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HI Gas as Function of Environment

HI Gas as Function of Environment. HI Gas as Function of Environment. When and where do galaxies stop accreting cool gas? How do they loose the cool gas? When do they stop forming stars?. Oosterloo, Fraternali, Sancisi, 2007, AJ 134, 1019. The lore.. if halos get too big, gas does not cool

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HI Gas as Function of Environment

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  1. HI Gas as Function of Environment

  2. HI Gas as Function of Environment When and where do galaxies stop accreting cool gas? How do they loose the cool gas? When do they stop forming stars?

  3. Oosterloo, Fraternali, Sancisi, 2007, AJ 134, 1019

  4. The lore.. if halos get too big, gas does not cool But.. at least some dry mergers are wet, and forming stars Donovan, Hibbard, an Gorkom, 2007, AJ 134, 1118

  5. The Morphology-Density Relation Postman and Geller 1984 Dressler 1980 It extends over 6 orders of magnitude!

  6. Gas content and star formation rate less in dense group environment and outskirts of clusters The outskirts of clusters Solanes et al find smooth variation of HI deficiency out to 2 RA This agrees nicely with results obtained on smoothly varying star formation rate out to 2 RA In clusters at intermediate z: Balogh et al 1998 Treu et al 2003 fraction early types steep decline to 1 Mpc, gradual to 5 Mpc Regions of mean high galaxy density In 2dF : Lewis et al 2002 In Sloan: Gomez et al 2003; Nichol 2004 General conclusion star formation declines if galaxy density exceeds a certain value

  7. Note that deficiency goes out to 2 RA Solanes et al 2001

  8. Possible Drivers for Environmental Evolution Gravitational galaxy galaxy : slow encounters mergers - tidal structures galaxy cluster : tidal stretching galaxy many galaxies: harassment cumulative effect of many fast encounters truncates or destroys small galaxies Affects both gas and stars Gas dynamical effects ram pressure stripping turbulent viscous stripping conduction Affects only the gas Starvation removes left over gas reservoir that fuels star formation

  9. VIVA VLA Imaging of Virgo Galaxies in Atomic Gas Aeree Chung, Hugh Crowl, Kenney, van Gorkom, Vollmer Select galaxies over wide range of local densities Select galaxies with wide range of star formation properties Identify galaxies undergoing trauma Make sophisticated guess as to what is happening Use simulation to make a more sophisticated guess Compare timescales from stellar population synthesis with timescales from simulation

  10. Viva-poster

  11. Subgroups Small gas disk further away from the cluster center Small gas disks (compared to the stellar counterpart) around the cluster center Comparable or more extended than the stellar disks

  12. In Center of Cluster Very small gas disk (blue) compared to optical

  13. Tails 2

  14. Can these tails be formed by ram pressure stripping? Five galaxy tails could have been formed by ram pressure N4654 probably combination of gravitational and rp N4396 possibly also, or viscous stripping

  15. HI TAIL Galaxies We see for the first time galaxies being affected at intermediate distances. These are galaxies radially falling in Their gas is being removed by ram pressure and/or by gravitational interaction Chung, van Gorkom, Kenney, Vollmer, 2007, ApJ 659, L115 NGC 4522 This galaxy is different, though far out in cluster, it is stripped well to within the disk

  16. HI stripped from NGC 4522 Kenney, van Gorkom & Vollmer 2004 NGC 4522 NGC 4522 WIYN BVR VLA HI on R 0.5L* galaxy with normal stellar disk Has only 25% of normal HI (HI def =0.6) HI truncated in disk at 0.3R25 extraplanar HI (40% of total) on only one side of disk

  17. Disk HI grey scale, extraplanar contours; Note acceleration toward cluster mean

  18. Young Stellar Population in Stripped Outer Disk of NGC 4522 GALEX FUV+NUV OPT + HI Strong Balmer lines and bright FUV emission in stripped outer disk indicate star formation stopped only ~100 Myr ago --> disk was stripped recently Crowl & Kenney 2006

  19. Evidence of Ongoing Pressure from Radio Continuum in NGC 4522 Vollmer, Beck, Kenney & van Gorkom 2004 Flattest spectral index (-0.7)  local electron acceleration suggestive of shock 6cm Polarized Flux on HI Spectral index 6/20 cm Eastern leading edge has: Enhanced 6cm polarization  suggests compressed magnetic field

  20. Simulations vs. HI Data in NGC 4522 Vollmer simulation Vollmer simulation HI data 50 Myr after peak pressure Large amounts of extraplanar HI close to disk truncation radius  early stage of active stripping Large extraplanar gas concentrations on both sides of minor axis --> disk-wind angle is more face-on than edge-on Vollmer etal 2006

  21. NGC 4522 is stripped locally and not in core • NGC 4522 cannot travel far in 100 Myr, so must be stripped locally & not in cluster core • NGC 4522 is located 3.5o = 0.8 Mpc from M87 • Time to reach core ~700 Myr

  22. Asca data Shibata et al 2001 M49 subcluster falling in 1300km/s ICM velocity could increase ram pressure by factor 10 ongoing stripping

  23. Just south of NGC 4522 2 tails pointing toward M49

  24. Oosterloo and van Gorkom, 2005

  25. Crowl et al 2005

  26. Conclusions from HI imaging of selected galaxies In center we see very small HI disks.. Almost certainly due to ram pressure stripping The stripping is important for the evolution of the galaxies. H alpha imaging (Koopmann Kenney 1998, 2004) shows that Virgo galaxies have reduced star formation rates compared to the field. This is primarily caused by truncation of starforming disks. A strong correlation is found between HI deficiency and normalized H alpha flux We see for the first time galaxies being affected at intermediate distances. Galaxies falling in radially are being affected by ram pressure and/or gravitational interactions Some galaxies at large distances being affected by strong rampressure. These galaxies are very HI deficient. Evidence for a dynamic ICM

  27. Chung, Crowl, JvG, Schiminovich, Kenney 2008

  28. Volume Limited Imaging of Clusters at 0.03< z < 0.2 Abell 1060 (Hydra), Abell 496, 85, 754, 2670 VLA Imaging 1.5x 1.5 degrees and 5000 km/s JvG, Bravo-Alfaro, Dwarakanath,Guhathakurta, Poggianti, Schiminovich, Verheijen, Wilcots, Zabludoff Abell 963 and 2192 at z=0.2 WSRT Imaging 5Mpc x 5 Mpc by 18000 km/s Verheijen, JvG, Szomoru, Dwarakanath, Poggianti,Schiminovich Boris Deshev

  29. Total HI A496 A2670 A85 A754 X-ray +HI X-ray

  30. Detection rates in volume limited surveys Hydra 50 galaxies pre merger A2670 50 galaxies pre merger A496 25 galaxies beginning merger A85 10 galaxies ongoing merger A 754 1 galaxy just past merger Detection rate depends on dynamical state of cluster

  31. HI imaging of clusters at z=0.2 Verheijen, JvG, Szomoru, Dwarakanath,Poggianti, Schiminovich, 2007, ApJL, 688, L9

  32. GALEX A963

  33. We probe a HUGE volume, 8.2Mpc x 8.2 Mpc x 18000 km/s (326 Mpc) 1.7 x 104 Mpc3

  34. We detect galaxies…. Can even derive rotation curves

  35. Stacked spectra of non detected galaxies No detection of blue B-O galaxies detection of blue field galaxies It is location of B-O galaxies that makes them different

  36. EVLA versus WSRT WSRT cover from 1160-1220 MHz (18000 km/s) EVLA cover from 1420 to 1050 MHz up to z=.35 using 8192 channels of 9 km/s

  37. The WSRT probes 8.2Mpc x 8.2 Mpc x 18000 km/s (326 Mpc) EVLA goes from z=0 to 0.35 in one setting

  38. EVLA HI Deep Field EVLA with prime focus feeds

  39. Movies by Greg Bryan (http://www.astro.columbia.edu/~gbryan/movies) using a hybrid adaptive mesh refinement algorith gaseous component, starformation, dark matter and stars (ENZO) 1. Gas temperature: cosmological simulation of cluster assembly 2. High resolution gas density: evolution of 1 cluster 3. High resolution: HI Analysis by Stephanie Tonnesen

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