Multiwavelength analysis of the Lyman alpha emitting galaxy Haro 2: relation between the diffuse Lyman alpha and soft X-ray emissions

Abstract

In order to use Lyman alpha (Lya) emission as star formation tracer in cosmological studies, we must understand how the resonant scattering affects the escape fraction of the Lya photons. Thus, high spatial resolution multiwavelength studies of nearby Lya emitters, like Haro 2, are highly needed. For that purpose, we have used Chandra X-ray and HST (UV, optical and NIR) images of Haro 2, and STIS and ground-based spectral images along its major and minor axes, to characterize the Lya emission and the properties of the stellar population. The UV, Ha (Halpha) and FIR luminosities of the Haro 2 nuclear starburst are reproduced using evolutionary synthesis models assuming a young stellar population with ages ~3.5-5.0 Myr, affected by differential interstellar extinctions. The observed X-ray emission is attributed to gas heated by the mechanical energy released by the starburst (soft component) and a Ultra-Luminous X-ray source candidate (hard). Both compact and diffuse Lya components are observed. Whereas Lya is spatially decoupled from Balmer lines emission, Balmer decrement and UV continuum, the diffuse Lya component is spatially correlated with the diffuse soft X-ray emission. Moreover, unlike the compact one, diffuse Lya shows luminosities larger than predicted from Ha, assuming case B recombination and dust extinction as derived from Ha/Hbeta. We propose that, whereas the compact Lya emission is associated to the massive stellar clusters and is affected by outflows and dust extinction, the diffuse Lya originates in gas ionized by the hot plasma responsible for the soft X-ray radiation, as suggested by their spatial correlation and by the measured L(Ha)/LsoftX ratios. Calibration of Lya as star formation rate tracer should therefore include both effects (destruction vs. enhancement) to avoid biases in the study of galaxies at cosmological distances.

Accepted for publication in A&A, 18 pages, 8 figures, 9 tables. If problems with quality of images, see http://www.cab.inta-csic.es/users/otih/haro2-v63.clean.pdf

References in corpus (12)

• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• Ly-alpha Emission-Line Galaxies at z = 3.1 in the Extended Chandra Deep Field South
• Iron line and diffuse hard X-ray emission from the starburst galaxy M82
• On the Detectability of Lyman-alpha Emission in Star-forming Galaxies: The Role of Dust
• Feedback in the local LBG Analog Haro 11 as probed by far-UV and X-ray observations
• A 62 Day X-Ray Periodicity and an X-Ray Flare from the Ultraluminous X-Ray Source in M82
• Lyman alpha emission in high-redshift galaxies
• The escape of Lyman photons from a young starburst: the case of Haro 11
• Extragalactic Constraints on the Initial Mass Function
• The Ultraluminous X-ray Sources near the Center of M82
• The evolution of H{\sc ii} galaxies: Testing the bursting scenario through the use of self-consistent models
• An X-ray spectral survey of the disc of M31 with XMM-Newton

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