Disturbed Things Come in small packages Jessica V. Bloom Disturbed Things Come in small packages Thanks to: Scott Croom Julia Bryant Joss Bland-Hawthorn

Kinematics can uncover processes shaping galaxy evolution Kinematic classification of SAMI galaxies Physical basis for scatter off the Tully-Fisher relation What determines asymmetry? Bloom et al., 2016 (submitted) Events which perturb kinematics (e.g. major/minor mergers, secular processes) play key role in galaxy evolution Morphology valuable, but kinematics allows different view, without Hubble type or bursts of SFR Low mass galaxies are known to be highly irregular – work on TFR etc Test case for different kinds/causes of asymmetry Shapiro et al., 2008

Data SAMI Galaxy Survey data cubes Hα emission line kinematic maps fit by LZIFU (Ho et al., 2014) – subsample of 816 galaxies MY SAMPLE: 532 galaxies after Hα S/N cuts Gas kinematics, range of morphological types, thanks to I-Ting Ho, Institute for Astronomy, University of Hawaii Explain colours/velocity fields

HIGHER MODES INDICATES KINEMATIC ASYMMETRY Krajnovic et al., 2007 KINEMETRY Asymmetry (n>1) POWER IN HIGHER MODES INDICATES KINEMATIC ASYMMETRY Regular rotation Fourier decomposition of velocity fields, such that they are separated into modes, with asymmetry signatures carried in higher order modes Fits first and higher order models to velocity and dispersion fields Take the median over ellipses

Classification using kinemetry Visually classified normal galaxies Bloom et al., 2016 (submitted) Bin counts (normalised) Visually classified perturbed galaxies

Scatter off the Tully-Fisher Relation (can be physically explained) Asymmetry Causes: TFR remains at all stellar masses PA offset SCATTER OFF TFR INVERSELY CORRELATES WITH STELLAR MASS Increases with scatter, decreases with mass Low Vrot - explain TFR Previous work, e.g. Kannapan et al., in Nearby Field Galaxy Survey Thanks to Luca Poorly constrained PA (due to mergers making the galaxy irregular) Large offset between photometric and kinematic PA (yay for spatially resolved kinematics!) – correlation between PA offset and scatter off TFR, as well as - inverse correlation between PA offset and stellar mass What this tells us: PA offset is a major cause of scatter below TFR, particularly at low stellar mass Scatter increases at low mass log(Stellar Mass) Vrot measurements by L. Cortese

Asymmetry is related to stellar mass Asymmetry-mass correlation: Slope=-0.27, p-value=5.8x10-8 GAS ASYMMETRY IS INVERSELY CORRELATED WITH MASS No trend with Halpha S/N and mass No trend with coverage and asymmetry Gas fraction linked to formation of massive instabilities – low mass galaxies have high gas fractions High gas fraction also linked to turbulent support, relative to rotational support Also maybe environmental – satellites? log(Stellar Mass)

Why are asymmetry and mass anticorrelated? Interactions? Are low mass galaxies satellites of large galaxies? Are low mass galaxies qualitatively different? High gas fraction  turbulence, star formation… More likely to be kinematically disturbed Less likely

What about distance to nearest neighbour? GAMA: Liske et al., 2015 Brough et al., 2013 DN = distance to first nearest neighbour AT ALL DN, LOW MASS GALAXIES HAVE HIGHER GAS ASYMMETRY log(M*)<9.0 log(M*)>10.0: Slope =-0.18, p-value=0.009 Stellar mass - Thanks to Sarah STRESS MEDIANS NOT TREND LINES High and not high are separate distributions (something is going to that is different for both of them) May tell us that interaction causes asymmetry in high mass galaxies, but something else is going on for low mass galaxies log(M*)>10.0 log(M*)<9.0: Slope=-0.063, p-value=0.49 DN measurements by S. Brough

Disturbed things trend small Stellar mass is more strongly related to asymmetry than distance to nearest neighbour Asymmetry can be caused by turbulence, bursty star formation Interaction is not the primary cause of asymmetry Scatter off the Tully-Fisher relation can be explained Scatter is often caused by offset between photometric and kinematic PA

Differences in PA  rotation velocity Kinematic PA Photometric PA