arXiv subjects

M. Carmen Eliche-Moral

Publications and source records attributed to M. Carmen Eliche-Moral.

At least 19 recordsLinked to original sources

arXiv2019

Optically-faint massive Balmer Break Galaxies at z>3 in the CANDELS/GOODS fields

We present a sample of 33 Balmer Break Galaxies (BBGs) selected as HST/F160W dropouts in the deepest CANDELS/GOODS fields ($H\gtrsim27.3$~mag) but relatively bright in {\it Spitzer}/IRAC ($[3.6],[4.5]<24.5$~mag), implying red colors (median and quartiles: $\langle H-[3.6]\rangle=3.1^{3.4}_{2.8}$\,mag). Half of these BBGs are newly identified sources. Our BBGs are massive ($\langle \log(\rm{M}/\rm{M}_\odot)\rangle=10.8$) high redshift ($\langle z\rangle=4.8$) dusty ($\langle \rm{A(V)}\rangle=2.0$~mag) galaxies. The SEDs of half of our sample indicate that they are star-forming galaxies with typical specific SFRs 0.5-1.0~Gyr$^{-1}$, qualifying them as main sequence (MS) galaxies at $3 10^{3}\,\rm{M}_\odot/yr$) that place them above the MS. The rest, 30\%, are post-starbursts or quiescent galaxies located $>2σ$ below the MS with mass-weighted ages older than 700~Myr. Only 2 of the 33 galaxies are X-ray detected AGN with optical/near-infrared SEDs dominated by stellar emission, but the presence of obscured AGN in the rest of sources cannot be discarded. Our sample accounts for 8\% of the total number density of $\log(\rm{M}/\rm{M}_\odot)>10$ galaxies at $z>3$, but it is a significant contributor (30\%) to the general population of red $\log(\rm{M}/\rm{M}_\odot)>11$ galaxies at $4 11$ galaxies in the local Universe was assembled in the first 1.5~Gyr after the Big Bang, a fraction that is not reproduced by state-of-the-art galaxy formation simulations.

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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/.

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arXiv2018

Evolution of the anti-truncated stellar profiles of S0 galaxies since $z=0.6$ in the SHARDS survey: II - Structural and photometric evolution

Type-III S0 galaxies present tight scaling relations between their surface brightness photometric and structural parameters. Several evolutionary models have been proposed for the formation of Type-III S0 galaxies but the observations of are usually limited to the local Universe. We study the evolution of the photometric and structural scaling relations found between the parameters of the surface brightness profiles in the rest-frame R-band of Type-III S0 galaxies with z and the possible differences between the rest-frame (B-R) colours of the inner and outer disc profiles. We make use of a sample of 14 Type-III E/S0--S0 galaxies at 0.2<z<0.6 to study if the correlations found in local Type-III S0 galaxies were present ~6 Gyr ago. We analyse the distribution of the surface brightness characteristic parameters as a function of the stellar mass and if there is a significant change with z. We also derive their rest-frame (B-R) colour profiles and we compare these results with the predictions from a grid of SSP models. We find that the inner and outer scale-lengths of Type-III S0 galaxies at 0.4<z<0.6 follow compatible trends and scaling relations with those observed in local S0 galaxies. We do not detect any significant differences between the location of Rbreak between z~0.6 and z=0 for a fixed stellar mass of the object, whereas the surface brightness at the break radius is ~1.5 mag arcsec-2 dimmer in the local Universe than at z~0.6 for a fixed stellar mass. In contrast to Type-II profiles, the Type-III surface brightness profiles of S0 galaxies present compatible Rbreak values and scaling relations during the last 6 Gyr. This result and the similarity of the colours of the inner and outer discs point to a highly scalable and stable formation process, probably more related to gravitational and dynamical processes than to the evolution of stellar populations (abridged).

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arXiv2017

Formation of S0 galaxies through mergers. Evolution in the Tully-Fisher relation since $z\sim1$

(Abridged version) We explore whether a scenario that combines an origin by mergers at $z\sim$1.8-1.5 with a subsequent passive evolution of the resulting S0 remnants since $z \sim$0.8-1 is compatible with observational data of S0s in the Tully-Fisher relation (TFR). We studied a set of major and minor merger experiments from the GalMer database that generate massive S0 remnants. We analysed the location of these remnants in the photometric and stellar TFRs assuming that they correspond to $z\sim0.8$ galaxies. We then estimated their evolution in these planes over the last 7 Gyr. The results were compared with data of real S0s and spirals at different redshifts. We also tested how the use of Vcirc or Vrot,max affects the results. We found that just after $\sim$1-2 Gyr of coalescence, major mergers generate S0 remnants that are outliers of the local photometric and stellar TFRs at $z\sim0.8$. After $\sim$4-7 Gyr of passive evolution in isolation, the S0 remnants move towards the local TFR, although the initial scatter among them persists. This scatter is sensitive to the indicator used for the rotation velocity: Vcirc values yield a lower scatter than when Vrot,max values are considered instead. In the planes involving Vrot,max, a clear segregation of the S0 remnants in terms of the spin-orbit coupling of the model is observed, in which the remnants of retrograde encounters overlap with local S0s hosting counter-rotating discs. The location of the S0 remnants at $z\sim 0$ agrees well with the observed distribution of local S0 galaxies in the $σ_0$-$M_K$, Vcirc-$σ_0$ and Vrot,max-$σ_0$ planes. Thus, massive S0 galaxies may have been formed through major mergers that occurred at high redshift and have later evolved towards the local TFR through passive evolution in relative isolation, a mechanism that would also contribute to the scatter observed in this relation.

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arXiv2017

Evolution of the anti-truncated stellar profiles of S0 galaxies since $z=0.6$ in the SHARDS survey: I - Sample and Methods

The controversy about the origin of the structure of S0--E/S0 galaxies may be due to the difficulty of comparing surface brightness profiles with different depths, photometric corrections and PSF effects (almost always ignored). We aim to quantify the properties of Type-III (anti-truncated) discs in a sample of S0 galaxies at 0.2<z<0.6. In this paper, we present the sample selection and describe in detail the methods to robustly trace the structure in their outskirts and correct for PSF effects. We have selected and classified a sample of 150 quiescent galaxies at 0.2<z<0.6 in the GOODS-N field. We perform a quantitative structural analysis of 44 S0-E/S0 galaxies. We corrected their surface brightness profiles for PSF distortions and analysed the biases in the structural and photometric parameters when the PSF correction is not applied. Additionally, we have developed Elbow, an automatic statistical method to determine whether a possible break is significant - or not - and its type and made it publicly available. We found 14 anti-truncated S0-E/S0 galaxies in the range 0.2<z<0.6 (~30% of the final sample). This fraction is similar to the those reported in the local Universe. In our sample, ~25% of the Type-III breaks observed in PSF-uncorrected profiles are artifacts, and their profiles turn into a Type I after PSF correction. PSF effects also soften Type-II profiles. We found that the profiles of Type-I S0 and E/S0 galaxies of our sample are compatible with the inner profiles of the Type-III, in contrast with the outer profiles. We have obtained the first robust and reliable sample of 14 anti-truncated S0--E/S0 galaxies beyond the local Universe, in the range 0.2<z<0.6. PSF effects significantly affect the shape of the surface brightness profiles in galaxy discs even in the case of the narrow PSF of HST/ACS images, so future studies on the subject should make an effort to correct them.

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arXiv2016

Type-II surface brightness profiles in edge-on galaxies produced by flares

Previous numerical studies had apparently ruled out the possibility that flares in galaxy discs could give rise to the apparent breaks in their luminosity profiles when observed edge-on. However the studies have not, until now, analyzed this hypothesis systematically using realistic models for the disc, the flare, and the bulge. We revisit this theme by analyzing a series of models which sample a wide range of observationally based structural parameters for these three components. We have considered realistic distributions of bulge to disc ratios, morphological parameters of bulges and discs, vertical scale heights of discs and their radial gradients defining the flare for different morphological types and stellar mass bins, based on observations. The surface brightness profiles for the face-on and edge-on views of each model were simulated to find out whether the flared disc produces a Type-II break in the disc profile when observed edge-on, and if so under what conditions. Contrary to previous claims, we find that discs with realistic flares can produce significant breaks in discs when observed edge-on. Specifically a flare with the parameters of that of the Milky Way would produce a significant break of the disc at a Rbreak of ~8.6 kpc if observed edge-on. Central bulges have no significant effects on the results. These simulations show that flared discs can explain the existence of many Type-II breaks observed in edge-on galaxies, in a range of galaxies with low-to-intermediate break strength values of -0.25<S<-0.1.

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arXiv2016

Creating lenticular galaxies with major mergers

Lenticular galaxies (S0s) represent the majority of early-type galaxies in the local Universe, but their formation channels are still poorly understood. While galaxy mergers are obvious pathways to suppress star formation and increase bulge sizes, the marked parallelism between spiral and lenticular galaxies (e.g. photometric bulge-disc coupling) seemed to rule out a potential merger origin. Here, we summarise our recent work in which we have shown, through N-body numerical simulations, that disc-dominated lenticulars can emerge from major mergers of spiral galaxies, in good agreement with observational photometric scaling relations. Moreover, we show that mergers simultaneously increase the light concentration and reduce the angular momentum relative to their spiral progenitors. This explains the mismatch in angular momentum and concentration between spirals and lenticulars recently revealed by CALIFA observations, which is hard to reconcile with simple fading mechanisms (e.g. ram-pressure stripping).

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arXiv2016

Pathways to quiescence: SHARDS view on the Star Formation Histories of massive quiescent galaxies at 1.0 < z < 1.5

We present Star Formation Histories (SFHs) for a sample of 104 massive (stellar mass M > 10$^{10}$ M$_{\odot}$) quiescent galaxies (MQGs) at $z$=1.0-1.5 from the analysis of spectro-photometric data from the SHARDS and HST/WFC3 G102 and G141 surveys of the GOODS-N field, jointly with broad-band observations from ultraviolet (UV) to far-infrared (Far-IR). The sample is constructed on the basis of rest-frame UVJ colours and specific star formation rates (sSFR=SFR/Mass). The Spectral Energy Distributions (SEDs) of each galaxy are compared to models assuming a delayed exponentially declining SFH. A Monte Carlo algorithm characterizes the degeneracies, which we are able to break taking advantage of the SHARDS data resolution, by measuring indices such as MgUV and D4000. The population of MQGs shows a duality in their properties. The sample is dominated (85%) by galaxies with young mass-weighted ages, tM $<$ 2 Gyr, short star formation timescales, $\langle τ\rangle$ $\sim$ 60-200 Myr, and masses log(M/M$_{\odot}$) $\sim$ 10.5. There is an older population (15%) with tM$=$2 - 4 Gyr, longer star formation timescales, $\langle τ\rangle$$\sim$ 400 Myr, and larger masses, log(M/M$_{\odot}$) $\sim$ 10.7. The SFHs of our MQGs are consistent with the slope and the location of the Main Sequence (MS) of star-forming galaxies at $z$ $>$ 1.0, when our galaxies were 0.5-1.0 Gyr old. According to these SFHs, all the MQGs experienced a Luminous Infrared Galaxy (LIRG) phase that lasts for $\sim$ 500 Myr, and half of them an Ultra Luminous Infrared Galaxy (ULIRG) phase for $\sim$ 100 Myr. We find that the MQG population is almost assembled at $z$ $\sim$ 1, and continues evolving passively with few additions to the population.

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arXiv2015

SHARDS: A global view of the star formation activity at z~0.84 and z~1.23

In this paper, we present a comprehensive analysis of star-forming galaxies (SFGs) at intermediate redshifts (z~1). We combine the ultra-deep optical spectro-photometric data from the Survey for High-z Absorption Red and Dead Sources (SHARDS) with deep UV-to-FIR observations in the GOODS-N field. Exploiting two of the 25 SHARDS medium-band filters, F687W17 and F823W17, we select [OII] emission line galaxies at z~0.84 and z~1.23 and characterize their physical properties. Their rest-frame equivalent widths (EW$_{\mathrm{rf}}$([OII])), line fluxes, luminosities, star formation rates (SFRs) and dust attenuation properties are investigated. The evolution of the EW$_{\mathrm{rf}}$([OII]) closely follows the SFR density evolution of the universe, with a trend of EW$_{\mathrm{rf}}$([OII])$\propto$(1+z)$^3$ up to redshift z~1, followed by a possible flattening. The SF properties of the galaxies selected on the basis of their [OII] emission are compared with complementary samples of SFGs selected by their MIR and FIR emission, and also with a general mass-selected sample of galaxies at the same redshifts. We demonstrate observationally that the UVJ diagram (or, similarly, a cut in the specific SFR) is only partially able to distinguish the quiescent galaxies from the SFGs. The SFR-M$_*$ relation is investigated for the different samples, yelding a logarithmic slope ~1, in good agreement with previous results. The dust attenuations derived from different SFR indicators (UV(1600), UV(2800), [OII], IR) are compared and show clear trends with respect to both the stellar mass and total SFR, with more massive and highly star-forming galaxies being affected by stronger dust attenuation.

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arXiv2015

Creating S0s with major mergers: a 3D view

A number of simulators have argued that major mergers can sometimes preserve discs (e.g. Springel & Hernquist 2005), but the possibility that they could explain the emergence of lenticular galaxies (S0s) has been generally neglected. In fact, observations of S0s reveal a strong structural coupling between their bulges and discs, which seems difficult to reconcile with the idea that they come from major mergers. However, in Querejeta et al. (2015a) we have used N-body simulations of binary mergers to show that, under favourable conditions, discs are first destroyed but soon regrow out of the leftover debris, matching observational photometric scaling relations (e.g. Laurikainen et al. 2010). Additionally, in Querejeta et al. (2015b) we have shown how the merger scenario agrees with the recent discovery that S0s and most spirals are not compatible in an angular momentum--concentration plane. This important result from CALIFA constitutes a serious objection to the idea that spirals transform into S0s mainly by fading (e.g. via ram-pressure stripping, as that would not explain the observed simultaneous change in $λ_\mathrm{Re}$ and concentration), but our simulations of major mergers do explain that mismatch. From such a 3D comparison we conclude that mergers must be a relevant process in the build-up of the current population of S0s.

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arXiv2015

Formation of S0 galaxies through mergers: Explaining angular momentum and concentration change from spirals to S0s

The CALIFA team has recently found that the stellar angular momentum and concentration of late-type spiral galaxies are incompatible with those of lenticular galaxies (S0s), concluding that fading alone cannot satisfactorily explain the evolution from spirals into S0s. Here we explore whether major mergers can provide an alternative way to transform spirals into S0s by analysing the spiral-spiral major mergers from the GalMer database that lead to realistic, relaxed S0-like galaxies. We find that the change in stellar angular momentum and concentration can explain the differences in the $λ_\mathrm{Re}$--$R_{90}/R_{50}$ plane found by the CALIFA team. Major mergers thus offer a feasible explanation for the transformation of spirals into S0s.

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arXiv2015

Photometric scaling relations of antitruncated stellar discs in S0-Scd galaxies

It has been recently found that the characteristic photometric parameters of antitruncated discs in S0 galaxies follow tight scaling relations. We investigate if similar scaling relations are satisfied by galaxies of other morphological types. We have analysed the trends in several photometric planes relating the characteristic surface brightness and scalelengths of the breaks and the inner and outer discs of local antitruncated S0-Scd galaxies, using published data and fits performed to the surface brightness profiles of two samples of Type-III galaxies in the R and Spitzer 3.6 microns bands. We have performed linear fits to the correlations followed by different galaxy types in each plane, as well as several statistical tests to determine their significance. We have found that: 1) the antitruncated discs of all galaxy types from Sa to Scd obey tight scaling relations both in R and 3.6 microns, as observed in S0s; 2) the majority of these correlations are significant accounting for the numbers of the available data samples; 3) the trends are clearly linear when the characteristic scalelengths are plotted on a logarithmic scale; and 4) the correlations relating the characteristic surface brightnesses of the inner and outer discs and the breaks with the various characteristic scalelengths significantly improve when the latter are normalized to the optical radius of the galaxy. The results suggest that the scaling relations of Type-III discs are independent of the morphological type and the presence (or absence) of bars within the observational uncertainties of the available datasets, although larger and deeper samples are required to confirm this. The tight structural coupling implied by these scaling relations impose strong constraints on the mechanisms proposed for explaining the formation of antitruncated stellar discs in the galaxies across the whole Hubble Sequence (Abridged).

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arXiv2015

The trace of a substantial assembly of massive E-S0 galaxies at 0.8<z<1.5 in galaxy number counts

K-band galaxy number counts (GNCs) exhibit a slope change at K~17.5 mag not present in optical bands. To unveil the nature of this feature, we have derived the contribution of different galaxy types to the total K-band GNCs at 0.3 2 cannot predict the slope change, whereas those imposing a relatively late assembly on them (z<1.5) can reproduce it. The K-band GNCs by redshift bins and morphological types point to a progressively definitive build-up of ~50% of this galaxy population at 0.8<z<1.5, which can be explained only through the major mergers reported by observations. We conclude that the slope change in total K-band GNCs is a vestige of the definitive assembly of a substantial fraction of present-day massive E-S0's at 0.8<z<1.5.

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arXiv2014

Formation of S0 galaxies through mergers. V. Antitruncated stellar discs resulting from major mergers

Lenticular galaxies (S0s) are more likely to host antitruncated (Type-III) stellar discs than galaxies of later Hubble types. Major mergers are popularly considered too violent mechanisms to form these breaks. We have investigated whether major mergers can result into S0-like remnants with realistic antitruncated stellar discs or not. We have analysed 67 relaxed S0 and E/S0 remnants resulting from dissipative N-body simulations of major mergers from the GalMer database. We have simulated realistic R-band surface brightness profiles of the remnants to identify those with antitruncated stellar discs. Their inner and outer discs and the breaks are quantitatively characterized to compare with real data. Nearly 70% of our S0-like remnants are antitruncated, meaning that major mergers that result in S0s have a high probability of producing Type-III stellar discs. Our remnants lie on top of the extrapolations of the observational trends (towards brighter magnitudes and higher break radii) in several photometric diagrams. In scale-free photometric diagrams, simulations and observations overlap and the remnants reproduce the observational trends, so the physical mechanism after antitruncations is highly scalable. We have found novel photometric scaling relations between the characteristic parameters of the antitruncations in real S0s, which are also reproduced by our simulations. The trends in all the photometric planes can be derived from three basic scaling relations that real and simulated Type-III S0s fulfill: h_i \prop R_brkIII, h_o \prop R_brkIII, and mu_brkIII \prop R_brkIII, where h_i and h_o are the scalelenghts of the inner and outer discs, and mu_brkIII and R_brkIII are the surface brightness and radius of the breaks. Mayor mergers provide a feasible mechanism to form realistic antitruncated S0 galaxies (abridged).

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arXiv2014

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to test whether these mergers can generate S0 galaxies with kinematics intermediate between fast and slow rotators. We find that minor mergers induce a lower decrease of the global rotational support than encounters of lower mass ratios, which results in S0s with properties intermediate between fast and slow rotators. The resulting remnants are intrinsically more triaxial, less flattened, and span the whole range of apparent ellipticities up to $ε_\mathrm{e} \sim 0.8$. They do not show lower apparent ellipticities in random projections than initially; on the contrary, the formation of oval distortions and the disc thickening increase the percentage of projections at $0.4 < ε_\mathrm{e} < 0.7$. In the experiments with S0b progenitor galaxies, minor mergers tend to spin up the bulge and to decrease slightly its intrinsic ellipticity, whereas in the cases of primary S0c galaxies they keep the rotational support of the bulge nearly constant and decrease significantly its intrinsic ellipticity. The remnant bulges remain nearly spherical ($B/A \sim C/A > 0.9$), but exhibit a wide range of triaxialities ($0.20 < T < 1.00$). In the plane of global anisotropy of velocities ($δ$) vs. intrinsic ellipticity ($ε_\mathrm{e,intr}$), some of our models extend the linear trend found in previous major merger simulations towards higher $ε_\mathrm{e,intr}$ values, while others depart from it. This is consistent with the wide dispersion exhibited by real S0s in this diagram compared with ellipticals, which follow the linear trend drawn by major merger simulations. The different trends exhibited by ellipticals and S0 galaxies in the $δ$ - $ε_\mathrm{e}$ diagram may be pointing to the different role played by major mergers in the build-up of each morphological type.

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arXiv2013

Evolution along the sequence of S0 Hubble types induced by dry minor mergers. II - Bulge-disk coupling in the photometric relations through merger-induced internal secular evolution

Galaxy mergers are considered as questionable mechanisms for the evolution of lenticular galaxies (S0's), on the basis that even minor ones induce structural changes that are difficult to reconcile with the strong bulge-disk coupling observed in the photometric scaling relations of S0's. We check if the evolution induced onto S0's by dry intermediate and minor mergers can reproduce their photometric scaling relations, analysing the bulge-disk decompositions of the merger simulations presented in Eliche-Moral et al. (2012). The mergers induce an evolution in the photometric planes compatible with the data of S0's, even in those ones indicating a strong bulge-disk coupling. The mergers drive the formation of the observed photometric relation in some cases, whereas they induce a slight dispersion compatible with data in others. Therefore, this evolutionary mechanism tends to preserve these scaling relations. In those photometric planes where the morphological types segregate, the mergers always induce evolution towards the region populated by S0's. The structural coupling of the bulge and the disk is preserved or reinforced because the mergers trigger internal secular processes in the primary disk that induce significant bulge growth, even although these models do not induce bars. Intermediate and minor mergers can thus be considered as plausible mechanisms for the evolution of S0's attending to their photometric scaling relations, as they can preserve and even strengthen any pre-existing structural bulge-disk coupling, triggering significant internal secular evolution (even in the absence of bars or dissipational effects). This means that it may be difficult to isolate the effects of pure internal secular evolution from those of the merger-driven one in present-day early-type disks (abridged).

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arXiv2012

Evolution along the sequence of S0 Hubble types induced by dry minor mergers. I - Global bulge-to-disk structural relations

Recent studies have argued that galaxy mergers are not important drivers for the evolution of S0's, on the basis that mergers cannot preserve the coupling between the bulge and disk scale-lengths observed in these galaxies and the lack of correlation of their ratio with the S0 Hubble type. We investigate whether the remnants resulting from collision-less N-body simulations of intermediate and minor mergers onto S0 galaxies evolve fulfilling global structural relations observed between the bulges and disks of these galaxies. Different initial bulge-to-disk ratios of the primary S0 have been considered, as well as different satellite densities, mass ratios, and orbits of the encounter. We have analysed the final morphology of the remnants in images simulating the typical observing conditions of S0 surveys. We derive bulge+disk decompositions of the final remnants to compare their global bulge-to-disk structure with observations. We show that all remnants present undisturbed S0 morphologies according to the prescriptions of specialized surveys. The dry intermediate and minor mergers induce noticeable bulge growth (S0c --> S0b and S0b --> S0a), but affect negligibly to the bulge and disk scale-lengths. Therefore, if a coupling between these two components exists prior to the merger, the encounter does not break this coupling. This fact provides a simple explanation for the lack of correlation between the ratio of bulge and disk scale-lengths and the S0 Hubble type reported by observations. These models prove that dry intermediate and minor mergers can induce global structural evolution within the sequence of S0 Hubble types compatible with observations, meaning that these processes should not be discarded from the evolutionary scenarios of S0's just on the basis of the strong coupling observed between the bulge and disk scale-lengths in these galaxies (abridged).

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arXiv2012

Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0's through major mergers

Some recent observations seem to disagree with hierarchical theories of galaxy formation about the role played by major mergers in the late buildup of massive E-S0's. We re-address this question by analysing the morphology, structural distortion level, and star formation enhancement of a sample of massive galaxies (M_* > 5 * 10^10 Msun) lying on the Red Sequence and its surroundings at 0.3 < z < 1.5. We have used an initial sample of ~1800 sources with K_s < 20.5 mag over an area ~155 arcmin^2 on the Groth Strip, combining data from the Rainbow Extragalactic Database and the GOYA Survey. Red galaxy classes that can be directly associated to intermediate stages of major mergers and to their final products have been defined. We report observational evidence of the existence of a dominant evolutionary path among massive red galaxies at 0.6 10^11 Msun at z=0 through gas-rich major mergers has frozen since z~0.6. All these facts support that major mergers have played the dominant role in the definitive buildup of present-day E-S0's with M_*> 10^11 Msun at 0.6<z<1.2, in good agreement with hierarchical scenarios of galaxy formation.

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