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Higher Forms Symmetries (HFS) of a closed bosonic M2-brane theory formulated from the world-volume perspective on a compactified target space $\mathcal{M}_9 \times T^2$ are obtained. We show that the cancellation of the 't Hooft anomaly present in the theory is related to a 3-form flux with 1-gerbe structure associated to the world-volume flux quantization condition. A Wilson surface is naturally defined on the topological operator that characterize the holonomy of the M2-brane. The projection of the flux quantization condition onto the spatial part of the worldvolume, leads to a flux quantization on the M2-brane. The topological operators realise discrete symmetries associated with the winding and the flux/monopole condition. The algebra of operators is well defined., Comment: Latex, 19 pages, some references added and typos corrected

We construct, following \cite{mpgm14,mpgm17}, a massive M2-brane (supermembrane) as the limit of a genus two M2-brane that becomes a twice punctured Riemann surface with particular boundary conditions on the fields defined on the punctures. The target space is $M_9\times LCD$, where $LCD$ is a genus one light cone diagram. It contains mass terms and a topological term associated with the non-triviality of the target surface that, at low energies, can be associated with the presence of a cosmological constant. We show that the supergravity background of the M2-brane considered in this formulation requires the presence of M9-branes acting as sources. They correspond to the 11D uplift of the characteristic D8's of Romans supergravity. To this end, we explicitly show that some of the background singularities of the massive M2-brane can be reproduced by the M9-branes found by \cite{Bergshoeff}. This establishes a relation between the Romans mass and the moduli of the massive M2-brane. When dimensionally reduced, we obtain a worldsheet Hamiltonian of a N=2 type IIA closed superstring in 10D. We denote it \textit{massive} string. The corresponding \textit{massive} string inherits a non-vanishing constant term from the topological massive M2-brane that shifts the Hamiltonian. The non-vanishing parameter is related to the non-trivial structure of the massive M2-brane background and it can be related to the Romans mass term. It also contains a modified tension due to the non-trivial dependence on the moduli and on the punctures associated with the target torus., Comment: 25 pages, 5 figures. arXiv admin note: text overlap with arXiv:2301.00686

In this paper, we obtain the explicit expression of the supersymmetric algebra associated with the recently proposed massive supermembrane including all surface terms. We formulate the theory as the limit of a supermembrane on a genus-two compact Riemann surface when one of the handles becomes a string attached to a torus. The formulation reduces to a supermembrane on a punctured torus with a "string spike" (in the sense of \cite{dwln}), attached to it. In this limit, we identify all surface terms of the algebra and give the explicit expression of the Hamiltonian in agreement with the previous formulation of it. The symmetry under area preserving diffeomorphisms, connected and nonconnected to the identity, is also discussed. Only parabolic $Sl(2,\mathbb{Z})$ discrete symmetries are preserved., Comment: 10 pages, 4 figures

In this work we consider the existence and uniqueness of the ground state of the regularized Hamiltonian of the Supermembrane in dimensions $D= 4,\,5,\,7$ and 11, or equivalently the $SU(N)$ Matrix Model. That is, the 0+1 reduction of the 10-dimensional $SU(N)$ Super Yang-Mills Hamiltonian. This ground state problem is associated with the solutions of the inner and outer Dirichlet problems for this operator, and their subsequent smooth patching (glueing) into a single state. We have discussed properties of the inner problem in a previous work, therefore we now investigate the outer Dirichlet problem for the Hamiltonian operator. We establish existence and uniqueness on unbounded valleys defined in terms of the bosonic potential. These are precisely those regions where the bosonic part of the potential is less than a given value $V_0$, which we set to be arbitrary. The problem is well posed, since these valleys are preserved by the action of the $SU(N)$ constraint. We first show that their Lebesgue measure is finite, subject to restrictions on $D$ in terms of $N$. We then use this analysis to determine a bound on the fermionic potential which yields the coercive property of the energy form. It is from this, that we derive the existence and uniqueness of the solution. As a by-product of our argumentation, we show that the Hamiltonian, restricted to the valleys, has spectrum purely discrete with finite multiplicity. Remarkably, this is in contrast to the case of the unrestricted space, where it is well known that the spectrum comprises a continuous segment. We discuss the relation of our work with the general ground state problem and the question of confinement in models with strong interactions., Comment: Latex, 31 pages

We show the relation between three non trivial sectors of M2-brane theory formulated in the LCG connected among them by canonical transformations. These sectors correspond to the supermembrane theory formulated on a $M_9\times T^2$ on three different constant three-form backgrounds: M2-brane with constant $C_{-}$, M2-brane with constant $C_{\pm}$ and M2-brane with a generic constant $C_3$ denoted as CM2-brane. The first two exhibit a purely discrete supersymmetric spectrum once the central charge condition, or equivalently, the corresponding flux condition has been turned on. The CM2-brane is conjectured to share this spectral property once that fluxes $C_{\pm}$ are turned on. As shown in [1] they are duals to three inequivalent sectors of the D2-branes with specific worldvolume and background RR and NSNS quantization conditions on each case., Comment: 6 pages. To be considered for publication in the Proc. of the XXII Chilean Physics Symposium 2020, Journal of Physics Conference Series IOP

We present the formulation of the bosonic Hamiltonian M2-brane compactified on a twice punctured torus following the procedure proposed in \cite{mpgm14}. In this work we analyse two possible metric choice, different from the one used in \cite{mpgm14}, over the target space and study some of the properties of the corresponding Hamiltonian., Comment: Proceeding SOCHIFI 2020 (Sociedad Chilena de F\'isica). 6 pages

We obtain the Hamiltonian formulation of the 11D Supermembrane theory non-trivially compactified on a twice-punctured torus times a 9D Minkowski space-time. It corresponds to a M2-brane formulated in 11D space with ten non-compact dimensions. The critical points like the poles and the zeros of the fields describing the embedding of the Supermembrane in the target space are treated rigorously. The non-trivial compactification generates non-trivial mass terms appearing in the bosonic potential, which dominate the full supersymmetric potential and should render the spectrum of the (regularized) Supermembrane discrete with finite multiplicity. The behaviour of the fields around the punctures generates a cosmological term in the Hamiltonian of the theory. The massive supermembrane can also be seen as a nontrivial uplift of a supermembrane torus bundle with parabolic monodromy in $M_9\times T^2$. The moduli of the theory is the one associated with the punctured torus, hence it keeps all the nontriviality of the torus moduli even after the decompactification process to ten noncompact dimensions. The formulation of the theory on a punctured torus bundle is characterized by the $(1,1)-Knots$ associated with the monodromies., Comment: 25 pages, 5 figures

We obtain the bosonic D-brane description of toroidally compactified non-trivial M2-branes with the unique property of having a purely discrete supersymmetric regularized spectrum with finite multiplicity. As a byproduct, we generalize the previous Hamiltonian formulation to describe a M2-brane on a completely general constant quantized background $C_3$ denoted by us as CM2-brane. We show that under this condition, the theory is equivalent to a more restricted one, denoted as an M2-brane with $C_\pm$ fluxes, which has been shown to have good quantum behavior. As a result, the spectral properties of both sectors must be the same.We then obtain its bosonic D-brane description and discover new symmetries. We find that it contains a new symplectic gauge field in addition to the expected U(1) Dirac-Born-Infeld gauge symmetry and a nontrivial $U(1)$ associated with the presence of 2-form fluxes. Its bundle description takes on a new structure in the form of a twisted torus bundle. By turning off some of the fields, the D-brane description of other toroidally nontrivial M2-brane sectors can be obtained from this one. The possibility of reinterpreting these sectors in terms of Dp-brane bound states is discussed. These D-brane descriptions constitute String theory sectors with a quantum consistent uplift to M-theory., Comment: 34 pages. Some typos were improved and the title was changed

We show that the $D=11$ Supermembrane theory (M2-brane) compactified on a $M_9 \times T^2$ target space, with constant fluxes $C_{\pm}$ naturally incorporates the geometrical structure of a twisted torus. We extend the M2-brane theory to a formulation on a twisted torus bundle. It is consistently fibered over the world volume of the M2-brane. It can also be interpreted as a torus bundle with a nontrivial $U(1)$ connection associated to the fluxes. The structure group $G$ is the area preserving diffeomorphisms. The torus bundle is defined in terms of the monodromy associated to the isotopy classes of symplectomorphisms with $\pi_{0} (G) = SL(2,Z)$, and classified by the coinvariants of the subgroups of $SL(2,Z)$. The spectrum of the theory is purely discrete since the constant flux induces a central charge on the supersymmetric algebra and a modification on the Hamiltonian which renders the spectrum discrete with finite multiplicity. The theory is invariant under symplectomorphisms connected and non connected to the identity, a result relevant to guaranteed the U-dual invariance of the theory. The Hamiltonian of the theory exhibits interesting new $U(1)$ gauge and global symmetries on the worldvolume induced by the symplectomorphim transformations. We construct explicitly the supersymmetric algebra with nontrivial central charges. We show that the zero modes decouple from the nonzero ones. The nonzero mode algebra corresponds to a massive superalgebra that preserves either $1/2$ or $1/4$ of the original supersymmetry depending on the state considered., Comment: Latex, 27pg

The formulation of supermembrane theory on nontrivial backgrounds is discussed. In particular, we obtain the Hamiltonian of the supermembrane on a background with constant bosonic three form on a target space $M_9 \times T^2$., Comment: Proceeding SOCHIFI 2018 (Sociedad Chilena de F\'isica). 6 pages

We describe a compactified Supermembrane, or M2-brane, with 2-form fluxes generated by constant three-forms that are turned on a 2-torus of the target space $M_9\times T^2$. We compare this theory with the one describing a $11D$ M2-brane formulated on $M_9\times T^2$ target space subject to an irreducible wrapping condition. We show that the flux generated by the bosonic 3-form under consideration is in a one to one correspondence to the irreducible wrapping condition. After a canonical transformation both Hamiltonians are exactly the same up to a constant shift in one particular case. Consequently both of them, share the same spectral properties. We conclude that the Hamiltonian of the M2-brane with 2-form target space fluxes on a torus has a purely discrete spectrum with eigenvalues of finite multiplicity and it can be considered to describe a new sector of the microscopic degrees of freedom of M-theory. We also show that the total membrane momentum in the direction associated to the flux condition acquires a quantized contribution in correspondence to the flux units that have been turned on., Comment: Latex, 15 pages, title changed, paper revised, results improved

We analyse the measure of the regularized matrix model of the supersymmetric potential valleys, $\Omega$, of the Hamiltonian of non zero modes of supermembrane theory. This is the same as the Hamiltonian of the BFSS matrix model. We find sufficient conditions for this measure to be finite, in terms the spacetime dimension. For $SU(2)$ we show that the measure of $\Omega$ is finite for the regularized supermembrane matrix model when the transverse dimensions in the light cone gauge $\mathrm{D}\geq 5$. This covers the important case of seven and eleven dimensional supermembrane theories, and implies the compact embedding of the Sobolev space $H^{1,2}(\Omega)$ onto $L^2(\Omega)$. The latter is a main step towards the confirmation of the existence and uniqueness of ground state solutions of the outer Dirichlet problem for the Hamiltonian of the $SU(N)$ regularized $\mathrm{D}=11$ supermembrane, and might eventually allow patching with the inner solutions., Comment: Latex, 11 pages, reference added

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 $\overline{\mu}=26$ 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 ($\mu>32.5$ mag arcsec$^{-2}$, $3\sigma$ 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/., Comment: Published in Astronomy & Astrophysics

Major mergers are popularly considered too destructive to produce the relaxed regular structures and the morphological inner components (ICs) usually observed in lenticular (S0) galaxies. We aim to test if major mergers can produce remnants with realistic S0 morphologies. We have selected a sample of relaxed discy remnants resulting from the dissipative merger simulations of the GalMer database and derived their properties mimicking the typical conditions of current observational data. We compare their global morphologies, visual components, and merger relics in mock photometric images with their real counterparts. Only $\sim$1-2 Gyr after the full merger, we find that: 1) many remnants (67 major and 29 minor events) present relaxed structures and typical S0 or E/S0 morphologies, for a wide variety of orbits and even in gas-poor cases. 2) Contrary to popular expectations, most of them do not exhibit any morphological traces of their past merger origin under typical observing conditions and at distances as nearby as 30 Mpc. 3) The merger relics are more persistent in minor mergers than in major ones for similar relaxing time periods. 4) No major-merger S0-like remnant develops a significant bar. 5) Nearly 58% of the major-merger S0 remnants host visually detectable ICs, such as embedded inner discs, rings, pseudo-rings, inner spirals, nuclear bars, and compact sources, very frequent in real S0s too. 6) All remnants contain a lens or oval, identically ubiquitous in local S0s. 7) These lenses and ovals do not come from bar dilution in major merger cases, but are associated with stellar halos or embedded inner discs instead (thick or thin). We conclude that the relaxed morphologies, lenses, ovals, and other ICs of real S0s do not necessarily come from internal secular evolution, gas infall or environmental mechanisms, as traditionally assumed, but they can result from major mergers as well., Comment: Accepted for publication in A&A, 37 pages, 21 figures, 9 tables. Version with better resolution and language edited. A version with full Appendices is available at: https://www.researchgate.net/publication/325905181_Formation_of_S0_galaxies_through_mergers_Morphological_properties_tidal_relics_lenses_ovals_and_other_inner_components_-_Version_of_the_corresponding_AA_paper_with_full_Appendices

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 $310^{3}\,\rm{M}_\odot/yr$) that place them above the MS. The rest, 30\%, are post-starbursts or quiescent galaxies located $>2\sigma$ 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 $411$ 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., Comment: 38 pages, 18 figures, Accepted for publication in The Astrophysical Journal 26/03/2019

We have undertaken a comprehensive search for both Lyman Alpha Emitters (LAEs) and Lyman Break Galaxies (LBGs) in the SHARDS Survey of the GOODS-N field. SHARDS is a deep imaging survey, made with the 10.4 m Gran Telescopio Canarias (GTC), employing 25 medium band filters in the range from 500 to 941 nm. This is the first time that both LAEs and LBGs are surveyed simultaneously in a systematic way in a large field. We draw a sample of 1558 sources; 528 of them are LAEs. Most of the sources (1434) show rest-frame UV continua. A minority of them (124) are pure LAEs with virtually no continuum detected in SHARDS. We study these sources from $z\sim3.35$ up to $z\sim6.8$, well into the epoch of reionization. Note that surveys done with just one or two narrow band filters lack the possibility to spot the rest-frame UV continuum present in most of our LAEs. We derive redshifts, Star Formation Rates (SFRs), Ly$\alpha$ Equivalent Widths (EWs) and Luminosity Functions (LFs). Grouping within our sample is also studied, finding 92 pairs or small groups of galaxies at the same redshift separated by less than 60 comoving kpc. In addition, we relate 87 and 55 UV-selected objects with two known overdensities at $z=4.05$ and $z=5.198$, respectively. Finally, we show that surveys made with broad band filters are prone to introduce many unwanted sources ($\sim20$% interlopers), which means that previous studies may be overestimating the calculated LFs, specially at the faint end., Comment: Accepted for publication in MNRAS. 18 pages, 19 figures

The physical processes driving the evolution of star formation (SF) in galaxies over cosmic time still present many open questions. Recent galaxy surveys allow now to study these processes in great detail at intermediate redshift. In this work, we build a complete sample of star-forming galaxies and analyze their properties, reaching systems with low stellar masses and low star formation rates (SFRs) at intermediate-to-low redshift. We use data from the SHARDS multiband survey in the GOODS-North field. Its depth (up to magnitude $\langle m_{3\sigma}\rangle\sim26.5$) and its spectro-photometric resolution ($R\sim50$) provides us with an ideal dataset to search for emission line galaxies (ELGs). We develop a new algorithm to identify low-redshift ($z$<0.36) ELGs by detecting the [OIII]5007 and $H\alpha$ emission lines simultaneously. We fit the spectral energy distribution (SED) of the selected sample, using a model with two single stellar populations. We find 160 star-forming galaxies with equivalent widths (EWs) as low as 12 {\AA}, with median values for the sample of $\sim$ 35 {\AA} in [OIII]5007 and $\sim$ 56 {\AA} in $H\alpha$, respectively. Results from the SED fitting show a young stellar population with low median metallicity (36% of the solar value) and extinction ($A_V \sim$ 0.37), with median galaxy stellar mass $\sim$ 10$^{8.5}$ M$_{\odot}$. Gas-phase metallicities measured from available spectra are also low. ELGs in our sample present bluer colors in the UVJ plane than the median color-selected star-forming galaxy in SHARDS. We suggest a new (V-J) color criterion to separate ELGs from non-ELGs in blue galaxy samples. In addition, several galaxies present high densities of O-type stars. Robust fits to the full SEDs can only be obtained including an old stellar population, suggesting the young component is built up by a recent burst of SF in an otherwise old galaxy., Comment: Accepted for publication in Astronomy & Astrophysics. 17 pages, 17 figures

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

The intrinsic shape of galactic bulges in nearby galaxies provides crucial information to separate bulge types. We intended to derive accurate constraints to the intrinsic shape of bulges to provide new clues on their formation mechanisms and set new limitations for future simulations. We retrieved the intrinsic shape of a sample of CALIFA bulges using a statistical approach. Taking advantage of GalMer numerical simulations of binary mergers we estimated the reliability of the procedure. Analyzing the $i$-band mock images of resulting lenticular remnants, we studied the intrinsic shape of their bulges at different galaxy inclinations. Finally, we introduced a new ($B/A$, $C/A$) diagram to analyze possible correlations between the intrinsic shape and the properties of bulges. We tested the method on simulated lenticular remnants, finding that for galaxies with inclinations $25^{\circ} < \theta < 65^{\circ}$ we can safely derive the intrinsic shape of their bulges. We found that our CALIFA bulges tend to be nearly oblate systems (66%), with a smaller fraction of prolate spheroids (19%) and triaxial ellipsoids (15%). The majority of triaxial bulges are in barred galaxies (75%). Moreover, we found that bulges with low S\'ersic indices or in galaxies with low bulge-to-total luminosity ratios form a heterogeneous class of objects; additionally, also bulges in late-type galaxies or in less massive galaxies have no preference in being oblate, prolate, or triaxial. On the contrary, bulges with high S\'ersic index, in early-type galaxies, or in more massive galaxies are mostly oblate systems. We concluded that various evolutionary pathways may coexist in galaxies, with merging events and dissipative collapse being the main mechanisms driving the formation of the most massive oblate bulges and bar evolution reshaping the less massive triaxial bulges.

(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 $\sigma_0$-$M_K$, Vcirc-$\sigma_0$ and Vrot,max-$\sigma_0$ 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., Comment: 19 pages, 15 figures. Accepted for publication in A&A

Supermembrane compactified on a $M_9\times T^2$ target space is globally described by the inequivalent classes of torus bundles over torus. These torus bundles have monodromy in $SL(2,Z)$ when they correspond to the nontrivial central charge sector and they are trivial otherwise. The first ones contain eight inequivalent classes of M2-brane bundles which at low energies, are in correspondence with the eight type II gauged supergravities in $9D$. The relation among them is completely determined by the global action of T-duality which interchanges topological invariants of the two tori. The M2-brane torus bundles are invariant under $SL(2,Z)\times SL(2,Z) \times Z_2$. From the effective point of view, there is another dual invariant theory, called Double Field Theory which describe invariant actions under $O(D,D)$. Globally it is formulated in terms of doubled $2D$ torus fibrations over the spacetime with a monodromy given by $O(D,D,Z)$. In this note we discuss T-duality global aspects considered in both theories and we emphasize certain similarities between both approaches which could give some hints towards a deeper relationship between them., Comment: 10 pages. arXiv admin note: text overlap with arXiv:1604.02579

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

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

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)., Comment: 3 pages, 1 figure, Proceedings of IAU Symposium 321, "Formation and evolution of galaxy outskirts", Eds. A. Gil de Paz, J. C. Lee & J. H. Knapen, Cambridge University Press, Cambridge

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 $\lambda_\mathrm{Re}$ 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., Comment: 10 pages, 3 figures. Proceedings from the European Week of Astronomy (EWASS), Tenerife, June 2015 (Sp3)

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., Comment: Replaced to match the accepted version (24 pages, 1 table, 17 figures). Published in ApJ, 812, 155 (2015): http://stacks.iop.org/0004-637X/812/155

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, $\langle \tau \rangle$ $\sim$ 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 \tau \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., Comment: 26 pages, 18 figures. Accepted for publication in MNRAS

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 $\lambda_\mathrm{Re}$--$R_{90}/R_{50}$ plane found by the CALIFA team. Major mergers thus offer a feasible explanation for the transformation of spirals into S0s., Comment: 7 pages, 1 figure, accepted for publication in A&A

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)., Comment: Accepted for publication in Astronomy & Astrophysics, 18 pages, 12 figures, 7 tables

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 0.32 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

In this note we explicitly show how the generalization of the T-duality symmetry of the supermembrane theory compactified in M9xT2 can be reduced to a parabolic subgroup of SL(2,Z) that acts non-linearly on the moduli parameters and on the KK and winding charges of the supermembrane. This is a first step towards a deeper understanding of the dual relation between the parabolic type II gauged supergravity in nine dimensions., Comment: 6 pages, Latex, Proceedings for the XIX Simposio Chileno de Fisica, SOCHIFI 2014 Conference, 26-28 November 2014, held at Concepcion U., Chile

We establish a general framework for the analysis of boundary value problems of matrix models at zero energy on compact regions. We derive existence and uniqueness of ground state wavefunctions for the mass operator of the $D=11$ regularized supermembrane theory, that is the $\mathcal{N}=16$ supersymmetric $SU(N)$ matrix model, on balls of finite radius. Our results rely on the structure of the associated Dirichlet form and a factorization in terms of the supersymmetric charges. They also rely on the polynomial structure of the potential and various other supersymmetric properties of the system., Comment: Latex, 26 pages. We have added some comments at the introduction in order to make it easier for the reader. Results of the paper unchanged

We discuss the existence and uniqueness of wavefunctions for inhomogenoeus boundary value problems associated to x^2y^2-type matrix model on a bounded domain of R^2. Both properties involve a combination of the Cauchy-Kovalewski Theorem and a explicit calculations., Comment: 3 pages, Latex Proceedings for the XIX Simposio Chileno de Fisica, SOCHIFI 2014 Conference, 26-28 November 2014, held at Concepcion U., Chile

We show the existence and uniqueness of a massless supersymmetric ground state wavefunction of a SU(2) matrix model in a bounded smooth domain with Dirichlet boundary conditions. This is a gauge system and we provide a new framework to analyze the quantum spectral properties of this class of supersymmetric matrix models subject to constraints which can be generalized for arbitrary number of colors., Comment: 12 pages, Latex. Somme clarifications. Minor changes. Version to appear at NPB

In this work we examine the existence and uniqueness of the groundstate of a SU(N)x G2 octonionic matrix model on a bounded domain of R^N. The existence and uniqueness argument of the groundstate wavefunction follows from the Lax-Milgram theorem. Uniqueness is shown by means of an explicit argument which is drafted in some detail., Comment: Latex, 6 pages

Observations reveal a strong structural coupling between bulge and disc in S0 galaxies, which seems difficult to explain if they have formed from supposedly catastrophic events such as major mergers. We face this question by quantifying the bulge-disc coupling in dissipative simulations of major and minor mergers that result in realistic S0s. We have studied the dissipative N-body binary merger simulations from the GalMer database that give rise to realistic, relaxed E/S0 and S0 remnants (67 major and 29 minor mergers). We simulate surface brightness profiles of these S0-like remnants in the K-band, mimicking typical observational conditions, to perform bulge-disc decompositions analogous to those carried out in real S0s. The global bulge-disc structure of these remnants has been compared with real data, and they distribute in the B/T - r_e - h_d parameter space consistently with real bright S0s, where B/T is the bulge-to-total luminosity ratio, r_e is the bulge effective radius, and h_d is the disc scalelength. Major mergers can rebuild a bulge-disc coupling in the remnants after having destroyed the structures of the progenitors, whereas minor mergers directly preserve them. Remnants exhibit B/T and r_e/h_d spanning a wide range of values, and their distribution is consistent with observations. Many remnants have bulge Sersic indices ranging 1

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)., Comment: Published in Astronomy & Astrophysics. 31 pages, 17 figures. Language corrections by the journal included in this new version. Title changed

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 $\epsilon_\mathrm{e} \sim 0.8$. 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 $0.4 < \epsilon_\mathrm{e} < 0.7$. 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 ($\delta$) vs. intrinsic ellipticity ($\epsilon_\mathrm{e,intr}$), some of our models extend the linear trend found in previous major merger simulations towards higher $\epsilon_\mathrm{e,intr}$ 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 $\delta$ - $\epsilon_\mathrm{e}$ diagram may be pointing to the different role played by major mergers in the build-up of each morphological type., Comment: Corrected typos. 20 pages, 14 figures. Accepted for publishing in A&A

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)., Comment: Accepted for publication in Astronomy & Astrophysics, 13 pages, 8 figures. Definitive version after proofs. Added references and corrected typos