Topic: “Ionized atomic lines in high-z galaxies” K. Kohno (IoA/RESCEU) Journal Club June 15 th, 2012 “Ionized nitrogen at high redshift”, Decarli et al. 2012, ApJ, 752, 2 “ALMA reveals a chemically evolved submillimeter galaxy at z=4.76” Nagao et al. 2012, A&A, in press (arXiv: )

Ionized atomic lines Forbidden atomic fine structure transitions: important cooling lines of ISM [CII] 2 P 3/2 - 2 P 1/2 at 158 μm: “now routinely measured” – Ionization potential 11.3 eV (< 13.6 eV of H)  a tracer for both the neutral atomic and ionized medium (predominantly PDRs) – Very strong ! ( % of L(FIR))  easier detection than CO  better for high-resolution imaging (for kinematics) [NII] 122μm, 205μm (13.6 eV) [OIII] 52μm, 88μm (14.5 eV) Critical densities of [NII]205μm and [CII]158μm: very similar (40-50 cm -3 at 8000K)  insensitive to gas density  N/C abundance ratio measurements (Matteucci & Padovani 1993; see also Nagao et al. 2012, A&A, in press) )  ionized medium

[CII] at z=7.084 quasar J Venemans et al. 2012, in press (avXiV: ) PdBI 235 GHz continuum  L(FIR) = 6x10^11 – 2x10^12 Lo, M(dust) = 7x10^7 – 6x10^8 Mo !!!

[CII] at HDF850.1 at z=5.18 VLA 37GHz PdBI 307 GHz PdBI 112 GHz PdBI 93 GHz L[CII] = 1.1x10^10 Lo L(FIR) = (6.5±1) x 10^12 Lo  L[CII]/L(FIR) ~ 2 x 10^-3 M(dust) = (2.8±0.5) x 10^8 Mo Walter et al. 2012, Nature, 486, 233

[NII] 205μm lines in galaxies Milky Way (with FIRAS/COBE; Wright et al. 1991) Galactic HII regions: G (Colgan et al. 1993), DR21 (White et al. 2010), Carina (Oberst et al. 2006) Galaxies: NGC 1097 (Beirao et al. 2010, Garcia-Carpio et al. 2011) Upper limits on high-z systems … Two detections of [NII]122μm: SMMJ (z=2.81) and Cloverleaf (z=2.56) (Ferkinhoff et al. 2011, ApJ, 740, L29) 1 st (firm) detection of [NII] 205μm : HLSJ at z=5.2 (Combes et al. 2012, A&A, 538, L4)

Observations PdBI `band 4’ receiver: GHz (a small gap at GHz due to atmosphere)  [NII] 205μm in 2.85 < z < 4.27 APM : 5 antennas, compact config., 4.5 hours on-source. MM : 6 antennas, compact and extended configs., 10 hours on-source. Tsys 150 – 350 K 1 σ ~ 3.4 mJy and 2.4 mJy, respectively (dv~20km/s)

[NII] 205μm detections at high-z galaxies (PdBI) Decarli et al. 2012, ApJ, 752, 2 z=5.243 Combes et al. 2012, A&A, 538, L4 CO(6-5) flux ~ 7 mJy CO(6-5) flux ~ 33 mJy [NII]205/CO(6-5) luminosity ratio ~ 2.3+/-0.3 SO 2 [NII]205/CO(6-5) luminosity ratio ~ 1.5+/- 0.4

MM maps 1mm continuum (uniform weight) [NII]205μm Natural weight Continuum subtracted [NII]205μm blue and red 1mm Cont. (contour) CO(2-1) color Black: 1mm White: [NII]

[NII]205um vs CO [NII]205μm/CO(6-5) luminosity ratios – – Very similar to DR21 (1.26+/-0.35), M82 (1.68+/- 0.05), and Mkn 231 (~1.2) [!]  KK comment: not very different even for AGN! Spatially resolved [NII] = ionized gas, 1mm = FIR, and CO  good correlation ΣFIR ∝ ΣCO^1.4±0.2 Spatially resolved star-formation law at z=3.9 !!

[NII]/L(FIR) ratios in galaxies Decarli et al. 2012, ApJ, 752, 2 [NII]122/205μm luminosity ratio of 5 is assumed If 122μm line is not available

Nagao et al. 2012: Introduction Metallicity in galaxies: powerful diagnostic for testing galaxy evolutionary models Rest-frame optical metallicity diagnostics: – not applicable to z>4 – not reliable for dusty objects ULIRGs show systematically lower metallicities than expected from the mass-metallicity relation (Rupke et al. 2008; Caputi et al. 2008) !?  just tracing outer, less enriched regions. High dust mass in these galaxies: disagrees with the metallicity from optical diagnostics (Santini et al. 2010)

ALMA observations Target: a luminous SMG LSS J – at z=4.76 ALMA band 6, 18 antennas, compact config., total obs time = 3.6 hours (3 separated runs, 1.2 hours each) F_obs = GHz ([NII]205 in USB) Bandwidth 1875 MHz PWV = 3-5mm for 1 st run, 1-2mm for 2 runs 1σ~0.3 mJy (?) for dv=41 km/s

ALMA detection of [NII] 205μm toward a SMG at z=4.76 Flux density in mJy Nagao et al. 2012, A&A, in press ( ) Continuum = 3.5±0.1 Chemically inhomogeneous?

AGN contribution?  not significant High-J CO is sensitive to XDRs No CO(12-11) was detected. CO(12-11)/CO(2-1) flux ratio < 3.8  inconsistent to the CO SED of APM i.e., AGN contribution to the heating and excitation is not significant. Agree with the [CII] results: XDR contribution to the [CII] 158μm is only 1.3%, based on the absorption-corrected L(2-10keV) = 2.5x10^44 erg/sec (Gili et al. 2011) and a scaling relation of L[CII], AGN = 2x10^-3 L(2-10keV)

Combes et al. 2012, A&A, 538, L4 A lensed Herschel source at z=5.2 including [NII] 205μm detection Red component  AGN? Blue component  Ionized gas wind?