The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez The environment of nearby Blue Compact Dwarf Galaxies Ángel R. López-Sánchez Ángel R. López-Sánchez CSIRO /Australia Telescope National Facility (ATNF, Australia) Bärbel Koribalski (CSIRO/ATNF), César Esteban (IAC), Janine van Eymeren (U. Manchester), Attila Popping (CSIRO/ATNF) & John Hibbard (NRAO) Galaxies in Isolation – Granada, Spain – 12 May 2009 Ángel R. López-Sánchez Ángel R. López-Sánchez CSIRO /Australia Telescope National Facility (ATNF, Australia) Bärbel Koribalski (CSIRO/ATNF), César Esteban (IAC), Janine van Eymeren (U. Manchester), Attila Popping (CSIRO/ATNF) & John Hibbard (NRAO) Galaxies in Isolation – Granada, Spain – 12 May 2009

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Blue Compact Dwarf Galaxies (BCDGs) Subset of low-luminosity (M B  -18) and low metallicity (~10 % solar) galaxies undergoing a strong and short-lived episode of star formation. Quickly gas consumption; unlike spirals, star formation occurs in transient, sporadic bursts. Compact, irregular morphologies Intense narrow emission lines superposed on a blue continuum (i.e. Thuan 1991). – Sometimes, even Wolf-Rayet features are detected! The starbust and a very young stellar population dominate the optical light (Cairós et al. 2001), very often masking all evidence of the underlying older stellar population, – High spatial resolution NIR photometry is sometimes needed to separate both components (Noeske et al. 2003). However, the origin and peculiar nature of their starburts is still poorly understood. Subset of low-luminosity (M B  -18) and low metallicity (~10 % solar) galaxies undergoing a strong and short-lived episode of star formation. Quickly gas consumption; unlike spirals, star formation occurs in transient, sporadic bursts. Compact, irregular morphologies Intense narrow emission lines superposed on a blue continuum (i.e. Thuan 1991). – Sometimes, even Wolf-Rayet features are detected! The starbust and a very young stellar population dominate the optical light (Cairós et al. 2001), very often masking all evidence of the underlying older stellar population, – High spatial resolution NIR photometry is sometimes needed to separate both components (Noeske et al. 2003). However, the origin and peculiar nature of their starburts is still poorly understood. II Zw 40 NOT, B + V + R) SBS NOT, U + B + V)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Á.R. López-Sánchez PhD Thesis (2006) supervised by C. Esteban (IAC) Massive star formation in Wolf-Rayet galaxies See López-Sánchez & Esteban, 2008, paper I (A&A 491, 131) and II (2009, in rev.) and III (2009, in prep.). We completed a detailed analysis of a sample of 20 Wolf-Rayet galaxies (many of them BCDGs) combining deep optical and NIR broad band and H  imaging together with optical spectroscopy (long slit and echelle) data. Our multiwavelength analysis revealed that the majority of studied objects (16 up to 20) shows features such as plumes, tails, TDGs, regions with very different chemical abundances inside galaxies, perturbed kinematics of the ionized gas or lack of neutral hydrogen gas, suggesting that interactions have played an important role in the triggering mechanism of the observed star-formation bursts. Our multiwavelength analysis revealed that the majority of studied objects (16 up to 20) shows features such as plumes, tails, TDGs, regions with very different chemical abundances inside galaxies, perturbed kinematics of the ionized gas or lack of neutral hydrogen gas, suggesting that interactions have played an important role in the triggering mechanism of the observed star-formation bursts.

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Multiwavelength observations of BCDGs We are obtaining deep multi-wavelength data of a sample of BCDGs combining Optical and NIR broad-band imagery, H  imagery, Optical spectroscopy (long slit, echelle, IFU), 21-cm radio continuum and HI observations Single-dish HI surveys (i.e. Thuan et al. 1999; HIPASS, Koribalski et al. 2004; Huchtmeier et al. 2005; 2007), But still not many high-resolution HI studies! And giving unexpected surprises. Importance of interferometric HI observ.: Estimation of neutral gas mass, Analysis of the H I kinematics (rotation or turbulence behaviour, total mass, dark matter), Neutral hydrogen gas is the best tracer for galaxy-galaxy interactions !!! Combining H I results with other parameters such as the absolute luminosity, star formation rate, stellar and dust content or oxygen abundance, provide powerful clues about the nature and evolution of BCDGs. We are obtaining deep multi-wavelength data of a sample of BCDGs combining Optical and NIR broad-band imagery, H  imagery, Optical spectroscopy (long slit, echelle, IFU), 21-cm radio continuum and HI observations Single-dish HI surveys (i.e. Thuan et al. 1999; HIPASS, Koribalski et al. 2004; Huchtmeier et al. 2005; 2007), But still not many high-resolution HI studies! And giving unexpected surprises. Importance of interferometric HI observ.: Estimation of neutral gas mass, Analysis of the H I kinematics (rotation or turbulence behaviour, total mass, dark matter), Neutral hydrogen gas is the best tracer for galaxy-galaxy interactions !!! Combining H I results with other parameters such as the absolute luminosity, star formation rate, stellar and dust content or oxygen abundance, provide powerful clues about the nature and evolution of BCDGs. NGC 2915 – HI (blue) + B (green) + R (red) II Zw 40 - B + HI contours van Zee et al 1998 Meurer et al. 1996

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Observations of BCDGs using the ATCA Australia Telescope Compact Array, 6 x 22m dishes, Narrabri, NSW, Australia Deep H I line & 20 cm radio continuum observations for a sample of BCDGs – NGC 1510* – NGC 5253* Australia Telescope Compact Array, 6 x 22m dishes, Narrabri, NSW, Australia Deep H I line & 20 cm radio continuum observations for a sample of BCDGs – NGC 1510* – NGC 5253* – POX 4 – He 2-10 – POX 4 – He 2-10 – Tol 9 – Tol 30 – Tol 9 – Tol 30 – IC 4662* – IC 4870 – IC 4662* – IC 4870 – Tol – ESO 108-G017 – Tol – ESO 108-G017 Full 12h x 4 arrays: EW 367m, 750m, 1.5km, 6 km – Velocity resolution of 4 km/s – HI column density: ~ 5 x cm -2 (for 40” beam) – Angular resolution of ~20” Observations were completed on Feb 2009 * Belonging to the Local Volume HI Survey (LVHIS) project, PI B. Koribalski, see TALK ON THURSDAY! Full 12h x 4 arrays: EW 367m, 750m, 1.5km, 6 km – Velocity resolution of 4 km/s – HI column density: ~ 5 x cm -2 (for 40” beam) – Angular resolution of ~20” Observations were completed on Feb 2009 * Belonging to the Local Volume HI Survey (LVHIS) project, PI B. Koribalski, see TALK ON THURSDAY!

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez BCDGs in different environments In galaxy groups: – Tol 9 – Tol 30 – NGC 5253 In galaxy groups: – Tol 9 – Tol 30 – NGC 5253 Tol ESO B In galaxy pairs: – Tol – NGC 1510 In galaxy pairs: – Tol – NGC 1510 Apparently isolated – IC 4662 – IC 4870 – ESO 108-G017 Apparently isolated – IC 4662 – IC 4870 – ESO 108-G017 – He 2-10 – POX 4 – He 2-10 – POX 4 Tol 9 within Klemola 13 group Galaxy pair Tol & ESO B IC 4870

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Klemola 13 group (HIPASS J ) Located at 43.3 Mpc Tol 9 (ESO ) is a starburt WR galaxy ESO is a spiral at 20 kpc from Tol 9. Several objects surrounding Tol 9. 2 slit positions using 2.5m INT & 2.56m NOT. Chemical abundances using direct method: – 12+log O/H = 8.57±0.10 – log N/O = – 0.81 ± 0.11 Klemola 13 group (HIPASS J ) Located at 43.3 Mpc Tol 9 (ESO ) is a starburt WR galaxy ESO is a spiral at 20 kpc from Tol 9. Several objects surrounding Tol 9. 2 slit positions using 2.5m INT & 2.56m NOT. Chemical abundances using direct method: – 12+log O/H = 8.57±0.10 – log N/O = – 0.81 ± 0.11 WR galaxy Tol 9 within the Klemola 13 group López-Sánchez & Esteban (2008, 2009)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Our new deep images reveal a bridge towards a dwarf companion object at 10 kpc. – Composed by an OLD pop. Our new deep images reveal a bridge towards a dwarf companion object at 10 kpc. – Composed by an OLD pop. WR galaxy Tol 9 within the Klemola 13 group Deep V image, 2.56m NOT López-Sánchez (2006) López-Sánchez & Esteban (2008)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Our new deep images reveal a bridge towards a dwarf companion object at 10 kpc. – Composed by an OLD pop. H  image reveals on-going star formation activity and a filamentary structure. Our new deep images reveal a bridge towards a dwarf companion object at 10 kpc. – Composed by an OLD pop. H  image reveals on-going star formation activity and a filamentary structure. WR galaxy Tol 9 within the Klemola 13 group Continuum-substracted H  i mage, 2.56m NOT López-Sánchez (2006) López-Sánchez & Esteban (2008)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Tol 9 and surroundings López-Sánchez & Esteban (2008)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez WR galaxy Tol 9 within the Klemola 13 group Tol 9 The kinematics of the ionized gas was studied via the analysis of emission line profiles of our spectra. – PA 49º: Strange velocity pattern that can not be attributed to rotation. – PA 109º: It crosses the filamentary H  structure, showing a very intriguing behaviour: a bipolar bubble expanding at about 80 km s -1 ? – PA 109º: It crosses the filamentary H  structure, showing a very intriguing behaviour: a bipolar bubble expanding at about 80 km s -1 ? PA 49º PA 109º López-Sánchez & Esteban (2009)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez HIPASS reveals a considerable amount of atomic gas, probably mostly associated with ESO WR galaxy Tol 9 within the Klemola 13 group We obtained ATCA H I ob- servations in 6 km, 1.5 km, 750m and 350m arrays Also cont. observations at 20, 13, 6 and 3 cm.

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez WR galaxy Tol 9 within the Klemola 13 group H I distribution Total HI mass: – M HI : 3.1  10 9 M  Tol 9 cloud (W): – M HI : 2.2  10 9 M  – M HI /L B = 0.21 – M Dyn /L B = 18.8 ESO : – M HI : 8.7  10 8 M  – M HI /L B = 0.07 – M Dyn /L B = 10.4 Tail: – M HI : 6.0  10 7 M  H : – M HI : 3.5  10 7 M  H I distribution Total HI mass: – M HI : 3.1  10 9 M  Tol 9 cloud (W): – M HI : 2.2  10 9 M  – M HI /L B = 0.21 – M Dyn /L B = 18.8 ESO : – M HI : 8.7  10 8 M  – M HI /L B = 0.07 – M Dyn /L B = 10.4 Tail: – M HI : 6.0  10 7 M  H : – M HI : 3.5  10 7 M  78” x 32” Tail Tol 9 ESO H

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez WR galaxy Tol 9 within the Klemola 13 group H I kinematics ESO : – M Dyn : 1.7  M  – M Dyn /L B = 10.4 Tol 9 cloud (W): – Disturbed kin. at E – M Dyn : 2.0  M  – M Dyn /L B = 18.8 Tail: - – Cte velocity H I kinematics ESO : – M Dyn : 1.7  M  – M Dyn /L B = 10.4 Tol 9 cloud (W): – Disturbed kin. at E – M Dyn : 2.0  M  – M Dyn /L B = 18.8 Tail: - – Cte velocity 78” x 32” Tail Tol 9 ESO H PA 273º PA 192º

The M 83 subgroup 5º Koribalski 2006 Koribalski et al (in prep)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez The galaxy NGC 5253 D Hel = 4.0 Mpc (Karachentsev et al. 2004) Scale: 19 pc / arcsec Optical size: 5.0’  1.9’ Classified as Im pec, H II starburst (NED), BCDG One of the closest starbursts, observed at all wavelengths It belongs to the M83 subgroup of the Centaurus Group Deep analysis of its ionized gas using López-Sánchez et al D Hel = 4.0 Mpc (Karachentsev et al. 2004) Scale: 19 pc / arcsec Optical size: 5.0’  1.9’ Classified as Im pec, H II starburst (NED), BCDG One of the closest starbursts, observed at all wavelengths It belongs to the M83 subgroup of the Centaurus Group Deep analysis of its ionized gas using López-Sánchez et al NGC 5253 – B (blue) + V (green) + I (red) 2.5m du Pont telescope, Las Campanas Observatory, combined by Á.R. López-Sánchez 8.8’ NGC 5253 – V (blue) + I (green) + H  (red) 2.5m du Pont telescope, LCO (V, I) + 1.5m CTIO (H  ) combined by Á.R. López-Sánchez

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez New radio data of NGC 5253 from the LVHIS (Local Volume HI Survey) project using four different ATCA arrays Properties: H I flux: 31.1  1.5 Jy km/s H I mass: (8.0  0.4)  10 7 M  Dynamical mass: ~10 8 M  López-Sánchez, Koribalski & Esteban 2007 New radio data of NGC 5253 from the LVHIS (Local Volume HI Survey) project using four different ATCA arrays Properties: H I flux: 31.1  1.5 Jy km/s H I mass: (8.0  0.4)  10 7 M  Dynamical mass: ~10 8 M  López-Sánchez, Koribalski & Esteban 2007 NGC 5253: H I radio data NGC 5253 – H I map (blue) + R (green) + H  (red)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez NGC 5253: H I radio data Optical major axis Rotation? NGC 5253 ATCA H I velocity field H I velocity field: Rotating about the optical MAJOR axis? H I velocity field: Rotating about the optical MAJOR axis?

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez NGC 5253: H I radio data ESO 154-G023 ATCA H I velocity field H I velocity field: Rotating about the optical MAJOR axis? Any kind of outflow? Formation of a polar ring? Interaction with M83 ~1 Gyr ago? Disruption/accretion of a gas-rich companion Kinematics of the ionized gas decopled from kinematics of stars? H I velocity field: Rotating about the optical MAJOR axis? Any kind of outflow? Formation of a polar ring? Interaction with M83 ~1 Gyr ago? Disruption/accretion of a gas-rich companion Kinematics of the ionized gas decopled from kinematics of stars? H I velocity field: Rotating about the optical MAJOR axis? H I velocity field: Rotating about the optical MAJOR axis?   López-Sánchez, Koribalski & Esteban 2007 and Kobulnicky & Skillman 2008 NGC 5253 ATCA H I velocity field

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez The galaxy pair NGC 1512 / 1510 NGC 1512: – SB(r)ab, Z ~0.7 Zo – D = 9.5 Mpc – Bar ~ 3’ = 8.3 kpc – Ring ~ 3’ x 2’ = 8.3 x 5.5 kpc – Nuclear ring ~ 16” x 12” (740 x 550 pc) NGC 1510: – S0, BCD, WR, Z~0.2 Zo – Probable N enrichment – 5’ = 13.8 kpc from NGC 1512 H  images (Meurer et al. 2006) reveal many star forming regions – Sizes 2”–5” (90–230 pc) – Dozens in the ring – NGC 1510 – But also in external regions with no evident continuum emission! NGC 1512: – SB(r)ab, Z ~0.7 Zo – D = 9.5 Mpc – Bar ~ 3’ = 8.3 kpc – Ring ~ 3’ x 2’ = 8.3 x 5.5 kpc – Nuclear ring ~ 16” x 12” (740 x 550 pc) NGC 1510: – S0, BCD, WR, Z~0.2 Zo – Probable N enrichment – 5’ = 13.8 kpc from NGC 1512 H  images (Meurer et al. 2006) reveal many star forming regions – Sizes 2”–5” (90–230 pc) – Dozens in the ring – NGC 1510 – But also in external regions with no evident continuum emission! NGC 1512: – SB(r)ab, Z ~0.7 Zo – D = 9.5 Mpc – Bar ~ 3’ = 8.3 kpc – Ring ~ 3’ x 2’ = 8.3 x 5.5 kpc – Nuclear ring ~ 16” x 12” (740 x 550 pc) NGC 1512: – SB(r)ab, Z ~0.7 Zo – D = 9.5 Mpc – Bar ~ 3’ = 8.3 kpc – Ring ~ 3’ x 2’ = 8.3 x 5.5 kpc – Nuclear ring ~ 16” x 12” (740 x 550 pc)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez H I in NGC 1512 / 1510 ATCA observ. using 7 arrays Mosaic using 4 pointings Total int. time: 3.11 days Huge amount of neutral gas! Two extended spiral arms Two TDG candidates NGC 1512: NGC 1510: ATCA observ. using 7 arrays Mosaic using 4 pointings Total int. time: 3.11 days Huge amount of neutral gas! Two extended spiral arms Two TDG candidates NGC 1512: NGC 1510: Koribalski & López-Sánchez (2009, MNRAS, in rev.) NGC 1512 NGC 1510 TDG – M HI = 5.7  10 9 M  – M Dyn ~ 4 x M  – M HI /L B = 1 – M HI ~ 4x10 7 M  – M HI /L B ~0.07 – M HI = 5.7  10 9 M  – M Dyn ~ 4 x M  – M HI /L B = 1 – M HI ~ 4x10 7 M  – M HI /L B ~0.07

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez NGC 1512 / 1510 Rotation fit and residues The velocity field is mainly rotation, But we found some discrepances in the most external regions and in the position of NGC Star formation activity and the external HI structures seem to be consequence of the interaction that NGC 1512 and NGC 1510 are experiencing. Minor merger ~ 400 Myr The velocity field is mainly rotation, But we found some discrepances in the most external regions and in the position of NGC Star formation activity and the external HI structures seem to be consequence of the interaction that NGC 1512 and NGC 1510 are experiencing. Minor merger ~ 400 Myr Koribalski & López-Sánchez 2009, MNRAS, in rev. NGC 1512 / 1510 also include in the THING project, with higher spatial resolution (Deane & de Blok, in prep) Koribalski & López-Sánchez 2009, MNRAS, in rev. NGC 1512 / 1510 also include in the THING project, with higher spatial resolution (Deane & de Blok, in prep)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Apparently isolated BCDGs IC 4662 van Eymeren 2008, PhD, van Eymeren (in prep) – BCDG included in The Local Volume HI Survey (Koribalski et al. 2009, in prep) D = 2.44 Mpc, Opt. size = 3.0’ x 1.6’ – H I morphology: H I size= 15’ x 12’ H I mass: 1.6  10 8 M  H I distribution has 2 parts: inner high column density and lower column density ending in a kind of tail. – Distorted H I velocity field Velocity gradient runs from NE with 220 km s -1 to SW with 380 km s -1. There is a change of ~90º in its center. IC 4662 van Eymeren 2008, PhD, van Eymeren (in prep) – BCDG included in The Local Volume HI Survey (Koribalski et al. 2009, in prep) D = 2.44 Mpc, Opt. size = 3.0’ x 1.6’ – H I morphology: H I size= 15’ x 12’ H I mass: 1.6  10 8 M  H I distribution has 2 parts: inner high column density and lower column density ending in a kind of tail. – Distorted H I velocity field Velocity gradient runs from NE with 220 km s -1 to SW with 380 km s -1. There is a change of ~90º in its center. – Intringuing H  kinematics, outflows – Chemical properties may indicate two objects! ( Hidalgo-Gámez et al. 2001) – Intringuing H  kinematics, outflows – Chemical properties may indicate two objects! ( Hidalgo-Gámez et al. 2001)

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Apparently isolated BCDGs IC 4870 – D = 10.2 Mpc – Optical prop: 35” compact core, Elliptical low-luminosity component 1.4’x0.4’ – H I reveals two long tails 3.7’ (N) and 4.2’(S) Knot in S tail has ~14% of the neutral mass. – Merger of two independent HI clouds? ESO 108-G017 – D = 28.2 Mpc – Faint optical tail – H I is +5 times optical s.! – Elongated HI cloud with some disturbed kinematics IC 4870 – D = 10.2 Mpc – Optical prop: 35” compact core, Elliptical low-luminosity component 1.4’x0.4’ – H I reveals two long tails 3.7’ (N) and 4.2’(S) Knot in S tail has ~14% of the neutral mass. – Merger of two independent HI clouds? ESO 108-G017 – D = 28.2 Mpc – Faint optical tail – H I is +5 times optical s.! – Elongated HI cloud with some disturbed kinematics He 2-10: Extended HI emission perpendicular to rotation axis? POX 4: Independent HI cloud + strange HI kinematics? He 2-10: Extended HI emission perpendicular to rotation axis? POX 4: Independent HI cloud + strange HI kinematics?

The environment of nearby BCDGs – Granada, May 12, 2009 Ángel R. López-Sánchez Conclusions Detailed multiwavelength analysis of BCDGs – Optical / NIR imagery – H  imagery – Deep optical spectroscopy (long slit and echelle) – H I and 20cm observations H I data are fundamental to understand the dynamical evolution of these objects. Despite the environment, ALL studied BCDGs show interactions features, very evident in the majority of them, confirming the main result found in our analysis of a sample of Wolf-Rayet galaxies (López-Sánchez PhD, 2006; López-Sánchez & Esteban 2008, 2009a,b) Detailed multiwavelength analysis of BCDGs – Optical / NIR imagery – H  imagery – Deep optical spectroscopy (long slit and echelle) – H I and 20cm observations H I data are fundamental to understand the dynamical evolution of these objects. Despite the environment, ALL studied BCDGs show interactions features, very evident in the majority of them, confirming the main result found in our analysis of a sample of Wolf-Rayet galaxies (López-Sánchez PhD, 2006; López-Sánchez & Esteban 2008, 2009a,b) Are interactions between dwarf objects the main triggering mechanism of starbursts, specially in BCDGs? Are BCDGs real isolated systems? Many surprises will come from HI surveys (i.e. using ASKAP, Australia SKA Pathfinder) Are interactions between dwarf objects the main triggering mechanism of starbursts, specially in BCDGs? Are BCDGs real isolated systems? Many surprises will come from HI surveys (i.e. using ASKAP, Australia SKA Pathfinder)