The ionized gas kinematics in dwarf galaxies: 3D spectroscopic study

The ionized gas kinematics in dwarf galaxies: 3D spectroscopic study Alexei Moiseev Special Astrophysical Observatory, Nizhnij Arkhyz, Russia

SCORPIO: multi-mode focal reducer with scanning FPI • Introduction: • velocity fields • Fabry-Perot interferometers • Kinematics of dIrr and BCDG: • Effects of starformation (outflow, bubles...) • Mergers • Polar rings and disks SAO RAS 6-m telescope

V V Vz Vz  Vr Velocity fields of galactic disk Thick disk approximation • Non-circular gas motions : • bar and spiral arms • active galactic nucleus • violent starformation • interacting galaxies, mergers

Fabry-Perot Interferometer Interferogram of M51 (Tully, 1974) 1901Fabry Ch. & PerotA.“On a New Form of Interferometer” (ApJ, 13, 265) 1914Buisson H., Fabry Ch. & Bourget H. turned a FP etalon on the Orion nebula 1950-60Courtes G. et al. revived this technique for observations of HII-regions 1974Tully R.B., constructed the first spectrophotometric data-cube (M 51) 1980-90sthe piezoelectrically IFP + panoramic detectors(photon counters and CCDs): TAURUS (Taylor K. & Atherthon P.), CIGALE (Boulesteix J. et al) Now:New generation devices for large telescopes: SCORPIO (BTA, 6-m), Kyoto3D (SUBARU) New generation photon counters: FaNTOmM, GHASP-instrument, GHaFAS

Y λ X Scanning Fabry-Perot Interferometer gap between plates Line intensity  • large field of view:1-10 arcmin • high spectralresolution: = 0.2…2Å • high orders: n= 100...1000 • small spectral range:= /n=5…50 Å 

Scanning Fabry-PerotInterferometer in SAO 1982 CIGALE system from Marseille Observatory (J.Boulesteix et al.) 1988 CIGALE with new IPCS ``KVANT`` (SAO team: V. Afanasiev, A. Burenkov, S. Dodonov, S. Drabek, V. Vlasyuk) 1997 set a CCD instead IPCS 2000 multimode focal reducer SCORPIO + fast CCD 2Kx2K (Moiseev, 2002; Afanasiev & Moiseev, 2005) 2009 new Fabry-Perot etalon (IC Optical System Ltd.) Observations in Hα, [NII], [SII] emission lines with resolution 0.4 A (20 km/s) Data reduction Observed cube Scaled in wavelength

GMRT(Begum et al, 2008) HII vs. HI kinematics HI Different spatial scales: beam smoothing+ difference in distribution of gas fractions Hα Direct comparison of HI and HII spatial-resolved kinematics in dwarf galaxies (bubles, outflow, envelopes of HII regions): IC1613 (Lozinskaya et al, 2003) IC10 (Lozinskaya et al, 2008) NGC 2366 (van Eymeren et al, 2008) NGC 4861 (van Eymeren et al, 2009) 6-m telescope, SCORPIO/FPI

FPI observations of dIrr/BCDG Individual objects: I Zw 18 (3.6 m, CFHT) — Petrosian et al (1997) Mrk 86 (3.6 m, CFHT) — Gil de Paz et al (1997) NGC4449 (4.2 m, WHT) — Muñoz-Tuñón et al (1998) Samples: 6 BVDGs (3.6 m, ESO) — Östlin et al (1999) 23 dIRR in GHASP survey (1.93-m,OHP) - Epinat et al (2008), (however only ~10 objects have good quality of velocity fields) Total: velocity fields of 37 BCDG and dIrr

H-image Rotation or peculiar motions? Östlin et al (1999): ``[the optical] velocity fields of the BCGs are complex and appear perturbed...'' • No regular circular rotation? • all ionized gas motions connect with regions of ongoing starformation VIIZw403 Lozinskaya et al. (2006)

H II kinematics in the region of ongoing starformation in the dIrr galaxyIC 1613: a complex of expanding shells: • re-estimation ages of the bubles • comparision with SF models 4 PV diagrams for ionized shells: R4 4 v1 v1 v2 v2 R4 (Lozinskaya et al., 2003)

Regular circular rotation Major part of the sample (24/37=65%) has regular velocity pattern that is described by the model of circular rotation: Vmax>>Vres Velocities-model Velocities Model Ha image Mrk 36 MB=-14.9 UGC5423 MB=-14.7

UGC 993: Merging of two dwarf disks GMRT HI data (courtesy to Chengalur & Pustilnik) titled-ring model (Pustilnik et al., submitted)

HS2236+1344: two disks major merger SDSS (Pustilnik, Moiseev & Kniazev, MNRAS, submitted) Velocities Model of circular rotation

NGC 7468: the circumnuclear polar disk Bettoni et al. (1990) Hvelocity field Н- image The velocity field shows a gaseous disk (r<900 pc) whose rotation plane is almost perpendicular to the main galactic plane. The merging of a gas-rich dwarf galaxy seem to be responsible for the formation of the polar disc (Shaliapina et al. 2004)

The polar-ring formation: Bournaud & Combes (2003) 1) the merging scenario: proposed by Bekki (1997, 1998), this scenario assumes a head-on collision between two orthogonal spiral galaxies. 2) the accretion scenario: this scenario (e.g. Schweizer et al. 1983, Reshetnikov & Sotnikova 1997) consists of the accretion of gas from another galaxy by the host.

Mrk 33 (Haro 2): inner polar disk SDSS Inner disk (kinematics): PA=171°, i=60° Outer disk (isophotes) : PA=120°, i=48° Two solutions for Δi: 86° and 41° B-band (Cairos et al, 2001) B-band (Cairos et al, 2001) B-band (Cairos et al, 2001) VLA 15'' beam (Bravo-Alfaro et al, 2004): ``..a dwarf elliptical that has recently captured gas in a close interaction or merger with an initially gas-rich companion.''

Mrk 370: outer HII regions on polar orbits Ha image(Cairós et al, 2002) Inner disk : PA=270°, i=40° Outer regions : PA=15°, i=70° Two solutions for Δi: 83° and 65° Tilted-rings models:

BCD galaxy Arp 212 (NGC 7625, III Zw 102)‏ Arp (1966) Hα-image Moiseev (2008) Inner disk (‘main body’) Outer filaments 6-m telescope, FPI

Warped outer disk? Tilted-ring model for outer disk Orbits of the gaseous clouds

Arp 212: HI distribution HI VLA (Li et al., 1993):‏ Precession of gas orbits in the triaxial garvitational potential

..Formation of the polar/warped gaseous disk after accretion from gas-rich dwarf galaxy UGC 12549.. (Mosieev, 2008)

Even in galaxies with strong starformation the regular component dominates in the ionized gas velocity fields (~2/3 of all cases) An important role of current/recent interactions and mergers in the observed enhanced star formation in BCDG (all objects in the sample of low-metallicity dwarfs are of interacted/mergers) Gas on polar/warped orbits (5/37=14% of observed sample)!

Thank you!

The ionized gas kinematics in dwarf galaxies: 3D spectroscopic study