q COSMOS Team Meeting ‘10 | June 10, 2010 Properties The ISM Properties of distant star-forming galaxies as constrained by the parameter (in its various guises) M. Sargent (MPIA) & you I.update on the (on-going) IR-radio relation work II.disk galaxy opacity at z ~ 0.7 III.final VLA-COSMOS Joint Catalog I.update on the (on-going) IR-radio relation work II.disk galaxy opacity at z ~ 0.7 III.final VLA-COSMOS Joint Catalog

June 3, Intro Radio & 60  m luminosity functions of galaxies in the IRAS 2 Jy-sample (Yun+ ‘01) : starbursts field galaxies ‘monsters’ Common link due to life cycle of massive stars: Non-thermal radio (synchrotron) emission and, in the IR, re-radiated UV light.

June 3, q = log(S IR /S radio ) 1.5 kpc regions in individual SINGS galaxies (Murphy+ ‘06) … and the transition to integrated IR/radio flux ratios (Yun+ ‘01) Intro - local galaxies (II) log(FIR flux [Wm -2 ]) log(1.4 GHz flux [mJy]) radio-loud AGN ‘regular’ star-forming galaxies nascent starbursts Early IRAS results, integrated IR/radio flux (Helou+ ‘85) :

June 3, Intro - Reasons to study the evolution Calibration of radio continuum emission as a star formation tracer in distant galaxies (see Alex’ talk!) Does or doesn’t the IR-radio relation evolve with redshift (see somewhat ambiguous results in the literature) ? Changes in the correlation due to (understandable) external factors could shed light on: - the physical processes shaping the relation (also at low-z) - state of the ISM (magnetic fields, intensity of UV radiation field, dust absorption) “…for the […] galaxies studied here, luminosity extrapolations based on the radio emission are considerably more reliable than those based on the mid-IR emission” (Magnelli+ ‘10) - the calculation of SFRs is affected less by uncertain radio spectral indices than by a sparsely sampled IR-SED - interferometric radio observations have a high spatial resolution, aiding the correct identification and attribution of flux to (multi- ) counterparts

June 3, Evolution of the brightest IR-emitters volume-limited sample of ULIRGs (rather than comparing most strongly starbursting systems at high z with mixture of high & low luminosity systems at low z) IR/radio non-detections included with survival analysis probabilistic (using rest-frame optical colours) classification into SFGs/AGN (cf. Smolčić+ ‘08) redshift median 〈 q TIR 〉 ULIRGs: L IR > L ☉ SFR > 100 M ☉ /yr After compensating for selection biases - NO evolution at z < 2 (implies B ~ 50  G). 〈 q TIR 〉 ∝ (1+z) -0.01±0.06 Sargent+ (‘10b)

1.4 GHz image stacks of reach rms noise of ~ 400 nJy thanks to 100s of sources in each mass/redshift bin -> statistical detections of LIRG luminosities out to z ~ 3 Sample based on 3.6  m IRAC detections in COSMOS field (cf. Sanders+ ‘07, Ilbert+ ‘09) -> expect unbiased estimate of average IR/radio ratios (as sample not IR- or radio-selected) Actively star forming galaxies selected with (NUV-r) colours (cf. Ilbert+ ‘09) Evolution of less extreme starbursts increasing stellar mass No differing behaviour between stacked and high(er) luminosity samples! normalization of starburst template SEDs adopted from direct detections redshift q 70, obs. Expected evolution of q 70 for galaxies with IR dust SEDs similar to local galaxies Sargent+ (‘10d), in prog. Alex’ hard work

June 3, Other IR/radio miscellanea… (Sargent+ ‘10a) 〈 q 〉 IR-sel. > 〈 q 〉 radio-sel. Analytical prediction of offset between IR- and radio-selected samples,  q bias = ln(10) [  -1]  2, (e.g. Kellermann ‘64; Condon ‘84) can reconcile discrepancies in the literature. ➠ At z < 1.5: many (optically classified) AGN have the same IR/radio ratios as star- forming galaxies. ➠ ➠ At 2.5 < z < 5: 〈 q TIR 〉 = , consistent with local average

June 3, The Effects of Dust… Parametrization of average variation of surface brightness with inclination due to dust attenuation: Driver+ (‘07) opacity increase surface bright- ness increase z ~ 0.7 z~0z~0 Sargent+ (‘10c)

June 3, q = b/a 1 - cosine(inclination angle) blue-band surface brightness Attenuation vs. inclination ‘real’ distant disk galaxies redshifted local disk galaxies brighter face-on edge-on low-z reference galaxies (from Kampczyk+ ‘07) show expected (cf. Möllenhoff+ ‘06; Driver+ ‘07) surface brightness variations also once redshifted; distant galactic disks behave as if (nearly perfectly!) optically thick… At z ~ 0.7: less va- riation between the average sur-face brightness of face- on and edge-on, large disk galaxies. Scant evidence for different extinction laws in distant galaxies (e.g., Calzetti+ ‘01; Conroy+ ‘10), a different distribution of attenuating material seems a likely explanation Correction relative to face-on ‘homogenizes’ population but does not provide the re-sidual face-on attenuation ➠ interpret shape of inclination-dependence with dust models

June 3, Summary Evolution of the IR-radio relation: No compelling evidence for an evolution of the IR-radio relation out to high redshift, also in luminosity ranges in which the observation of evolution would not have been a surprise… The understanding/awareness of selection effects is essential for the derivation of the correct (non-)evolution Many optically-selected AGN at z < 1 have similar IR/radio ratios as star forming galaxies Inclination-dependent attenuation in disk galaxies at z ~ 0.7: Blue light escapes high- and low-z disk galaxies with a different (3D-)angular emission pattern, suggesting a different distribution of attenuating material Plus…: final VLA-COMOS Joint (source catalog from survey components ‘Large’ & ‘Deep’) catalog is IRSA and published as Schinnerer+ ‘10, ApJS, 188, 384

June 3, Final VLA-COSMOS Joint catalog (irsa.ipac.caltech.edu/data/COSMOS/tables/vla/… …vla-cosmos_dp_sources_ tbl) central 1 deg 2 (seven pointings) re-imaged for additional 8.3 hr each 2865 sources with S/N > GHz resolution 1.5” & 2.5” available rms at field centre ~ 10  Jy 1/3 spectroscopically followed-up (pre 20k) catalog paper accepted to ApJS rms ~ 30  Jy Counterpart searches ➠ use new Joint catalog Statistical studies requiring flux-limited samples ➠ use revised Large Project catalog