1 / 44

ALFALFA: Preliminary Results from a strip through Virgo

ALFALFA: Preliminary Results from a strip through Virgo. Catalog in preparation: Brian Kent et al. RA: 09:00h to 14:00h Dec: 12deg to 16deg Solid Angle: 291 sq deg (4% of survey). Catalog in preparation: Sabrina Stierwalt et al. R. Giovanelli Cornell University.

laird
Download Presentation

ALFALFA: Preliminary Results from a strip through Virgo

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ALFALFA: Preliminary Results from a strip through Virgo Catalog in preparation: Brian Kent et al. RA: 09:00h to 14:00h Dec: 12deg to 16deg Solid Angle: 291 sq deg (4% of survey) Catalog in preparation: Sabrina Stierwalt et al. R. Giovanelli Cornell University Catalog in preparation: R. Koopmann et al.

  2. ? Sources of log (HIMass)<7.5: N=12 N=42 Parkes HIPASS survey: Zwaan et al. 2003

  3. Problem with Virgo/foreground Distances RA Range: 1144 – 1400 (largely Virgo) 0900 - 1400

  4. + + + HIPASS Completeness + + + HIPASS Limit + + A Comparison with HIPASS

  5. A Comparison with HIPASS, HIJASS, etc • Over the 132 sq. deg. including the northern part of Virgo, i.e. RA=[11:44-14:00], Dec=[14.-16.0] : • ALFALFA detects 716 sources, HIPASS 40 (2 unconfirmed) • While this region is perhaps the most intensively studied in the local Universe, at all wavelength bands (including HI, using optically selected samples),  69% of ALFALFA detections are new (the conventional wisdom on which optical targets would turn out to be HI-rich appears to have been limited) Over the region of max HIJASS sensitivity:  ALFALFA detects 193 sources, HIJASS 15

  6. cz<5000 • HI (ALFALFA) N=1709 5000<cz<10000 10000<cz<18000 cz<5000 cz<18000 5000<cz<10000 Optical  N=2529 10000<cz<18000 cz<18000

  7. HI (ALFALFA) N=1709 Optical  N=2529

  8. Centroiding HI: 20” (med)

  9. So what do we find?

  10. 800 pc Distance ~ 8 Mpc HPBW=3.8’x3.3’

  11. A “high” z LSB… log(HI Mass)=9.86

  12. A low z LSB… log(HI Mass)=8.89

  13. A nearby LSB… log(HI Mass)=7.75

  14. A few goodies in Virgo…

  15. Two “stray” clouds

  16. Brian Kent et al. (in preparation) 4.76 x 107 M 7.29 x 107 M

  17. 1o=300 kpc IC3068 BCD cz=1288

  18. 1o=300 kpc IC 679 Sbc cz=2213

  19. The Cardiff “Dark Galaxy”

  20. NGC 4254 10’ DSS2 Blue 45 kpc

  21. Combined ALFALFA data around NGC 4254cz = 2243 to 2557 km/s 10’ 45 kpc Haynes et al. (in preparation)

  22. Combined ALFALFA data around VIRGOHI21cz = 1946 to 2259 km/s 10’ 45 kpc Haynes et al. (in preparation)

  23. 220 kpc Minchin et al 2005 (WSRT) Haynes et al. (in preparation)

  24. Haynes et al. (in preparation)

  25. A cloud complex

  26. MHI = 0.83E8 solar V = 527 km/s W = 120 km/s MHI = 0.52E8 solar V = 601 km/s W = 45 km/s MHI = 1.9E8 solar V = 605 km/s W = 257 km/s 235 kpc MHI = 1.7E8 solar V = 490 km/s W = 66 km/s MHI = 0.75E8 solar V = 476 km/s W = 48 km/s 100 km/s = 100 kpc/Gyr

  27. VCC1357 0.2x0.1 I? 603 km/s

  28. NGC4424 3.6x1.8 SBa: 476 km/s

  29. Cloud complex is in Virgo cluster • Complex is not gravitationally bound • Cloud-to-cloud Dv ~ 100 km/s, Dr ~ 100 kpc •  mean cloud separation will double in 1 Gyr •  cloud complex is transient phenomenon, • at first pass through the cluster • If individual clouds are bound their individual • total masses average 1-2 x 10 9 solar • Possible Origin: • Group of mini-halos falling in cluster for first time • Separated outskirts from single spiral galaxy • Satellites separated from main galaxy in group HYDRO (Ram Pressure)? TIDAL (gravi)?

  30. Galaxy harassment? High velocity, - but long-lasting - encounters in a cluster can drastically impact galaxy evolution. Animation by G. Lake

  31. A Void Dweller Most of the mass within the HI boundaries is accounted by the HI itself cz=3264 km/s MHI= 3.5x108 Msun GMRT Map Amelie Saintonge et al. (2007, in prep)

  32. Does metallicity correlate with local density? galaxies in voids : Popescu et al (1999) / Hidalgo-Gamez et al (1998)  Amelie Saintonge, Ph.D. Thesis, Cornell 2007

  33. Extremely metal-poor galaxy cz 280 km/s W 27 km/s F 0.64 Jy km/s D 6.3 Mpc log(MHI) 6.77 DSS2B Alfalfa Spectrum HI0141+27, a metal-poor galaxy : Saintonge et al. (in prep)

  34. R V U B GMRT (A.Begum) Palomar (DBSP) Extremely metal-poor galaxy Most of the mass within the HI boundaries is accounted by the HI itself Ha WISE (N.Brosch) WIYN0.9m log(O/H)+12 ~ 7.4 Radius ~ 400 pc HI0141+27, a metal-poor galaxy : Saintonge et al. (in prep)

  35. And then there are lots of narrow features, near the noise, with no optical counterpart: they’ll be chased one by one

  36. … some more credible than others…

  37. The LSS characteristics of HI-selected galaxies are the same as those optically-selected, albeit with lower density contrast • ALFALFA does not detect a population of high mass (say > 1010 solar), optically inert systems (e.g. Cardiff “dark galaxy”) • A number of optically inert systems are detected, which appear to be of tidal origin • ALFALFA detects a numerically conspicuous pop of HI-rich, optically faint, low mass systems: dynamics within the boundaries of the HI appear dominated by the HI mass • Candidate sources w/o optical counterparts are either of apparent tidal origin or have very narrow (<30 km/s) linewidths & will need corroboration • A population of HVCs with positive velocities (cz>150 km/s) near the NGP may be related to nearby, low mass galaxies

  38. We’re just getting started. Stay tuned

More Related