Galaxy kinematics with WEAVE high spectral resolution IFU data

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1 Galaxy kinematics with WEAVE high spectral resolution IFU data Johan H. Knapen Instituto de Astrofísica de Canarias

2 IFU galaxy kinematics Widely available now from many surveys and instruments, incl. SAURON, MUSE, CALIFA, MaNGA, SAMI Usually either limited spectral resolution, or field of view (or both ) WEAVE IFU will give much higher spectral resolution data over field of view of 1.5 arcmin

3 Example 1: high-res data to look at gas streaming motions Hα intensity (left) and velocity field (right) of NGC From Zurita et al. 2004, A&A, 413, 73 Data from TAURUS at WHT, 19 km/s/pixel

4 Model of circular motions (left) and residuals after subtracting this from velocity field (right)

5 Velocity gradient map (left) shows regions of high shear, which coincide with location of dust lanes (right) Clearly indicates shocks in bar-driven gas From Zurita et al. 2004, A&A, 413, 73

6 Example 2: Inner rotation curve slopes Fabry-Perot Hα data with res. 8 km/s/pixel (FWHM 19.6 km/s) GHaFaS instrument on WHT Derive detailed inner rotation curves of few dozen galaxies Could measure inner slopes of rotation curves, and compare with physical parameters of the galaxies Erroz-Ferrer et al. 2016, MNRAS 458, 1119

7 µ0 and T-type correlate with inner slope of rotation curve => T-type is related to the dynamics in the central parts of galaxies, quite plausibly through the radial mass distribution. B/T and Mbulge correlate with inner slope => bulges play a role in the dynamics of the central parts => baryonic mass dominates the dynamics in the inner regions From Erroz-Ferrer et al. 2016, MNRAS 458, 1119 (see also Lelli et al. 2013)

8 WEAVE Multi-object spectrograph for 4.2m William Herschel Telescope on La Palma Operational early fibres MOS + IFUs 2 deg field Low and high resolution modes Robotic fibre positioner

9 WEAVE Characteristics Telescope, diameter Field of view Number of fibers Fiber size Number of small IFUs, size LIFU size Low-resolution mode resolution Low-resolution mode wavelength coverage (Å) High-resolution mode resolution High-resolution mode wavelength coverage (Å) WHT, 4.2m 2º 960 (plate A)/940 (plate B) x 11 x12 (1.3 spaxels) 1.3 x1.5 (2.6 spaxels) 5750 ( ) ( ) , (LIFU half of this) (LIFU half of this)

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11 Clockwise: WEAVE dummy top-end being lifted onto WHT; fibre positioner robots; part of spectrograph enclosure; holographic grating

12 Spectrograph Two arms split at 595 nm Switchable from low- to high-resolution

13 WEAVE-APERTIF survey strategy Will observe 225 galaxies, each in HR (R=10000) and LR (R=2500) Observing period Typical exposure time ~4h per galaxy (ranging from 30min to 10h, from the brightest objects to the fainter LSBs) Wavelength ranges HR ( Å Å), LR ( Å) Main lines: HR: Hß, Mgb, Fe5270, Hα LR: D4000, Hδ, Hß, Mgb, Fe5270, Hα, NaD, TiO2, CaT PI is Jesús Falcón-Barroso (IAC)

14 Science goals Why is there a bimodality in galaxy properties today, so that there are both star-forming blue galaxies and red, dead galaxies? Where does the gas come from that fuels the star formation in these galaxies? How is the star formation shut down? How much dark matter do disc galaxies have, and how is it distributed? How do processes like scattering of stars off spiral arms and bars, radial migration, or accretion of satellites manifest themselves in external disc galaxies? Always combine information on gas flows (neutral and ionised) and stellar kinematics

15 Sample and data Of order 225 nearby galaxies: need <1 kpc scale and few km/s spectral resolution Neutral and ionised gas, and stellar tracers APERTIF HI will give neutral gas velocity fields WEAVE LIFU will give stellar and ionised gas kinematics and stellar populations

16 Participation WEAVE is built by consortium of the partners in Isaac Newton Group of Telescopes (UK, NL, ES), plus participation from F, IT and various smaller parties All researchers from UK, NL, ES are free to join, others may be able to join Will operate with policies similar to SDSS, AS-4, in terms of participation, projects, publication All reduced data available internally first, plus annual public data releases

17 Summary IFUs are powerful instruments to derive gas and stellar kinematics in galaxies Low spectral resolution and limited field of view are almost always limitations to science output WEAVE will deliver high-resolution IFU data of over 200 nearby galaxies, starting 2018/19 Welcome collaborations and use of the data (subject to participation rules)