New tools from Infrared Space Observatory (ISO) mid-infrared spectroscopy have recently become available to determine the power sources of dust-obscured ultraluminous infrared galaxies (ULIRGs). We compare ISO classifications – starburst or active galactic nucleus (AGN) – with classifications from optical spectroscopy, and with optical/near-infrared searches for hidden broad-line regions. The a...

We present high angular resolution (0.15 − 0.5) near infrared images and spectroscopy of the Circinus galaxy, the closest Seyfert 2 galaxy known. The data reveal a non–stellar nuclear source at 2.2μm whose size is smaller than 1.5 pc in radius. The coronal line region and the hot molecular gas emission extend for 20–50 pc in the ionization cone. The data do not show evidence for a point–like co...

Starburst galaxies are significant contributors to the production of light and matter in the local universe. I review the results of recent surveys of starburst galaxies from the radio to X-rays for a panchromatic picture of a “typical” local starburst. The two prototypical examples NGC 7714 and M 82 are discussed in some detail. The overall galaxy properties are tightly related to those of the...

We have imaged the central ∼ 1 kpc of the circumnuclear starburst disk in the galaxy NGC253 in the HCN(1→0), HCO(1→0), and CO(1→0) transitions at 60 pc resolution using the Owens Valley Radio ObservatoryMillimeter-Wavelength Array (OVRO). We have also obtained Atacama Pathfinder Experiment (APEX) observations of the HCN(4→3) and the HCO(4→3) lines of the starburst disk. We find that the emissio...

We present sub-mm photometry for 11 Hyperluminous Infrared Galaxies (HLIRGs, LIR > 10 h 65 L⊙) and use radiative transfer models for starbursts and AGN to examine the nature of the IR emission. In all the sources both a starburst and AGN are required to explain the total IR emission. The mean starburst fraction is 35%, with a range spanning 80% starburst dominated to 80% AGN dominated. In all c...

We present Expanded Very Large Array and Arecibo observations of two lensed submm galaxies at z ∼ 2.5, in order to search for redshifted 22.235 GHz water megamaser emission. Both SMM J14011+0252 and SMM J16359+6612 have multi-wavelength characteristics consistent with ongoing starburst activity, as well as CO line emission indicating the presence of warm molecular gas. Our observations do not r...

We report the transition towards a type 1 Seyfert experienced by the classical type 2 Seyfert nucleus in NGC 7582. The transition, found at most 20 days from its maximum peak, presents a unique opportunity to study these rare events in detail. At maximum the Hα line width is of about 12000 km s−1. We examine three scenarios that could potentially explain the transition: capture of a star by a s...

We present a preliminary study of using the template of an ensemble of evolving shells we developed for M 82 (Yao 2009). we apply the model to represent various stages of starburst evolution in a well known sample of nearby luminous infrared galaxies (LIRGs). In this way, we attempt to interpret the relationship between the degree of molecular excitation and ratio of far-infrared (FIR) to CO lu...

We report the transition towards a type 1 Seyfert experienced by the classical type 2 Seyfert nucleus in NGC 7582. The transition, found at most 20 days from its maximum peak, presents a unique opportunity to study these rare events in detail. At maximum the Hα line width is of about 12000 km s. We examine three scenarios that could potentially explain the transition: capture of a star by a sup...

I discuss the properties of gas-rich forming galaxies. I particularly emphasize the latest results on Lyα emission that are relevant to the search of distant young galaxies. The interdependance of the Lyα escape with the properties of the ISM in starburst galaxies is outlined. A new model from G. Tenorio-Tagle and his collaborators explain Lyα profiles in starburst galaxies from the hydrodynami...