ionized and neutral gas in the starburst galaxy ngc 5253 australia telescope national facility...

Ionized and neutral gas Ionized and neutral gas in the starburst galaxy in the starburst galaxy

NGC 5253NGC 5253

Ionized and neutral gas Ionized and neutral gas in the starburst galaxy in the starburst galaxy

NGC 5253NGC 5253

Australia Telescope National Facility (ATNF, Australia) Galaxies in the Local Volume – Sydney – 9 July 2007Galaxies in the Local Volume – Sydney – 9 July 2007

Australia Telescope National Facility (ATNF, Australia) Galaxies in the Local Volume – Sydney – 9 July 2007Galaxies in the Local Volume – Sydney – 9 July 2007

Ángel R. López SánchezÁngel R. López SánchezÁngel R. López SánchezÁngel R. López Sánchez

IONIZED AND NEUTRAL GAS IN THE STARBURST GALAXY NGC 5253 Ángel R. López-Sánchez

Galaxies in the Local Volume Sydney – 9 July 2007

The galaxy NGC 5253

DHel= 3.3 Mpc (Gibson et al. 2000)

Scale: 16 pc / arcsec Optical size: 5.0’ 1.9’ Classified as Im pec, H II

starburst (NED), blue compact dwarf galaxy

One of the closest starbursts, observed at all wavelengths

It belongs to the M83 subgroup of the Centaurus Group

Other names: – HARO 10, – UGCA 369, – IRAS 13370-3123, – PGC 048334, – AM 1337-312, – HIPASS J1339-31A

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 M 83 subgroup

5º

Koribalski 2006Koribalski et al. In preparation



NGC 5253 new optical and radio observations

Optical deep VLT echelle spectroscopy

– UVES @ 8.2m Kueyen, 30 March 2003– Slit 12” 1.5” size, PA 0º, 3100 – 10400 Å– Excellent seeing, ~0.5”– High spatial (0.18 arcsec/pix) and spectral

(0.02 Å/pix) resolution– Study performed with César Esteban (IAC),

Jorge García-Rojas (IAC), Manuel Peimbert (UNAM) & Mónica Rodríguez (INAOE), López-Sánchez et al. 2007, ApJ 656, 168

1.4 GHz data (H I and continuum) from the ATCA

– Data from LVHIS project (Koribalski et al.)

– Combining data from 1.5km, 750m and EW367m arrays

8.2m VLT

ATCA

ionized gas

neutral gas



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.

López-Sánchez, Esteban, García-Rojas, Peimbert & Rodríguez 2007, ApJ 656, 168

and López-Sánchez PhD Thesis

A

B

C

D

NGC 5253 – WFPC @ 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.



Detection of O and C recombination lines (RLs) in NGC 5253

RLs are very weak! (103

to 104 weaker than CEL)

Abundances using CEL lines depend strongly on Te, but in RL lines the Te dependence is weak

PROBLEM: Abundance discrepancy:

O++/H+ (RL) O++/H+ (CEL)

The abundance discrepance is also found in NGC 5253 and with similar values than that obser-

ved in Galactic H II regions! (García-Rojas et al. 2004, 2005,

2006; Esteban et al. 2004)

Te Fluctuations? (Peimbert 1967; Esteban 2002)

>


López-Sánchez et al. 2007, ApJ 656, 168




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 = – 1.50

12+log O/H = 8.18 log N/O = – 0.91

López-Sánchez et al. 2007, ApJ 656, 168



NGC 5253 VLA H I total intensity (contours) and optical image (gray image), Kobulnicky & Skillman, 1995, ApJ, 454, L121

NGC 5253: H I radio data

New radio data of NGC 5253 from the LVHIS project using three different ATCA arrays:

1.5A, 2x750A, EW367, no ant. 6. 6 km/s resolution, 32 channels Beam size: 86” 47”, PA 5º rms ~ 1.9 mJy /beam

NGC 5253 ATCA H I total intensity (false color) and DSS R optical image (contours)

Kobulnicky & Skillman, 1995



Total H I flux: ATCA: 31.1 1.5 Jy km/s VLA: 33.4 9.9 Jy km/s (Paturel et al. 2003)

H I mass: (8.0 0.4) 107 M

Dynamical mass: ~108 M


NGC 5253 – H I map (blue) + R (green) + H (red)




Optical major axis

Rotation?

NGC 5253 ATCA H I velocity field

H I velocity field:

Rotating about the optical MAJOR axis?



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?

See poster “Interactions and star formation activity in Wolf-Rayet galaxies” and López-Sánchez PhD Thesis.

H I velocity field:

Rotating about the optical MAJOR axis?




H I velocity field:

Rotating about the optical MAJOR axis? Any kind of outflow? Formation of a polar ring? Interaction with M83 ~1000 Ga ago? Disruption/accretion of a gas-rich companion?

See poster “Interactions and star formation activity in Wolf-Rayet galaxies” and López-Sánchez PhD Thesis.



1.4 GHz radio-continuum:

S1.4 GHz = 87.1 3.5 mJy

S1.4 GHz = 85.8 3.4 mJy

(Yun et al. 2001)

Star Formation Rate:

SFR1.4 GHz ~ 0.03 M yr-1

(using Condon et al. 2002)

SFRFIR ~ 0.08 M yr-1

(using IRAS fluxes and Kennicutt 1998)

SFRH ~ 0.27 M yr-1

(Calzetti et al. 2004)


NGC 5253 – R map + 1.4 GHz continuum



Conclusions NGC 5253 is still a puzzling BCD galaxy.

IONIZED GAS in the center of the starburst using VLT:

– Detection of O and C recombination lines, the first time in a starburst

– We confirm a localized N enrichment and possible He pollution, consistent with the existence of WR stars.

NEUTRAL GAS combining data from LVHIS project:

– Distribution and mass of H I.

– VERY intringuing H I kinematics... Outflow, interaction M83 / gas-rich companion?

NGC 5253 – H I map (blue) + R (green) + H (red)

ionized and neutral gas in the starburst galaxy ngc 5253 australia telescope national facility...

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