Hubble Sequence Research Articles

Observational constraints on the emergent universe with non-linear equation of state and interacting fluids

We investigate a flat emergent universe (EU) with a nonlinear equation of state equivalent to three different composition of fluids. In the EU initially, the evolution of the universe began with no interaction but as time evolves an interaction sets in among the three fluids leading to the observed universe. The characteristic of an EU is that it is a singularity free universe that evolves with all the basic features of the early evolution. For a given nonlinear equation of state parameter, it permits a universe with three different fluids, we get a universe with dark energy, cosmic string, and radiation domination to begin with which at a later epoch transits into a universe with three different fluids with matter domination (baryonic as well as dark matter) and dark energy for a given interaction strength among the cosmic fluids. The evolution of the universe is probed with exponential interactions to obtain a universe with late acceleration. The model parameters are constrained using the observed Hubble data and Type Ia Supernova (SnIa) data from the Pantheon data set. An interacting EU transforms to a matter dominated phase with DE accommodating the present universe satisfactorily. The stability of the cosmological model is also discussed.

Cross-method Analysis of Corotation Radii Data Set for Spiral Galaxies

A corotation radius is a key characteristic of disk galaxies that is essential to determine the angular speed of the spiral structure Ω p , and therefore understand its nature. In the literature, there are plenty of methods to estimate this value, but do these measurements have any consistency? In this work, we collected a data set of corotation radius measurements for 547 galaxies, 300 of which had at least two values. An initial analysis reveals that most objects have rather inconsistent corotation radius positions. Moreover, a significant fraction of galactic disks is distinguished by a large error coverage and almost uniform distribution of measurements. These findings do not have any relation to spiral type, Hubble classification, or presence of a bar. Among other reasons, obtained results could be explained by the transient nature of spirals in a considerable part of galaxies. We have made our collected data sample publicly available, and have demonstrated on one example how it could be useful for future research by investigating a winding time value for a sample of galaxies with possible multiple spiral arm patterns.

Grand Design versus Multiarmed Spiral Galaxies: Dependence on Galaxy Structure

We developed an algorithm to use Galaxy Zoo 3D spiral arm masks produced by citizen scientist volunteers to semiautomatically classify spiral galaxies as either multiarmed or grand design spirals. Our final sample consists of 299 multiarmed and 245 grand design galaxies. On average, the grand design galaxies have smaller stellar masses than the multiarmed galaxies. For a given stellar mass, the grand design galaxies have larger concentrations, earlier Hubble types, smaller half-light radii, and larger central surface mass densities than the multiarmed galaxies. Lower-mass galaxies of both arm classes have later Hubble types and lower concentrations than higher-mass galaxies. In our sample, a higher fraction of grand design galaxies have classical bulges rather than pseudo-bulges, compared to multiarmed galaxies. These results are consistent with theoretical models and simulations, which suggest that dense classical bulges support the development and/or longevity of two-armed spiral patterns. Similar specific star formation rates (sSFRs) are found in multiarmed and grand design galaxies with similar stellar masses and concentrations. This implies that the sSFRs in spiral galaxies are a function of concentration and stellar mass, but independent of the number of spiral arms. Our classifications are consistent with arm counts from the Galaxy Zoo 2 project and published m = 3 Fourier amplitudes.

The impact of cosmic rays on the interstellar medium and galactic outflows of Milky Way analogues

Abstract During the last decade, cosmological simulations have managed to reproduce realistic and morphologically diverse galaxies, spanning the Hubble sequence. Central to this success was a phenomenological calibration of the few included feedback processes, whilst glossing over higher complexity baryonic physics. This approach diminishes the predictive power of such simulations, preventing to further our understanding of galaxy formation. To tackle this fundamental issue, we investigate the impact of cosmic rays (CRs) and magnetic fields on the interstellar medium (ISM) and the launching of outflows in a cosmological zoom-in simulation of a Milky Way-like galaxy. We find that including CRs decreases the stellar mass of the galaxy by a factor of 10 at high redshift and ∼4 at cosmic noon, leading to a stellar mass to halo mass ratio in good agreement with abundance matching models. Such decrease is caused by two effects: i) a reduction of cold, high-density, star-forming gas, and ii) a larger fraction of SN events exploding at lower densities, where they have a higher impact. SN-injected CRs produce enhanced, multi-phase galactic outflows, which are accelerated by CR pressure gradients in the circumgalactic medium of the galaxy. While the mass budget of these outflows is dominated by the warm ionised gas, warm neutral and cold gas phases contribute significantly at high redshifts. Importantly, our work shows that future JWST observations of galaxies and their multi-phase outflows across cosmic time have the ability to constrain the role of CRs in regulating star formation.

Testing the effect of anisotropy on the parametrization of deceleration parameter from recent observational data

In this work, we investigate Bianchi type I universe in the presence of dark energy and dark matter by three parameterizations of deceleration parameter models, which are considered to find solutions of the models. In the framework of an anisotropic cosmology, we constrain the parameters of these models and compared the results with the [Formula: see text]CDM model, by using the datasets from different observational, namely, the Hubble data and type Ia Supernovae Pantheon data. Additionally, the evolution of kinematic cosmographic parameters is investigated. In particular, we analyze the effects of anisotropy on the physical behavior of our mentioned models and compare them with standard [Formula: see text]CDM model.

Catalogue of nearby blue and near-solar gas metallicity SDSS dwarf galaxies

ABSTRACT A less explored aspect of dwarf galaxies is their metallicity evolution. Generally, dwarfs have lower metallicities than Hubble sequence late-type galaxies, but in reality, dwarfs span a wide range of metallicities with several open questions regarding the formation and evolution of the lowest and the highest metallicity dwarfs. We present a catalogue of 3459 blue, nearby, star-forming dwarf galaxies extracted from SDSS DR-16 including calculation of their metallicities using the mean of several calibrators. To compile our catalogue we applied redshift, absolute magnitude, stellar mass, optical diameter, and line flux signal-to-noise criteria. This produced a catalogue from the upper end of the dwarf galaxy stellar mass range. Our catalogued dwarfs have blue g – i colours and Hβ equivalent widths, indicative of having undergone a recent episode of star formation, although their star formation rates (SFRs) suggest only a moderate to low enhancement in star formation, similar to the SFRs in low surface brightness and evolved tidal dwarfs. While the catalogued dwarfs cover a range of metallicities, their mean metallicity is ∼0.2 dex below solar metallicity, indicating relatively chemically evolved galaxies. The vast majority of the catalogue, with clean photometry, are relatively isolated dwarfs with only modest SFRs and a narrow range of g – i colour, consistent with internally driven episodic mild bursts of star formation. The presented catalogue’s robust metallicity estimates for nearby SDSS dwarf galaxies will help target future studies to understand the physical processes driving the metallicity evolution of dwarfs.

H ii regions and diffuse ionized gas in the AMUSING++ Compilation – I. Catalogue presentation

ABSTRACT We present a catalogue of ∼52 000 extragalactic H ii regions and their spectroscopic properties obtained using Integral Field Spectroscopy (IFS) from MUSE observations. The sample analysed in this study contains 678 galaxies within the nearby Universe (0.004 <z < 0.06) covering different morphological types and a wide range of stellar masses (6 < log(M*/M⊙) < 13). Each galaxy was analysed using the pipe3d and pyhiiextractor codes to obtain information of the ionized gas and underlying stellar populations. Specifically, the fluxes, equivalent widths, velocities and velocity dispersions of 30 emission lines covering the wavelength range between λ4750 to λ9300 Å, were extracted and were used to estimate luminosity weighted ages and metallicities of the underlying stellar populations from each H ii region (of the original sample we detect H ii regions in 539 galaxies). In addition, we introduce and apply a novel method and independent of any intrinsic physical property to estimate and decontaminate the contribution of the diffuse ionized gas. Using the final catalogue, we explore the dependence of properties of the H ii regions on different local and global galaxy parameters: (i) Hubble type, (ii) stellar mass, (iii) galactocentric distance, and (iv) the age and metallicity of the underlying/neighbour stellar populations. We confirm known relations between properties of the H ii regions and the underlying stellar populations (in particular, with the age) uncovered using data of lower spatial and spectral resolution. Furthermore, we describe the existence of two main families of diffuse ionized gas different for galaxies host or not of H ii regions.

JWST reveals a high fraction of disk breaks at 1 ≤ z ≤ 3

We analyzed the deconvolved surface brightness profiles of 247 massive and angularly large disk galaxies at 1 ≤ z ≤ 3 to study high-redshift disk breaks, using F356W-band images from the Cosmic Evolution Early Release Science survey (CEERS). We found that 12.6% of these galaxies exhibit type I (exponential) profiles, 56.7% exhibit type II (down-bending) profiles, and 34.8% exhibit type III (up-bending) profiles. Moreover, we showed that galaxies that are more massive, centrally concentrated, or redder, tend to show fewer type II and more type III breaks. These fractions and the detected dependencies on galaxy properties are in good agreement with those observed in the Local Universe. In particular, the ratio of the type II disk break radius to the bar radius in barred galaxies typically peaks at a value of 2.25, perhaps due to bar-induced radial migration. However, the timescale for secular evolution may be too lengthy to explain the observed breaks at such high redshifts. Instead, violent disk instabilities may be responsible, where spiral arms and clumps torque fling out the material, leading to the formation of outer exponential disks. Our results provide further evidence for the assertion that the Hubble Sequence was already in place during these early periods.

Исследование усреднённых азимутальных профилей поверхностной яркости спиральных рукавов при помощи декомпозиции

For the first time we perform the decomposition of 29 galaxies from S4G survey considering spiral arms as a separate component. We analyze the contribution of spiral arms to the azimuthally-averaged profiles of galaxies’ surface brightness using our models, using models obtained with decomposition. We show that spiral arms’ contribution varies strongly with distance to the center, usually reaching its highest value at the radius of about 1,5 exponential scale of the disk and decreasing to zero at the center and on the periphery of the galaxy. We obtain the characteristic values of the «bump» height on the galaxy’s azimuthally-averaged profile which is caused by the spiral arms. Spiral arms’ contribution to the overall luminosity of the galaxy is investigated, its connection with the Hubble type is also confirmed. Our results can be applied, for the rough estimates of axisymmetric components’ share in galaxy’s light, which is important for determination of disk parameters based on azimuthally-averaged surface brightness profiles, or for analysis of the spectral energy distribution in galaxy.

The JWST Hubble Sequence: The Rest-frame Optical Evolution of Galaxy Structure at 1.5 < z < 6.5

We present results on the morphological and structural evolution of a total of 3956 galaxies observed with JWST at 1.5 < z < 6.5 in the JWST CEERS observations that overlap with the CANDELS EGS field. This is the biggest visually classified sample observed with JWST yet, ∼20 times larger than previous studies, and allows us to examine in detail how galaxy structure has changed over this critical epoch. All sources were classified by six individual classifiers using a simple classification scheme aimed at producing disk/spheroid/peculiar classifications, whereby we determine how the relative number of these morphologies has evolved since the Universe’s first billion years. Additionally, we explore structural and quantitative morphology measurements using Morfometryka, and show that galaxies with M * > 109 M ⊙ at z > 3 are not dominated by irregular and peculiar structures, either visually or quantitatively, as previously thought. We find a strong dominance of morphologically selected disk galaxies up to z = 6 in this mass range. We also find that the stellar mass and star formation rate densities are dominated by disk galaxies up to z ∼ 6, demonstrating that most stars in the Universe were likely formed in a disk galaxy. We compare our results to theory to show that the fraction of types we find is predicted by cosmological simulations, and that the Hubble Sequence was already in place as early as one billion years after the Big Bang. Additionally, we make our visual classifications public for the community.

LeMMINGs

We used high-resolution HST imaging and e-MERLIN 1.5-GHz observations of galaxy cores from the LeMMINGs survey to investigate the relation between optical structural properties and nuclear radio emission for a large sample of galaxies. We performed accurate, multi-component decompositions of new surface brightness profiles extracted from HST images for 163 LeMMINGs galaxies and fitted up to six galaxy components (e.g. bulges, discs, AGN, bars, rings, spiral arms, and nuclear star clusters) simultaneously with Sérsic and/or core-Sérsic models. By adding such decomposition data for ten LeMMINGs galaxies from our past work, the final sample of 173 nearby galaxies (102 Ss, 42 S0s, 23 Es, plus six Irr) with a typical bulge stellar mass of M∗,bulge ∼ 106 − 1012.5 M⊙ encompasses all optical spectral classes: low-ionisation nuclear emission-line region (LINER), Seyfert, Absorption Line Galaxy (ALG), and H II. We show that the bulge mass can be significantly overestimated in many galaxies when components such as bars, rings, and spirals are not included in the fits. We additionally implemented a Monte Carlo method to determine errors on the bulge, disc, and other fitted structural parameters. Moving (in the opposite direction) across the Hubble sequence, that is from the irregular to elliptical galaxies, we confirm that bulges become larger, more prominent, and round. Such bulge dominance is associated with a brighter radio core luminosity. We also find that the radio detection fraction increases with bulge mass. At M∗,bulge ≥ 1011 M⊙, the radio detection fraction is 77%, declining to 24% for M∗,bulge &lt; 1010 M⊙. Furthermore, we observe that core-Sérsic bulges tend to be systematically round and to possess high radio core luminosities and boxy-distorted or pure elliptical isophotes. However, there is no evidence for the previously alleged strong tendency of galaxies’ central structures (i.e. a sharp Sérsic, core-Sérsic dichotomy) with their radio loudness, isophote shape, and flattening.

The profiles of bars in spiral galaxies

ABSTRACT We present an analysis of major-axis surface-brightness profiles of bars in a volume-limited sample of 182 barred spiral galaxies, using Spitzer 3.6 $\mu$m images. Unlike most previous studies, we use the entire bar profile, and we classify profiles into four categories. These are ‘Peak+Shoulders’ (P+Sh) – updating the classic ‘flat bar’ profile – and three subtypes of the classic ‘exponential’ profile: (true) Exponential, ‘Two-Slope’ (shallow inner slope + steeper outer slope), and ‘Flat-Top’ (constant inner region, steep outer slope). P+Sh profiles are preferentially found in galaxies with high stellar masses, early Hubble types, red colours, and low gas fractions; the most significant factor is stellar mass, and previous correlations with Hubble type can be explained by the tendency of higher-mass galaxies to have earlier Hubble types. The most common type of non-P+Sh profile is Exponential, followed by Flat-Top profiles; all non-P+Sh profiles appear to have similar distributions of stellar mass, Hubble type, colour, and gas fraction. We also morphologically classify the bars of an inclined subsample into those with and without boxy/peanut-shaped (B/P) bulges; as previously reported, the presence of a B/P bulge is very strong function of stellar mass. Essentially all bars with B/P bulges have P+Sh profiles; we associate the profile shoulders with the outer, vertically thin part of the bar. We find a small number of P+Sh profiles in bars without clear B/P bulges, which may indicate that P+Sh formation precedes the formation of B/P bulges.

Observational constraints on the modification of standard ΛCDM cosmology with dark radiation

We revisit a cosmological model modified by an extra “radiation-like” energy component in the Universe, which can be interpreted as many physical phenomena. Here, we derive the constraint on the energy density from this modification with current cosmological observations, including Cosmic Microwave Background, Baryon Acoustic Oscillation, Observational Hubble Parameter data and Type Ia supernovae. Performing a Bayesian analysis gives at 95% confidence level. Our work shows the dark radiation energy is small. Alleviating H 0 tension by introducing this term can also be interpreted as the systematic error caused by the numerical method.

Resequencing the Hubble sequence and the quadratic (black hole mass)–(spheroid stellar mass) relation for elliptical galaxies

ABSTRACT One of the most protracted problems in astronomy has been understanding the evolution of galaxy morphology. Much discussion has surrounded how lenticular galaxies may form a bridging population between elliptical and spiral galaxies. However, with recourse to a galaxy’s central black hole mass, accretion-built spiral galaxies have emerged as the bridging population between low-mass lenticular galaxies and the dusty merger-built lenticular galaxies contiguous with elliptical galaxies and ‘brightest cluster galaxies’ in the black hole/galaxy mass diagram. Spiral galaxies, including the Milky Way, appear built from gas accretion and minor mergers onto what were initially lenticular galaxies. These connections are expressed as a new morphology sequence, dubbed the ‘Triangal’, which subsumes elements of the Hubble sequence and the van den Bergh trident and reveals the bridging nature of the often overlooked ellicular galaxies. Furthermore, a quadratic black hole/galaxy mass relation is found to describe ordinary elliptical galaxies. The relation is roughly parallel to the quadratic-like relations observed for the central spheroidal component of spiral galaxies, dust-rich lenticular galaxies, and old dust-poor lenticular galaxies. The brightest cluster galaxies are offset according to expectations from an additional major merger. The findings have implications for feedback from active galactic nuclei, mapping morphology into simulations, and predicting gravitational wave signals from colliding supermassive black holes. A new galaxy speciation model is presented. It disfavours the ‘monolithic collapse’ scenario for spiral, dusty lenticular, and elliptical galaxies. It reveals substantial orbital angular momentum in the Universe’s first galaxies and unites dwarf and ordinary ‘early-type’ galaxies.

Orientation of the spins of galaxies in the local volume

ABSTRACT We estimated the angular momentum, J, of 720 galaxies in the Local Volume with distances r &amp;lt; 12 Mpc. The distribution of the average angular momentum along the Hubble sequence has a maximum at the morphological type T = 4 (Sbc), while the dispersion of the J-values for galaxies is minimal. Among the Local Volume population, 27 elite spiral galaxies stand out, with an angular momentum &amp;gt; 0.15 of the Milky Way, J &amp;gt; 0.15JMW, making the main contribution ($\gt 90~{{\ \rm per\ cent}}$ ) to the total angular momentum of galaxies in the considered volume. Using observational data on the kinematics and structure of these galaxies, we determined the direction of their spins. We present the first map of the distribution of the spins of 27 nearby massive spiral galaxies in the sky and note that their pattern does not exhibit significant alignment with respect to the Local Sheet plane. The relationship between the magnitude of the angular momentum and stellar mass of the local galaxies is well represented by a power law with an exponent of (5/3) over an interval of six orders of magnitude of the mass of galaxies.

Recent Extragalactic Nova Rate Determinations and their Implications

Comparing the rates of novae in galaxies of differing Hubble types reveals the sensitivity of nova eruptions to the properties (age, star formation history, metallicity) of the underlying stellar population. Recent studies using the Hubble Space Telescope have suggested that earlier ground-based surveys may have underestimated extragalactic nova rates by factors of five or more. Here we discuss the implications of such high specific nova rates on nova theory in general, and on the chemical evolution of galaxies, including the Milky Way, in particular.

Are Milky-Way-like galaxies like the Milky Way? A view from SDSS-IV/MaNGA

ABSTRACTIn this paper, we place the Milky Way (MW) in the context of similar-looking galaxies in terms of their star-formation and chemical evolution histories. We select a sample of 138 Milky Way analogues (MWAs) from the SDSS-IV/MaNGA survey based on their masses, Hubble types, and bulge-to-total ratios. To compare their chemical properties to the detailed spatially-resolved information available for the MW, we use a semi-analytic spectral fitting approach, which fits a self-consistent chemical-evolution and star-formation model directly to the MaNGA spectra. We model the galaxies’ inner and outer regions assuming that some of the material lost in stellar winds falls inwards. We also incorporate chemical enrichment from type II and Ia supernovae to follow the alpha-element abundance at different metallicities and locations. We find some MWAs where the stellar properties closely reproduce the distribution of age, metallicity, and alpha enhancement at both small and large radii in the MW. In these systems, the match is driven by the longer time-scale for star formation in the outer parts, and the inflow of enriched material to the central parts. However, other MWAs have very different histories. These divide into two categories: self-similar galaxies where the inner and outer parts evolve identically; and centrally-quenched galaxies where there is very little evidence of late-time central star formation driven by material accreted from the outer regions. We find that, although selected to be comparable, there are subtle morphological differences between galaxies in these different classes, and that the centrally-quenched galaxies formed their stars systematically earlier.

Mass and Color Dependence of the Hubble Spiral Sequence

In the classic Hubble spiral sequence, arm windiness correlates with bulge size; Sa type spiral galaxies with larger bulges also have the most tightly wound spirals. Exceptions to this have long been known, and in recent work using Galaxy Zoo morphologies no strong correlation was seen in a volume limited sample. In this Research Note, we explore the impact of galaxy mass and integrated color upon this correlation in the Galaxy Zoo sample, finding that bluer and lower mass spirals show the “expected” correlation; however, it becomes slightly negative for redder and/or more massive spiral galaxies.

HALOGAS: Strong constraints on the neutral gas reservoir and accretion rate in nearby spiral galaxies

Context. Galaxies in the local Universe are thought to require ongoing replenishment of their gas reservoir in order to maintain the observed star formation rates. Cosmological simulations predict that this accretion can occur in both a dynamically hot and cold mode, depending on the redshift, halo mass, and the details of the included feedback processes. However, until now, observational evidence of the accretion required to match the observed star formation histories is lacking. Aims. Within the framework of the Hydrogen Accretion in LOcal GalaxieS (HALOGAS) survey, this paper attempts to determine whether galaxies in the local Universe possess a significant reservoir of cold neutral gas and the possible accretion rates these reservoirs could provide. Additionally, with this moderately sized sample, we can start to investigate whether the observed accretion is connected to intrinsic properties of the galaxies such as Hubble type, star formation rate, or environment. Methods. We searched the vicinity of 22 nearby galaxies in a systematic and automated manner for isolated H I clouds or distinct streams that are not yet connected to the galaxy disk. The HALOGAS observations were carried out with the Westerbork Synthesis Radio Telescope and represent one of the most sensitive and detailed H I surveys to date. These observations typically reach column density sensitivities of ∼1019 cm−2 over a 20 km s−1 line width. Results. We find 14 secure H I cloud candidates without an observed optical counterpart in the entire HALOGAS sample. These cloud candidates appear to be analogs to the most massive clouds detected in the extensive cloud distributions around the Milky Way and M 31. However, their numbers seem significantly reduced on average compared to the numbers in these galaxies. Within the framework of cold accretion, we constrain upper limits for H I accretion in the local Universe. The average H I mass currently observed in a state suggestive of accretion onto the galaxies amounts to a rate of 0.05 M⊙ yr−1 with a stringent upper limit of 0.22 M⊙ yr−1, confirming previous estimates. This is much lower than the average star formation rate in this sample. Our best estimate, based on the Green Bank Telescope detection limits of several galaxies in the sample, suggests that another 0.04 M⊙ yr−1 of neutral hydrogen at most could be accreted from clouds and streams that remain undetected. Conclusions. These results show that in nearby galaxies, neutral hydrogen is not being accreted at the same rate as stars are currently being formed. Our study cannot exclude that other forms of gas accretion are at work, such as those provided by direct infall of ionized intergalactic gas or the condensation of coronal gas, triggered by galactic fountain activities. However, these observations do not reveal extended neutral gas reservoirs around most nearby spiral galaxies either.

Spatial metallicity distribution statistics at ≲100 pc scales in the AMUSING++ nearby galaxy sample

ABSTRACT We analyse the spatial statistics of the 2D gas-phase oxygen abundance distributions in a sample of 219 local galaxies. We introduce a new adaptive binning technique to enhance the signal-to-noise ratio of weak lines, which we use to produce well-filled metallicity maps for these galaxies. We show that the two-point correlation functions computed from the metallicity distributions after removing radial gradients are in most cases well-described by a simple injection–diffusion model. Fitting the data to this model yields the correlation length lcorr, which describes the characteristic interstellar medium (ISM) mixing length-scale. We find typical correlation lengths lcorr ∼ 1 kpc, with a strong correlation between lcorr and stellar mass, star formation rate (SFR), and effective radius, and a weak correlation with Hubble type. Two galaxies in the sample show significantly larger lcorr, and both prove to be interacting or merging systems. We show that the trend of lcorr with SFR can be reproduced by a simple transport + feedback model of ISM turbulence at high SFR, and plausibly also at low SFR if dwarf galaxy winds have large mass-loading factors. We also report the first measurements of the injection width that describes the initial radii over which supernova remnants deposit metals. Inside this radius the metallicity correlation function is not purely the product of a competition between injection and diffusion. We show that this size scale is generally smaller than 60 pc.