Neutral Hydrogen Gas in Abell 370 a Galaxy

Neutral Hydrogen Gas in Abell 370, a Galaxy Cluster at z = 0. 37 Philip Lah NCRA 17 th July 2008

Collaborators: Jayaram Chengalur (NCRA) Michael Pracy (ANU) Frank Briggs (ANU) Matthew Colless (AAO) Roberto De Propris (CTIO)

Giant Metrewave Radio Telescope

Talk Outline Introduction • evolution in clusters & star formation rate density vs redshift • HI 21 -cm emission & the HI coadding technique • review of current HI measurements at z > 0. 1 Abell 370, a Galaxy Cluster at z = 0. 37 • HI in Abell 370 • star formation in Abell 370 • two unusual radio continuum objects around Abell 370 Future Observations with SKA pathfinders • using ASKAP and Wiggle. Z • using Meer. KAT and z. COSMOS

Evolution in Galaxy Clusters

Galaxy Cluster: Coma

$Butcher-Oemler Effect increasing fraction of blue galaxies in clusters with redshift nearby clusters neutral$

Butcher-Oemler Effect increasing fraction of blue galaxies in clusters with redshift nearby clusters neutral hydrogen gas deficient

The Cosmic Star Formation Rate Density

SFRD vs z Hopkins 2004

HI Gas and Star Formation Neutral atomic hydrogen gas cloud (HI) molecular gas cloud (H 2) star formation

Neutral Atomic Hydrogen (HI) 21 -cm Emission

Neutral atomic hydrogen creates 21 cm radiation proton electron

Neutral atomic hydrogen creates 21 cm radiation

Neutral atomic hydrogen creates 21 cm radiation photon

Neutral atomic hydrogen creates 21 cm radiation

HI 21 cm Emission at High Redshift

HI 21 cm emission at z > 0. 1 • single galaxy at z = 0. 176 WSRT 200 hours (Zwaan et al. 2001, Science, 293, 1800) • single galaxy at z = 0. 1887 VLA ~80 hours (Verheijen et al. 2004, in IAU Symposium Vol 195, p. 394) • two galaxy clusters at z = 0. 188 and z = 0. 206 WSRT 420 hours 42 galaxies detected HI gas masses 5 109 to 4 1010 M (Verheijen et al. 2007, Ap. JL, 668, L 9) • galaxies with redshifts z = 0. 17 to 0. 25 observed with Arecibo detected 26 from 33 observed HI gas masses (2 to 6) 1010 M (Catinella et al. 2007, in IAU Symposium Vol 235, p. 39)

HI 21 cm emission at z > 0. 1 • our group using the GMRT measured the coadded HI signal from 121 star forming galaxies at z = 0. 24 (look-back time ~3. 8 Gyr) GMRT ~48 hours on field weighted average MHI = (2. 26 ± 0. 90) × 109 M (Lah et al. 2007, MNRAS, 376, 1357)

Abell 370 a Galaxy Cluster at z = 0. 37

Abell 370, a galaxy cluster at z = 0. 37 large galaxy cluster of order same size as Coma optical imaging ANU 40 inch telescope spectroscopic followup with the AAT GMRT ~34 hours on cluster

Abell 370 – R band images Thumbnails 10’’ sq 324 galaxies with useful redshifts (z~0. 37) ordered by observed R band magnitudes

Abell 370 galaxy cluster 324 galaxies 105 blue (B -V 0. 57) 219 red (BV > 0. 57)

Abell 370 galaxy cluster 3σ extent of X-ray gas R 200 radius at which cluster 200 times denser than the general field

redshift histogram 324 useful redshifts

redshift histogram 324 useful redshifts GMRT sideband frequency limits

Galaxy Sizes I want galaxies to be unresolved. For the galaxies at z = 0. 24 I used an estimate of the HI size from the optical properties of spiral and irregular field galaxies and the smoothed radio data. Major Complication!! The Abell 370 galaxies are a mixture of early and late types in a variety of environments.

HI mass 324 galaxies 219 galaxies 105 galaxies 94 galaxies 156 galaxies 168 galaxies 110 galaxies 214 galaxies

HI all spectrum all Abell 370 galaxies neutral hydrogen gas measurement using 324 redshifts – large smoothing MHI = (6. 6 ± 3. 5) × 109 M

HI Flux – All Galaxies

HI blue outside x-ray gas blue galaxies outside of x-ray gas measurement of neutral hydrogen gas content using 94 redshifts – large smoothing MHI = (23. 0 ± 7. 7) × 109 M

HI Flux – Blue Galaxies Outside X-ray Gas

Comparisons with the Literature

Average HI Mass Comparisons with Coma

Abell 370 and Coma Comparison 110 galaxies 324 galaxies 214 galaxies

HI Density Comparisons

HI density field

HI density - inner regions of clusters within 2. 5 Mpc of cluster centers

HI Mass to Light Ratios

HI Mass to Light Ratios HI mass to optical B band luminosity for Abell 370 galaxies Uppsala General Catalog Local Super Cluster (Roberts & Haynes 1994)

Galaxy HI mass vs Star Formation Rate

Galaxy HI Mass vs Star Formation Rate HIPASS & IRAS data z~0 Doyle & Drinkwater 2006

HI Mass vs Star Formation Rate in Abell 370 all 168 [OII] emission galaxies Average line from Doyle & Drinkwater 2006

HI Mass vs Star Formation Rate in Abell 370 81 blue [OII] emission galaxies Average 87 red [OII] emission galaxies line from Doyle & Drinkwater 2006

Star Formation Rate from [OII] and radio continuum emission

Radio Continuum – Star Formation Connection • radio continuum emission produced from relativistic electrons moving in magnetic field of the galaxy - synchrotron radiation • relativistic electrons produced by supernova remnants, what remains after the death of massive, short-lived stars • in theory - number of supernova remnants related to star formation rate in galaxy • in practice - empirical relationship - agrees with other star formation rate indicators

Radio Continuum vs. [OII] Star Formation Rate all 168 [OII] emission galaxies Average line from Bell 2003

Radio Continuum vs. [OII] Star Formation Rate Average 87 red [OII] emission galaxies 81 blue [OII] emission galaxies line from Bell 2003

Two Unusual Radio Continuum Objects in the field of Abell 370

1. The De Propris Structure

Example Radio Continuum Jet

The De Propris Structure FIRST image 60 arcsec across VLA at 1. 4 GHz Resolution ~5 arcsec

GMRT image The De Propris Structure resolution ~3. 3 arcsec at 1040 MHz Peak flux = 1. 29 m. Jy/Beam Total flux density ~ 23. 3 m. Jy

The De Propris Structure V band optical image from ANU 40 inch WFI

The De Propris Structure Radio contours at 150, 300, 450, 600, 750, 900 & 1150 Jy/beam RMS ~ 20 Jy

The De Propris Structure Optical as Contours

The De Propris Structure Galaxies all at similar redshifts z ~ 0. 3264

The De Propris Group

The De Propris Group Abell 370 ~167 Mpc difference between cluster Abell 370 and De Propris group in comoving distance NOT related objects De Propris Group group well outside GMRT HI redshift range

De Propris Structure Galaxy 4 – source of De Propris Structure The De Propris Group

The De Propris Group 10 arcmin square box ~2800 kpc at z = 0. 326 galaxy group/small cluster galaxies moving through intra-group medium of hot ionised gas pushes radio jet bending it back on itself to create the strange shape

2. A Radio Gravitational Arc?

Radio Arc V band optical image from ANU 40 inch Abell 370 cluster 8 arcmin square

Radio Arc V band optical image from ANU 40 inch image centred on one of the two c. D galaxies near the centre of the Abell 370 cluster 50 arcsec square

Radio Arc optical image from Hubble Space Telescope optical arc in Abell 370 was the first detected gravitational lensing event by a galaxy cluster (Soucail et al. 1987)

Radio Arc GMRT image resolution ~3. 3 arcsec at 1040 MHz Peak flux = 490 Jy/Beam c. D galaxy Peak flux = 148 Jy/Beam Noise ~20 Jy noise

Radio Arc Radio contours at 80, 100, 120, 140, 180, 220, 260, 320, 380 & 460 Jy/beam RMS ~ 20 Jy

Radio Arc Optical as Contours

Future Observations HI coadding with SKA Pathfinders

SKA – Square Kilometer Array • SKA promises both high sensitivity with wide field of view • possible SKA sites – South Africa and Australia • final site decision by 2012? ? – money will be the deciding factor • both South Africa and Australia are building SKA pathfinder telescopes to strengthen their case for site selection – also do science

Why South Africa and Australia?

Population Density – India

Population Density – South Africa

Population Density – Australia

Radio Interference 108 Frequency (Hz) 109

The SKA Pathfinders

ASKAP

Meer. KAT South African SKA pathfinder

ASKAP and Meer. KAT ASKAP parameters Meer. KAT Number of Dishes Dish Diameter Aperture Efficiency System Temp. Frequency range Instantaneous bandwidth Field of View: at 1420 MHz (z = 0) at 700 MHz (z = 1) Maximum Baseline Length 45 80 12 m 0. 8 35 K 30 K 700 – 1800 MHz 700 – 2500 MHz 300 MHz 512 MHz 30 deg 2 1. 2 deg 2 4. 8 deg 2 8 km 10 km

ASKAP and Meer. KAT ASKAP parameters Meer. KAT Number of Dishes Dish Diameter Aperture Efficiency System Temp. Frequency range Instantaneous bandwidth Field of View: at 1420 MHz (z = 0) at 700 MHz (z = 1) Maximum Baseline Length 45 80 12 m 0. 8 35 K 30 K 700 – 1800 MHz 700 – 2500 MHz 300 MHz 512 MHz z = 0. 45 to 1. 0 in a single 30 observation deg 2 z = 0. 2 to 1. 0 in a single 1. 2 observation deg 2 30 deg 2 4. 8 deg 2 8 km 10 km

Simulated ASKAP HI detections z = 0. 45 to 1. 0 980 MHz to 700 MHz one year observations (8760 hours) single pointing assumes no evolution in the HI mass function (Johnston et al. 2007) Meer. KAT - will detect galaxies easier - more sensitive - but in a single pointing will end up with fewer total detections due to smaller field of view

What I could do with the SKA pathfinders using optical coadding of HI if you gave them to me TODAY.

Wiggle. Z and z. COSMOS Wiggle. Z z. COSMOS Instrument/Telescope AAOmega on the AAT VIMOS on the VLT Target Selection ultraviolet using the GALEX satellite optical I band IAB < 22. 5 Survey Area 1000 deg 2 total 7 fields minimum size of ~100 deg 2 COSMOS field single field ~2 deg 2 Primary Redshift Range 0. 5 < z < 1. 0 0. 1 < z < 1. 2 Survey Timeline 2006 to 2010 2005 to 2008 nz by survey end 176, 000 20, 000 nz in March 2008 ~62, 000 ~10, 000

Wiggle. Z and ASKAP

Wiggle. Z field ~10 degrees across data as of March 2008 z = 0. 45 to 1. 0 ASKAP beam size Diameter 6. 2 degrees Area 30 deg 2

ASKAP & Wiggle. Z 100 hrs nz = 3887

ASKAP & Wiggle. Z 1000 hrs nz = 3887

z. COSMOS and Meer. KAT

z. COSMOS field Meer. KAT beam size at 1420 MHz z = 0 Meer. KAT beam size at 1000 MHz z = 0. 4 square ~1. 3 degrees across data as of March 2008 z = 0. 2 to 1. 0 7118 galaxies

Meer. KAT & z. COSMOS 100 hrs nz = 3559

Meer. KAT & z. COSMOS 1000 hrs nz = 3559

Conclusion

Conclusion • Abell 370 a galaxy cluster at z = 0. 37 has significantly more gas than similar clusters at z ~ 0 • despite this fact, galaxies in regions of higher density within Abell 370 have less gas than galaxies located in regions of lower density, the same trend seen in nearby clusters • there are two unusual radio continuum structures in the field of Abell 370 – a twisted radio jet and a possible radio gravitational arc • the SKA pathfinders ASKAP and Meer. KAT can measure significant amounts of HI 21 cm emission out to z = 1. 0 using the coadding technique with existing redshift surveys

Additional Slides

Why not GMRT? • RFI – 950 MHz mobile phones • Field of view small – 45 m dishes • bandpass small 32 MHz – upgrade coming but will not soon work for all dishes simultaneously • longer baselines resolve HI in galaxies