arXiv subjects

María Cebrián

Publications and source records attributed to María Cebrián.

5 recordsLinked to original sources

arXiv2019

The missing light of the Hubble Ultra Deep Field

The Hubble Ultra Deep field (HUDF) is the deepest region ever observed with the Hubble Space Telescope. With the main objective of unveiling the nature of galaxies up to $z \sim 7-8$, the observing and reduction strategy have focused on the properties of small and unresolved objects, rather than the outskirts of the largest objects, which are usually over-subtracted. We aim to create a new set of WFC3/IR mosaics of the HUDF using novel techniques to preserve the properties of the low surface brightness regions. We created ABYSS: a pipeline that optimises the estimate and modelling of low-level systematic effects to obtain a robust background subtraction. We have improved four key points in the reduction: 1) creation of new absolute sky flat fields, 2) extended persistence models, 3) dedicated sky background subtraction and 4) robust co-adding. The new mosaics successfully recover the low surface brightness structure removed on the previous HUDF published reductions. The amount of light recovered with a mean surface brightness dimmer than $\overlineμ=26$ mar arcsec$^{-2}$ is equivalent to a m=19 mag source when compared to the XDF and a m=20 mag compared to the HUDF12. We present a set of techniques to reduce ultra-deep images ($μ>32.5$ mag arcsec$^{-2}$, $3σ$ in $10\times10$ arcsec boxes), that successfully allow to detect the low surface brightness structure of extended sources on ultra deep surveys. The developed procedures are applicable to HST, JWST, EUCLID and many other space and ground-based observatories. We will make the final ABYSS WFC3/IR HUDF mosaics publicly available at http://www.iac.es/proyecto/abyss/.

astro-ph.GA↗

arXiv2017

Relic galaxies: where are they?

The finding that massive galaxies grow with cosmic time fired the starting gun for the search of objects which could have survived up to the present day without suffering substantial changes (neither in their structures, neither in their stellar populations). Nevertheless, and despite the community efforts, up to now only one firm candidate to be considered one of these relics is known: NGC 1277. Curiously, this galaxy is located at the centre of one of the most rich near galaxy clusters: Perseus. Is its location a matter of chance? Should relic hunters focus their search on galaxy clusters? In order to reply this question, we have performed a simultaneous and analogous analysis using simulations (Millennium I-WMAP7) and observations (New York University Value-Added Galaxy Catalogue). Our results in both frameworks agree: it is more probable to find relics in high density environments.

astro-ph.GA↗

arXiv2017

The effect of environment on the structure of disc galaxies

We study the influence of environment on the structure of disc galaxies, using \texttt{IMFIT} to measure the g- and r-band structural parameters of the surface-brightness profiles for $\sim$700 low-redshift (z$<$0.063) cluster and field disc galaxies with intermediate stellar mass (0.8 $\times$ 10$^{10}$ $M_{\odot}$ $<$ $M_{\star}$ $<$ 4 $\times$ 10$^{10}$ $M_{\odot}$) from the Sloan Digital Sky Survey, DR7. Based on this measurement, we assign each galaxy to a surface-brightness profile type (Type I $\equiv$ single-exponential, Type II $\equiv$ truncated, Type III $\equiv$ anti-truncated). In addition, we measure (g-r) restframe colour for disc regions separated by the break radius. Cluster disc galaxies (at the same stellar mass) have redder (g-r) colour by $\sim$0.2 mag than field galaxies. This reddening is slightly more pronounced outside the break radius. Cluster disc galaxies also show larger global Sérsic-indices and are more compact than field discs, both by $\sim$15\%. This change is connected to a flattening of the (outer) surface-brightness profile of Type I and - more significantly - of Type III galaxies by $\sim$8\% and $\sim$16\%, respectively, in the cluster environment compared to the field. We find fractions of Type I, II and III of (6$\pm$2)\%, (66$\pm$4)\% and (29$\pm$4)\% in the field and (15$_{-4}^{+7}$)\%, (56$\pm$7)\% and (29$\pm$7)\% in the cluster environment, respectively. We suggest that the larger abundance of Type I galaxies in clusters (matched by a corresponding decrease in the Type II fraction) could be the signature of a transition between Type II and Type I galaxies produced/enhanced by environment-driven mechanisms.

astro-ph.GA↗

arXiv2016

Massive relic galaxies prefer dense environments

We study the preferred environments of $z \sim 0$ massive relic galaxies ($M_\star \gtrsim 10^{10}~\mathrm{M_\odot}$ galaxies with little or no growth from star formation or mergers since $z \sim 2$). Significantly, we carry out our analysis on both a large cosmological simulation and an observed galaxy catalogue. Working on the Millennium I-WMAP7 simulation we show that the fraction of today massive objects which have grown less than 10 per cent in mass since $z \sim 2$ is ~0.04 per cent for the whole massive galaxy population with $M_\star > 10^{10}~\mathrm{M_\odot}$. This fraction rises to ~0.18 per cent in galaxy clusters, confirming that clusters help massive galaxies remain unaltered. Simulations also show that massive relic galaxies tend to be closer to cluster centres than other massive galaxies. Using the New York University Value-Added Galaxy Catalogue, and defining relics as $M_\star \gtrsim 10^{10}~\mathrm{M_\odot}$ early-type galaxies with colours compatible with single-stellar population ages older than 10 Gyr, and which occupy the bottom 5-percentile in the stellar mass-size distribution, we find $1.11 \pm 0.05$ per cent of relics among massive galaxies. This fraction rises to $2.4 \pm 0.4$ per cent in high-density environments. Our findings point in the same direction as the works by Poggianti et al. and Stringer et al. Our results may reflect the fact that the cores of the clusters are created very early on, hence the centres host the first cluster members. Near the centres, high-velocity dispersions and harassment help cluster core members avoid the growth of an accreted stellar envelope via mergers, while a hot intracluster medium prevents cold gas from reaching the galaxies, inhibiting star formation.

astro-ph.GA↗

arXiv2014

The effect of the environment on the stellar mass - size relation of present-day galaxies

To study how the environment can influence the relation between stellar mass and effective radius of nearby galaxies (z < 0.12), we use a mass-complete sample extracted from the NYU-Value Added Catalogue. This sample contains almost 232000 objects with masses up to $3\times10^{11}M_{\odot}$. For every galaxy in our sample, we explore the surrounding density within 2 Mpc using two different estimators of the environment. We find that galaxies tend to be larger in the field than in high density regions. This effect is more pronounced for late-type morphologies (~7.5% larger) and especially at low masses ($M < 2\times10^{10}M_{\odot}$), although early-type galaxies also show differences (~3.5%). The environment also leaves a subtle imprint in the scatter of the stellar mass-size relation. This scatter is larger in low density regions than in high density regions for both morphologies, on average ~3.5% larger for early-type and ~0.8% for late-type galaxies. Late-type galaxies with low masses ($M<2\times10^{10}M_{\odot}$) show the largest differences in the scatter among environments. The scatter is ~20% larger in the field than in clusters for these objects. Our analysis suggest that galaxies in clusters form earlier than those in the field. In addition, cluster galaxies seem to be originated from a more homogeneous family of progenitors.

astro-ph.GA↗