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The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Nitrogen excess in starburst galaxies: chemical enrichment via winds of Wolf-Rayet.

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Presentation on theme: "The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Nitrogen excess in starburst galaxies: chemical enrichment via winds of Wolf-Rayet."— Presentation transcript:

1 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Nitrogen excess in starburst galaxies: chemical enrichment via winds of Wolf-Rayet stars? Ángel R. López-Sánchez Ángel R. López-Sánchez César Esteban (IAC), Jorge García-Rojas (IA-UNAM), Adal Mesa Delgado (IAC) & Luis López-Martín (IAC) Ángel R. López-Sánchez Ángel R. López-Sánchez César Esteban (IAC), Jorge García-Rojas (IA-UNAM), Adal Mesa Delgado (IAC) & Luis López-Martín (IAC) CSIRO /Australia Telescope National Facility (ATNF, Australia) The Cosmic Odyssey of the Elements – Aegina – Greece – 23 Jun 2008 CSIRO /Australia Telescope National Facility (ATNF, Australia) The Cosmic Odyssey of the Elements – Aegina – Greece – 23 Jun 2008

2 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Chemical evolution of galaxies  elements (S, Ne, Ar): const. with O/H – Primary production in massive stars (Izotov & Thuan 1999; Izotov et al. 2006) N/O is not so evident!  elements (S, Ne, Ar): const. with O/H – Primary production in massive stars (Izotov & Thuan 1999; Izotov et al. 2006) N/O is not so evident! – Constant for 12+log O/H < 7.6 Primary production – Dispersion for 7.6 < 12+log O/H < 8.3 Delay in N production & loss via galactic winds – Increases for 12+log O/H > 8.3 Secondary production Kobulnicky et al.1997; Izotov et al – Constant for 12+log O/H < 7.6 Primary production – Dispersion for 7.6 < 12+log O/H < 8.3 Delay in N production & loss via galactic winds – Increases for 12+log O/H > 8.3 Secondary production Kobulnicky et al.1997; Izotov et al  log (N/O) ~ 0.5

3 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Starburst galaxies with high N/O  log (N/O) ~ 0.5 for the typical O/H value – Pustilnik et al Common feature: Wolf-Rayet galaxies! – Winds of the WR stars may produce a N enrichment – However, the N enrichment should be very localized and a short episode Observational problem: – [N II] 6548,6583 are very close to H . – + broadening effects (kinematics)  log (N/O) ~ 0.5 for the typical O/H value – Pustilnik et al Common feature: Wolf-Rayet galaxies! – Winds of the WR stars may produce a N enrichment – However, the N enrichment should be very localized and a short episode Observational problem: – [N II] 6548,6583 are very close to H . – + broadening effects (kinematics) New data with enough spectral resolution and a systematic study is needed !! Gaussian fit for H  and [N II] in HS using long-slit spectroscopic data from 6m BTA and a spectral resolution of 2.38 A/pix (Pustilnik et al. 2004). HS :  log (N/O) = m WHT : 0.36 A/pix 8.2m VLT: A/pix 4.2m WHT : 0.36 A/pix 8.2m VLT: A/pix

4 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Wolf-Rayet galaxies A subset of emission-line and H II galaxies whose integrated spectra show broad emission features attributed to the presence of Wolf-Rayet stars. Emission lines : Recombination lines (RL) of H y He Recombination lines (RL) of H y He Collisionally excited lines (CEL) of O, N, S, Ne, Ar, Cl, Fe... Collisionally excited lines (CEL) of O, N, S, Ne, Ar, Cl, Fe... Emission lines of WR stars WN WC Last catalogue of WR galaxies 140 objects (Schaerer et al. 1999), nowadays ~250 WR galaxies known – The number of WR stars with respect O stars is high, the burst shoud be short. – IMF extended to HIGH masses – Short-lived starburst (< 6 Myr) – The number of WR stars with respect O stars is high, the burst shoud be short. – IMF extended to HIGH masses – Short-lived starburst (< 6 Myr) Blue WR Bump ~ 4650 Å WNL stars Blue WR Bump ~ 5800 Å WC stars

5 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez 1.NGC Mkn Haro 15 4.Mkn Mkn 5 6.POX 4 7.UM III Zw IRAS IRAS SBS SBS SBS SBS SBS SBS Tol 9 18.Tol Arp NGC 5253 III Zw 107SBS SBS SBS Massive star formation in WR galaxies Á.R. López-Sánchez PhD Thesis (2006) supervised by C. Esteban (IAC): The sample: Mkn 5 IRAS SBS SBS UM NGC Mkn Haro 15 4.Mkn Mkn 5 6.POX 4 7.UM III Zw IRAS IRAS SBS SBS SBS SBS SBS SBS Tol 9 18.Tol Arp NGC 5253 Main aim: Study the massive star formation activity in WR galaxies and the role that interactions with dwarf objects have in the triggering mechanism of starbursts. See López-Sánchez & Esteban, 2008, paper I (in rev.) and II & III (in prep.) We have performed a detailed analysis of a sample of 20 WR galaxies combining deep optical and NIR broad band and H  imaging together with optical spectroscopy (long slit and echelle) data.

6 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez UM 420 Located at 237 Mpc At 16.5” from UGC 1809, located at 97 Mpc It has very blue colors (U-B) = -0.8 and a lot of H  emission, with SFR = 3.7 Mo/yr Located at 237 Mpc At 16.5” from UGC 1809, located at 97 Mpc It has very blue colors (U-B) = -0.8 and a lot of H  emission, with SFR = 3.7 Mo/yr UM 420 Disturbed morphology and kinematics New optical spectra (4.2m WHT) Disturbed morphology and kinematics New optical spectra (4.2m WHT) UGC 1809 López-Sánchez, 2006, PhD López-Sánchez & Esteban, 2008 López-Sánchez, 2006, PhD López-Sánchez & Esteban, 2008

7 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez UM 420 New optical spectra (4.2m WHT) – We detect both the WR bump and the He II 4686 emission line – Very good estimation of Te, Ne and C(H  ) – Excellent estimation of [N II] and H  fluxes – 12 + log (O/H) = 7.95 ± 0.05 – log (N/O) = ± 0.08 New optical spectra (4.2m WHT) – We detect both the WR bump and the He II 4686 emission line – Very good estimation of Te, Ne and C(H  ) – Excellent estimation of [N II] and H  fluxes – 12 + log (O/H) = 7.95 ± 0.05 – log (N/O) = ± 0.08  0.4 dex higher than expected!

8 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez NGC 1741 (Mkn 1089) NGC 1741 is the main member (A+C) in Hickson Compact Group 31 A very luminous WR galaxy A merger in progress!! Optical spectrum – We detect the WR bump – Direct estimation of Te, Ne and C(H  ) – 12+log (O/H) = 8.22 ± 0.05 – log (N/O) = ± 0.10 NGC 1741 is the main member (A+C) in Hickson Compact Group 31 A very luminous WR galaxy A merger in progress!! Optical spectrum – We detect the WR bump – Direct estimation of Te, Ne and C(H  ) – 12+log (O/H) = 8.22 ± 0.05 – log (N/O) = ± 0.10 López-Sánchez, Esteban & Rodríguez (2004a), ApJS  Typical values!

9 The Cosmic Odyssey of the Elements – Jun 23, 2008 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

10 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez NGC 5253: Deep VLT echelle spectroscopy Four independent regions analized in detail: Physical conditions: Ne, Te, reddening. Chemical abundances: O, N, Ne, S, Cl, Ar, Fe, He, C Kinematics of the ionized gas 169 emission lines identified in region B 2 main results: The confirmation of a localized chemical pollution, The detection of O and C recombination lines. Four independent regions analized in detail: Physical conditions: Ne, Te, reddening. Chemical abundances: O, N, Ne, S, Cl, Ar, Fe, He, C Kinematics of the ionized gas 169 emission lines identified in region B 2 main results: The confirmation of a localized chemical pollution, The detection of O and C recombination lines. López-Sánchez, Esteban, García-Rojas, Peimbert & Rodríguez 2007, ApJ 656, 168 and López-Sánchez PhD Thesis López-Sánchez, Esteban, García-Rojas, Peimbert & Rodríguez 2007, ApJ 656, 168 and López-Sánchez PhD Thesis A B C D NGC 5253 – HST UV (blue) + H  (green) + [S II] (red) Combined by Á.R. López-Sánchez H  contours over the 2200 Å continuum image (Kobulnicky et al. 1997) and our VLT slit position.

11 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez NGC 5253: Deep VLT echelle spectroscopy Our deep VLT spectra CONFIRM the strong N overabundance in a particular zone and also suggest He enrinchement. The comparison of our empirical stellar yields with – those obtained by stellar evolution models (Meynet & Maeder 2002) – empirical yields for ring nebulae associated to Galactic WR stars (Esteban et al. 1992) indicates that few WR stars CAN PRODUCE the observed N and He pollution The amount of enrichment material needed is consistent with the mass lost by the number of WR stars estimated. Our deep VLT spectra CONFIRM the strong N overabundance in a particular zone and also suggest He enrinchement. The comparison of our empirical stellar yields with – those obtained by stellar evolution models (Meynet & Maeder 2002) – empirical yields for ring nebulae associated to Galactic WR stars (Esteban et al. 1992) indicates that few WR stars CAN PRODUCE the observed N and He pollution The amount of enrichment material needed is consistent with the mass lost by the number of WR stars estimated. 12+log O/H = 8.28 log N/O = – log O/H = 8.18 log N/O = – 0.91 López-Sánchez et al. 2007, ApJ 656, 168

12 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez NGC 5253: Deep VLT echelle spectroscopy [O III] H  [N II] [O III] H  [N II]

13 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez New radio data of NGC 5253 from the LVHIS (Local Volume HI Survey) project using three 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 three 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)

14 The Cosmic Odyssey of the Elements – Jun 23, 2008 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 López-Sánchez, Koribalski & Esteban 2007 and Kobulnicky & Skillman 2008 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 López-Sánchez, Koribalski & Esteban 2007 and Kobulnicky & Skillman 2008 H I velocity field: Rotating about the optical MAJOR axis? H I velocity field: Rotating about the optical MAJOR axis?  

15 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Local starburst galaxy IC 10 Starburst in the Local Group at ~660 kpc 12+log (O/H) = 8.26 (Garnett 1990) A lot of WR stars! (26 studied by Crowther et al. 2003) A good place to look for localized N enrichment!

16 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Local starburst galaxy IC 10 Optical 3D spectra: 3.5m CAHA – 1”/pix, 0.8 A/pix – Detected WR signatures (WR-24 A, Crowther et al. 2003) – No detection of weak auroral lines (or affected by an ugly Hg emission line!) – But the maps do not show any evidence of localized N enrichment  Optical 3D spectra: 3.5m CAHA – 1”/pix, 0.8 A/pix – Detected WR signatures (WR-24 A, Crowther et al. 2003) – No detection of weak auroral lines (or affected by an ugly Hg emission line!) – But the maps do not show any evidence of localized N enrichment  López-Sánchez, López-Martín, Mesa-Delgado & Esteban, 2008, in prep. WR

17 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez NGC 1512: – SB(r)ab, – Z ~0.7 Zo – D = 9.5 Mpc – Many SF regions (H  and UV-rich) NGC 1510: – S0, BCD, WR – 5’ = 13.8 kpc from NGC log(O/H) ~ 7.95 log(N/O) ~ -1.2 Using data provided by Storch-Bergmann+ (1995) NGC 1512: – SB(r)ab, – Z ~0.7 Zo – D = 9.5 Mpc – Many SF regions (H  and UV-rich) NGC 1510: – S0, BCD, WR – 5’ = 13.8 kpc from NGC log(O/H) ~ 7.95 log(N/O) ~ -1.2 Using data provided by Storch-Bergmann+ (1995)  0.3 dex higher than expected! ATCA H I mosaic (3.1 days integr. time) Interaction features!! Koribalski, López-Sánchez & McIntyre (2008, sub.) ATCA H I mosaic (3.1 days integr. time) Interaction features!! Koribalski, López-Sánchez & McIntyre (2008, sub.) NGC 1512 NGC 1510

18 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Conclusions (I) UM 420 Mkn 1089 X X NGC 5253 A NGC 5253 C NGC 1510 Data of more galaxies with enough spectral and spatial resolution to get more definitive results (WORK IN PROGRESS Data of more galaxies with enough spectral and spatial resolution to get more definitive results (WORK IN PROGRESS)

19 The Cosmic Odyssey of the Elements – Jun 23, 2008 Ángel R. López-Sánchez Conclusions (II) The multiwavelength analysis of a sample of Wolf-Rayet galaxies (López-Sánchez PhD, 2006; López-Sánchez & Esteban 2008) revealed that the majority of them (17 up to 20) show interaction features. New deep data are confirming this result in other WR galaxies. Are interactions between dwarf objects the main triggering mechanism of starbursts, specially in BCDGs? Is this fact related with the detection of N enrichment only in WR galaxies? (Very localized and short event consequence of the recent pollution of the WR winds?) Are interactions between dwarf objects the main triggering mechanism of starbursts, specially in BCDGs? Is this fact related with the detection of N enrichment only in WR galaxies? (Very localized and short event consequence of the recent pollution of the WR winds?)


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