Benedetta Vulcani - Academia.edu (original) (raw)
Papers by Benedetta Vulcani
Monthly Notices of the Royal Astronomical Society, 2014
On May 27th 2010, the Italian astronomical community learned with concern that the National Insti... more On May 27th 2010, the Italian astronomical community learned with concern that the National Institute for Astrophysics (INAF) was going to be suppressed, and that its employees were going to be transferred to the National Research Council (CNR). It was not clear if this applied to ...
Analyzing 24 mu m MIPS/Spitzer data and the [O II]3727 line of a sample of galaxies at 0.4 < z... more Analyzing 24 mu m MIPS/Spitzer data and the [O II]3727 line of a sample of galaxies at 0.4 < z < 0.8 from the ESO Distant Cluster Survey (EDisCS), we investigate the ongoing star formation rate (SFR) and the specific star formation rate (SSFR) as a function of stellar mass in galaxy clusters and groups, and compare with field studies.
Monthly Notices of the Royal Astronomical Society, 2015
Monthly Notices of the Royal Astronomical Society, 2015
ABSTRACT We present the Morphology-Density and Morphology-Radius relations (T-Sigma and T-R, resp... more ABSTRACT We present the Morphology-Density and Morphology-Radius relations (T-Sigma and T-R, respectively) obtained from the WINGS database of galaxies in nearby clusters. Aiming to achieve the best statistics, we exploit the whole sample of galaxies brighter than MV=-19.5 (5,504 objects), stacking up the 76 clusters of the WINGS survey altogether. Using this global cluster sample, we find that the T-Sigma relation holds only in the inner cluster regions (R<1/3xR200), while the T-R relation keeps almost unchanged over the whole range of local density. A couple of tests and two sets of numerical simulations support the robustness of these results against the effects of the limited cluster area coverage of the WINGS imaging. The above mentioned results hold for all cluster masses (X-ray luminosity and velocity dispersion) and all galaxy stellar masses (M). The strength of the T-Sigma relation (where present) increases with increasing M, while this effect is not found for the T-R relation. Noticeably, the absence/presence of subclustering determines the presence/absence of the T-Sigma relation outside the inner cluster regions, leading us to the general conclusion that the link between morphology and local density is preserved just in dynamically evolved regions. We hypothesize that some mechanism of morphological broadening/redistribution operates in the intermediate/outer regions of substructured (non relaxed) clusters, producing a strong weakening of the T-Sigma relation.
The Astrophysical Journal, 2014
ABSTRACT Central Galaxies (CGs) in massive halos live in unique environments with formation histo... more ABSTRACT Central Galaxies (CGs) in massive halos live in unique environments with formation histories closely linked to that of the host halo. In local clusters they have larger sizes ($R_e$) and lower velocity dispersions (sigma) at fixed stellar mass M_star, and much larger R_e at a fixed sigma\sigmasigma than field and satellite galaxies (non-CGs). Using spectroscopic observations of group galaxies selected from the COSMOS survey, we compare the dynamical scaling relations of early-type CGs and non-CGs at z~0.6, to distinguish possible mechanisms that produce the required evolution. CGs are systematically offset towards larger R_e at fixed sigma\sigmasigma compared to non-CGs with similar M_star. The CG R_e-M_star relation also shows differences, primarily driven by a sub-population (~15%) of galaxies with large ReR_eRe, while the M_star-sigma relations are indistinguishable. These results are accentuated when double Sersic profiles, which better fit light in the outer regions of galaxies, are adopted. They suggest that even group-scale CGs can develop extended components by these redshifts that can increase total ReR_eRe and M_star estimates by factors of ~2. To probe the evolutionary link between our sample and cluster CGs, we also analyze two cluster samples at z~0.6 and z~0. We find similar results for the more massive halos at comparable z, but much more distinct CG scaling relations at low-z. Thus, the rapid, late-time accretion of outer components, perhaps via the stripping and accretion of satellites, would appear to be a key feature that distinguishes the evolutionary history of CGs.
The Astrophysical Journal, 2014
ABSTRACT Exploiting a mass complete (M_*>10^(10.25)M_sun) sample at 0.03<z<0... more ABSTRACT Exploiting a mass complete (M_*>10^(10.25)M_sun) sample at 0.03<z<0.11 drawn from the Padova Millennium Galaxy Group Catalog (PM2GC), we use the (U-B)_rf color and morphologies to characterize galaxies, in particular those that show signs of an ongoing or recent transformation of their star formation activity and/or morphology - green galaxies, red passive late types, and blue star-forming early types. Color fractions depend on mass and only for M_*<10^(10.7)M_sun on environment. The incidence of red galaxies increases with increasing mass, and, for M_*<10^(10.7)M_sun, decreases toward the group outskirts and in binary and single galaxies. The relative abundance of green and blue galaxies is independent of environment, and increases monotonically with galaxy mass. We also inspect galaxy structural parameters, star-formation properties, histories and ages and propose an evolutionary scenario for the different subpopulations. Color transformations are due to a reduction and suppression of SFR in both bulges and disks which does not noticeably affect galaxy structure. Morphological transitions are linked to an enhanced bulge-to-disk ratio due to the removal of the disk, not to an increase of the bulge. Our modeling suggests that green colors might be due to star formation histories declining with long timescales, as an alternative scenario to the classical "quenching" processes. Our results suggest that galaxy transformations in star formation activity and morphology depend neither on environment nor on being a satellite or the most massive galaxy of a halo. The only environmental dependence we find is the higher fast quenching efficiency in groups giving origin to post-starburst signatures.
Monthly Notices of the Royal Astronomical Society: Letters, 2012
We investigate the relationship between colour and structure within galaxies using a large, volum... more We investigate the relationship between colour and structure within galaxies using a large, volume-limited sample of bright, low-redshift galaxies with optical-near-infrared imaging from the Galaxy And Mass Assembly survey. We fit single-component, wavelength-dependent, elliptical Sérsic models to all passbands simultaneously, using software developed by the MegaMorph project. Dividing our sample by n and colour, the recovered wavelength variations in effective radius (Re) and Sérsic index (n) reveal the internal structure, and hence formation history, of different types of galaxies. All these trends depend on n; some have an additional dependence on galaxy colour. Late-type galaxies (nr < 2.5) show a dramatic increase in Sérsic index with wavelength. This might be a result of their two-component (bulge-disc) nature, though stellar population gradients within each component and dust attenuation are likely to play a role. All galaxies show a substantial decrease in Re with wavelength. This is strongest for early types (nr > 2.5), even though they maintain constant n with wavelength, revealing that ellipticals are a superimposition of different stellar populations associated with multiple collapse and merging events. Processes leading to structures with larger Re must be associated with lower metallicity or younger stellar populations. This appears to rule out the formation of young cores through dissipative gas accretion as an important mechanism in the recent lives of luminous elliptical galaxies.
Monthly Notices of the Royal Astronomical Society, 2011
... templates. 3.1 Low-z: WINGS For WINGS spectroscopically confirmed cluster galaxies, the total... more ... templates. 3.1 Low-z: WINGS For WINGS spectroscopically confirmed cluster galaxies, the total luminosity LB has been derived from the total (SEXTRACTOR AUTO) observed B magnitude (Varela et al. 2009), corrected for distance ...
Monthly Notices of the Royal Astronomical Society, 2011
Monthly Notices of the Royal Astronomical Society, 2012
Monthly Notices of the Royal Astronomical Society, 2011
The Astrophysical Journal, 2010
We find a significant number of massive and compact galaxies in clusters from the ESO Distant Clu... more We find a significant number of massive and compact galaxies in clusters from the ESO Distant Clusters Survey (EDisCS) at 0.4 < z < 1. They have similar stellar masses, ages, sizes, and axial ratios to local z ~ 0.04 compact galaxies in WIde field Nearby Galaxy clusters Survey (WINGS) clusters, and to z = 1.4-2 massive and passive galaxies found in the general field. If non-brightest cluster galaxies of all densities, morphologies, and spectral types are considered, the median size of EDisCS galaxies is only a factor 1.18 smaller than in WINGS. We show that for morphologically selected samples, the morphological evolution taking place in a significant fraction of galaxies during the last Gyr may introduce an apparent, spurious evolution of size with redshift, which is actually due to intrinsic differences in the selected samples. We conclude that the median mass-size relation of cluster galaxies does not evolve significantly from z ~ 0.7 to z ~ 0.04. In contrast, the masses and sizes of BCGs and galaxies with M *>4 × 1011 M sun have significantly increased by a factor of 2 and 4, respectively, confirming the results of a number of recent works on the subject. Our findings show that progenitor bias effects play an important role in the size-growth paradigm of massive and passive galaxies.
The Astrophysical Journal, 2014
ABSTRACT
The Astrophysical Journal, 2011
... 2. OUR GALAXY SAMPLE SELECTION The present work is based on the data of the Wide-field Nearby... more ... 2. OUR GALAXY SAMPLE SELECTION The present work is based on the data of the Wide-field Nearby Galaxy-clusters Survey (WINGS; see, eg, Fasano et al. 2006; Varela et al. 2009; Cava et al. 2009; Valentinuzzi et al. 2009; D&amp;amp;amp;#x27;Onofrio et al. 2008). ...
The Astrophysical Journal, 2010
Astronomy & Astrophysics, 2013
Astronomy & Astrophysics, 2011
Monthly Notices of the Royal Astronomical Society, 2014
On May 27th 2010, the Italian astronomical community learned with concern that the National Insti... more On May 27th 2010, the Italian astronomical community learned with concern that the National Institute for Astrophysics (INAF) was going to be suppressed, and that its employees were going to be transferred to the National Research Council (CNR). It was not clear if this applied to ...
Analyzing 24 mu m MIPS/Spitzer data and the [O II]3727 line of a sample of galaxies at 0.4 < z... more Analyzing 24 mu m MIPS/Spitzer data and the [O II]3727 line of a sample of galaxies at 0.4 < z < 0.8 from the ESO Distant Cluster Survey (EDisCS), we investigate the ongoing star formation rate (SFR) and the specific star formation rate (SSFR) as a function of stellar mass in galaxy clusters and groups, and compare with field studies.
Monthly Notices of the Royal Astronomical Society, 2015
Monthly Notices of the Royal Astronomical Society, 2015
ABSTRACT We present the Morphology-Density and Morphology-Radius relations (T-Sigma and T-R, resp... more ABSTRACT We present the Morphology-Density and Morphology-Radius relations (T-Sigma and T-R, respectively) obtained from the WINGS database of galaxies in nearby clusters. Aiming to achieve the best statistics, we exploit the whole sample of galaxies brighter than MV=-19.5 (5,504 objects), stacking up the 76 clusters of the WINGS survey altogether. Using this global cluster sample, we find that the T-Sigma relation holds only in the inner cluster regions (R<1/3xR200), while the T-R relation keeps almost unchanged over the whole range of local density. A couple of tests and two sets of numerical simulations support the robustness of these results against the effects of the limited cluster area coverage of the WINGS imaging. The above mentioned results hold for all cluster masses (X-ray luminosity and velocity dispersion) and all galaxy stellar masses (M). The strength of the T-Sigma relation (where present) increases with increasing M, while this effect is not found for the T-R relation. Noticeably, the absence/presence of subclustering determines the presence/absence of the T-Sigma relation outside the inner cluster regions, leading us to the general conclusion that the link between morphology and local density is preserved just in dynamically evolved regions. We hypothesize that some mechanism of morphological broadening/redistribution operates in the intermediate/outer regions of substructured (non relaxed) clusters, producing a strong weakening of the T-Sigma relation.
The Astrophysical Journal, 2014
ABSTRACT Central Galaxies (CGs) in massive halos live in unique environments with formation histo... more ABSTRACT Central Galaxies (CGs) in massive halos live in unique environments with formation histories closely linked to that of the host halo. In local clusters they have larger sizes ($R_e$) and lower velocity dispersions (sigma) at fixed stellar mass M_star, and much larger R_e at a fixed sigma\sigmasigma than field and satellite galaxies (non-CGs). Using spectroscopic observations of group galaxies selected from the COSMOS survey, we compare the dynamical scaling relations of early-type CGs and non-CGs at z~0.6, to distinguish possible mechanisms that produce the required evolution. CGs are systematically offset towards larger R_e at fixed sigma\sigmasigma compared to non-CGs with similar M_star. The CG R_e-M_star relation also shows differences, primarily driven by a sub-population (~15%) of galaxies with large ReR_eRe, while the M_star-sigma relations are indistinguishable. These results are accentuated when double Sersic profiles, which better fit light in the outer regions of galaxies, are adopted. They suggest that even group-scale CGs can develop extended components by these redshifts that can increase total ReR_eRe and M_star estimates by factors of ~2. To probe the evolutionary link between our sample and cluster CGs, we also analyze two cluster samples at z~0.6 and z~0. We find similar results for the more massive halos at comparable z, but much more distinct CG scaling relations at low-z. Thus, the rapid, late-time accretion of outer components, perhaps via the stripping and accretion of satellites, would appear to be a key feature that distinguishes the evolutionary history of CGs.
The Astrophysical Journal, 2014
ABSTRACT Exploiting a mass complete (M_*>10^(10.25)M_sun) sample at 0.03<z<0... more ABSTRACT Exploiting a mass complete (M_*>10^(10.25)M_sun) sample at 0.03<z<0.11 drawn from the Padova Millennium Galaxy Group Catalog (PM2GC), we use the (U-B)_rf color and morphologies to characterize galaxies, in particular those that show signs of an ongoing or recent transformation of their star formation activity and/or morphology - green galaxies, red passive late types, and blue star-forming early types. Color fractions depend on mass and only for M_*<10^(10.7)M_sun on environment. The incidence of red galaxies increases with increasing mass, and, for M_*<10^(10.7)M_sun, decreases toward the group outskirts and in binary and single galaxies. The relative abundance of green and blue galaxies is independent of environment, and increases monotonically with galaxy mass. We also inspect galaxy structural parameters, star-formation properties, histories and ages and propose an evolutionary scenario for the different subpopulations. Color transformations are due to a reduction and suppression of SFR in both bulges and disks which does not noticeably affect galaxy structure. Morphological transitions are linked to an enhanced bulge-to-disk ratio due to the removal of the disk, not to an increase of the bulge. Our modeling suggests that green colors might be due to star formation histories declining with long timescales, as an alternative scenario to the classical "quenching" processes. Our results suggest that galaxy transformations in star formation activity and morphology depend neither on environment nor on being a satellite or the most massive galaxy of a halo. The only environmental dependence we find is the higher fast quenching efficiency in groups giving origin to post-starburst signatures.
Monthly Notices of the Royal Astronomical Society: Letters, 2012
We investigate the relationship between colour and structure within galaxies using a large, volum... more We investigate the relationship between colour and structure within galaxies using a large, volume-limited sample of bright, low-redshift galaxies with optical-near-infrared imaging from the Galaxy And Mass Assembly survey. We fit single-component, wavelength-dependent, elliptical Sérsic models to all passbands simultaneously, using software developed by the MegaMorph project. Dividing our sample by n and colour, the recovered wavelength variations in effective radius (Re) and Sérsic index (n) reveal the internal structure, and hence formation history, of different types of galaxies. All these trends depend on n; some have an additional dependence on galaxy colour. Late-type galaxies (nr < 2.5) show a dramatic increase in Sérsic index with wavelength. This might be a result of their two-component (bulge-disc) nature, though stellar population gradients within each component and dust attenuation are likely to play a role. All galaxies show a substantial decrease in Re with wavelength. This is strongest for early types (nr > 2.5), even though they maintain constant n with wavelength, revealing that ellipticals are a superimposition of different stellar populations associated with multiple collapse and merging events. Processes leading to structures with larger Re must be associated with lower metallicity or younger stellar populations. This appears to rule out the formation of young cores through dissipative gas accretion as an important mechanism in the recent lives of luminous elliptical galaxies.
Monthly Notices of the Royal Astronomical Society, 2011
... templates. 3.1 Low-z: WINGS For WINGS spectroscopically confirmed cluster galaxies, the total... more ... templates. 3.1 Low-z: WINGS For WINGS spectroscopically confirmed cluster galaxies, the total luminosity LB has been derived from the total (SEXTRACTOR AUTO) observed B magnitude (Varela et al. 2009), corrected for distance ...
Monthly Notices of the Royal Astronomical Society, 2011
Monthly Notices of the Royal Astronomical Society, 2012
Monthly Notices of the Royal Astronomical Society, 2011
The Astrophysical Journal, 2010
We find a significant number of massive and compact galaxies in clusters from the ESO Distant Clu... more We find a significant number of massive and compact galaxies in clusters from the ESO Distant Clusters Survey (EDisCS) at 0.4 < z < 1. They have similar stellar masses, ages, sizes, and axial ratios to local z ~ 0.04 compact galaxies in WIde field Nearby Galaxy clusters Survey (WINGS) clusters, and to z = 1.4-2 massive and passive galaxies found in the general field. If non-brightest cluster galaxies of all densities, morphologies, and spectral types are considered, the median size of EDisCS galaxies is only a factor 1.18 smaller than in WINGS. We show that for morphologically selected samples, the morphological evolution taking place in a significant fraction of galaxies during the last Gyr may introduce an apparent, spurious evolution of size with redshift, which is actually due to intrinsic differences in the selected samples. We conclude that the median mass-size relation of cluster galaxies does not evolve significantly from z ~ 0.7 to z ~ 0.04. In contrast, the masses and sizes of BCGs and galaxies with M *>4 × 1011 M sun have significantly increased by a factor of 2 and 4, respectively, confirming the results of a number of recent works on the subject. Our findings show that progenitor bias effects play an important role in the size-growth paradigm of massive and passive galaxies.
The Astrophysical Journal, 2014
ABSTRACT
The Astrophysical Journal, 2011
... 2. OUR GALAXY SAMPLE SELECTION The present work is based on the data of the Wide-field Nearby... more ... 2. OUR GALAXY SAMPLE SELECTION The present work is based on the data of the Wide-field Nearby Galaxy-clusters Survey (WINGS; see, eg, Fasano et al. 2006; Varela et al. 2009; Cava et al. 2009; Valentinuzzi et al. 2009; D&amp;amp;amp;#x27;Onofrio et al. 2008). ...
The Astrophysical Journal, 2010
Astronomy & Astrophysics, 2013
Astronomy & Astrophysics, 2011