arXiv subjects

F. Ferrari

Publications and source records attributed to F. Ferrari.

At least 19 recordsLinked to original sources

arXiv2026

Operation and performance of the Probe for Luminosity Measurement at LHCb

The Probe for LUminosity MEasurement (PLUME) detector is a dedicated luminosity monitor at the LHCb interaction point. It is a hodoscope comprising 48 Hamamatsu R760 photomultiplier tubes that detect Cherenkov light produced by particles travelling in the direction opposite to the LHCb spectrometer acceptance. PLUME provides real-time, bunch-by-bunch luminosity measurements during LHCb data taking and serves as the primary detector for controlling the luminosity levelling process at LHCb. In addition, its data are used offline, together with other dedicated counters from LHCb sub-systems, to determine the integrated luminosity delivered to the experiment. This paper reports on the detector's operational performance during the 2024-2026 data-taking period of Run 3. The integrated luminosity recorded by the LHCb experiment in $pp$ collisions at $\sqrt{s} = 13.6$ TeV during this period, as measured by the PLUME online luminosity counters for detector performance monitoring, amounts to $\mathcal{L} = (26.71 \pm 1.07)$ fb$^{-1}$. The luminosity values used in physics analyses are determined separately through dedicated offline calibrations based on van der Meer scans and Beam Gas Imaging techniques, and will be reported in a dedicated publication, as they are beyond the scope of this paper.

hep-ex↗

arXiv2026

Small and Complex II: Characterizing the Disk and Stellar Envelope of Edge-on $z \sim 0$ Massive Compact Galaxies

We present multi-component photometric decompositions of $r$-band Hyper Suprime-Cam images for a sample of 75 edge-on massive compact galaxies (MCGs) at $z < 0.1$, selected as $+2\sigma$ outliers in the stellar mass-velocity dispersion relation and $-2\sigma$ outliers in the velocity dispersion-size relation. MCGs are composed of compact bulges and disks embedded within stellar envelopes of unclear physical nature. Comparing MCGs to a mass- and redshift-matched control sample of non-compact edge-on S0 galaxies with a similar three-component structure, we find that the smaller sizes of MCGs are not driven by a single component. MCGs host more compact bulges and envelopes ($R_\mathrm{e,bulge} \sim 0.3$ versus $0.5$kpc; $R_\mathrm{e,env} \sim 4.4$ versus $5.7$kpc), as well as shorter and thicker disks ($h_R \sim 1.1$ versus $1.7$kpc; $h_R/z_0 \sim 3.9$ versus $5.3$). The sizes of the structural components are coupled, suggesting their formation processes are linked. Median bulge- and disk-to-total flux fractions are similar in both samples, with $B/T \sim 0.3$ and $D/T \sim 0.4$. Envelope ellipticities span $\epsilon_\mathrm{env} \sim 0$-$0.7$, with MCGs exhibiting rounder envelopes. Low- and high-ellipticity envelopes are broadly consistent with stellar halos and thick disks, respectively. However, the nature of intermediate ellipticity envelopes remains ambiguous from photometry alone. The coupling between component sizes, together with the survival of a substantial disk component, argues against dry minor mergers as the dominant envelope-building mechanism. A comparison with 8 relic galaxies reveals that MCGs and relics share similar bulge-disk-envelope structures and follow the same component size-mass relations, consistent with belonging to a common structural family.

astro-ph.GA↗

arXiv2026

Small and Complex I: The Three Component Structure of $z \sim 0$ Massive Compact Quiescent Galaxies

We investigate the morphology and structural properties of 246 massive compact quiescent galaxies (MCGs; $\log M_{\star} \sim 10$-$11$, $\sigma_{\mathrm{e}} \sim 150$-$350\,$km\,s$^{-1}$, $R_{\mathrm{e}} \sim 0.7$-$2.5\,$kpc) at $z \sim 0$, selected as outliers in the stellar mass-velocity dispersion and velocity dispersion-size relations, using $g$-, $r$-, and $i$-band Hyper Suprime-Cam images. We compare them to a control sample of average-sized quiescent galaxies (CSGs) matched in stellar mass, star formation rate, redshift, and $g-i$ color. Both samples are dominated by S0 galaxies, comprising $93\%$ of MCGs and $71\%$ of CSGs, while ellipticals account for $4\%$ and $11\%$, respectively. The fraction of interacting or morphologically disturbed systems is low in both samples ($13\%$ for MCGs and $16\%$ for CSGs). Multi-component decompositions of the $g$- and $r$-band images show that $75\%$ of MCGs require a three-component model (bulge, disk, and envelope), while $21\%$ are best fit by two components and $4\%$ by a single S\'ersic profile. Two-component MCGs are preferentially low-inclination systems, suggesting that the three-component fraction represents a lower limit. In contrast, only $7\%$ of CSGs exhibit a comparable three-component structure. Bars are present in $29\%$ of CSGs but are absent in MCGs. For three-component systems, MCGs and CSGs have similar bulge ($R_\mathrm{e}=0.39$ vs.\ $0.45$\,kpc) and envelope ($R_\mathrm{e}=6.4$ vs.\ $5.8$\,kpc) sizes, while MCG disks are significantly more compact ($R_\mathrm{e}=1.9$ vs.\ $3.3$\,kpc). The envelope component shows a broad ellipticity distribution ($\epsilon_\mathrm{Envelope} \sim 0.0$-$0.6$), which we interpret as corresponding to either a stellar halo or a thick disk.

astro-ph.GA↗

arXiv2026

Performance characterisation of the Hamamatsu R760 photomultiplier tube for the PLUME detector

The Probe for Luminosity Measurement detector is a novel luminometer designed to monitor the luminosity and beam conditions of the Large Hadron Collider at the interaction point of the LHCb experiment, starting from Run 3. The detector is based on a hodoscope composed of 48 Hamamatsu R760 photomultiplier tubes, which detect the Cherenkov light produced by charged particles originating from the interaction region. The accurate and stable operation of these sensors is essential to ensure reliable luminosity measurements throughout the full data-taking period. This paper presents a detailed characterisation of the photomultiplier tubes currently installed in the detector. In particular, their absolute gain, transit-time drift, linearity, dark current, and ageing behaviour are systematically studied under controlled laboratory conditions. The results provide a comprehensive assessment of the performance of the detection modules and establish the optimal operating conditions required to ensure stable and precise measurements throughout Run 3 and Run 4.

physics.ins-det↗

arXiv2026

Galaxy interactions in void substructures: Morphology and stellar populations of two triplets from CAVITY

Context. Cosmic voids are underdense regions of the Universe that provide a unique environment to study galaxy evolution in relative isolation. Galaxy triplets in voids are rare systems where local interactions may strongly influence galaxy properties. Aims. We study the stellar populations, morphologies, mass assembly histories, and dynamical properties of six galaxies belonging to two void triplets from the Calar Alto Void Integral-field Treasury surveY (CAVITY): CAVITY5273X and VGS31. Methods. We used integral-field unit spectroscopy and performed full spectral fitting with the FADO code, which models stellar and nebular emission simultaneously. Spatially resolved maps of stellar age, metallicity, and star formation rate were reconstructed using the integrated nested Laplace approximation. Morphological properties were derived using morfometryka, emission-line diagnostics were applied, and mass assembly functions were computed. Stellar masses and metallicities were compared to the mass-metallicity relation for void galaxies. Results. The two triplets show different evolutionary behaviours. CAVITY52731 is a massive quenched galaxy hosting an active galactic nucleus, while its companions and all galaxies in VGS31 are dominated by young stellar populations and recent star formation. Five galaxies experienced rapid stellar mass growth in the last 2 Gyr. Disturbed morphologies, including asymmetries and tidal features, indicate ongoing interactions. Galaxies in CAVITY5273X follow the expected void mass-metallicity relation, while VGS31 members show significant deviations. Conclusions. Our results show that local interactions can drive significant galaxy evolution even in the most underdense cosmic environments.

astro-ph.GA↗

arXiv2024

Physical properties of asteroid Dimorphos as derived from the DART impact

On September 26, 2022, NASA's Double Asteroid Redirection Test (DART) mission successfully impacted Dimorphos, the natural satellite of the binary near-Earth asteroid (65803) Didymos. Numerical simulations of the impact provide a means to explore target surface material properties and structures, consistent with the observed momentum deflection efficiency, ejecta cone geometry, and ejected mass. Our simulation, which best matches observations, indicates that Dimorphos is weak, with a cohesive strength of less than a few pascals (Pa), similar to asteroids (162173) Ryugu and (101955) Bennu. We find that a bulk density of Dimorphos, rhoB, lower than 2400 kg/m3, and a low volume fraction of boulders (<40 vol%) on the surface and in the shallow subsurface, are consistent with measured data from the DART experiment. These findings suggest Dimorphos is a rubble pile that might have formed through rotational mass shedding and re-accumulation from Didymos. Our simulations indicate that the DART impact caused global deformation and resurfacing of Dimorphos. ESA's upcoming Hera mission may find a re-shaped asteroid, rather than a well-defined crater.

astro-ph.EP↗

arXiv2022

Euclid preparation. XXV. The Euclid Morphology Challenge -- Towards model-fitting photometry for billions of galaxies

The ESA Euclid mission will provide high-quality imaging for about 1.5 billion galaxies. A software pipeline to automatically process and analyse such a huge amount of data in real time is being developed by the Science Ground Segment of the Euclid Consortium; this pipeline will include a model-fitting algorithm, which will provide photometric and morphological estimates of paramount importance for the core science goals of the mission and for legacy science. The Euclid Morphology Challenge is a comparative investigation of the performance of five model-fitting software packages on simulated Euclid data, aimed at providing the baseline to identify the best suited algorithm to be implemented in the pipeline. In this paper we describe the simulated data set, and we discuss the photometry results. A companion paper (Euclid Collaboration: Bretonni\`ere et al. 2022) is focused on the structural and morphological estimates. We created mock Euclid images simulating five fields of view of 0.48 deg2 each in the $I_E$ band of the VIS instrument, each with three realisations of galaxy profiles (single and double S\'ersic, and 'realistic' profiles obtained with a neural network); for one of the fields in the double S\'ersic realisation, we also simulated images for the three near-infrared $Y_E$, $J_E$ and $H_E$ bands of the NISP-P instrument, and five Rubin/LSST optical complementary bands ($u$, $g$, $r$, $i$, and $z$). To analyse the results we created diagnostic plots and defined ad-hoc metrics. Five model-fitting software packages (DeepLeGATo, Galapagos-2, Morfometryka, ProFit, and SourceXtractor++) were compared, all typically providing good results. (cut)

astro-ph.GA↗

arXiv2022

Euclid preparation XXVI. The Euclid Morphology Challenge. Towards structural parameters for billions of galaxies

The various Euclid imaging surveys will become a reference for studies of galaxy morphology by delivering imaging over an unprecedented area of 15 000 square degrees with high spatial resolution. In order to understand the capabilities of measuring morphologies from Euclid-detected galaxies and to help implement measurements in the pipeline, we have conducted the Euclid Morphology Challenge, which we present in two papers. While the companion paper by Merlin et al. focuses on the analysis of photometry, this paper assesses the accuracy of the parametric galaxy morphology measurements in imaging predicted from within the Euclid Wide Survey. We evaluate the performance of five state-of-the-art surface-brightness-fitting codes DeepLeGATo, Galapagos-2, Morfometryka, Profit and SourceXtractor++ on a sample of about 1.5 million simulated galaxies resembling reduced observations with the Euclid VIS and NIR instruments. The simulations include analytic S\'ersic profiles with one and two components, as well as more realistic galaxies generated with neural networks. We find that, despite some code-specific differences, all methods tend to achieve reliable structural measurements (10% scatter on ideal S\'ersic simulations) down to an apparent magnitude of about 23 in one component and 21 in two components, which correspond to a signal-to-noise ratio of approximately 1 and 5 respectively. We also show that when tested on non-analytic profiles, the results are typically degraded by a factor of 3, driven by systematics. We conclude that the Euclid official Data Releases will deliver robust structural parameters for at least 400 million galaxies in the Euclid Wide Survey by the end of the mission. We find that a key factor for explaining the different behaviour of the codes at the faint end is the set of adopted priors for the various structural parameters.

astro-ph.GA↗

arXiv2021

Some evaluations of the fractional $p$-Laplace operator on radial functions

We face a rigidity problem for the fractional $p$-Laplace operator to extend to this new framework some tools useful for the linear case. It is known that $(-\Delta)^s(1-|x|^{2})^s_+$ and $-\Delta_p(1-|x|^{\frac{p}{p-1}})$ are constant functions in $(-1,1)$ for fixed $p$ and $s$. We evaluated $(-\Delta_p)^s(1-|x|^{\frac{p}{p-1}})^s_+$ proving that it is not constant in $(-1,1)$ for some $p\in (1,+\infty)$ and $s\in (0,1)$. This conclusion is obtained numerically thanks to the use of very accurate Gaussian numerical quadrature formulas.

math.AP↗

arXiv2021

Deep Learning Assessment of galaxy morphology in S-PLUS DataRelease 1

The morphological diversity of galaxies is a relevant probe of galaxy evolution and cosmological structure formation, but the classification of galaxies in large sky surveys is becoming a significant challenge. We use data from the Stripe-82 area observed by the Southern Photometric Local Universe Survey (S-PLUS) in twelve optical bands, and present a catalogue of the morphologies of galaxies brighter than $r=17$ mag determined both using a novel multi-band morphometric fitting technique and Convolutional Neural Networks (CNNs) for computer vision. Using the CNNs we find that, compared to our baseline results with 3 bands, the performance increases when using 5 broad and 3 narrow bands, but is poorer when using the full $12$ band S-PLUS image set. However, the best result is still achieved with just 3 optical bands when using pre-trained network weights from an ImageNet data set. These results demonstrate the importance of using prior knowledge about neural network weights based on training in unrelated, extensive data sets, when available. Our catalogue contains 3274 galaxies in Stripe-82 that are not present in Galaxy Zoo 1 (GZ1), and we also provide our classifications for 4686 galaxies that were considered ambiguous in GZ1. Finally, we present a prospect of a novel way to take advantage of $12$ band information for morphological classification using morphometric features, and we release a model that has been pre-trained on several bands that could be adapted for classifications using data from other surveys. The morphological catalogues are publicly available.

astro-ph.GA↗

arXiv2021

S-PLUS: LEnticular Galaxies in Stripe 82

This work is a Brazilian-Indian collaboration. It aims at investigating the structuralproperties of Lenticular galaxies in the Stripe 82 using a combination of S-PLUS (Southern Photometric Local Universe Survey) and SDSS data. S-PLUS is a noveloptical multi-wavelength survey which will cover nearly 8000 square degrees of the Southern hemisphere in the next years and the first data release covers the Stripe 82 area. The morphological classification and study of the galaxies' stellar population will be performed combining the Bayesian Spectral type (from BPZ) and Morfometryka (MFMTK) parameters. BPZ and MFMTK are two complementary techniques, since the first one determines the most likely stellar population of a galaxy, in order to obtain its photometric redshift (phot-z), and the second one recovers non-parametric morphological quantities, such as asymmetries and concentration. The combination ofthe two methods allows us to explore the correlation between galaxies shapes (smooth, with spiral arms, etc.) and their stellar contents (old or young population). The preliminary results, presented in this work, show how this new data set opens a new window on our understanding of the nearby universe.

astro-ph.GA↗

arXiv2020

Quantifying Non-parametric Structure of High-redshift Galaxies with Deep Learning

At high redshift, due to both observational limitations and the variety of galaxy morphologies in the early universe, measuring galaxy structure can be challenging. Non-parametric measurements such as the CAS system have thus become an important tool due to both their model-independent nature and their utility as a straightforward computational process. Recently, convolutional neural networks (CNNs) have been shown to be adept at image analysis, and are beginning to supersede traditional measurements of visual morphology and model-based structural parameters. In this work, we take a further step by extending CNNs to measure well known non-parametric structural quantities: concentration ($C$) and asymmetry ($A$). We train CNNs to predict $C$ and $A$ from individual images of $\sim 150,000$ galaxies at $0 < z < 7$ in the CANDELS fields, using Bayesian hyperparameter optimisation to select suitable network architectures. Our resulting networks accurately reproduce measurements compared with standard algorithms. Furthermore, using simulated images, we show that our networks are more stable than the standard algorithms at low signal-to-noise. While both approaches suffer from similar systematic biases with redshift, these remain small out to $z \sim 7$. Once trained, measurements with our networks are $> 10^3$ times faster than previous methods. Our approach is thus able to reproduce standard measures of non-parametric morphologies and shows the potential of employing neural networks to provide superior results in substantially less time. This will be vital for making best use of the large and complex datasets provided by upcoming galaxy surveys, such as Euclid and Rubin-LSST.

astro-ph.GA↗

arXiv2020

The properties and environment of very young galaxies in the local Universe

In the local Universe, there is a handful of dwarf compact star-forming galaxies with extremely low oxygen abundances. It has been proposed that they are young, having formed a large fraction of their stellar mass during their last few hundred Myr. However, little is known about the fraction of young stellar populations in more massive galaxies. In a previous article, we analyzed 280 000 SDSS spectra to identify a surprisingly large sample of more massive Very Young Galaxies (VYGs), defined to have formed at least $50\%$ of their stellar mass within the last 1 Gyr. Here, we investigate in detail the properties of a subsample of 207 galaxies that are VYGs according to all three of our spectral models. We compare their properties with those of control sample galaxies (CSGs). We find that VYGs tend to have higher surface brightness and to be more compact, dusty, asymmetric, and clumpy than CSGs. Analysis of a subsample with HI detections reveals that VYGs are more gas-rich than CSGs. VYGs tend to reside more in the inner parts of low-mass groups and are twice as likely to be interacting with a neighbour galaxy than CSGs. On the other hand, VYGs and CSGs have similar gas metallicities and large scale environments (relative to filaments and voids). These results suggest that gas-rich interactions and mergers are the main mechanisms responsible for the recent triggering of star formation in low-redshift VYGs, except for the lowest mass VYGs, where the starbursts may arise from a mixture of mergers and gas infall.

astro-ph.GA↗

arXiv2020

The miniJPAS survey: a preview of the Universe in 56 colours

The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) will soon start to scan thousands of square degrees of the northern extragalactic sky with a unique set of $56$ optical filters from a dedicated $2.55$m telescope, JST, at the Javalambre Astrophysical Observatory. Before the arrival of the final instrument (a 1.2 Gpixels, 4.2deg$^2$ field-of-view camera), the JST was equipped with an interim camera (JPAS-Pathfinder), composed of one CCD with a 0.3deg$^2$ field-of-view and resolution of 0.23 arcsec pixel$^{-1}$. To demonstrate the scientific potential of J-PAS, with the JPAS-Pathfinder camera we carried out a survey on the AEGIS field (along the Extended Groth Strip), dubbed miniJPAS. We observed a total of $\sim 1$ deg$^2$, with the $56$ J-PAS filters, which include $54$ narrow band (NB, $\rm{FWHM} \sim 145$Angstrom) and two broader filters extending to the UV and the near-infrared, complemented by the $u,g,r,i$ SDSS broad band (BB) filters. In this paper we present the miniJPAS data set, the details of the catalogues and data access, and illustrate the scientific potential of our multi-band data. The data surpass the target depths originally planned for J-PAS, reaching $\rm{mag}_{\rm {AB}}$ between $\sim 22$ and $23.5$ for the NB filters and up to $24$ for the BB filters ($5\sigma$ in a $3$~arcsec aperture). The miniJPAS primary catalogue contains more than $64,000$ sources extracted in the $r$ detection band with forced photometry in all other bands. We estimate the catalogue to be complete up to $r=23.6$ for point-like sources and up to $r=22.7$ for extended sources. Photometric redshifts reach subpercent precision for all sources up to $r=22.5$, and a precision of $\sim 0.3$% for about half of the sample. (Abridged)

astro-ph.CO↗

arXiv2019

A parallel-GPU code for asteroid aggregation problems with angular particles

The paper presents a numerical implementation of the gravitational N-body problem with contact interactions between non-spherically shaped bodies. The work builds up on a previous implementation of the code and extends its capabilities. The number of bodies handled is significantly increased through the use of a CUDA/GPU-parallel octree structure. The implementation of the code is discussed and its performance are compared against direct N$^2$ integration. The code features both smooth (force-based) and non-smooth (impulse-based) methods, as well as a visco-elastic non-smooth method, to handle contact interaction between bodies. The numerical problem of simulating "rubble-pile" asteroid gravitational aggregation processes is addressed. We discuss the features of the problem and derive criteria to set up the numerical simulation from the dynamical constraints of the combined gravitational-collisional problem. Examples of asteroid aggregation scenarios that could benefit from such implementation are finally presented.

astro-ph.EP↗

arXiv2019

The Southern Photometric Local Universe Survey (S-PLUS): improved SEDs, morphologies and redshifts with 12 optical filters

The Southern Photometric Local Universe Survey (S-PLUS) is imaging ~9300 deg^2 of the celestial sphere in twelve optical bands using a dedicated 0.8 m robotic telescope, the T80-South, at the Cerro Tololo Inter-American Observatory, Chile. The telescope is equipped with a 9.2k by 9.2k e2v detector with 10 um pixels, resulting in a field-of-view of 2 deg^2 with a plate scale of 0.55"/pixel. The survey consists of four main subfields, which include two non-contiguous fields at high Galactic latitudes (8000 deg^2 at |b| > 30 deg) and two areas of the Galactic plane and bulge (for an additional 1300 deg^2). S-PLUS uses the Javalambre 12-band magnitude system, which includes the 5 u, g, r, i, z broad-band filters and 7 narrow-band filters centered on prominent stellar spectral features: the Balmer jump/[OII], Ca H+K, H-delta, G-band, Mg b triplet, H-alpha, and the Ca triplet. S-PLUS delivers accurate photometric redshifts (delta_z/(1+z) = 0.02 or better) for galaxies with r < 20 AB mag and redshift < 0.5, thus producing a 3D map of the local Universe over a volume of more than 1 (Gpc/h)^3. The final S-PLUS catalogue will also enable the study of star formation and stellar populations in and around the Milky Way and nearby galaxies, as well as searches for quasars, variable sources, and low-metallicity stars. In this paper we introduce the main characteristics of the survey, illustrated with science verification data highlighting the unique capabilities of S-PLUS. We also present the first public data release of ~336 deg^2 of the Stripe-82 area, which is available at http://datalab.noao.edu/splus.

astro-ph.GA↗

arXiv2019

Gemini IFU, VLA, and HST observation of the OH Megamaser Galaxy IRAS17526+3253

We present a multiwavelength study of the OH megamaser galaxy (OHMG) IRAS17526+3253, based on new Gemini Multi-Object Spectrograph Integral Field Unit (GMOS/IFU) observations, Hubble Space Telescope F814W and H$\alpha$+[N{\sc ii}] images, and archival 2MASS and 1.49GHz VLA data. The HST images clearly reveal a mid-to-advanced stage major merger whose northwestern and southeastern nuclei have a projected separation of $\sim$8.5kpc. Our HST/H$\alpha$+[N{\sc ii}] image shows regions of ongoing star-formation across the envelope on $\sim$10kpc scales, which are aligned with radio features, supporting the interpretation that the radio emission originates from star-forming regions. The measured H$\alpha$ luminosities imply that the unobscured star-formation rate is $\sim$10-30\,M$_{\odot}$yr$^{-1}$. The GMOS/IFU data reveal two structures in northwestern separated by 850\,pc and by a discontinuity in the velocity field of $\sim$~200~km~s$^{-1}$. We associate the blue-shifted and red-shifted components with, respectively, the distorted disk of northwestern and tidal debris, possibly a tail originating in southeastern. Star-formation is the main ionization source in both components, which have SFRs of $\sim$2.6-7.9\,M$_{\odot}$yr$^{-1}$ and $\sim$1.5-4.5\,M$_{\odot}$yr$^{-1}$, respectively. Fainter line emission bordering these main components is consistent with shock ionization at a velocity $\sim$200~km~s$^{-1}$ and may be the result of an interaction between the tidal tail and the northwestern galaxy's disk. IRAS17526+3253 is one of only a few systems known to host both luminous OH and H$_{2}$O masers. The velocities of the OH and H$_{2}$O maser lines suggest that they are associated with the northwestern and southeastern galaxies, respectively.

astro-ph.GA↗

arXiv2015

GHASP: an H$\alpha$ kinematic survey of spiral galaxies - X. Surface photometry, decompositions and the Tully-Fisher relation in the Rc-band

We present Rc-band surface photometry for 170 of the 203 galaxies in GHASP, Gassendi H-Alpha survey of SPirals, a sample of late-type galaxies for which high-resolution Fabry-Perot H{\alpha} maps have previously been obtained. Our data set is constructed by new Rc-band observations taken at the Observatoire de Haute-Provence (OHP), supplemented with Sloan Digital Sky Survey (SDSS) archival data, obtained with the purpose of deriving homogeneous photometric profiles and parameters. Our results include Rc-band surface brightness profiles for 170 galaxies and $ugriz$ profiles for 108 of these objects. We catalogue several parameters of general interest for further reference, such as total magnitude, effective radius and isophotal parameters -- magnitude, position angle, ellipticity and inclination. We also perform a structural decomposition of the surface brightness profiles using a multi-component method in order to separate disks from bulges and bars, and to observe the main scaling relations involving luminosities, sizes and maximum velocities. We determine the Rc-band Tully Fisher relation using maximum velocities derived solely from H$\alpha$ rotation curves for a sample of 80 galaxies, resulting in a slope of $-8.1 \pm 0.5$, zero point of $-3.0 \pm 1.0$ and an estimated intrinsic scatter of $0.28 \pm 0.07$. We note that, different from the TF-relation in the near-infrared derived for the same sample, no change in the slope of the relation is seen at the low-mass end (for galaxies with $V_{max} < 125$ km/s). We suggest that this different behaviour of the Tully Fisher relation (with the optical relation being described by a single power-law while the near-infrared by two) may be caused by differences in the stellar mass to light ratio for galaxies with $V_{max} < 125$ km/s.

astro-ph.GA↗