The EVLA View of HI Dwarfs in the Leo Ring

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1 The EVLA View of HI Dwarfs in the Leo Ring Aeree Chung Harvard-Smithsonian Astrophysical Observatory Steven Myers, Jürgen Ott, Joan Wrobel, Michael Rupen WIDAR commissioning team (NRAO)

2 The Leo HI Ring NGC3384 M Discovery (Arecibo) - Schneider S. E., et al Found around a pair of early type galaxies 2. Properties - 1.7x10 9 Msun of HI - Ring of 200 kpc 3. Origin Primordial or Tidal? M96

3 The Leo HI Ring 200 kpc NGC3384 M Discovery (Arecibo) - Schneider S. E., et al Found around a pair of early type galaxies 2. Properties - 1.7x10 9 Msun of HI - Ring of 200 kpc 3. Origin Primordial or Tidal? M96

formation than disruptive collisions No obvious signs of intergalactic stars, molecular gas, dust or planetary nebulae (Schneider et al.

4 Origin of the Large-Scale HI Gas Ring Primordial vs. Tidal Primordial Smooth velocity gradient along the ring with the orbital period of 4x10 9 yr (Schneider 1985) Leftover gas after group formation than disruptive collisions No obvious signs of intergalactic stars, molecular gas, dust or planetary nebulae (Schneider et al. 1989; Castro- Rodriguez et al. 2003) UV clumps found in a few high HI density peaks with low (1/50 ~ 1/5 solar) metallicity (Thilker et al. 2009) star forming from primordial gas than tidally stripped gas km/s 830 km/s km/s

5 Origin of the Large-Scale HI Gas Ring Primordial vs. Tidal Tidal Mvirial/LB, too large to be stable over a Hubble time in the group (Pierce & Tully 1985) The lower limit on a dust to gas ratio - no less than 1/20 solar (Bot et al. 2009) Gaseous intragroup rings/arcs can be formed by dynamical interaction between LSB galaxies with extended HI discs and the group potential (Bekki et al. 2005) Recently stripped gas through tidal interactions

6 Origin of the Large-Scale HI Gas Ring Primordial vs. Tidal Primordial Smooth velocity gradient along the ring with the orbital period of 4x10 9 yr (Schneider 1985) Leftover gas after group formation than disruptive collisions No obvious signs of intergalactic stars, molecular gas, dust or planetary nebulae (Schneider et al. 1989; Castro- Rodriguez et al. 2003) UV clumps found in a few high HI density peaks with low (1/50 ~ 1/5 solar) metallicity (Thilker et al. 2009) star forming from primordial gas than tidally stripped gas Tidal Mvirial/LB, too large to be stable over a Hubble time in the group (Pierce & Tully 1985) The lower limit on a dust to gas ratio - no less than 1/20 solar (Bot et al. 2009) Gaseous intragroup rings/arcs can be formed by dynamical interaction between LSB galaxies with extended HI discs and the group potential (Bekki et al. 2005) Recently stripped gas through tidal interactions

7 Origin of the Large-Scale HI Gas Ring Primordial or Tidal? Formation of Dwarfs Any sign of dark halos associated with dwarf galaxies identified in the ring? ALFALFA SDSS Break the ring into smaller structure using the VLA and resolve kinematics with WIDAR ALFALFA, km/s (Stierwalt et al. 2009)

8 WIDAR The New Powerful Correlator for the Expanded VLA Parameter VLA EVLA Factor Point Source Sensitivity (1sigma, 12hr) 10 μjy 1 μjy 10 Maximum BW in each polarization 0.1 GHz 8 GHz 80 # of frequency channels at max. BW 16 16, Maximum number of freq. channels 512 4,194, Coarsest frequency resolution 50 MHz 2 MHz 25 Finest frequency resolution 381 Hz 0.12 Hz 3180 # of full-polarization spectral windows (Log) Frequency Coverage (1-50 GHz) 22% 100% The Expanded VLA, Rick Perley (Thu afternoon)

WIDAR The New Powerful Correlator for the Expanded VLA Parameter VLA EVLA Factor Point Source Sensitivity (1sigma, 12hr) 10 μjy 1 μjy 10 Maximum BW in each polarization 0.

9 WIDAR The New Powerful Correlator for the Expanded VLA Parameter VLA EVLA Factor Point Source Sensitivity (1sigma, 12hr) 10 μjy 1 μjy 10 Maximum BW in each polarization 0.1 GHz 8 GHz 80 # of frequency channels at max. BW 16 16, Maximum number of freq. channels 512 4,194, Coarsest frequency resolution 50 MHz 2 MHz 25 Finest frequency resolution 381 Hz 0.12 Hz 3180 # of full-polarization spectral windows (Log) Frequency Coverage (1-50 GHz) 22% 100% The Expanded VLA, Rick Perley (Thu afternoon)

10 WIDAR+VLA-D Obs. of LEO HI Ring EVLA Commissioning Science Observations The southern part of the ring + M96 (1.5 hrs per pointing) Covering 650~1100 km/s with 256 channels of 1.66 km/s separation (WIDAR-0 prototype) in VLA-D array but only with 12 antennas 3-sigma, 6x10 18 cm -2 ALFALFA, km/s (Stierwalt et al. 2009)

11 WIDAR+VLA-D Obs. of LEO HI Ring EVLA Commissioning Science Observations The southern part of the ring + M96 (1.5 hrs per pointing) Covering 650~1100 km/s with 256 channels of 1.66 km/s separation (WIDAR-0 prototype) in VLA-D array but only with 12 antennas 3-sigma, 6x10 18 cm -2 ALFALFA, km/s (Stierwalt et al. 2009)

12 WIDAR+VLA-D Obs. of LEO HI Ring EVLA Commissioning Science Observations The southern part of the ring + M96 (1.5 hrs per pointing) Covering 650~1100 km/s with 256 channels of 1.66 km/s separation (WIDAR-0 prototype) in VLA-D array but only with 12 antennas 3-sigma, 6x10 18 cm -2 ALFALFA, km/s (Stierwalt et al. 2009)

13 VLA D + WIDAR Data ALFALFA, km/s (Stierwalt et al. 2009) ALFALFA Position Velocity Diagram (lowest contour - 4 sigma) Tip of the iceberg? Deeper EVLA Observations of mosaicking the entire gas ring is highly likely to happen! Potential optical counterparts near HI over density region (TDGs?)

Unveiling the Radio Sky with the JVLA and VLASS. Julie Hlavacek-Larrondo Canada Research Chair, Université de Montréal

Unveiling the Radio Sky with the JVLA and VLASS Julie Hlavacek-Larrondo Canada Research Chair, Université de Montréal Very Large Array What is it? Located in Southern New Mexico at 2100 m altitude Composed