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

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Presentation on theme: "The ionized gas kinematics in dwarf galaxies: 3D spectroscopic study Alexei Moiseev Special Astrophysical Observatory, Nizhnij Arkhyz, Russia."— Presentation transcript:

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

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

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

4 Fabry-Perot Interferometer Interferogram of M51 (Tully, 1974) 1901 Fabry Ch. & Perot A. “On a New Form of Interferometer” (ApJ, 13, 265) 1914 Buisson H., Fabry Ch. & Bourget H. turned a FP etalon on the Orion nebula 1950-60 Courtes G. et al. revived this technique for observations of HII-regions 1974 Tully R.B., constructed the first spectrophotometric data-cube (M 51) 1980-90s the 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

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

6 Scanning Fabry-Perot Interferometer 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

7 HII vs. HI kinematics Fabry-Perot interferometers 21 cm radio inrerferometers ISMIonized gasNeutral hydrogen Spatial resolution 1-2 arcsec10-50 arcsec Velocity resolution 10-50 km/s2-10 km/s GMRT(Begum et al, 2008) 6-m telescope, SCORPIO/FPI 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) HI HαHα Different spatial scales: beam smoothing + difference in distribution of gas fractions

8 FPI observations of dIrr/BCDG Galaxies 6-m telescope proposal PI Puplications IC10, IC1613, U6456Lozinskaya Lozinskaya, et al (2003, 2006- 2009) KK12, DDO125, U8508Begum 10 BCDGs Muñoz-Tuñ ó n Martines-Delgado, et al. (2007) 10 low-metallicity BCDGsPustilnikPustilnik et al., submitted 10 dwarfsKhlypin NGC 7468 Hagen-ThornShaliapina et al (2004) 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

9 Rotation or peculiar motions? H  -image No regular circular rotation? all ionized gas motions connect with regions of ongoing starformation Lozinskaya et al. (2006) Östlin et al (1999): ``[the optical] velocity fields of the BCGs are complex and appear perturbed...'' VIIZw40 3

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

11 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 Ha image Velocities Model Velocities-model Mrk 36 M B =-14.9 UGC5423 M B =-14.7

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

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

14 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 Н  - image H  velocity field (Shaliapina et al. 2004) NGC 7468: the circumnuclear polar disk Bettoni et al. (1990)

15 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.

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

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

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

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

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

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

22 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)!

23 Thank you!

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