The HI Universe: The ALFA and the Omega(HI) Patricia Henning Cosmic Web: galaxies and the large-scale structure Socorro NM, 16 May 2008

HI surveys – the past HI Parkes All Sky Survey - HIPASS (2004; Meyer, Zwaan et al.) 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, – 12,700 km/s –280 galaxies with log M HI < 8.5 in south

Meyer et al. 2004

A deeper southernhemisphere Galactic plane survey

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

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

ALFA surveys Arecibo Legacy Fast ALFA Survey - ALFALFA Arecibo Legacy Fast ALFA Survey - ALFALFA –Ongoing, planned 7000 deg 2 of high-galactic latitude Arecibo sky –~2.2 mJy per 3.5 arcmin beam, at 10 km/s velocity resolution –100 MHz BW, – 18,000 km/s (+ new broad-band spectrometer?) –30,000 expected detections in ~5 years, to z=0.06, hundreds of objects to HI mass to 10 8

Wedge plot of 2700 HI sources detected with ALFALFA (with 7.5% of survey) Wedge plot of 2700 HI sources detected with ALFALFA (with 7.5% of survey) Z=0.05

ALFA Surveys (cont) Arecibo Galaxies Environment Survey - AGES Arecibo Galaxies Environment Survey - AGES –Ongoing, planned 200 deg 2 total on 13 selected areas (Virgo, groups, individual gals, filaments, Local Void) –~0.8 mJy per 3.5 arcmin beam (300 vs. 40 sec per beam), at 10 km/s velocity resolution –Will find low-mass galaxies to larger distances, but not as large-angle survey

Sky dist. and HI mass vs. distance for 100 HI sources in AGES Abell 1367 region sample (Cortese et al.). Solid line detection limit S/N=6.5, W=200 km/s, dotted line same for ALFALFA, dashed HIPASS Sky dist. and HI mass vs. distance for 100 HI sources in AGES Abell 1367 region sample (Cortese et al.). Solid line detection limit S/N=6.5, W=200 km/s, dotted line same for ALFALFA, dashed HIPASS

ALFA Surveys (cont) Arecibo Ultra-Deep Survey – AUDS Arecibo Ultra-Deep Survey – AUDS –Strategy: very long integration time on small patches of sky –~1000 hours on 0.36 square degree field, 75 hours/beam, few x10 8 M 0 at z=0.16 –Stats should be sufficient to discriminate strong evolution vs. no-evolution scenario –Done precursor obs, not full sensitivity survey yet

More science goal for AUDS –The cosmic web (reach ~10 16 cm -2 per 5 km/s channel, gas filling beam) –Low column density gas in the local Universe –Extragalactic OH megamaser emission –Extragalactic HI absorption

The ALFA ZOA survey –Map obscured galaxies, large-scale structures at low Galactic latitude –Provide redshifts for partially-obscured galaxies, particularly 2MASS for all-sky flow fields –Two phases: shallow (5 mJy), deep (1 mJy) –Deep survey will have ~sensitivity of AGES over ~2-4 times sky area, HIMF study over “fairer” volume

Delphinus void Local void Cygnus void Microscopium void Pisces-perseus supercluster A539 A569 Orion void? Gemini void Canis Major void Puppis filament

–Define edges of the Gemini, Canis Major, Microscopium, and Cygnus voids –Determine reality of Orion void –Confirm/Refute connection between A539 and A569 –Probe newly-discovered nearby Monoceros filament –Study HI in variety of densities, survey region not selected by LSS

ALFA ZOA survey status –Survey began May Hundreds of hours, starting in inner Galaxy, ~1000 square degrees –Have completed two small, shallow “precursor” regions (38 sq deg near l=40, 100 sq deg near l=190)

Inner Galaxy: 10 galaxies detected, only 1 has a cataloged counterpart in any other waveband (IR) 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 Outer Galaxy: 62 galaxies detected, 49 have counterparts 25 previous redshifts

Beyond ALFA Current generation ALFA surveys will yield ~several x 10 4 galaxies to z~0.1, will characterize the local HI mass function very well. (Arecibo capable of going deeper, but confusion issues for high z, especially for blind surveys – beam about size of a cluster at z=0.25) Current generation ALFA surveys will yield ~several x 10 4 galaxies to z~0.1, will characterize the local HI mass function very well. (Arecibo capable of going deeper, but confusion issues for high z, especially for blind surveys – beam about size of a cluster at z=0.25) HI detection beyond z = 0.1 has been achieved eg. z=0.28 with AO (Catinella et al.) also z=0.2 WSRT (Verheijen et al.) and z=0.24 in aggregate sense with GMRT (Lah et al.) HI detection beyond z = 0.1 has been achieved eg. z=0.28 with AO (Catinella et al.) also z=0.2 WSRT (Verheijen et al.) and z=0.24 in aggregate sense with GMRT (Lah et al.)

Neutral gas density in Universe (from Lah et al. 2007). z=0 triangle is from HIPASS, large triangle is GMRT measurement. High redshift points come from damped Ly-  measurements. Consistent with constant! (note uncertainty in redshift range z = 0.1 – 1.5, corresponding to 2/3 age of Universe) Neutral gas density in Universe (from Lah et al. 2007). z=0 triangle is from HIPASS, large triangle is GMRT measurement. High redshift points come from damped Ly-  measurements. Consistent with constant! (note uncertainty in redshift range z = 0.1 – 1.5, corresponding to 2/3 age of Universe)

Cosmic star formation history (Panter et al. 2007) Cosmic star formation history (Panter et al. 2007) Want record of HI over redshift with large evolution in SFR – where, how, is gas going to stars? Want record of HI over redshift with large evolution in SFR – where, how, is gas going to stars?

The next step A Goal: Evolution of HIMF. Most of the action should be between z=0-1, M HI =(0.4 – 4) x 10 9 M sun (vd Hulst et al. 2004) A Goal: Evolution of HIMF. Most of the action should be between z=0-1, M HI =(0.4 – 4) x 10 9 M sun (vd Hulst et al. 2004) Predicted evolution of HIMF in hierarchical picture (Baugh et al. 2004). Dots are measured z=0 (Zwaan 03). Lines are predictions: solid z=0, dotted z=1, dashed z=3, dot-dashed z=4

Square Kilometer Array pathfinders E.g. ASKAP, MHz, with strawman 30 12m dishes with PAF, upgrade/expansion to 45. E.g. ASKAP, MHz, with strawman 30 12m dishes with PAF, upgrade/expansion to sigma detections for all southern- hemisphere, “shallow” (1 yr) survey strawman, expansion FOV 30 deg 2 – depends on success of PAF technology - N=600,000 Z=0.05 Johnston et al. 2007

ASKAP (cont.) Similar simulation for a deep (1 yr) single pointing, N= 100,000 Z=0.2 Johnston et al. 2007

New pathfinders include ATA – currently ATA-42, 6m dishes, FoV 2.45 deg at 21cm. Full array could do deep HI ATA – currently ATA-42, 6m dishes, FoV 2.45 deg at 21cm. Full array could do deep HI MeerKAT – design decisions ongoing, aim 80 12m dishes, single pixel feeds MeerKAT – design decisions ongoing, aim 80 12m dishes, single pixel feeds APERTIF/WSRT – developing FPA on WSRT, 25x FOV, 2x BW of current WSRT APERTIF/WSRT – developing FPA on WSRT, 25x FOV, 2x BW of current WSRT FAST – 500m dish, significant funding, design developing FAST – 500m dish, significant funding, design developing

What’s next? Next science step must be significant, or not worth funding Next science step must be significant, or not worth funding Big step forward could be HIMF to z=1 Big step forward could be HIMF to z=1 Want SB sensitivity, but also want resolution to assign proper HI mass (e.g. at z=1, 20”=160 kpc, 5 km baseline) Want SB sensitivity, but also want resolution to assign proper HI mass (e.g. at z=1, 20”=160 kpc, 5 km baseline)

10% SKA At z=1, reach 3.6 x 10 9 M sun in 360 hours, 2.1 x 10 9 M sun in 1000 hours (Draft Phase I science case) But descope??? At z=1, reach 3.6 x 10 9 M sun in 360 hours, 2.1 x 10 9 M sun in 1000 hours (Draft Phase I science case) But descope??? To reach 5 x 10 8 M sun ~750 day survey with 10% SKA. Long time, but worthwhile To reach 5 x 10 8 M sun ~750 day survey with 10% SKA. Long time, but worthwhile If few pointings, long time, then prefer large FoV (of course) If few pointings, long time, then prefer large FoV (of course)

Key Science Project for the full SKA – 10 9 HI galaxies to z=1.5, for galaxy evolution, Cosmology (BAO) Key Science Project for the full SKA – 10 9 HI galaxies to z=1.5, for galaxy evolution, Cosmology (BAO)

Timescales, Questions ALFA surveys complete ~5 years, new pathfinders underway ALFA surveys complete ~5 years, new pathfinders underway Connection to multi-  large optical/IR surveys (e.g. LSST) going concerns in the 2010’s, time will be ripe for deep HI surveys Connection to multi-  large optical/IR surveys (e.g. LSST) going concerns in the 2010’s, time will be ripe for deep HI surveys When/how do we best join forces with international community given US funding realities? Timescales plausible? SKA must be capable instrument…Descope troubling… When/how do we best join forces with international community given US funding realities? Timescales plausible? SKA must be capable instrument…Descope troubling… Coordinate with other SKA-mid science/tech issues: mid-freq Radio Synoptic SKA Coordinate with other SKA-mid science/tech issues: mid-freq Radio Synoptic SKA