Susan Kassin (Oxford) with Ben Weiner (Steward), Christopher Willmer (Steward), + DEEP2 Survey Team (Faber, Koo, Davis, Guhathakurta)

Transcription

1 Disk Galaxy Kinematics Over the Last ~8 Gyrs Susan Kassin (Oxford) with Ben Weiner (Steward), Christopher Willmer (Steward), + DEEP2 Survey Team (Faber, Koo, Davis, Guhathakurta)

2 Data are from the DEEP2 Survey Deep Extragalactic Evolutionary Probe - 2 (DEEP2) is a redshift survey done with the DEIMOS instrument on the Keck-2 telescope. PIs: Marc Davis, S. M. Faber, D. Koo, P. Guhathakurta >30,000 solid spectroscopic redshifts over 0.1 < z < 1.5 Magnitude limit of R AB < 24.1 DEEP2 consists of four fields, one field has one orbit depth Hubble imaging at V and I. Wavelength range ~ Å. The [OII] 3727Å doublet is visible for 0.7 < z < 1.4. Spectral resolution R ~ 5000, 0.33 Å/pixel

3 Data are selected from the DEEP2 Survey to study the Tully-Fisher relation The final sample is selected essentially on magnitude (R AB < 24.1) and emission line strength. Primary requirements: z <1.2 Emission lines required to have total counts > 1500 e-/a => Flux (corrected for slit losses) =1e-17 ergs/s/cm 2 Hubble images (deeper than the spectral survey) 1692 galaxies Secondary requirements: Spectrographic slits within 40 º of major axes of galaxies (Weiner, SAK et al. 2006, Fig 13) 30 º < inclination < 70 º to get reliable V rot and avoid dust effects 755 galaxies Tertiary requirements: Interference with sky lines, Instrument artifacts 544 galaxies used for Tully-Fisher analysis

4 DEEP2 Kinematic Measurements ROTCURVE: automated rotation curve reduction pipeline (Ben Weiner) 1-D correction for seeing/ beam smearing Measures V*sini and σ w/o Hubble Space Telescope image arcsec along slit arcsec along slit rotation curve V (km/s) light profile (cont&emiss) arcsec along slit arcsec along slit dispersion profile σ (km/s) observed flux, z=1.14 Intensity λ of central row [OII] doublet

5 (Ben Weiner, SAK et al 2006)

6 Generally M * Only Tully-Fisher Well-Ordered Relation Galaxies for Galaxies Follow in Literature Low z Bin Relations 0.1 < z < Rotation Velocities (V rot ) from specta; corrected for inclination as measured from HST images Stellar masses (M * ) from photometry (Bundy et al 2005) log 10 M * Key: = disturbed or compact morphology = normal morphology Classified V-band HST images for z<0.6 and I-band for z>0.6 log 10 V rot. _ Bell & de Jong (2001) Conselice et al (2005)

7 Generally Only Well-Ordered Galaxies Follow Literature Relations: Trend Continues to Higher z < z < log 10 M * (M sun ) log 10 V rot = disturbed or compact morphology = normal morphology

8 Stellar Mass Tully-Fisher Relation to z=1.2 Redshift > Puech et al. (2008); IMAGES Survey

9 Possible Evidence For Disk Settling Redshift > 18% 35% 42% 62% Decreasing Number of Higher Mass Galaxies With Lower V Puech et al. (2008); IMAGES Survey rot With Time Disk Settling? Low Mass Disk Galaxies Currently Settling?

10 Neither V rot nor σ Describes Velocity Scale HST/ACS (Ben Weiner, SAK et al. 2006) 6 z=0.950 V rot sini=208km/s, σ=40km/s Rotation-dominated 8 z=1.040 V rot sini=75km/s, σ=55km/s Mixed z=1.033 V rot sini=29km/s, σ=59km/s Dispersion-dominated V rot [OII] doublet (Spectra from DEIMOS on Keck-2) radius

11 New Kinematic quantity combining rotation velocity and integrated velocity dispersion Given a potential created by dark matter and stars and a spherically symmetric tracer population (gas); assume the gas is distributed as a powerlaw with density ρ r -α and isotropic σ. If V rot varies slowly with radius, then σ = V rot / α (Binney & Tremaine 1987). Therefore, we adopt the kinematic quantity: S K 2 KV rot 2 + σ 2 where K=1/α. S K is a good combined velocity scale. Galaxies generally have stellar/gas distributions with α=2 3, this implies K= We choose K=0.5, or S 0.5. (Binney & Tremaine 1987; Ben Weiner, SAK et al. 2006; Covington, SAK et al. 2010)

12 Stellar Mass Tully-Fisher Relation If merging creates ellipticals, then origin of F-J could be pre-existing S 0.5 Relation for disk galaxies (Faber-Jackson from Gallazzi et al. 2006) Evidence that galaxies are approx virialized since at least ~ 8 Gyrs ago log S 0.5 =a + b log M * c=intrinsic scatter Kassin et al. 2007; log 10 ( S 0.5 = 0.5V 2 + σ 2 ) Covington, SAK et al. 2010

13 V rot /S 0.5 (ie, V rot / (σ *V 2 rot )) vs Redshift Pure rotation V rot /S 0.5t V rot /S 0.5t DEEP2 M * TFR Sample with log M*>9.8 z = disturbed morphology = compact morphology = normal morphology z DEEP2 + Literature = Cresci et al. (2009)/SINS = Law et al. (2009) (V shear ) = Lemoine-Busserolle et al. (2010)

14 V rot /S 0.5 (ie, V rot / (σ *V 2 rot )) vs Redshift Pure rotation V rot /S 0.5t V rot /S 1.0t 0.5t DEEP2 M * TFR Sample with log M*>9.8 z = disturbed morphology = compact morphology = normal morphology DEEP2 + Literature = Cresci et al. (2009) = Forster-Schreiber = Cresci et al. (2009)/SINS et al. (v = obs /2σ Law int et ) not al. (2009) i-corrd, (Vbinned shear ) in black = Law = Lemoine-Busserolle et al. (2009) (V shear ) et al. (2010) = Lemoine-Busserolle et al. (2010) z

15 DEEP2 Velocity Function Use linewidths (σ) to measure number of galaxies as a function of σ Will compare with models: Nbody sims and SAMs log slope ~ 3.5 Work in progress! Incomplete

16 Conclusions 1. V rot M * Tully-Fisher Relation has large scatter to low V ( rot ~ 1 dex) due to disturbed and compact galaxies. Most studies have selected only rotationdominated galaxies, biasing their results! 2. S 0.5 M * Tully-Fisher Relation is: Tight (intrinsic scatter < ~ 0.1 dex) ~ Independent of morphology: fundamental to all types of galaxies Non-evolving to z=1.2 Coincident with Faber-Jackson This is an interesting regularity that we have yet to fully understand! Sigma is important! 3. Both Vrot and S0.5 Relations Reproduced by SPH Merger Simulations. (Covington, SAK et al. 2010) 4. Galaxies likely approximately virialized since at least ~ 8 Gyrs ago. 5. Evidence for disk settling.