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Large-Scale Winds in Starbursts and AGN

This groundbreaking study by Rupke, Veilleux, and Sanders (2005) presents the largest survey of superwinds in starburst and active galactic nucleus (AGN) galaxies to date. The study covers a wide range of galaxies, including both luminous and ultraluminous infrared galaxies, and compares the properties of winds in different subsamples. The results suggest that winds occur in nearly all starburst and AGN galaxies, with hints of AGN contributions in certain cases. Key findings include correlations between outflow properties, galaxy properties, and the ionized and neutral gas components. These results provide valuable insights into the physics of galactic winds and their relation to star formation and AGN activity.

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Large-Scale Winds in Starbursts and AGN

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  1. Large-Scale Winds in Starbursts and AGN Rupke, Veilleux, & Sanders 2005a,b,c, submitted David S. Rupke University of Maryland Collaborators: Sylvain Veilleux D. B. Sanders v = -1550 km s-1

  2. Density Temperature Cooper, Bicknell, & Sutherland 2005, in prep., and . . . Veilleux, Cecil, & Bland-Hawthorn 2005, ARAA, in press

  3. Sample • 78 starbursts • 50% luminous infrared galaxies (LIR > 1011 L) • 50% ultraluminous infrared galaxies (LIR > 1012 L) • 26 AGN • mostly Seyfert 2 ULIRGs • a few Seyfert 1s • 104 total galaxies!  the largest superwind survey to date at z < 3

  4. Method • Spectroscopy of the Na I D doublet • Moderate resolution 65-85 km s-1 • Data from Keck II (10m), MMT (6.5m), KPNO (4m) • Fit absorption lines • multiple velocity components • Gaussians in optical depth • yields velocity, Doppler parameter, optical depth, covering fraction • Compute • Mass, Momentum, Energy, and their outflow rates • *Simple model of constant-velocity, mass-conserving wind (* Model assumes thin shell, time-averaged outflow rates)

  5. Detection rates • Comparison of different subsamples • starburst LIRGs 45% (± 10%) • Seyfert 2 ULIRGs 45% (± 10%) • starburst ULIRGs 70 – 80% (± 10%) • Differences in detection rate appear to reflect GEOMETRY • wind opening angle for moderate starbursts and Seyfert 2s in local universe is CΏ ~ 0.4-0.5 there are winds in all starburst LIRGs and Seyfert 2 ULIRGs! • Same conclusion applies to ULIRGs

  6. Spectral Type V(H II) < V(LINER) < V(Sy2) 120 km/s < 230 km/s < 310 km/s Velocities } significant Star Formation rate / Nuclear Activity V(LIRG) < V(SB ULIRG) < V(Sy2 ULIRG) 100 km/s < 170 km/s < 220 km/s

  7. AGN- vs. Starburst-driven winds? • Can we demonstrate that AGNs help drive winds in Seyfert ULIRGs? • No! The statistics don’t convincingly indicate it. • But there are hints . . . • Seyfert 2 ULIRGs are statistically indistinguishable from SB ULIRGs • however, the SFRs and outflow detection rates are lower in Seyfert 2 ULIRGs than in SB ULIRGs • So differences between Sy2 ULIRGs and LIRGs may imply an AGN contribution.

  8. Outflow properties vs. Galaxy properties • = Starbursts  = Seyfert 2s isothermal escape speed Murray et al. 2004, Martin 2005 Outflow velocity Circular velocity Star formation rate dwarf galaxies from Schwartz & Martin 2004

  9. = Starbursts  = Seyfert 2s Starburst99 prediction (tSB > 40 Myr, Z = Z) Mass outflow rate Circular velocity Infrared luminosity

  10. = Starbursts  = Seyfert 2s Radiation pressure SB99 Momentum outflow rate Circular velocity Infrared luminosity

  11. = Starbursts  = Seyfert 2s SB99 Energy outflow rate Circular velocity Infrared luminosity

  12. Slopes of Correlations • Strong dependence on galactic mass • velocity, mass, momentum, and energy all increase sharply with circular velocity • Power-law slopes of 3-5! • Linear dependence of mass, momentum on SFR • but energy increases more sharply as SFR increases  increase in thermalization efficiency with SFR? • v  SFR0.2 • Metallicity effects • incorporating the K-band L–Z relationship (Salzer et al. 2005) does not change these conclusions significantly • I.e. metallicity is not driving these trends! (preliminary)

  13. Correlations at SFR  100 M yr-1 • We observe a statistically significant flattening in dependence of outflow properties on galaxy properties. • Possible explanations: • depletion of gas reservoirs • decrease in thermalization efficiency • velocity ceiling (Murray et al. 2004, Martin 2005) • saturation in star formation surface density (Strickland et al. 2004a,b)

  14. Na I D model [N II] [O III] Vmax(ionized)  Vmax(neutral)

  15. Neutral/Ionized Correlations All galaxies Galaxies with BELA FWHM [O III] 5007 Na I D velocity Na I D velocity

  16. Mrk 231 – AGN + Starburst winds? • A Seyfert 1 ULIRG • Small-scale AGN outflow observed in Na I D • broad, high-velocity (v = 4000 – 8000 km s-1) absorption (e.g., Boksenberg et al. 1977) • highest velocity component is variable • A large-scale outflow observed • blueshifted emission lines (Hamilton & Keel 1987) • blueshifted absorption lines (v  2000 km s-1) • Jet or wide-angle outflow? • disk geometry and measured velocities favor wide-angle outflow • however, jet could still inject energy . . .

  17. blueshifted Na I D 4 kpc Nuclear offset (kpc) 4 kpc vsys Heliocentric velocity

  18. Summary/Outlook • Winds occur in ~ all LIRGs and ULIRGs • Can’t yet convincingly demonstrate influence of AGNs on large-scale outflow • need more data on Seyfert 2s • there are hints • Outflow and galaxy properties are strongly correlated • flattening at high SFR, galaxy mass • Ionized and neutral gas is correlated • Vmax(ionized)  Vmax(neutral) • Mrk 231 is a good example of a galaxy with both a small- and a (spatially-resolved!) large-scale wind.

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