Estudio de galaxias luminosas y ultraluminosas en el infrarrojo con VTL-SINFONI

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 23/05/2014Fac. de Ciencias FísicasTRUEunpu

Warm molecular gas temperature distribution in six local infrared bright Seyfert galaxies

We simultaneously analyze the spectral line energy distributions (SLEDs) of CO and H2 of six local luminous infrared (IR) Seyfert galaxies. For the CO SLEDs, we used new Herschel/SPIRE FTS data (from J=4-3 to J=13-12) and ground-based observations for the lower-J CO transitions. The H2 SLEDs were constructed using archival mid-IR Spitzer/IRS and near-IR VLT/SINFONI data for the rotational and ro-vibrational H2 transitions, respectively. In total, the SLEDs contain 26 transitions with upper level energies between 5 and 15000 K. A single, constant density, model (n$_{H_2}$ ~ 10$^{4.5-6}$ cm$^{-3}$) with a broken power-law temperature distribution reproduces well both the CO and H2 SLEDs. The power-law indices are $\beta_1$ ~ 1-3 for warm molecular gas (20 K < T 100 K). We show that the steeper temperature distribution (higher $\beta$) for hot molecular gas can be explained by shocks and photodissociation region (PDR) models, however, the exact $\beta$ values are not reproduced by PDR or shock models alone and a combination of both is needed. We find that the three major mergers among our targets have shallower temperature distributions for warm molecular gas than the other three spiral galaxies. This can be explained by a higher relative contribution of shock excitation, with respect to PDR excitation, for the warm molecular gas in these mergers. For only one of the mergers, IRASF 05189-2524, the shallower H2 temperature distribution differs from that of the spiral galaxies. The presence of a bright active galactic nucleus in this source might explain the warmer molecular gas observed.Comment: A&A in press; 15 pages, 7 figures. Fixed several typo

Formation of b-Bi2O3 and d-Bi2O3 during laser irradiation of Bi films studied in-situ by spatially resolved Raman spectroscopy

The formation of different phases of Bi2O3 induced by laser irradiation of Bi films has been assessed in situ by micro-Raman spectroscopy as a function of laser wavelength, power density and irradiation time. Raman mapping of the irradiated samples enabled a spatially-resolved study of the distribution of the formed Bi2O3 phases. Red laser (633 nm) irradiation was found to induce the appearance of b-Bi2O3, within a certain range of power densities, by diffusion-controlled processes. In contrast, ultraviolet (UV, 325 nm) laser irradiation, above a certain power density threshold, initially induces the formation of both b and d-Bi2O3 phases. The amount of the produced d-Bi2O3 phase increases by increasing the irradiation time, while that of the b phase follows the opposite trend. UV laser irradiation seems to be a suitable method to produce room temperature stable d-Bi2O3 patterns on Bi film

Study of structural-changes in YBa_2Cu_3O_(7-x) by cathodoluminescence in the scanning electron-microscope

Changes in the visible and infrared cathodoluminescence(CL)spectra of YBa2Cu3O7−x are detected during irradiation in the scanning electron microscope. Results indicate the influence of oxygen content on the appearance of a CL band at 450–600 nm. In irradiated samples an infrared band at 1600–1700 nm has been observed

VLT-SINFONI sub-kpc study of the star formation in local LIRGs and ULIRGs: Analysis of the global ΣSFR\Sigma_{\rm SFR} structure and characterisation of individual star-forming clumps

We present a 2D study of star formation at kpc and sub-kpc scales of a sample of local (z<0.1) U/LIRGs, based on near-IR VLT-SINFONI observations. We obtained integrated measurements of the star formation rate (SFR) and star formation rate surface density, together with their 2D distributions, based on Br_gamma and Pa_alpha emission. We observe a tight linear correlation between the SFR derived from our extinction-corrected measurements and that derived from 24 micron data, and a reasonable agreement with SFR derived from total IR luminosity. Our near-IR measurements are on average a factor 3 larger than optical SFR, even when extinction corrections are applied. We found that LIRGs have a median-observed star formation rate surface density of 1.72 Msun/yr/kpc^2 for the extinction-corrected distribution, whilst ULIRGs have 0.23 Msun/yr/kpc^2, respectively. These median values for ULIRGs increase up to 2.90 Msun/yr/kpc^2, when only their inner regions, covering the same size as the average FoV of LIRGs, are considered. We identified a total of 95 individual SF clumps in our sample, with sizes within 60-1500pc, and extinction-corrected Pa_alpha luminosities of 10^5-10^8 Lsun. Star-forming clumps in LIRGs are about ten times larger and thousands of times more luminous than typical clumps in spiral galaxies. Clumps in ULIRGs have sizes similar (x0.5-1) to those of high-z clumps, having Pa_alpha luminosities similar to some high-z clumps, and about 10 times less luminous than the most luminous high-z clumps identified so far. We also observed a change in the slope of the L-r relation. A likely explanation is that most luminous galaxies are interacting and merging, and therefore their size represents a combination of the distribution of the star-forming clumps within each galaxy in the system plus the effect of the projected distance.Comment: 27 pages, 27 figures, accepted for publication in A&A. Abstract abridged due to arXiv requirement

Influence of Li doping on the morphology and luminescence of Ga_2O_3 microrods grown by a vapor-solid method

Gallium oxide microrods have been grown by an evaporation-deposition method by using a precursor containing lithium in order to check the influence of such dopant on the morphology and physical properties of the obtained ß-Ga_2O_3 structures. SEM studies show that the morphology is modified with respect to undoped gallium oxide, promoting the growth of micropyramids transversal to the microwire axis. Raman analysis reveals good crystal quality and an additional Raman peak centred at around 270 cm^(-1), characteristic of these samples and not present in undoped monoclinic gallium oxide. The presence of the Li^(+) ions also influences the luminescence emission by inducing a red-shift of the characteristic UV-blue defect band of gallium oxide. In addition, an intense sharp peak centred around 717 nm observed both by cathodoluminescence (CL) and photoluminescence (PL) is also attributed to the presence of these ions. The Li related luminescence features have also been investigated by PL excitation (PLE) spectra and by the temperature dependence of the luminescence

Understanding the two-dimensional ionization structure in luminous infrared galaxies. A near-IR integral field spectroscopy perspective

We investigate the 2D excitation structure of the ISM in a sample of LIRGs and Seyferts using near-IR IFS. This study extends to the near-IR the well-known optical and mid-IR emission line diagnostics used to classify activity in galaxies. Based on the spatially resolved spectroscopy of prototypes, we identify in the [FeII]1.64/Br$\gamma$ - H_2 1-0S(1)/Br$\gamma$ plane regions dominated by the different heating sources, i.e. AGNs, young MS massive stars, and evolved stars i.e. supernovae. The ISM in LIRGs occupy a wide region in the near-IR diagnostic plane from -0.6 to +1.5 and from -1.2 to +0.8 (in log units) for the [FeII]/Br$\gamma$ and H_2/Br$\gamma$ line ratios, respectively. The corresponding median(mode) ratios are +0.18(0.16) and +0.02(-0.04). Seyferts show on average larger values by factors ~2.5 and ~1.4 for the [FeII]/Br$\gamma$ and H_2/Br$\gamma$ ratios, respectively. New areas and relations in the near-IR diagnostic plane are defined for the compact, high surface brightness regions dominated by AGN, young ionizing stars, and SNe explosions, respectively. In addition, the diffuse regions affected by the AGN radiation field cover an area similar to that of Seyferts, but with high values in [FeII]/Br$\gamma$ that are not as extreme. The extended, non-AGN diffuse regions cover a wide area in the diagnostic diagram that overlaps that of individual excitation mechanisms (i.e. AGN, young stars, and SNe), but with its mode value to that of the young SF clumps. This indicates that the excitation conditions of the diffuse ISM are likely due to a mixture of the different ionization sources. The integrated line ratios in LIRGs show higher excitation conditions i.e. towards AGNs, than those measured by the spatially resolved spectroscopy. If this behaviour is representative, it would have clear consequences when classifying high-z, SF galaxies based on their near-IR integrated spectra.Comment: 18 pages, 13 figures, accepted for publication in A&