Related papers: Explaining the emission lines in early-type galaxi…
Spectroscopic analyses of gravity-sensitive line strengths give growing evidence towards an excess of low-mass stars in massive early-type galaxies (ETGs). Such a scenario requires a bottom-heavy initial mass function (IMF). However, strong…
A sophisticated analysis of EGRET data has found evidence for gamma-ray emission from the galactic halo. I entertain the possibility that part of the EGRET signal is due to WIMP annihilations in the halo. I show that a viable candidate with…
(abridged) Context. Gravitational fields at the outskirts of early-type galaxies (ETGs) are difficult to constrain observationally. It thus remains poorly explored how well the LCDM and MOND hypotheses agree with ETGs. Aims. This led us to…
Several observational and theoretical arguments suggest that starburst galaxies may rival quasars as sources of metagalactic ionizing radiation at redshifts z > 3. Reionization of the intergalactic medium (IGM) at z > 5 may arise, in part,…
The most massive early-type galaxies (ETGs) are known to form through numerous galaxy mergers. Thus, it is intriguing to study whether their formation in low-density environments, where nearby companions are almost absent, is associated…
The build-up of galaxies is regulated by a complex interplay between gravitational collapse, galaxy merging and feedback related to AGN and star formation. The energy released by these processes has to dissipate for gas to cool, condense,…
We identify an abundant population of extreme emission line galaxies (EELGs) at redshift z~1.7 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). 69…
Recent observations have successfully detected UV or infrared flux from galaxies at the epoch of reionization. However, the origin of their radiative properties has not been fully understood yet. Combining cosmological hydrodynamic…
Massive outflows are known to exist, in the form of extended emission-line regions (EELRs), around about one-third of powerful FR II radio sources. We investigate the origin of these EELRs by studying the emission-line regions around…
Star forming galaxies represent a valuable tracer of cosmic history. Recent observational progress with Hubble Space Telescope has led to the discovery and study of the earliest-known galaxies corresponding to a period when the Universe was…
In the light of the recent finding that nebular emission lines are commonly found in the inner regions of early-type galaxies, we evaluate their effect to stellar absorption-line indices. We derive analytical expressions for changes induced…
The star formation and the subsequent metallic enrichment of spiral galaxies, occurring at the early phases of their evolution, produce emission lines whose contribution may change the colors of these objects. We have computed this…
We explore the so-called softness diagram -- whose main function is to provide the hardness of the ionizing radiation in star-forming regions -- in order to check whether hot and old low-mass evolved stars (HOLMES) are significant…
Lyman-alpha emission from high-redshift galaxies may be a powerful probe of the ionization history of the IGM at z>6: the observed Lyman-alpha emission line is sensitive to the neutral fraction of IGM hydrogen in the range 0.1-1. We present…
The discovery of Lyman-alpha emission from galaxies at redshifts beyond z~6.5 should not be naively interpreted as implying that the intergalactic medium (IGM) had been reionized at higher redsifts. We show that a cluster of faint…
We review the origin, evolution and physical nature of hot gas in elliptical galaxies and associated galaxy groups. Unanticipated recent X-ray observations with Chandra and XMM indicate much less cooling than previously expected.…
A hot gas halo is predicted by chemodynamical models during the early evolution of spheroidal galaxies. Cold condensations, arising from thermal instabilities in the hot gas, are expected to be embedded in the hot halo. In the early phases…
The properties of the dust in the cold and hot gas phases of early-type galaxies (ETGs) are key to understand ETG evolution. We thus conducted a systematic study of the dust in a large sample of local ETGs, focusing on relations between the…
Objective-prism surveys which select galaxies on the basis of line-emission are extremely effective at detecting low-luminosity galaxies and constitute some of the deepest available samples of dwarfs. In this study, we confirm that…
We present near-infrared spectroscopy of a sample of 22 Extreme Emission Line Galaxies at redshifts 1.3 < z < 2.3, confirming that these are low-mass (M* = 10^8 - 10^9 M_sun) galaxies undergoing intense starburst episodes (M*/SFR ~ 10-100…