HII Galaxies Eduardo Telles

Observatório Nacional, Rio de Janeiro, Brasil

Patricio Lagos Vinicius Bordalo

•HII galaxies are dwarf starburst galaxies

•typically have low metallicities •Large HI content •Low dust content •High current SF rates

• No obvious signs of an evolved underlying galaxy

Are they young galaxies in the local universe forming their first generation of stars? (Sargent & Searle 1970)

1D

Lagos, Telles & Melnick 2007)

What is *the Star Formation History?

*the Star Formation Mode?

What triggers SF?

Mk36 - R Mk36 - J

UM461 - R UM 461 - J

Galáxias HII da nossa amostra : imagens no infra-vermelho próximo e no óptico (Telles, Sampson, Tapia 2004) (Telles & Terlevich 1997)

(See also Mendez & Esteban 2000)

SF bursts not only in time but in space too!

Mk36 - R Mk36 - J

Lagos, Telles, Carrasco, Nigoche 2011

clusters

observations are redder than models (models at low metalicities are never red enough) The problem may be caused by a number of things: i) nebular (line and continuum) ii) dust emission iii) Massive star evolution at low metallicities stellar interior rotation n(RSG)/n(BSG) (at ~10^7 yr) t(He), N(H+) iv) Extended SFH – composite pop. - TPAGB (at 1Gy)

• Stellar cluster formation and evolution is the mode of recent SF in HII galaxies (stochastic rather than propagation?!). HII galaxies are very "blobby", but have homogeneous physical conditions.

Temporal and spatial analysis: -SF is synchronized in galactic scales <108 yrs -SF in locus simultaneously (stochastic) due to physical conditions of the ISM

→→ Pop-corn model for HII galaxies (Telles 2009)

What is the distribution of the

physical conditions?

The Chemo-physical condition distribution in UM 408 Lagos, P.; Telles, E.; Munoz-Tunon,C.; Carrasco, R.; Cuisinier, F. & Tenorio-Tagle, G.;

2009, The Astronomical Journal 137 5068-5079

Fig. 7.— [OIII]/Hβ versus [SII]/Hα. Red crosses correspond to region A, green crosses to region B and the blackcrosses to the outer part of the galaxy. The integrated value for the galaxy is represented by the blue star. The solid line shows the maximum starburst line in the Kewley et al. (2001) model. »12% of the data points (»5% of the Hα flux) are lying in the nonphotoionized region. These points are associated with the outer part of the observed region of the galaxy.

L(Hβ) ∝ σ 4 Size ∝σ2

Aperture effects Systematic effects LUBVRIJHK

M/L of starbursts Infalling gas Turbulence, Rotation Outflows Dust extinction Calibration of emission lines Improper application to High

redshift galaxies (galaxy families)

?

The origin of supersonic motions • range of �σ • σmin - σmax •Gravity •Shells? •SN, Winds

FP (O/H, W(Hβ), ΣSB)

Validity to high redshift Cosmological Distance Indicator Hubble Diagram

Microphysics of SF GMC

density, temperature, pressure

Line profiles: •Gaussian •Irregular •Asymetric

What is the origin of the supersonic

motions? σ ??

The Kinematics of II Zw 40 Bordalo, V.; Plana, H. & Telles, E; (2009) ApJ, 696, 1668

Hα Radial velocity σ

σgas == σ* ??

Calibrating The

L-σ relation

Bordalo & Telles (2011)

The dark energy equation of state using alternative cosmic high-z tracers M Plionis et al 2010 J. Phys.: Conf. Ser. 222 012025

Broad lines? SF vs. AGN

An exceptional BCD with an very dense nucleus: Mrk 996 Telles, Thuan & Izotov 2012

The ld/hd imaging method (Steiner etal 2009a)

Associating kinematics & Physical conditions

Beyond standard IFU methods

PCA Tomography of Mrk 996 (see Steiner etal 2009a,b,2010)

PCA → correlated coordinates into a system of uncorrelated coordinates ordered by principal components of decreasing variance (eigenvectors) Tomograms → images produced by the projections of the data on to these coordinates the eigenvector’s orthogonality may be instrumental in separating and identifying uncorrelated physical phenomena one can enhance features, extract noise, compress data, extract spectra, etc. Answer → question Data cube → data matrix → pca → eigenspectra an tomograms → reconstruction

Data transmission reduction: -original data cube →40.5 Mb -eigenspectrum → 206 Kb -tomogram → 17.3 Kb -5 eigenspectra and tomograms with most information → 1.1 Mb -reduction facton !→ 37

Summary • HII galaxies are at least “middle aged • HII galaxies are dwarf starbursts and mostly isolated • internal mechanims are able to trigger SF • SF occurs in association with the formation of SSCs • SF is synchronized and stochastics (≤ Δages) in scales of Kpc, and propagation may occur is scales of ≤ 100 pc • overal physical conditions of ISM are responsible for SF

HII galaxies form stars like “pop in a pan” (Telles 2009) • analysis of the interplay of the evolution of SSCs and the phases of the ISM is a promising path to unveil details of SF • 3D spectroscopy allow a direct view of the spatial and temporal evolution

What’s next in the business with Gemini? GMOS σ gas == σ* ?? GNIRS L – σ @ z~0.5 NIFS/ALTAIR SF vs. AGN (low Z) GSAOI/GEMS cluster age dating (starburst elementary entities)