18 research outputs found

    V, R, I and Halpha photometry of circumnuclear star forming regions in four galaxies with different levels of nuclear activity

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    V,R,I continuum bands and Halpha + [NII] photometry for circumnuclear star forming regions (CNSFR) is presented, for galaxies with different kinds of nuclear activity: NGC 7469 (Sy 1), NGC 1068 (Sy 2), NGC 7177 (LINER) and NGC 3310 (Starburst). Their Halpha luminosities (0.02 - 7x10**40 erg/s; uncorrected for internal extinction), are comparable to those observed in other galaxies. No systematic differences in the broad band colours are found for the CNSFR in the different galaxies, except for those in NGC 3310 which are considerably bluer, partially due to a younger stellar population. Using theoretical evolutionary synthesis models some colours can be reproduced by single populations (between 7 and 300 Myr) and extinction 0.5-1.5 mag). However, in many cases, the observed equivalent width of Halpha, require a younger population. NGC 1068, 7177 and 7469, are fitted by a two-burst population model at solar metallicity; the age difference between both populations is around 5-7 Myr and the younger burst involves 3 - 61% of the total mass of the cluster,consistent with the younger burst being originated by supernova activity from the previous one. NGC 3310, requires younger ionizing population ages and lower metallicity. An excess (R-I) observed/predicted, not consistent with a normal reddening law can be atributted to red supergiants present in the older population, and not properly accounted for by the models. The two-population scenario seems to show a trend of the evolutionary state of the CNSFR with the nuclear type of the parent galaxy that remains to be explored.Comment: Accepted for publication in MNRAS, 22pages, 11 figure

    Search for H alpha emitters in Galaxy Clusters with Tunable Filters

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    The studies of the evolution of galaxies in Galaxy Clusters have as a traditional complication the difficulty in establishing cluster membership of those sources detected in the field of view. The determination of spectroscopic redshifts involves long exposure times when it is needed to reach the cluster peripherical regions of/or clusters at moderately large redshifts, while photometric redshifts often present uncertainties too large to offer significant conclusions. The mapping of the cluster of galaxies with narrow band tunable filters makes it possible to reach large redshifts intervals with an accuracy high enough to establish the source membership of those presenting emission/absorption lines easily identifiable, as H alpha. Moreover, the wavelength scan can include other lines as [NII], [OIII] or HβH_{\beta} allowing to distinguish those sources with strong stellar formation activity and those with an active galactic nuclei. All this makes it possible to estimate the stellar formation rate of the galaxies observed. This, together with ancillary data in other wavelengths may lead to a good estimation of the stellar formation histories. It will shed new light over the galaxy evolution in clusters and will improve our understanding of galaxy evolution, especially in the outer cluster regions, usually less studied and with significant unexploited data that can not be correctly interpreted without redshift determination.Comment: 4 pages, 2 figures. "Highlights of Spanish Astrophysics V", Proceedings of the VIII Scientific Meeting of the Spanish Astronomical Society (SEA) held in Santander, 7-11 July, 200

    La rotación de personal de serenazgo de la Subgerencia de Serenazgo de la Gerencia de Seguridad Ciudadana de la Municipalidad Distrital de Miraflores, dentro del Plan Estratégico Distrital de Seguridad Ciudadana del año 2018 como un indicador de gestión

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    El presente trabajo de investigación refiere a la rotación de personal de serenazgo de la Subgerencia de Serenazgo de la Gerencia de Seguridad Ciudadana de la Municipalidad Distrital de Miraflores dentro del Plan Estratégico Distrital de Seguridad Ciudadana del año 2018 como un indicador de gestión, siendo que dicha comuna tiene como domicilio fiscal sito en la Av. Larco N° 400, Miraflores - Lima. Los resultados que se obtengan en el presente estudio nos permitirá conocer las posibles causas que da origen a este fenómeno, toda vez que viene afectando el cumplimiento del objetivo general del Plan Estratégico Distrital de Seguridad Ciudadana del 2018, que establece: “Fortalecer el trabajo multisectorial en el distrito mediante la interrelación, capacitación, asistencia técnica y administrativa de los sectores e instituciones comprometidas, con la participación de la comunidad organizada, a fin de mejorar los niveles de percepción de seguridad ciudadana”. La hipótesis general del presente estudio señala que: “La insatisfacción en el trabajo percibido por el personal de serenazgo aumentará el índice de rotación del personal”; por lo que, a través de una contrastación, se obtendrá los resultados respectivos, y que en el contenido de las conclusiones y recomendaciones se pondrá de manifiesto las causas que originan la rotación de personal de serenazgo y como evitarlas, a efectos de que los funcionarios competentes del Corporativo Municipal puedan implementarlas para mitigar este fenómeno.Trabajo de investigaciónCampus Lima Centr

    OSIRIS Software: The Mask Designer Tool

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    OSIRIS is a Day One instrument that will be available at the 10m GTC telescope which is being built at La Palma observatory in the Canary Islands. This optical instrument is designed to obtain wide-field narrow-band images using tunable filters and to do low-resolution spectroscopy in both long-slit and multislit modes. For the multislit spectroscopy mode, we have developed a software to assist the observers to design focal plane masks. In this paper we describe the characteristics of this Mask Designer tool. We discuss the main design concepts, the functionality and particular features of the software.Comment: 6 figures; accepted for publication in Experimental Astronom

    The lack of star formation gradients in galaxy groups up to z~1.6

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    In the local Universe, galaxy properties show a strong dependence on environment. In cluster cores, early type galaxies dominate, whereas star-forming galaxies are more and more common in the outskirts. At higher redshifts and in somewhat less dense environments (e.g. galaxy groups), the situation is less clear. One open issue is that of whether and how the star formation rate (SFR) of galaxies in groups depends on the distance from the centre of mass. To shed light on this topic, we have built a sample of X-ray selected galaxy groups at 0<z<1.6 in various blank fields (ECDFS, COSMOS, GOODS). We use a sample of spectroscopically confirmed group members with stellar mass M >10^10.3 M_sun in order to have a high spectroscopic completeness. As we use only spectroscopic redshifts, our results are not affected by uncertainties due to projection effects. We use several SFR indicators to link the star formation (SF) activity to the galaxy environment. Taking advantage of the extremely deep mid-infrared Spitzer MIPS and far-infrared Herschel PACS observations, we have an accurate, broad-band measure of the SFR for the bulk of the star-forming galaxies. We use multi-wavelength SED fitting techniques to estimate the stellar masses of all objects and the SFR of the MIPS and PACS undetected galaxies. We analyse the dependence of the SF activity, stellar mass and specific SFR on the group-centric distance, up to z~1.6, for the first time. We do not find any correlation between the mean SFR and group-centric distance at any redshift. We do not observe any strong mass segregation either, in agreement with predictions from simulations. Our results suggest that either groups have a much smaller spread in accretion times with respect to the clusters and that the relaxation time is longer than the group crossing time.Comment: Accepted for publication in MNRA

    The OTELO survey: A case study of [O III] lambda 4959,5007 emitters at z=0.83

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    Context. The OSIRIS Tunable Filter Emission Line Object (OTELO) survey is a very deep, blind exploration of a selected region of the Extended Groth Strip and is designed for finding emission-line sources (ELSs). The survey design, observations, data reduction, astrometry, and photometry, as well as the correlation with ancillary data used to obtain a final catalogue, including photo-z estimates and a preliminary selection of ELS, were described in a previous contribution. Aims. Here, we aim to determine the main properties and luminosity function (LF) of the [O III] ELS sample of OTELO as a scientific demonstration of its capabilities, advantages, and complementarity with respect to other surveys. Methods. The selection and analysis procedures of ELS candidates obtained using tunable filter pseudo-spectra are described. We performed simulations in the parameter space of the survey to obtain emission-line detection probabilities. Relevant characteristics of [O III] emitters and the LF ([O III]), including the main selection biases and uncertainties, are presented. Results. From 541 preliminary emission-line source candidates selected around z = 0.8, a total of 184 sources were confirmed as [O III] emitters. Consistent with simulations, the minimum detectable line flux and equivalent width in this ELS sample are ∼5 × 10−19 erg s−1 cm2 and ∼6 Å, respectively. We are able to constrain the faint-end slope (α = −1.03 ± 0.08) of the observed LF ([O III]) at a mean redshift of z = 0.83. This LF reaches values that are approximately ten times lower than those from other surveys. The vast majority (84%) of the morphologically classified [O III] ELSs are disc-like sources, and 87% of this sample is comprised of galaxies with stellar masses of M⋆ <  1010 M⊙

    On Star Formation Rates and Star Formation Histories of Galaxies out to z ~ 3

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    We compare multi-wavelength SFR indicators out to z~3 in GOODS-South. Our analysis uniquely combines U-to-8um photometry from FIREWORKS, MIPS 24um and PACS 70, 100, and 160um photometry from the PEP survey, and Ha spectroscopy from the SINS survey. We describe a set of conversions that lead to a continuity across SFR indicators. A luminosity-independent conversion from 24um to total infrared luminosity yields estimates of LIR that are in the median consistent with the LIR derived from PACS photometry, albeit with significant scatter. Dust correction methods perform well at low to intermediate levels of star formation. They fail to recover the total amount of star formation in systems with large SFR_IR/SFR_UV ratios, typically occuring at the highest SFRs (SFR_UV+IR \gtrsim 100 Msun/yr) and redshifts (z \gtrsim 2.5) probed. Finally, we confirm that Ha-based SFRs at 1.5<z<2.6 are consistent with SFR_SED and SFR_UV+IR provided extra attenuation towards HII regions is taken into account (Av,neb = Av,continuum / 0.44). With the cross-calibrated SFR indicators in hand, we perform a consistency check on the star formation histories inferred from SED modeling. We compare the observed SFR-M relations and mass functions at a range of redshifts to equivalents that are computed by evolving lower redshift galaxies backwards in time. We find evidence for underestimated stellar ages when no stringent constraints on formation epoch are applied. We demonstrate how resolved SED modeling, or alternatively deep UV data, may help to overcome this bias. The age bias is most severe for galaxies with young stellar populations, and reduces towards older systems. Finally, our analysis suggests that SFHs typically vary on timescales that are long (at least several 100 Myr) compared to the galaxies' dynamical time.Comment: Accepted for publication in The Astrophysical Journal, 19 pages, 15 figure

    La rotación de personal de serenazgo de la Subgerencia de Serenazgo de la Gerencia de Seguridad Ciudadana de la Municipalidad Distrital de Miraflores, dentro del Plan Estratégico Distrital de Seguridad Ciudadana del año 2018 como un indicador de gestión

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    Trabado de investigacionEl presente trabajo de investigación refiere a la rotación de personal de serenazgo de la Subgerencia de Serenazgo de la Gerencia de Seguridad Ciudadana de la Municipalidad Distrital de Miraflores dentro del Plan Estratégico Distrital de Seguridad Ciudadana del año 2018 como un indicador de gestión, siendo que dicha comuna tiene como domicilio fiscal sito en la Av. Larco N° 400, Miraflores - Lima. Los resultados que se obtengan en el presente estudio nos permitirá conocer las posibles causas que da origen a este fenómeno, toda vez que viene afectando el cumplimiento del objetivo general del Plan Estratégico Distrital de Seguridad Ciudadana del 2018, que establece: “Fortalecer el trabajo multisectorial en el distrito mediante la interrelación, capacitación, asistencia técnica y administrativa de los sectores e instituciones comprometidas, con la participación de la comunidad organizada, a fin de mejorar los niveles de percepción de seguridad ciudadana”. La hipótesis general del presente estudio señala que: “La insatisfacción en el trabajo percibido por el personal de serenazgo aumentará el índice de rotación del personal”; por lo que, a través de una contrastación, se obtendrá los resultados respectivos, y que en el contenido de las conclusiones y recomendaciones se pondrá de manifiesto las causas que originan la rotación de personal de serenazgo y como evitarlas, a efectos de que los funcionarios competentes del Corporativo Municipal puedan implementarlas para mitigar este fenómeno

    COALAS : I. ATCA CO(1-0) survey and luminosity function in the Spiderweb protocluster at z=2.16

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    We report a detailed CO(1−0) survey of a galaxy protocluster field at z = 2.16, based on 475 h of observations with the Australia Telescope Compact Array. We constructed a large mosaic of 13 individual pointings, covering an area of 21 arcmin2 and ±6500 km s−1 range in velocity. We obtained a robust sample of 46 CO(1−0) detections spanning z = 2.09−2.22, constituting the largest sample of molecular gas measurements in protoclusters to date. The CO emitters show an overdensity at z = 2.12−2.21, suggesting a galaxy super-protocluster or a protocluster connected to large-scale filaments of ∼120 cMpc in size. We find that 90% of CO emitters have distances >0.5−4 to the center galaxy, indicating that small area surveys would miss the majority of gas reservoirs in similar structures. Half of the CO emitters have velocities larger than escape velocities, which appears gravitationally unbound to the cluster core. These unbound sources are barely found within the R200 radius around the center, which is consistent with a picture in which the cluster core is collapsed while outer regions are still in formation. Compared to other protoclusters, this structure contains a relatively higher number of CO emitters with relatively narrow line widths and high luminosities, indicating galaxy mergers. We used these CO emitters to place the first constraint on the CO luminosity function and molecular gas density in an overdense environment. The amplitude of the CO luminosity function is 1.6 ± 0.5 orders of magnitude higher than that observed for field galaxy samples at z ∼ 2, and one order of magnitude higher than predictions for galaxy protoclusters from semi-analytical SHARK models. We derive a high molecular gas density of 0.6−1.3 × 109 cMpc−3 for this structure, which is consistent with predictions for cold gas density of massive structures from hydro-dynamical DIANOGA simulations
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