Photometric Components Research Articles

Revisiting Consistency for Semi-Supervised Semantic Segmentation.

Semi-supervised learning is an attractive technique in practical deployments of deep models since it relaxes the dependence on labeled data. It is especially important in the scope of dense prediction because pixel-level annotation requires substantial effort. This paper considers semi-supervised algorithms that enforce consistent predictions over perturbed unlabeled inputs. We study the advantages of perturbing only one of the two model instances and preventing the backward pass through the unperturbed instance. We also propose a competitive perturbation model as a composition of geometric warp and photometric jittering. We experiment with efficient models due to their importance for real-time and low-power applications. Our experiments show clear advantages of (1) one-way consistency, (2) perturbing only the student branch, and (3) strong photometric and geometric perturbations. Our perturbation model outperforms recent work and most of the contribution comes from the photometric component. Experiments with additional data from the large coarsely annotated subset of Cityscapes suggest that semi-supervised training can outperform supervised training with coarse labels. Our source code is available at https://github.com/Ivan1248/semisup-seg-efficient.

The Black Hole–Bulge Mass Relation Including Dwarf Galaxies Hosting Active Galactic Nuclei

Abstract We present a new relationship between central black hole (BH) mass and host galaxy stellar bulge mass extending to the lowest BH masses known in dwarf galaxies (M BH ≲ 105 M ⊙; M ⋆ ∼ 109 M ⊙). We have obtained visible and near-infrared Hubble Space Telescope imaging of seven dwarf galaxies with optically selected broad-line active galactic nuclei (AGNs) and BH mass estimates from single-epoch spectroscopy. We perform 2D photometric modeling with GALFIT to decompose the structure of these galaxies and find that the majority have an inner bulge/pseudo-bulge component with an exponential disk that dominates the total stellar mass. Using the modeling results and color-dependent mass-to-light ratios, we determine the stellar mass of each photometric component in each galaxy. We determine the M BH–M bulge relation using a total of 12 dwarf galaxies hosting broad-line AGNs, along with a comparison sample of 88 galaxies with dynamical BH masses and 37 reverberation-mapped AGNs. We find a strong correlation between BH mass and bulge mass with . The near-linear slope and normalization are in good agreement with correlations found previously when only considering higher-mass systems. This work has quadrupled the number of dwarf galaxies on the BH–bulge mass relation, with implications for BH seeding and predictions for gravitational wave detections of merging BHs at higher redshifts with LISA.

An approach to mitigate effects of colour variation, specularity and pores on microtexture analysis of aggregates

ABSTRACTPrevious research indicated that color variation, specularity, and porosity, which are not related to surface roughness or texture of aggregate, affect the value of Texture Index (TI) determined using standard procedures associated with Aggregate Image Measurement System (AIMS). In response, a new technique called Photometric Stereo-Independent Component Analysis (PS-ICA) was developed and found to effectively mitigate color variation effect. Reduced light intensity was found to partially, but not completely, mitigate specularity effect. However, effect of pores could not be mitigated with measurements obtained from existing AIMS procedures. An extensive evaluation was conducted on a broad range of aggregates to determine whether TI values obtained before and after polishing using PS-ICA and reduced light intensity resulted in appropriate assessment of polishing resistance. For aggregates exhibiting strong specularity, it was found that specularity effect increased after initial polishing, which increased TI, thereby confounding and sometimes overwhelming the reduction in TI associated with reduced roughness. The specularity effect appeared to remain constant after initial polishing, such that further polishing resulted in a more consistent reduction in TI. For aggregates not exhibiting specularity, reduction in PS-ICA TI after initial polishing was found to be an excellent parameter to assess polishing resistance.

The Great Observatories All-Sky LIRG Survey: Herschel Image Atlas and Aperture Photometry*

Abstract Far-infrared images and photometry are presented for 201 Luminous and Ultraluminous Infrared Galaxies [LIRGs: log , ULIRGs: log ], in the Great Observatories All-Sky LIRG Survey (GOALS), based on observations with the Herschel Space Observatory Photodetector Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) instruments. The image atlas displays each GOALS target in the three PACS bands (70, 100, and 160 μm) and the three SPIRE bands (250, 350, and 500 μm), optimized to reveal structures at both high and low surface brightness levels, with images scaled to simplify comparison of structures in the same physical areas of ∼100 × 100 kpc2. Flux densities of companion galaxies in merging systems are provided where possible, depending on their angular separation and the spatial resolution in each passband, along with integrated system fluxes (sum of components). This data set constitutes the imaging and photometric component of the GOALS Herschel OT1 observing program, and is complementary to atlases presented for the Hubble Space Telescope, Spitzer Space Telescope, and Chandra X-ray Observatory. Collectively, these data will enable a wide range of detailed studies of active galactic nucleus and starburst activity within the most luminous infrared galaxies in the local universe.

Testing the Presence of Multiple Photometric Components in Nearby Early-type Galaxies Using SDSS

Abstract We investigate two-dimensional image decomposition of nearby, morphologically selected early-type galaxies (ETGs). We are motivated by recent observational evidence of significant size growth of quiescent galaxies and theoretical development advocating a two-phase formation scenario for ETGs. We find that a significant fraction of nearby ETGs show changes in isophotal shape that require multi-component models. The characteristic sizes of the inner and outer component are ∼3 and ∼15 kpc. The inner component lies on the mass–size relation of ETGs at z ∼ 0.25–0.75, while the outer component tends to be more elliptical and hints at a stochastic buildup process. We find real physical differences between single- and double-component ETGs, with double-component galaxies being younger and more metal-rich. The fraction of double-component ETGs increases with increasing σ and decreases in denser environments. We hypothesize that double-component systems were able to accrete gas and small galaxies until later times, boosting their central densities, building up their outer parts, and lowering their typical central ages. In contrast, the oldest galaxies, perhaps due to residing in richer environments, have no remaining hints of their last accretion episode.

Two-dimensional multi-component photometric decomposition of CALIFA galaxies

We present a two-dimensional multi-component photometric decomposition of 404 galaxies from the CALIFA Data Release 3. They represent all possible galaxies with no clear signs of interaction and not strongly inclined in the final CALIFA data release. Galaxies are modelled in the g, r, and i SDSS images including, when appropriate, a nuclear point source, bulge, bar, and an exponential or broken disc component. We use a human-supervised approach to determine the optimal number of structures to be included in the fit. The dataset, including the photometric parameters of the CALIFA sample, is released together with statistical errors and a visual analysis of the quality of each fit. The analysis of the photometric components reveals a clear segregation of the structural composition of galaxies with stellar mass. At high masses (log(Mstar/Msun)>11), the galaxy population is dominated by galaxies modelled with a single Sersic or a bulge+disc with a bulge-to-total (B/T) luminosity ratio B/T>0.2. At intermediate masses (9.5<log(Mstar/Msun)<11), galaxies described with bulge+disc but B/T < 0.2 are preponderant, whereas, at the low mass end (log(Mstar/Msun)<9.5), the prevailing population is constituted by galaxies modelled with either pure discs or nuclear point sources+discs (i.e., no discernible bulge). We obtain that 57% of the volume corrected sample of disc galaxies in the CALIFA sample host a bar. This bar fraction shows a significant drop with increasing galaxy mass in the range 9.5<log(Mstar/Msun)<11.5. The analyses of the extended multi-component radial profile result in a volume-corrected distribution of 62%, 28%, and 10% for the so-called Type I, Type II, and Type III disc profiles, respectively. These fractions are in discordance with previous findings. We argue that the different methodologies used to detect the breaks are the main cause for these differences.

Beyond Sérsic + exponential disc morphologies in the Coma Cluster

[abridged] We explore the diversity of internal galaxy structures in the Coma cluster across a wide range of luminosities ($-17$\,$>$\,$M_g$\,$>$\,$-22$) and cluster-centric radii ($0$\,$<$\,$r_{\rm{cluster}}$\,$<$\,1.3 $r_{200}$) through analysis of deep Canada-France-Hawaii Telescope $i$ band imaging. We present 2D multi-component decomposition via GALFIT, encompassing a wide range of candidate model morphologies with up to three photometric components. Particular focus is placed on early-type galaxies with outer discs (i.e. S0s), and deviations from simple (`unbroken') exponential discs. Rigorous filtering ensures that each model component provides a statistically significant improvement to the goodness-of-fit. The majority of Coma cluster members in our sample (478 of 631) are reliably fitted by symmetric structural models. Of these, 134 ($28\%$) are single S\'{e}rsic objects, 143 ($30\%$) are well-described by 2 component structures, while 201 ($42\%$) require more complex models. Multi-component S\'{e}rsic galaxies resemble compact psuedobulges ($n\sim$\,2, $R_e \sim$\, 4 kpc) surrounded by extended Gaussian-like outer structures ($R_e > 10$ kpc). 11\% of galaxies ($N=52$) feature a break in their outer profiles, indicating `truncated' or `anti-truncated' discs. Beyond the break radius, truncated galaxies are structurally consistent with exponential discs, disfavouring physical truncation as their formation mechanism. Bulge luminosity in anti-truncated galaxies correlates strongly with galaxy luminosity, indicating a bulge-enhancing origin for these systems. Both types of broken disc are found overwhelmingly ($>70\%$) in `barred' galaxies, despite a low measured bar fraction for Coma ($20\pm2\%$). Thus, galaxy bars play an important role in formation of broken disc structures. No strong variation in galaxy structure is detected with projected cluster-centric radius.

Constraining recent oscillations in quintessence models with Euclid

Euclid is a future space-based mission that will constrain dark energy with unprecedented accuracy. Its photometric component is optimized for Weak Lensing studies, while the spectroscopic component is designed for Baryon Acoustic Oscillations (BAO) analysis. We use the Fisher matrix formalism to make forecasts on two quintessence dark energy models with a dynamical equation of state that leads to late-time oscillations in the expansion rate of the Universe. We find that Weak Lensing will place much stronger constraints than the BAO, being able to discriminate between oscillating models by measuring the relevant parameters to $1\sigma$ precisions of 5 to $20\%$. The tight constraints suggest that Euclid data could identify even quite small late-time oscillations in the expansion rate of the Universe.

Mass decomposition of galaxies using DECA software package

The new DECA software package, which is designed to perform photometric analysis of the images of disk and elliptical galaxies having a regular structure, is presented. DECA is written in Python interpreted language and combines the capabilities of several widely used packages for astronomical data processing such as IRAF, SExtractor, and the GALFIT code used to perform two-dimensional decomposition of galaxy images into several photometric components (bulge+disk). DECA has the advantage that it can be applied to large samples of galaxies with different orientations with respect to the line of sight (including edge-on galaxies) and requires minimum human intervention. Examples of using the package to study a sample of simulated galaxy images and a sample of real objects are shown to demonstrate that DECA can be a reliable tool for the study of the structure of galaxies.

The ATLAS3D Project – XXIII. Angular momentum and nuclear surface brightness profiles

[Abridged and Edited] We investigate nuclear light profiles in 135 ATLAS3D galaxies for which the Hubble Space Telescope (HST) imaging is available and compare them to the large scale kinematics obtained with the SAURON integral-field spectrograph. Specific angular momentum, lambda_R, correlates with the shape of nuclear light profiles, where cores are typically found in slow rotators and core-less galaxies are fast rotators. Cores are found only in massive galaxies and only in systems with the stellar mass M>8x10^10 Msun. Based on our sample, we, however, see no evidence for a bimodal distribution of nuclear slopes. The best predictor for finding a core is based on the stellar velocity dispersion within an effective radius, sigma_e, and specific angular momentum, where cores are found for lambda_R<0.25 and sigma_e>160 km/s. We estimate that only about 10% of nearby early-type galaxies contain cores. Furthermore, we show that there is a genuine population of fast rotators with cores. We also show that core fast rotators are morphologically, kinematically and dynamically different from core slow rotators. The cores of fast rotators could harbour black holes of similar masses to those in core slow rotators, but typically more massive than those found in core-less fast rotators. Core-less galaxies, and especially core-less fast rotators, are under-luminous in the diffuse X-ray emission, but the presence of a core does not imply high X-ray luminosities. We postulate a possible population of core-less galaxies among slow rotators, which can not be explained as face-on discs, but comprise a genuine sub-population of slow rotators. These galaxies are typically less massive and flatter than core slow rotators, and show evidence for dynamical cold structures and exponential photometric components. We discuss possible processes for formation of cores and their subsequent preservation.

Planetary Nebula Spectrograph survey of S0 galaxy kinematics – II. Clues to the origins of S0 galaxies

The stellar kinematics of the spheroids and discs of S0 galaxies contain clues to their formation histories. Unfortunately, it is difficult to disentangle the two components and to recover their stellar kinematics in the faint outer parts of the galaxies using conventional absorption line spectroscopy. This paper therefore presents the stellar kinematics of six S0 galaxies derived from observations of planetary nebulae (PNe), obtained using the Planetary Nebula Spectrograph. To separate the kinematics of the two components, we use a maximum-likelihood method that combines the discrete kinematic data with a photometric component decomposition. The results of this analysis reveal that: the discs of S0 galaxies are rotationally supported; however, the amount of random motion in these discs is systematically higher than in comparable spiral galaxies; and the S0s lie around one magnitude below the Tully--Fisher relation for spiral galaxies, while their spheroids lie nearly one magnitude above the Faber--Jackson relation for ellipticals. All of these findings are consistent with a scenario in which spirals are converted into S0s through a process of mild harassment or "pestering," with their discs somewhat heated and their spheroid somewhat enhanced by the conversion process. In such a scenario, one might expect the properties of S0s to depend on environment. We do not see such an effect in this fairly small sample, although any differences would be diluted by the fact that the current location does not necessarily reflect the environment in which the transformation occurred. Similar observations of larger samples probing a broader range of environments, coupled with more detailed modelling of the transformation process to match the wide range of parameters that we have shown can now be measured, should take us from these first steps to the definitive answer as to how S0 galaxies form.

EVOLUTION IN THE CONTINUUM MORPHOLOGICAL PROPERTIES OF Lyα-EMITTING GALAXIES FROMz= 3.1 TOz= 2.1

We present a rest-frame ultraviolet morphological analysis of 108 z=2.1 Lyman Alpha Emitters (LAEs) in the Extended Chandra Deep Field South (ECDF-S) and compare it to a similar sample of 171 LAEs at z=3.1. Using Hubble Space Telescope (HST) images from the Galaxy Evolution from Morphology and SEDs survey, Great Observatories Origins Deep Survey, and Hubble Ultradeep Field, we measure size and photometric component distributions, where photometric components are defined as distinct clumps of UV-continuum emission. At both redshifts, the majority of LAEs have observed half-light radii <~ 2 kpc, but the median half-light radius rises from 1.0 kpc at z=3.1 to 1.4 kpc at z=2.1. A similar evolution is seen in the sizes of individual rest-UV components, but there is no evidence for evolution in the number of multi-component systems. In the z=2.1 sample, we see clear correlations between the size of an LAE and other physical properties derived from its SED. LAEs are found to be larger for galaxies with higher stellar mass, star formation rate, and dust obscuration, but there is no evidence for a trend between equivalent width and half-light radius at either redshift. The presence of these correlations suggests that a wide range of objects are being selected by LAE surveys at z~2, including a significant fraction of objects for which a massive and moderately extended population of old stars underlies the young starburst giving rise to the Lyman alpha emission.

Properties of the Photometric Components of Lenticular Galaxies

After almost one century since their definition, the origin of lenticular galaxies is still a matter of debate. Several formation processes have been proposed in order to explain the wide variety of their observational properties. These properties could indicate that the class of lenticulars is a family formed by galaxies with different formations and evolutions. Here I review the main observational properties of the photometric components of lenticular galaxies reported in recent decades. I revise the main processes proposed in order to explain their origin and evolution. I also explain the different properties of the lenticular galaxies that have evolved through each of these formation processes. A unique opportunity for understanding the origin of S0 galaxies will shortly be forthcoming. This is due to the morphological classifications of large galaxy samples that have recently been published. These classifications have given us our first ever opportunity to study large samples of lenticulars within a wide range of masses and located in a great variety of environments. These large samples will provide us with a real census of nearby lenticular galaxies and could be crucial in finally helping us to understand the origin and evolution of these galaxies.

Simulations of Galaxy Formation in a Λ Cold Dark Matter Universe. I. Dynamical and Photometric Properties of a Simulated Disk Galaxy

We present a detailed analysis of the dynamical and photometric properties of a disk galaxy simulated in the Λ cold dark matter (ΛCDM) cosmogony. The galaxy is assembled through a number of high-redshift mergers followed by a period of quiescent accretion after z ~ 1 that lead to the formation of two distinct dynamical components: a spheroid of mostly old stars and a rotationally supported disk of younger stars. The surface brightness profile is very well approximated by the superposition of an R1/4 spheroid and an exponential disk. Each photometric component contributes a similar fraction of the total luminosity of the system, although less than a quarter of the stars form after the last merger episode at z ~ 1. In the optical bands the surface brightness profile is remarkably similar to that of Sab galaxy UGC 615, but the simulated galaxy rotates significantly faster and has a declining rotation curve dominated by the spheroid near the center. The decline in circular velocity is at odds with observation and results from the high concentration of the dark matter and baryonic components, as well as from the relatively high mass-to-light ratio of the stars in the simulation. The simulated galaxy lies ~1 mag off the I-band Tully-Fisher relation of late-type spirals but seems to be in reasonable agreement with Tully-Fisher data on S0 galaxies. In agreement with previous simulation work, the angular momentum of the luminous component is an order of magnitude lower than that of late-type spirals of similar rotation speed. This again reflects the dominance of the slowly rotating, dense spheroidal component, to which most discrepancies with observation may be traced. On its own, the disk component has properties rather similar to those of late-type spirals: its luminosity, its exponential scale length, and its colors are all comparable to those of galaxy disks of similar rotation speed. This suggests that a different form of feedback than adopted here is required to inhibit the efficient collapse and cooling of gas at high redshift that leads to the formation of the spheroid. Reconciling, without fine-tuning, the properties of disk galaxies with the early collapse and high merging rates characteristic of hierarchical scenarios such as ΛCDM remains a challenging, yet so far elusive, proposition.

An automatic photometric method with high precision by gradually diluting a sample

An automatic photometric method to increase the precision of measurement is proposed, which is based on the injection of a very small volume of sample by rotary valve and the subsequent homogeneous mixing in a small reaction cell made of glass of the sample with a color-developing reagent gradually delivered by a syringe piston pump until the absorbance of the mixture approaches 0.434, where the lowest relative error in the concentration locates. This photometric method is characteristic of uniformly high precision, low sample and reagent consumption, and high sampling rate of 30 samples per h. The other advantages of this method include easy calibration with only one standard solution and no strict requirements on photometric components. While applied for the determination of cobalt ranging from 0.21 to 1.43 g 1 −1, the relative standard deviations are all below 0.4%.

Calcium measurement: Picomole quantitation by continuous-flow colorimetry

A new microcolorimeter with a 220-nl volume, 1.1-cm light path cuvet and solid-state photometric components is described. It has been used in a continuous-flow analysis system for the colorimetric measurement of total calcium in biologic fluids. The sensitivity is 0.5 pmol and it is linear beyond 50 pmol.

Photometric measurement of retroreflection: a new calibration procedure

The problems involved in photometry of retroreflectors are considered: for example, low light levels, heterochromatic photometry, and critical effect of geometric parameters. In order to simulate practical use conditions the visibility of the retroreflector depends on the illumination received in normal driving situations at various distances and incidence angles from the headlamps of the following car and on the luminous itensity retroreflected in the direction of observation. The test apparatus consists of precise realisation of geometric parameters, adequate photometric components and practical calibration procedure with the highest accuracy. A new calibration technique, used at IEN, is here suggested. This requires one uncalibrated reference light source and two uncalibrated photo-detectors instead of calibrated light sources or calibrated photo-detectors as conventional procedures need.

Crude Kalmykian oils

1. The curde oils from the Tengutino, Severo-Kamyshan, and Krasno-Kamyshan fields (N-APT) and that from the Kaspiisk field (baios) in the Kalmykian Autonomic Socialistic Soviet Republic are light, and contain a large amount of paraffins, but the sulfur content is low. The crude oil from the Beshkul'sk field (baios) is heavy, and contains large amounts of resins and sulfur. 2. Lamp kerosenes with good photometric properties and components of car gasolines can be produced from the crude Kalmykian oils, which contain large amounts of paraffins. “Galosha” gasoline can be produced from the crude oils from the Tengutino and Beshkul'sk fields, without any additional purification being needed. 3. A fraction rich in paraffin can be conveniently distilled from the petroleum residues of crude Kalmykian oils, which contain large amounts of paraffins; commercial paraffin can be produced from this fraction.