forming galaxies. We find that the Mass-Excitation (MEx) diagnostic, which separates purely star-forming and AGN hosting local galaxies in the [O III]/Hβ versus stellar mass plane, does not properly separate z ∼ 2 galaxies classified according to the BPT diagram. However, if we shift the galaxies based on the offset between the local and z ∼ 2 mass-metallicity relation (i.e., to the mass they would have at z ∼ 0 with the same metallicity), we find better agreement between the MEx and BPT diagnostics. Finally, we find that metallicity calibrations based on [N II]/Hα are more biased by shocks and AGNs at high-z than the [O III]/Hβ/[N II]/Hα calibration.
AB - Based on high-resolution, spatially resolved data of 10 z ∼ 2 star-forming galaxies from the SINS/zC-SINF survey and LUCI data for 12 additional galaxies, we probe the excitation properties of high-z galaxies and the impact of active galactic nuclei (AGNs), shocks, and photoionization. We explore how these spatially resolved line ratios can inform our interpretation of integrated emission line ratios obtained at high redshift. Many of our galaxies fall in the "composite" region of the z ∼ 0 [N II]/Hα versus [O III]/Hβ diagnostic (BPT) diagram, between star-forming galaxies and those with AGNs. Based on our resolved measurements, we find that some of these galaxies likely host an AGN, while others appear to be affected by the presence of shocks possibly caused by an outflow or from an enhanced ionization parameter as compared with H II regions in normal, local star-forming galaxies. We find that the Mass-Excitation (MEx) diagnostic, which separates purely star-forming and AGN hosting local galaxies in the [O III]/Hβ versus stellar mass plane, does not properly separate z ∼ 2 galaxies classified according to the BPT diagram. However, if we shift the galaxies based on the offset between the local and z ∼ 2 mass-metallicity relation (i.e., to the mass they would have at z ∼ 0 with the same metallicity), we find better agreement between the MEx and BPT diagnostics. Finally, we find that metallicity calibrations based on [N II]/Hα are more biased by shocks and AGNs at high-z than the [O III]/Hβ/[N II]/Hα calibration.
KW - galaxies: evolution
KW - galaxies: high-redshift
KW - infrared: galaxies
UR - http://www.scopus.com/inward/record.url?scp=84891869787&partnerID=8YFLogxK
U2 - https://doi.org/10.1088/0004-637X/781/1/21
DO - https://doi.org/10.1088/0004-637X/781/1/21
M3 - مقالة
SN - 0004-637X
VL - 781
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 21
ER -