Probing galaxy assembly and evolution through neutral hydrogen studies

1. Probing galaxy assembly and evolution through neutral hydrogen studies Patricia (Trish) Henning University of New Mexico 2010 SKA SA Project Postgraduate Bursary Conference Stellenbosch, 2 December 2010

2. Galaxy formation, evolution • A major unsolved problem in astrophysics: how does a galaxy accrete baryons, and subsequently form stars? • Simulations unable to comprehensively represent gas physics, reproduce galaxies • Observations just beginning to detect star formation fuel over range of redshifts and environments

3. Major and minor mergers? • Smooth accretion from IGM? • “Hot mode” Shock-heat, form diffuse hot halo component • “Cold mode” Cold, filamentary accretion • What happens when, where, to which galaxies? Fig from D. Keres

4. HI observations reveal evidence of ongoing interactions/accretion of cold gas • Extraplanar gas: disk-halo flow, also cold accretion? Sancisi et al. 2008

5. 220 kpc HI traces “environmental impact” • How do galaxies gain and lose gas? • Infall vs. removal processes • Gas serves as a tracer of interactions Bauermeister & Blitz NGC 4254 Arecibo Chung et al.

6. What we need to know • the evolution of the HI content of galaxies from z~2 to z=0 • the accretion of gas onto galaxies • the complete census of HI clouds/emission in the halos of galaxies arising from the condensation of hot gas • the effect of environment • fine scale structure of the ISM in star-forming galaxies •  HI surveys are far behind our O/IR colleagues in size, depth, resolution

7. HI surveys – the past • HI Parkes All Sky Survey - HIPASS (2004; Meyer, Zwaan et al.) • All southern hemisphere, plus northern extension to Dec = +25 deg • 5300 galaxies over 70% of sky • sensitivity 13 mJy per 15 arcmin beam, at 18 km/s velocity resolution • 64 MHz BW, -1280 – 12,700 km/s • 280 galaxies with log MHI < 8.5 in south

8. HIMF for 4315 southern HIPASS sources • Omega(HI), using HI emission, 3.5 x 10-4 Zwaan et al. 2005 Meyer et al. 2004

9. ZOA project focused on low-Galactic latitude sky GA: l ~ 300o – 340o H-A filament: ~280o Puppis filament: ~240o Local, Sag voids: ~350o – 52o New filament ~220o

11. New New Part of Norma SC PKS1343 cluster New Puppis void Puppis Hydra wall and Monoceros extension

12. Extragalactic Arecibo L-band Feed Array (ALFA) Surveys • Arecibo Legacy Fast ALFA (ALFALFA) Team leaders: Giovanelli, Haynes (Cornell) • Arecibo Galaxy Environments Survey (AGES) Team leader: Davies (Cardiff) • ALFA Ultra-Deep Survey (AUDS) Team leader: Freudling (ESO) • Zone of Avoidance Survey (ALFA ZOA) Team leader: Henning (UNM)

13. ALFALFA Team: 87 names, see ALFALFA website • Arecibo Legacy Fast ALFA Survey • 7000 deg2 high-galactic latitude Arecibo sky • ~2.2 mJy per 3.5 arcmin beam, at 10 km/s velocity resolution • 100 MHz BW, -1600 – 18,000 km/s • ~30,000 expected detections in ~5 years, to z=0.06, hundreds of objects to HI mass to 108

14. ALFALFA science goals • A legacy survey: HI in the Nearby Universe • The HI Mass Function and the “Missing Satellite Problem” • Galaxy evolution and dynamics within local large scale structures • Extent and origin of HI disks • Nature of High Velocity Clouds • Blind survey for HI absorbers z < 0.06 • Blind survey for OH megamasers 0.16 < z < 0.25 • Comparison with other surveys

15. Catalogs, maps of selected regions published, more appearing • No cosmologically important pop of dark, HI galaxies (clouds in Virgo likely remnants of interactions) • HIMF with 40% sample: consistent with HIPASS, ΩHI 16% larger Kent et al. 2009 Z=0.05 2700 HI sources plotted with 7.5% of survey, much more has been done 40% ALFALFA HIMF, Martin et al. 2010

16. Arecibo Galaxies Environment Survey Davies, Auld, Baes, Bothun, Boselli, Brinks, Brosch Catinella, Cortese, de Blok, Disney, Gavazzi, Giovanelli, Haynes, Henning, Hoffman, Irwin, Karachentsev, Kilborn, Linder, Minchin, Momjian, Muller, O’Neil, Putman, Rosenberg, Sabatini, Schneider, Scott, Spekkens, van Driel • Study HI properties in different environments to lower mass limits than ALFALFA (5 x 106 MSun at Virgo vs. 2 x 107 MSun), low NHI (3 x 1018 cm-2) • HIMF in various environments • Spatial distribution of HI-selected objects • Low mass, low NHI objects, and low- NHI extent of large objects • HVCs • Omega(HI) • Signatures of mergers and interactions (tidal features), relation to galaxy formation simulations

17. #distinct vols sampled • Simulation showing two surveys, equal total time, roughly same relative integration times of ALFALFA (red), and AGES (blue) • Shallower detects more sources, deeper detects lower mass sources at all distances • ALFALFA excellent probe of high-mass end of HIMF, but deeper surveys critical for low-mass end of HIMF in environments beyond Local Supercluster Schneider et al. 2008

18. AGES • 200 deg2 total on 13 selected areas (Virgo, groups, individual gals, filaments, Local Void, also background volumes) • ~0.8 mJy per 3.5 arcmin beam (300 vs. 40 sec per beam), at 10 km/s velocity resolution • Finds low-mass galaxies to larger distances, (eg. 5 x 106 MSun at Virgo, 5 x 107 out to 3 times this distance) but not as large-angle survey Auld et al. 2006

19. A1367 and outskirts, 5o x 1o strip • 100 HI detections (Cortese et al. 2008), 79 new. Solid line detection limit S/N=6.5, W=200 km/s, dotted line same for ALFALFA, dashed HIPASS HI does not show rich cluster red is SDSS g < 17 mag (Lg > 2 x 109 LSun)

20. NGC 7332/7339 pair: 2 HI dwarfs discovered, have optical counterparts (5 total dwarfs) MHI 7 x 107 MHI/Lg 0.13+-0.01 MHI 5 x 107 MHI/Lg 2.0+-0.2 Minchin et al. 2010

21. NGC 1156 • D=7.8 Mpc (Karachentsev et al.) isolated, no cataloged companion within 10 deg • AGES: MHI = 1 x 109 MSun, and new dwarf 25 arcmin away, MHI = 1.6 x 106 MSun , counterpart on DSS Minchin et al. 2010

22. Total co-moving volume 24,000 Mpc3: 82 galaxies, 45 new discoveries, few previously known redshifts Two sheets LSS Known voids HI mass versus distance with SNR = 5, cp. ALFALFA (dotted) Red for NGC 1156 region, black NGC 7332/7339 region Minchin et al. 2010

23. AGES Virgo fields Rhys Taylor thesis, Cardiff

24. HI dets outlined in blue, Non-dets in red, VC1 Blue background, Red VC members • No dark galaxies • 30% of HI detections not in optical VCC. Small, faint, blue • 21 new detections vs. 270 VCC galaxies • Detected S0’s fainter, redder, less gas than S, show some structure, transition region CMD, evolved by gas loss? • Detected dE’s comparable MHI/L to dIrr’s – recently accreted? • Virgo still assembling, gas-rich dwarfs interspersed with HI-deficient giant spirals • No direct evidence of stripped gas (stacking) <5 x 1017, ionized?

25. The ALFA Ultra-Deep Survey AUDS Freudling, Brinks, Brosch, Catinella, Conselice, Davies, de Blok, Kilborn, Linder, Masters, Meyer, Minchin, Momjian, O'Neil, Pisano, Quinn, Rosenberg, Spekkens, Staveley-Smith, van Driel, Zwaan  0.36 square degrees • 2 fields, 1 within AGES NGC 2577 survey, 1 random at ra=17, dec=20 “drift & chase”: repeated drift scans, 1000 hours200 MHz => 0 < z < 0.16sensitivity 50 Jy corresponds to a few 109Mprecursor program of 60 hours demonstrated feasibility Cold Gas Evolution

26. Precursor observations detected 18 galaxies between z = 0.07 – 0.15 Freudling et al. 2010

27. Result: detection rate consistent with z=0 HIMF Green solid line: local HI mass function. Dashed is corrected for overdensity of SDSS volume. Solid points = all detections Open points = high quality detections ρHI (z=0.125) = 1.0 ± 0.3 ρHI (z=0) Freudling et al. 2010

28. ALFA Zone of Avoidance • Henning, McIntyre, Day, Springob, Minchin, Momjian, Catinella, Muller, Koribalski, Masters, Pantoja, Putman, Rosenberg, Schneider, Staveley-Smith, van Driel • Obscuration due to dust, high stellar density of MW blocks optical Universe over ~20% of sky • 2MRS retains ZOA of several deg width in outer Galaxy, tens of deg in inner Galaxy, forcing statistical treatment of missing data for reconstruction of density and velocity fields • Misalignment CMB dipole vs. 2MASS flux-weighted dipole, evidence for unmapped mass, esp. behind inner Galaxy • Goal: Map hidden galaxies, LSS in HI • Those with NIR counterparts – provide z, Tully-Fisher, flow fields • Done commensally, with Galactic ALFA and Pulsar ALFA

29. Precursor results Precursor: 38 deg2 near l=40, 100 deg2 near l=190 (Henning et al. 2010) Inner Galaxy: 10 galaxies detected, only 1 has a cataloged counterpart in any other waveband (IR) Outer Galaxy: 62 galaxies detected, 49 have counterparts 25 previous redshifts LSS in outer Galaxy – concentration at l ~ 183o, b ~ -10o, between 5000-6000 km/s (~5hr), lies near Orion concentration and feature “C5” in 2MRS density field reconstruction (Erdogdu et al. 2006). Voids evident. Full survey of AO ZOA underway, expect thousands of galaxies!

30. Beyond ALFA • Current generation ALFA surveys will yield ~several x 104 galaxies to z~0.1, will characterize the local HI mass function very well. • HI detection beyond z = 0.1 has been achieved: • direct at z=0.2+ with WSRT (Verheijen et al.), AO (Catinella et al.) • Stacking at z=0.24, 0.37 with GMRT (Lah et al.), z=0.8 with GBT (Chang et al. 2010).

31. The action at high z • Star formation rate has evolved dramatically since z~1 • Predictions of smaller evolution of cold gas content z < 2 due to self-regulated equilibrium between net gas inflow and SF • Want detailed account of HI over redshift with large evolution in SFR – where, how, is gas going to stars? Hopkins & Beacom 2006 Noterdaeme et al .2009

32. Progress: existing/upgraded,new facilities • Existing/upgraded/new facilities • WSRT/APERTIF, FPA on WSRT, 8 deg2 FOV, 300 MHz BW • EVLA, z=0-0.5 • GMRT, GBT stacking • AO, a 10% SKA in area, niche local-intermediate z, confusion an issue at high z: beam about size of a cluster at z = 0.25. AO40 • ATA, 42 6m dishes, FoV 2.5 deg at 21cm. • FAST • New interferometers – SKA precursors • MeerKAT • ASKAP • Ultimately, SKA

33. MeerKAT • 64 13.5m dishes, single pixel feeds • Majority of dishes within 1 km, others to 8 km (+spur?) • Primary beam ~1o • 0.9 – 1.75 GHz initially, 0.6 – 2.5 GHz (+high freq) later, 30 K • HI Niche: sensitivity, resolution • Approved projects include • MeerKAT ultradeep HI, 5000 hours. Direct detection to z~0.5, stacking z~1 (Blyth, Holwerda, Baker +team) • sensitive nearby galaxies survey, 6000 hours. 30 galaxies to NHI ~ 1019 (30”), 5x1017 (90”) (de Blok + team) • Much more on this tomorrow from Blyth and de Blok!

34. Z=0.05 • Australian SKA Pathfinder (ASKAP) • 36 12-m antennas • 700-1800 MHz • Max baseline 6 km • PAFs: FOV 30 deg2 • Approved projects include: • Widefield ASKAP L-band Legacy All-sky Blind SurveY (Koribalski, Staveley-Smith + team) • -90o < Dec < +30o • Typical depth z=0.05, massive galaxies to z = 0.15 • ~500,000 detections • Deep Investigations of Neutral Gas Origins (Meyer + team) • 150 deg2 deep field (z<0.29), 60 deg2 ultradeep (z<0.4), (GAMA region; spectroscopy, imaging from UV-IR) • ~105 HI sources for 7500 hrs of combined observing time Johnston et al. 2007 Baseline, Upgrade Z=0.2

35. Square Kilometer Array • Existing and near-term facilities will push to intermediate z, do pathfinding science work for ultimate deep, hi-res SKA surveys • HI at cosmological distances original driver toward ~1 km2

36. Halo clouds beyond Virgo, discriminate between modes of cold gas accretion, and any HI beyond z=1 requires SKA • MW to z~1.5 in all-sky survey, to z~2-3 in deep survey SKA DRM

37. Angular resolution: eg. 2” corresponds to ~15 kpc at z=2 (60 km baseline at 500 MHz), exquisite detail in local Universe • Connection to multi-l: large optical/IR surveys going concerns in the coming years, time will be ripe for deep HI surveys • Today, surveys of HI in galaxies in infancy cp to large optical surveys. With SKA, bring HI picture to maturity Thanks!