Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

Complex gas kinematics in compact, rapidly assembling star-forming galaxies

R. O. Amorín, J. M. Vílchez, G. F. Hägele, V. Firpo, E. Pérez-Montero, P. Papaderos

Abstract
Deep, high resolution spectroscopic observations have been obtained for six compact, strongly star-forming galaxies at redshift z ∼ 0.1 - 0.3, most of them also known as green peas. Remarkably, these galaxies show complex emission-line profiles in the spectral region including Hα, [N II]λλ6548, 6584Å and [S II]λλ6717, 6731Å, consisting of the superposition of different kinematical components on a spatial extent of few kpc: a very broad line emission underlying more than one narrower component. For at least two of the observed galaxies some of these multiple components are resolved spatially in their 2D-spectra, whereas for another one a faint detached Hα blob lacking stellar continuum is detected at the same recessional velocity ∼7 kpc away from the galaxy. The individual narrower Hα components show high intrinsic velocity dispersion (σ ∼30–80 kms-1), suggesting together with unsharped masking HST images that star formation proceeds in an ensemble of several compact and turbulent clumps, with relative velocities of up to ∼500 kms-1. The broad underlying Hα components indicate in all cases large expansion velocities (full width zero intensity FWZI≥1000 km s-1) and very high luminosities (up to ∼1042erg s-1), probably showing the imprint of energetic outflows from SNe. These intriguing results underline the importance of green peas for studying the assembly of low-mass galaxies near and far.

Keywords
galaxies: dwarf – galaxies: evolution – galaxies: kinematics and dynamics – galaxies: starburst

Notes
Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

The Astrophysical Journal Letters
Volume 754, Page L22_1
August 2012

>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website