Metallicity evolution of AGNs from UV emission-lines based on a new index

We analyzed the evolution of the metallicity of the gas with the redshift for a sample of AGNs in a very wide redshift range (0<z<4) using ultraviolet emission-lines from the narrow-line regions (NLRs) and photoionization models. The new index C43=log(CIV+CIII])/HeII is suggested as a metallicity indicator for AGNs. Based on this indicator, we confirmed the no metallicity evolution of NLRs with the redshift pointed out by previous works. We found that metallicity of AGNs shows similar evolution than the one predicted by cosmic semi-analytic models of galaxy formation set within the Cold Dark Matter merging hierarchy (for z < 3). Our results predict a mean metallicity for local objects in agreement with the solar value (12+log(O/H)=8.69). This value is about the same that the maximum oxygen abundance value derived for the central parts of local spiral galaxies. Very low metallicity log(Z/Z_{\odot})~ -0.8 for some objects in the range 1.5 < z <3 is derived.Comment: 25 pages, 10 figures, accepted MNRA

Implications of the kinematical structure of circumnuclear star-forming regions on their derived properties

[Abbreviated] We review the results of high dispersion spectroscopy of 17 circumnuclear starforming regions (CNSFRs) in 3 nearby early spiral galaxies, NGC2903, NGC3310 and NGC3351. We find that single Gaussian fitting to the H$\beta$ and [OIII]5007A line profiles results in velocity dispersions around 32km/s and 52km/s, respectively, while the IR CaII triplet cross-correlation technique provides stellar velocity dispersion values close to 50km/s. Even though multiple kinematical components are present, the relation between gas velocity dispersion and Balmer emission line luminosity (L-sigma relation) reproduces the correlation for disk giant HII regions albeit with a larger scatter. The scatter in the L-sigma relation is considerably reduced when theoretical evolutionary corrections are applied suggesting that an age range is present in the sample of CNSFRs. To analyse the observed complex profiles, we performed multiple Gaussian component fits to the Hbeta and [OIII]?5007A lines obtaining optimal fits with two Gaussians of different width. These best fits indicate that the narrower component has average velocity dispersion close to 23km/s while the broader component shows average values in the range 50-60km/s for both lines, close to the observed stellar velocity dispersions. The fluxes of the broad and narrow Hbeta components are similar. This is not the case for [OIII]5007A for which the broad components have higher fluxes than the narrow ones, thus producing a clear segregation in their [OIII]/Hbeta ratios. We suggest a possible scenario for understanding the behaviour of CNSFRs in the L-sigma and sigma_gas-sigma_star diagrams involving an inner gaseous disk responsible for the narrow component of the emission lines.Comment: 14 pages, 10 figures, accepted by MNRA

Optical and mid-infrared neon abundance determinations in star-forming regions

We employed observational spectroscopic data of star-forming regions compiled from the literature and photoionization models to analyse the neon ionic abundances obtained using both optical and mid-infrared emission-lines. Comparing Ne++/H+ ionic abundances from distinct methods, we found that, in average, the abundances obtained via IR emission-lines are higher than those obtained via optical lines by a factor of 4. Photoionization models with abundance variations along the radius of the hypothetical nebula provide a possible explanation for a large part of the difference between ionic abundances via optical and infrared emission-lines. Ionization Correction Factor (ICF) for the neon is obtained from direct determinations of ionic fractions using infrared emission-lines. A constant Ne/O ratio (logNe/O \approx -0.70) for a large range of metallicity, independently of the ICF used to compute the neon total abundance is derived.Comment: 17 pages, 14 figures, accepted by MNRA

Extragalactic Star-forming Regions: a Study of the Physical Properties and Chemical Abundances

Extragalactic star-forming regions are characterized by the large number of young and massive stars that ionize the surrounding gas. These regions can be observed as very luminous spots in the disk of spiral galaxies and as large areas in Blue Compact Dwarf galaxies. We present preliminary results of the study of a sample of star-forming regions in two spiral and one Blue Compact Dwarf galaxies observed with the GMOS/Long-slit configuration on the Gemini-South Telescope. We are presenting a preliminary study of two regions of each galaxy for which we estimated: reddening, electron densities, and electron temperatures by using direct method, temperature relations based on photoionization models, and empirical relations. From the electron temperatures we de- rived ionic and total chemical abundances of, O, S, N, Ne, Ar and He. In addition we computed star formation rates and the ionization state for all regions.Fil: Muñoz Vergara, D.. Gemini Observatory; Chile. Universidad de La Serena; ChileFil: Firpo, V.. Gemini Observatory; Chile. Universidad de La Serena; ChileFil: Hägele, Guillermo Federico. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Bosch, Guillermo Luis. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cardaci, Monica Viviana. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Sanmartim, D.. Gemini Observatory; ChileFil: Gimeno, G.. Gemini Observatory; ChileII workshop on Chemical Abundances in Gaseous Nebulae: Open problems in Nebular AstrophysicsSao Jose dos CamposBrasilUniversidade do Vale do Paraíb

The internal kinematic of star-forming regions in interacting galaxies

Star formation processes can be found in colliding galaxies, where the gas compression can trigger the formation of giant star-forming regions. We present the results from a detailed kinematic analysis in a sample of HII regions located in three strongly interacting galaxies. The velocity dispersion and the luminosity of the multiple-components analyzed in the emission-line profiles suggest that these star-forming objects correspond to giant complexes. In addition, the star formation rates and the ionization state in these regions revealed the presence of ongoing star formation events.Fil: Firpo, V.. Gemini Observatory; Chile. Universidad de La Serena; ChileFil: Muthukrishna, D.. Institute Of Astronomy; Reino UnidoFil: Campuzano Castro, Federico. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Bosch, Guillermo Luis. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Hägele, Guillermo Federico. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Torres Flores, S.. Universidad de La Serena; ChileFil: Cardaci, Monica Viviana. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaII workshop on Chemical Abundances in Gaseous Nebulae: Open problems in Nebular AstrophysicsSao Jose dos CamposBrasilUniversidade do Vale do Paraíb

X-rays as dominant excitation mechanism of [Fe ii] and H2 emission lines in active galaxies

We investigate the excitation mechanisms of near-infrared [Fe ii] and H2 emission lines observed in Active Galactic Nuclei (AGNs). We built a photoionization model grid considering a two-component continuum, one accounts for the Big Bump component peaking at 1Ryd and another represents the X-ray source that dominates the continuum emission at high energies. Photoionization models considering as ionizing source a spectral energy distribution obtained from photometric data of the Sy 2 Mrk 1066 taken from the literature were considered. Results of these models were compared with a large sample of observational long-slit and Integral field Unit (IFU) spectroscopy data of the nuclear region for a sample of active objects. We found that the correlation between the observational [Fe ii]{\lambda}1.2570 {\mu}m/Pa{\beta} vs. H2{\lambda}2.1218 {\mu}m/Br{\gamma} is well reproduced by our models as well as the relationships that involve the H2 emission line ratios observed in the spectroscopic data.We conclude that the heating by X-rays produced by active nuclei can be considered a common and very important mechanism of excitation of [Fe ii] and H2.Comment: 10 pages, 9 figures, accepted by MNRA

Chemodynamics in Blue Compact Dwarf galaxies: II Zw 33 and Mrk 600

Realizamos un estudio cinemático de cinco regiones de formación estelar pertenecientes a dos galaxias enanas compactas azules: II Zw 33 and Mrk 600, utilizando datos espectroscópicos de alta resolución obtenidos con el espectrógrafo MIKE del telescopio Clay. Los espectros presentan líneas de emisión con perfiles muy complejos revelando multiples componentes Gaussianas. Con el propósito de analizar la cinemática de estas regiones de formación estelar, desarrollamos un programa en Python, basado en el paquete de minimización de mínimos cuadrados no lineal y ajuste de curvas (LMFit), y utilizamos un método estadístico, para analizar la bondad de la inclusión de una nueva componente gaussiana en el modelo. Se estimaron las propiedades físicas del gas (densidades y temperaturas electrónicas), abundancias químicas iónicas y totales de diversas especies atómicas y el grado de ionización en cada región de formación estelar.We performed a kinematic study of five star-formation regions belonging to two Blue Compact Dwarf galaxies: IIZw33 and Mrk600, using high resolution spectroscopic data obtained with the MIKE spectrograph mounted at the Clay telescope. The spectra present very complex emission-line profiles showing multiple Gaussian components. In order to analyze the kinematics of these star-forming regions we developed a Python code, based on the Non-Linear Least-Square Minimization and Curve-Fitting (LMFit) package, and used a statistical method, to analyze the goodness of the inclusion of a new Gaussian in the model. We estimated the physical conditions (electron densities and temperatures), ionic and total chemical abundances of several atomic species and the ionization degree on each star-forming region.Fil: Campuzano Castro, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Hägele, Guillermo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Bosch, Guillermo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Firpo, V.. Gemini Observatory; ChileFil: Cardaci, Monica Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Muthukrishna, D.. University of Cambridge; Reino UnidoFil: Morrell, Nidia Irene. Las Campanas Observatory; ChileSegunda Reunión Binacional entre la Sociedad Chilena de Astronomía (SOCHIAS)La SerenaChileSociedad Chilena de AstronomíaAsociación Argentina de Astronomí

Alignment of the CMS silicon tracker during commissioning with cosmic rays

This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3–4 microns RMS in the barrel and 3–14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Commissioning and performance of the CMS pixel tracker with cosmic ray muons

This is the Pre-print version of the Article. The official published verion of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe pixel detector of the Compact Muon Solenoid experiment consists of three barrel layers and two disks for each endcap. The detector was installed in summer 2008, commissioned with charge injections, and operated in the 3.8 T magnetic field during cosmic ray data taking. This paper reports on the first running experience and presents results on the pixel tracker performance, which are found to be in line with the design specifications of this detector. The transverse impact parameter resolution measured in a sample of high momentum muons is 18 microns.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Performance of the CMS drift-tube chamber local trigger with cosmic rays

The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained with muon beams