The structural properties of classical bulges and discs from z~2
Paola Dimauro, Marc Huertas-Company, Emanuele Daddi, Pablo G. Pérez-González, Mariangela Bernardi, Fernando Caro, Andrea Cattaneo, Boris Häußler, Ulrike Kuchner… 展开作者
Paola Dimauro, Marc Huertas-Company, Emanuele Daddi, Pablo G. Pérez-González, Mariangela Bernardi, Fernando Caro, Andrea Cattaneo, Boris Häußler, Ulrike Kuchner, Francesco Shankar, Guillermo Barro, Fernando Buitrago, Sandra M. Faber, Dale D. Kocevski, Anton M. Koekemoer, David C. Koo, Simona Mei, Reynier Peletier, Joel Primack, Aldo Rodriguez-Puebla, Mara Salvato, Diego Tuccillo
We study the rest-frame optical mass-size relation of bulges and discs from z~2 to z~0 for a complete sample of massive galaxies in the CANDELS fields using 2 component Sérsic models (Dimauro et a. 2018). Discs and star forming galaxies follow similar mass-size relations. The mass-size relation of bulges is less steep than the one of quiescent galaxies (best fit slope of ~ 0.7 for quiescent galaxies against ~ 0.4 for bulges). We find little dependence of the structural properties of massive bulges and discs with the global morphology of galaxies (disc vs. bulge dominated) and the star formation activity (star-forming vs. quiescent). This result suggests similar bulge formation mechanisms for most massive galaxies and also that the formation of the bulge component does not significantly affect the disc structure. Our findings pose a challenge to models envisioning multiple channels for massive bulge growth, such as disc instabilities and mergers.
This paper studies pseudo-bulges (P-bulges) and classical bulges (C-bulges) in Sloan Digital Sky Survey central galaxies using the new bulge indicator $ΔΣ_1$, which measures relative central stellar-mass surface density within 1 kpc. We compare $ΔΣ_1$ to the established bulge-type indicator $Δ\langleμ_e\rangle$ from Gadotti (2009) and show that classifying by $ΔΣ_1$ agrees well with $Δ\langleμ_e\rangle$. $ΔΣ_1$ requires no bulge-disk decomposition and can be measured on SDSS images out to $z = 0.07$. Bulge types using it are mapped onto twenty different structural and stellar-population proper…
Establishing a correlation (or lack thereof) between the bimodal colour distribution of galaxies and their structural parameters is crucial to understand the origin of bimodality. To achieve that, we have performed 2D mass-based structural decomposition (bulge+disc) of all disc galaxies (total$=$1263) in the Herschel imaging area of the Stripe 82 region using $K_s$ band images from the VICS82 survey. The scaling relations thus derived are found to reflect the internal kinematics and are employed in combination to select an indubitable set of classical and pseudo bulge hosting disc galaxies. Th…
Disky bulges in spiral galaxies are commonly thought to form out of disk materials (mainly) via bar driven secular processes, they are structurally and dynamically distinct from `classical bulges' built in violent merger events. We use high-resolution GTC/MEGARA integral-field unit spectroscopic observations of the Sa galaxy NGC 7025, obtained during the MEGARA commissioning run, together with detailed 1D and 2D decompositions of this galaxy's SDSS $i$-band data to investigate the formation of its disky (bulge) component which makes up $\sim 30\%$ of the total galaxy light. With a Sérsic index…
We introduce PHI, a fully Bayesian Markov-chain Monte Carlo algorithm designed for the structural decomposition of galaxy images. PHI uses a triple layer approach to effectively and efficiently explore the complex parameter space. Combining this with the use of priors to prevent nonphysical models, PHI offers a number of significant advantages for estimating surface brightness profile parameters over traditional optimisation algorithms. We apply PHI to a sample of synthetic galaxies with SDSS-like image properties to investigate the effect of galaxy properties on our ability to recover unbiase…
We present NGC 4565 and NGC 5746 as structural analogs of our Milky Way. All three are giant, SBb - SBbc galaxies with two pseudobulges, i. e., a compact, disky, star-forming pseudobulge embedded in a vertically thick, "red and dead", boxy pseudobulge that really is a bar seen almost end-on. The stars in the boxy bulge of our Milky Way are old and enhanced in alpha elements, indicating that star formation finished within ~ 1 Gyr of when it started. Here, we present Hobby-Eberly Telescope spectroscopy of the boxy pseudobulges of NGC 4565 and NGC 5746 and show that they also are made of old and …
We study the statistical properties of 320 bulges of disk galaxies in the Carnegie-Irvine Galaxy Survey, using robust structural parameters of galaxies derived from image fitting. We apply the Kormendy relation to classify classical and pseudo bulges and characterize bulge dichotomy with respect to bulge structural properties and physical properties of host galaxies. We confirm previous findings that pseudo bulges on average have smaller Sérsic indices, smaller bulge-to-total ratios, and fainter surface brightnesses when compared with classical bulges. Our sizable sample statistically shows th…
We measure optical colors for the bulges of 312 disk galaxies from the Carnegie-Irvine Galaxy Survey and convert their previously available $R$-band structural parameters to stellar mass parameters. We also measure their average stellar mass surface density in the central 1 kpc ($Σ_{1}$). Comparing the mass-based Kormendy relation with the original one based on flux, we find that the majority of the classifications into classical and pseudo bulges, as well as their overall statistical properties, remain essentially unchanged. While the bulge type classifications of the Kormendy relation are ro…
We study the structural properties of Low Surface Brightness galaxies (LSB) using a sample of 263 galaxies observed by the Green Bank Telescope (Schneider et al 1992). We perform 2D decompositions of these galaxies in the SDSS $g$, $r$ and $i$ bands using the GALFIT software. Our decomposition reveals that about $60\%$ of these galaxies are bulgeless i.e., their light distributions are well modelled by pure exponential disks. The rest of the galaxies were fitted with two components: a Sersic bulge and an exponential disk. Most of these galaxies have bulge-to-total (B/T) ratio less than 0.1. Ho…
We analyse the bulge/spheroid size-(stellar mass), $R_{\rm e,Sph}-M_{\rm *,Sph}$, relation and spheroid structural parameters for 202 local (predominantly $\lesssim 110~\rm Mpc$) galaxies spanning $ M_*\sim 3\times10^{9}-10^{12}~\rm M_{\odot}$ and $ 0.1 \lesssim R_{\rm e, Sph}\lesssim32~\rm kpc$ from multicomponent decomposition. The correlations between the spheroid Sérsic index ($n_{\rm Sph}$), central surface brightness ($μ_{\rm 0, Sph}$), effective half-light radius ($R_{\rm e, Sph}$), absolute magnitude ($\mathfrak{M}_{\rm Sph}$) and stellar mass ($M_{\rm *,Sph}$) are explored. We also in…
Following from our recent work, we present here a detailed structural analysis of a representative sample of nearby spiral and early-type galaxies taken from the KINGFISH/ SINGS survey. The photometric parameters of bulges are obtained from bulge-disc decompositions using GALFIT data analysis algorithm. The method and corrections for projection and dust effects previously obtained are used to derive intrinsic photometric and structural bulge parameters. We show the main bulge scaling relations and the black hole relations, both observed and intrinsic ones, in B band. We find dust and inclinati…
We present structural parameters and (g-i) bulge/disk colors for a large sample (189) of isolated AMIGA galaxies. The structural parameters of bulges were derived from the 2D bulge/disk/bar decomposition of SDSS i-band images using GALFIT. Galaxies were separated between classical bulges (n_b>2.5) and pseudobulges (n_b<2.5), resulting in a dominant pseudobulge population (94%) with only 12 classical bulges. In the <mu_e>-Re plane, pseudobulges are distributed below the elliptical relation (smaller Re and fainter mu_e), with the closest region to the Kormendy relation populated by those pseudob…
Quantitative characterization of galaxy morphology is vital in enabling comparison of observations to predictions from galaxy formation theory. However, without significant overlap between the observational footprints of deep and shallow galaxy surveys, the extent to which structural measurements for large galaxy samples are robust to image quality (e.g., depth, spatial resolution) cannot be established. Deep images from the Sloan Digital Sky Survey (SDSS) Stripe 82 co-adds provide a unique solution to this problem - offering $1.6-1.8$ magnitudes improvement in depth with respect to SDSS Legac…
(abridged) A fundamental subject in Extragalactic Astronomy concerns the formation and evolution of late-type galaxies (LTGs). The standard scenario comprises the early assembly of the bulge followed by disk accretion. However, recent observational evidence points to a joint formation and perpetual co-evolution of these structural components. Our current knowledge on the properties of bulge and disk is mostly founded on photometric decomposition studies, which sensitively depend on the adopted methodology and enclosed assumptions on the structure of LTGs. A critical assumption whose validity w…
In this review our aim is to summarize the observed properties of pseudobulges and classical bulges. We utilize an empirical approach to studying the properties of bulges in disk galaxies, and restrict our analysis to statistical proper- ties. A clear bimodality is observed in a number of properties including morphology, structural properties, star formation, gas content & stellar population, and kinematics. As well as summarizing known methods to identify pseudobulges and classical bulges we also show new results, including absorption line indices that can be used to identify different bulge …
We present the results of two-component (disc+bar) and three-component (disc+bar+bulge) multiwavelength 2D photometric decompositions of barred galaxies in five SDSS bands ($ugriz$). This sample of $\sim$3,500 nearby ($z<0.06$) galaxies with strong bars selected from the Galaxy Zoo citizen science project is the largest sample of barred galaxies to be studied using photometric decompositions which include a bar component. With detailed structural analysis we obtain physical quantities such as the bar- and bulge-to-total luminosity ratios, effective radii, Sérsic indices and colours of the indi…
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…
We use our catalogue of structural decomposition measurements for the extended GALEX Arecibo SDSS Survey (xGASS) to study the role of bulges both along and across the galaxy star-forming main sequence (SFMS). We show that the slope in the $sSFR$-$M_{\star}$ relation flattens by $\sim$0.1 dex per decade in $M_{\star}$ when re-normalising $sSFR$ by disc stellar mass instead of total stellar mass. However, recasting the $sSFR$-$M_{\star}$ relation into the framework of only disc-specific quantities shows that a residual trend remains against disc stellar mass with equivalent slope and comparable …
Pseudo-bulges are expected to markedly differ from classical, quasi-monolithically forming bulges in their star formation history (SFH) and chemical abundance patterns. To test this simple expectation, we carry out a comparative structural and spectral synthesis analysis of 106 red, massive galaxies issued from the SDSS, subdivided into bulgeless, pseudo-bulge and classical bulge galaxies according to their photometric characteristics, and further obeying a specific selection to minimize uncertainties in the analysis and ensure an unbiased derivation and comparison of SFHs. Our 2D photometry a…
The relation between the stellar mass and size of a galaxy's structural subcomponents, such as discs and spheroids, is a powerful way to understand the processes involved in their formation. Using very large catalogues of photometric bulge+disc structural decompositions and stellar masses from the Sloan Digital Sky Survey Data Release Seven, we carefully define two large subsamples of spheroids in a quantitative manner such that both samples share similar characteristics with one important exception: the 'bulges' are embedded in a disc and the 'pure spheroids' are galaxies with a single struct…
We present a multi-component structural analysis of the internal structure of $1074$ high redshift massive galaxies at $1<z<3$ from the CANDELS HST Survey. In particular we examine galaxies best-fit by two structural components, and thus likely forming discs and bulges. We examine the stellar mass, star formation rates, and colours of both the inner `bulge' and outer `disc' components for these systems using SED information from the resolved ACS+WFC3 HST imaging. We find that the majority of both inner and outer components lie in the star-forming region of UVJ space ($68$ and $90$ per cent res…
In this work we introduce the curvature of a galaxy brightness profile to identify its structural subcomponents in a non-parametrically fashion. Bulges, bars, disks, lens, rings and spiral arms are key to understand the formation and evolution path the galaxy undertook. Identifying them is also crucial for morphological classification of galaxies. We measure and analyse in detail the curvature of $14$ galaxies with varied morphology. High (low) steepness profiles show high (low) curvature measures. Transitions between components are identified as local peaks oscillations in the values of the c…
Tracing the dynamical and structural complexity of spiral galaxy centres
University of Vienna（维也纳大学）；Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉古纳大学）；Graduate Institute for Advanced Studies, SOKENDAI（综合研究大学院大学）；Subaru Telescope, National Astronomical Observatory of Japan（日本国立天文台 Subaru 望远镜）；Leiden University（莱顿大学）；Durham University（杜伦大学）
We review the observed morphological, photometric, and kinematic properties of boxy/peanut (B/P) shape bulges. Nearly half of the bulges in the nearby edge-on galaxies have these characteristics, which fraction is similar to the observed bar fraction in Hubble types earlier than Scd. B/P bulges are generally detected in the edge-on view, but it has been recently demonstrated that barlenses, which are lens-like structures embedded in bars, are the more face-on counterparts of the B/P bulges. Multi-component structural decompositions have shown that B/P/barlens structures are likely to account f…
Disc galaxies show a large morphological diversity with varying contribution of three major structural components; thin discs, thick discs, and central bulges. Dominance of bulges increases with the galaxy mass (Hubble sequence) whereas thick discs are more prominent in lower mass galaxies. Because galaxies grow with the accretion of matter, this observed variety should reflect diversity in accretion history. On the basis of the prediction by the cold-flow theory for galactic gas accretion and inspired by the results of previous studies, we put a hypothesis that associates different accretion …
The Milky Way bulge offers a unique opportunity to investigate in detail the role that different processes such as dynamical instabilities, hierarchical merging, and dissipational collapse may have played in the history of the Galaxy formation and evolution based on its resolved stellar population properties. Large observation programmes and surveys of the bulge are providing for the first time a look into the global view of the Milky Way bulge that can be compared with the bulges of other galaxies, and be used as a template for detailed comparison with models. The Milky Way has been shown to …
Cosmological simulations predict more classical bulges than their observational counterpart in the local Universe. Here, we quantify evolution of the bulges since $z=0.1$ using photometric parameters of nearly 39,000 unbarred disc galaxies from SDSS DR7 which are well represented by two components. We adopted a combination of the Sérsic index and Kormendy relation to separate classical bulges and disc-like pseudo-bulges. We found that the fraction of pseudo-bulges (classical bulges) smoothly increases (decreases) as the Universe gets older. In the history of the Universe, there comes a point (…
Long slit spectra recorded with GMOS on Gemini South are used to examine the star-forming history of the lenticular galaxy NGC 5102. Structural and supplemental photometric information are obtained from archival Spitzer [3.6] images. Comparisons with model spectra point to luminosity-weighted metallicities that are consistent with the colors of resolved red giant branch stars in the disk. The nucleus has a luminosity-weighted age at visible wavelengths of ~1 Gyr, and the integrated light is dominated by stars that formed over a time period of only a few hundred Myr. For comparison, the luminos…
We present a structural decomposition analysis of the galaxies in the extended GALEX Arecibo SDSS Survey (xGASS) using (gri) images from the Sloan Digital Sky Survey. Utilising the 2D Bayesian light profile fitting code ProFit, we fit single- and double-component models taking advantage of a robust Markov chain Monte Carlo optimisation algorithm in which we assume a Sersic profile for single-component models and a combination of a Sersic bulge and near-exponential disc (0.5 < n < 1.5) for double-component models. We investigate the effect of bulges on the atomic hydrogen (HI) content in galaxi…
We study the relation between the properties of the bulge/disc components and the HI mass fraction of galaxies. We find that at fixed stellar mass, disc colours are correlated with the HI mass fraction, while bulge colours are not. The lack of a correlation between the bulge colour and the HI mass fraction is regardless whether the bulges are pseudo, or whether the galaxies host bars or are interacting with a neighbour. There is no strong correlation between the colours of the discs and bulges either. These results suggest that the current total amount of HI is closely related to the formation…
We study structural properties of spectroscopically confirmed massive quiescent galaxies at $z\approx 3$ with one of the first sizeable samples of such sources, made of ten $10.8<\log(M_{\star}/M_{\odot})<11.3$ galaxies at $2.4 < z < 3.2$ in the COSMOS field whose redshifts and quiescence are confirmed by HST grism spectroscopy. Although affected by a weak bias toward younger stellar populations, this sample is deemed to be largely representative of the majority of the most massive and thus intrinsically rarest quiescent sources at this cosmic time. We rely on targeted HST/WFC3 observations an…
About 20% of low-redshift galaxies are late-type spirals with a small or no bulge component. Although they are the simplest disk galaxies in terms of structure and dynamics, the role of the different physical processes driving their formation and evolution is not yet fully understood. We investigated whether small bulges of late-type spirals follow the same scaling relations traced by ellipticals and large bulges and if they are disk-like or classical bulges. We derived the photometric and kinematic properties of 9 nearby late-type spirals. To this aim, we analyzed the surface brightness distr…
With a large sample of bright, low-redshift galaxies with optical$-$near-IR imaging from the GAMA survey we use bulge-disc decompositions to understand the wavelength-dependent behavior of single-Sérsic structural measurements. We denote the variation in single-Sérsic index with wavelength as $\mathcal{N}$, likewise for effective radius we use $\mathcal{R}$. We find that most galaxies with a substantial disc, even those with no discernable bulge, display a high value of $\mathcal{N}$. The increase in Sérsic index to longer wavelengths is therefore intrinsic to discs, apparently resulting from …
We use bulge-type classifications of 809 representative SDSS galaxies by Gadotti (2009) to classify a large sample of galaxies into real bulges (classical or elliptical) and pseudobulges using Random Forest. We use structural and stellar population predictors that can easily be measured without image decomposition. Multiple parameters such as the central mass density with 1 kpc, concentration index, Sérsic index and velocity dispersion do result in accurate bulge classifications when combined together. We classify $\sim 44,500$ face-on galaxies above stellar mass of 10$^{10}$ M$_\odot$ and red…
We present an image-based method for comparing the structural properties of galaxies produced in hydrodynamical simulations to real galaxies in the Sloan Digital Sky Survey. The key feature of our work is the introduction of extensive observational realism, such as object crowding, noise and viewing angle, to the synthetic images of simulated galaxies, so that they can be fairly compared to real galaxy catalogs. We apply our methodology to the dust-free synthetic image catalog of galaxies from the Illustris simulation at $z=0$, which are then fit with bulge+disc models to obtain morphological …
Bulge-disc decomposition is a valuable tool for understanding galaxies. However, achieving robust measurements of component properties is difficult, even with high quality imaging, and it becomes even more so with the imaging typical of large surveys. In this paper we consider the advantages of a new, multi-band approach to galaxy fitting. We perform automated bulge-disc decompositions for 163 nearby galaxies, by simultaneously fitting multiple images taken in five photometric filters. We show that we are able to recover structural measurements that agree well with various other works, and con…
This series of papers aims at understanding the formation and evolution of non-barred disc galaxies. We use the new spectro-photometric decomposition code, C2D, to separate the spectral information of bulges and discs of a statistically representative sample of galaxies from the CALIFA survey. Then, we study their stellar population properties analising the structure-independent datacubes with the Pipe3D algorithm. We find a correlation between the bulge-to-total ($B/T$) luminosity (and mass) ratio and galaxy stellar mass. The $B/T$ mass ratio has only a mild evolution with redshift, but the b…
Terzan 5 is a globular cluster-like stellar system in the Galactic Bulge which has been recently found to harbor two stellar populations with different iron content and probably different ages (Ferraro et al. 2009). This discovery suggests that Terzan 5 may be the relic of a primordial building block which contributed to the formation of the Galactic Bulge. Here we present a re-determination of the structural parameters (center of gravity, density and surface brightness profiles, total luminosity and mass) of Terzan 5, as obtained from the combination of high-resolution (ESO-MAD and HST ACS-WF…
We re-analyse photometric near-infrared data in order to investigate why it is so hard to get a consensus for the shape and density law of the bulge, as seen from the literature. To solve the problem we use the Besancon Galaxy Model to provide a scheme for parameter fitting of the structural characteristics of the bulge region. The fitting process allows the determination of the global shape of the bulge main structure. We explore various parameters and shape for the bulge/bar structure based on Ferrer's ellipsoids and fit the shape of the inner disc in the same process. The results show that …
We use the MaNGA integral-field spectroscopic survey of low-redshift galaxies to compare the stellar populations of the bulge and disc components, identified from their Sersic profiles, for various samples of galaxies. Bulge dominated regions tend to be more metal-rich and have slightly older stellar ages than their associated disc dominated regions. The metallicity difference is consistent with the deeper gravitational potential in bulges relative to discs, which allows bulges to retain more of the metals produced by stars. The age difference is due to star formation persisting longer in disc…
Galaxies are complex systems made up of different structural components such as bulges, discs, and bars. Understanding galaxy evolution requires unveiling, independently, their history of stellar mass and metallicity assembly. We introduce C2D, a new algorithm to perform spectro-photometric multi-component decompositions of integral field spectroscopy (IFS) datacubes. The galaxy surface-brightness distribution at each wavelength (quasi-monochromatic image) is fitted using GASP2D, a 2D photometric decomposition code. As a result, C2D provides both a characteristic one-dimensional spectra and a …
Morphology and structure of galaxies reflect their star formation and assembly histories. We use the framework of mutual information ($\mathrm{MI}$) to quantify interdependence among several structural variables and to rank them according to their relevance for predicting specific star formation rate (SSFR) by comparing the $\mathrm{MI}$ of the predictor variables with SSFR and penalizing variables that are redundant. We apply this framework to study $\sim 3,700$ face-on star-forming galaxies (SFGs) with varying degrees of bulge dominance and central concentration and with stellar mass $M_\sta…
Studying bright ($M_B<-20$), intermediate-redshift ($0.4<z<1.0$), disc dominated ($n_B<2.5$) galaxies from HST/ACS and WFC3 in Chandra Deep Field South, in rest-frame B and I-band, we found a new class of bulges which is brighter and more compact than ellipticals. We refer to them as "Bright, Compact Bulges" (BCBs) - they resemble neither classical nor pseudo-bulges and constitute $\sim12$% of the total bulge population at these redshifts. Examining free-bulge $+$ disc decomposition sample and elliptical galaxy sample from Simard et al. (2011), we find that only $\sim0.2$% of the bulges can be…
Many processes have been proposed to explain the quenching of star formation in spiral galaxies and their transformation into S0s. These processes affect the bulge and disc in different ways, and so by isolating the bulge and disc spectra, we can look for these characteristic signatures. In this work, we used BUDDI to cleanly extract the spectra of the bulges and discs of 78 S0 galaxies in the MaNGA Survey. We compared the luminosity and mass weighted stellar populations of the bulges and discs, finding that bulges are generally older and more metal rich than their discs. When considering the …
Combining the catalogue of galaxy morphologies in the COSMOS field and the sample of H$α$ emitters at redshifts $z=0.4$ and $z=0.84$ of the HiZELS survey, we selected $\sim$ 220 star-forming bulgeless systems (Sérsic index $n \leq 1.5$) at both epochs. We present their star formation properties and we investigate their contribution to the star formation rate function (SFRF) and global star formation rate density (SFRD) at $z < 1$. For comparison, we also analyse H$α$ emitters with more structurally evolved morphologies that we split into two classes according to their Sérsic index $n$: interme…
We present detailed morphological, photometric, and stellar-kinematic analyses of the central regions of two massive, early-type barred galaxies with nearly identical large-scale morphologies. Both have large, strong bars with prominent inner photometric excesses that we associate with boxy/peanut-shaped (B/P) bulges; the latter constitute ~ 30% of the galaxy light. Inside its B/P bulge, NGC 4608 has a compact, almost circular structure (half-light radius R_e approx. 310 pc, Sérsic n = 2.2) we identify as a classical bulge, amounting to 12.1% of the total light, along with a nuclear star clust…
We investigate the scaling relations between the supermassive black holes mass (M_bh) and the host bulge mass in elliptical galaxies, classical bulges, and pseudo-bulges. We use two-dimensional image analysis software BUDDA to obtain the structural parameters of 57 galaxies with dynamical M_bh measurement, and determine the bulge K-band luminosities (L_bul,K), stellar masses (M_s), and dynamical masses (M_d). The updated M_bh-L_bul,K, M_bh-M_s, and M_bh-M_d correlations for elliptical galaxies and classical bulges give M_bh~0.006M_s or 0.003M_d. The most tight relationship is log(M_bh/M_sun)=a…
Bulgeless Evolution And the Rise of Discs (BEARD) II. The role of mergers in shaping the Milky Way analogues in TNG50
Donostia International Physics Centre (DIPC)（多诺西亚国际物理中心）；Universidad de Córdoba（科尔多瓦大学）；Universidad de La Laguna（拉帕尔马大学）；Instituto de Astrofísica de Canarias（加那利群岛天体物理学研究所）
It is widely accepted that within the framework of LCDM a significant fraction of giant-disk galaxies has recently experienced a violent galactic merger. We present numerical simulations of such major mergers of gas-rich pure disk galaxies, and focus on the innermost stellar component (bulge) of the disk remnants. The simulations have high spatial and mass resolutions, and resolve regions deep enough to allow bulge classification according to standard kinematical and structural characteristics. In agreement with recent studies we find that these bulges are dominated by stars formed in the fina…
Investigating the Bulge Morphology of Dual AGN Host Galaxies from the GOTHIC survey
Indian Institute of Science Education and Research, Bhopal（印度科学教育研究所博帕尔分校）；Indian Institute of Astrophysics, Bangalore（班加罗尔天体物理研究所）；Observatoire de Paris, LERMA, College ‘ de France, PSL University, Sorbonne University, CNRS, Paris（巴黎天文台，LERMA，法兰西学院，PSL大学，索邦大学，法国国家科学研究中心，巴黎）；Siebel School of Computing and Data Science, University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校赛布尔计算与数据科学学院）；Birla Institute of Technology & Science, Goa（戈亚邦比尔拉理工科学与艺术学院）；HappyMonk AI
A randomly chosen star in today's Universe is most likely to live in a galaxy with a stellar mass between that of the Milky Way and Andromeda. Yet it remains uncertain how the structural evolution of these bulge-disk systems proceeded. Most of the unobscured star formation we observe building Andromdeda progenitors at 0.7<z<1.5 occurs in disks, but >90% of their star formation is reprocessed by dust and remains unaccounted for. Here we map 500micron dust continuum emission in an Andromeda progenitor at z=1.25 to probe where it is growing through dust-obscured star formation. Combining resolved…
We present results from 2MASS JKs photometry on the physical reality of recently reported globular cluster (GC) candidates in the Milky Way (MW) bulge. We relied our analysis on photometric membership probabilities that allowed us to distinguish real stellar aggregates from the composite field star population. When building colour-magnitude diagrams and stellar density maps for stars at different membership probability levels, the genuine GC candidate populations are clearly highlighted. We then used the tip of the red giant branch (RGB) as distance estimator, resulting heliocentric distances …
