COSMOS Team Meeting ‘10 | June 10, 2010

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

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

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

4. 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

5. ULIRGs: LIR > 1012 L☉ SFR > 100 M☉/yr median 〈qTIR〉 〈qTIR〉 ∝ (1+z)-0.01±0.06 After compensating for selection biases - NO evolution at z < 2 (implies B ~50 G). redshift Evolution of the brightest IR-emitters Sargent+ (‘10b) • 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)

6. normalization of starburst template SEDs adopted from direct detections Alex’ hard work Expected evolution of q70 for galaxies with IR dust SEDs similar to local galaxies Evolution of less extreme starbursts Sargent+ (‘10d), in prog. No differing behaviour between stacked and high(er) luminosity samples! q70, obs. increasing stellar mass redshift • 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)

7. At z < 1.5: many (optically classified) AGN have the same IR/radio ratios as star-forming galaxies. ➠ ➠ At 2.5 < z < 5:〈qTIR〉= 2.71+0.09, consistent with local average. -0.14 ➠ Analytical prediction of offset between IR- and radio-selected samples, qbias = ln(10) [-1] 2, (e.g. Kellermann ‘64; Condon ‘84)can reconcile discrepancies in the literature. 〈q〉IR-sel. > 〈q〉radio-sel. Other IR/radio miscellanea… (Sargent+ ‘10a)

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

9. ‘real’ distant disk galaxies redshifted local disk galaxies q = b/a blue-band surface brightness brighter face-on edge-on 1 - cosine(inclination angle) Attenuation vs. inclination At z~0.7: less va-riation between the average sur-face brightness of face-on and edge-on, large disk galaxies. • 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… • 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

10. 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 available @ IRSA and published as Schinnerer+ ‘10, ApJS, 188, 384

11. rms ~30 Jy Final VLA-COSMOS Joint catalog (irsa.ipac.caltech.edu/data/COSMOS/tables/vla/… …vla-cosmos_dp_sources_20100504.tbl) • central 1 deg2 (seven pointings) re-imaged for additional 8.3 hr each • 2865 sources with S/N > 5 • 1.4 GHz maps @ resolution 1.5” & 2.5” available • rms at field centre ~10 Jy • 1/3 spectroscopically followed-up (pre 20k) • catalog paper accepted to ApJS • Counterpart searches ➠ use new Joint catalog • Statistical studies requiring flux-limited samples ➠ use revised Large • Project catalog