Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · astro-ph/0604068

The SPITZER IRS view of stellar populations in Virgo early type galaxies

A. Bressan·P. Panuzzo·L. Buson·M. Clemens·G. L. Granato·R. Rampazzo·L. Silva·J. R. Valdes·O. Vega·L. Danese
View original source ↗Read source document ↗Export metadata ↓

Abstract

We have obtained high S/N Spitzer IRS spectra of 17 Virgo early-type galaxies that lie on the colour-magnitude relation of passively evolving galaxies in the cluster. To flux calibrate these extended sources we have devised a new procedure that allows us to obtain the intrinsic spectral energy distribution and to disentangle resolved and unresolved emission within the same object. Thirteen objects of the sample (76%) show a pronounced broad silicate feature (above 10micron) which is spatially extended and likely of stellar origin, in agreement with model predictions. The other 4 objects (24%) are characterized by different levels of activity. In NGC 4486 (M87) the line emission and the broad silicate emission are evidently unresolved and, given also the typical shape of the continuum, they likely originate in the nuclear torus. NGC 4636 show emission lines superimposed to extended silicate emission (i.e. likely of stellar origin, pushing the percentage of galaxies with silicate emission to 82%). Finally NGC 4550 and NGC 4435 are characterized by PAH and line emission, arising from a central unresolved region.

Explore related subjects

astro-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

A. Bressan, P. Panuzzo, L. Buson, M. Clemens, G. L. Granato, R. Rampazzo, L. Silva, J. R. Valdes, O. Vega, L. Danese. 2006-04-04. The SPITZER IRS view of stellar populations in Virgo early type galaxies. https://arxiv.org/abs/astro-ph/0604068

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2024

Deformation procedure for scalar fields in cosmology

This work offers an extension of the deformation procedure introduced in field theory to the case of standard cosmology in the presence of real scalar field in flat space-time. The procedure is shown to work for many models, which give rise to several different cosmic scenarios, evolving under the presence of first-order differential equations which solve the corresponding equations of motion very appropriately.

astro-ph↗
arXiv2023

Dark Energy is the Cosmological Quantum Vacuum Energy of Light Particles-The Axion and the Lightest Neutrino

We uncover the general mechanism producing the dark energy(DE). This is only based on well known quantum physics and cosmology. We show that the observed DE originates from the cosmological quantum vacuum of light particles which provides a continuous energy distribution able to reproduce the data. Bosons give positive contributions to the DE while fermions yield negative contributions. As usual in field theory, ultraviolet divergences are subtracted from the physical quantities. The subtractions respect the symmetries of the theory and we normalize the physical quantities to be zero for the Minkowski vacuum. The resulting finite contributions to the energy density and the pressure from the quantum vacuum grow as log a(t) where a(t) is the scale factor, while the particle contributions dilute as 1/a^3(t), as it must be for massive particles. The DE equation of state P = w(z)H turns to be w(z)<-1 with w(z) asymptotically reaching the value -1 from below.A scalar particle can produce the observed DE through its quantum cosmological vacuum provided:(i)its mass is of the order of 10^{-3} eV = 1 meV,(ii) it is very weakly coupled and (iii) it is stable on the time scale of the age of the universe. The axion vacuum thus appears as a natural candidate. The neutrino vacuum (especially the lightest mass eigenstate) can give negative contributions to the DE. We find that w(z=0) is slightly below -1 by an amount ranging from [-1.5 10^{-3}] to [-8 10^{-3}] and we predict the axion mass to be in the range between 4 and 5 meV. We find that the universe will expand in the future faster than the de Sitter universe, as an exponential in the square of the cosmic time. DE arises from the quantum vacua of light particles in FRW cosmological space time in an analogous way to the Casimir effect in Minkowski spacetime with non trivial boundaries.

astro-ph↗