Close Major-merger Pairs at z=0: Star-forming Galaxies with Pseudobulges

We present a study of star-forming galaxies (SFGs) with pseudobulges (bulges with Sérsic index n<2) in a loca close major-merger galaxy pair sample (H-KPAIR).With data from new aperture photometries in the optical and near-infrared bands (aperture size of 7 kpc) and from the literature,we find that the mean Age of central stellar populations in Spirals with pseudobulges is consistent with that of disky galaxies and is nearly constant against the bulge-to-total ratio (B/T).Paired Spirals have a slightly lower fraction of pure disk galaxies (B/T≤0.1) than their counterparts in the control sample.Compared to SFGs with classical bulges,those with pseudobulges have a higher (>2σ) mean of specific star formation rate (sSFR) enhancement (sSFR_(enh)=0.33±0.07 versus sSFR_(enh)=0.12±0.06) and broader scatter (by~1 dex).The eight SFGs that have the highest sSFR_(enh)in the sample all have pseudobulges.A majority (69%) of paired SFGs with strong enhancement (having sSFR more than5 times the median of the control galaxies) have pseudobulges.The Spitzer data show that the pseudobulges in these galaxies are tightly linked to nuclear/circum-nuclear starbursts.Pseudobulge SFGs in S+S and in S+E pairs have significantly (>3σ) different sSFR enhancement,with the means of sSFR_(enh)=0.45±0.08 and-0.04±0.11respectively.We find a decrease in the sSFR enhancements with the density of the environment for SFGs with pseudobulges.Since a high fraction (5/11) of pseudobulge SFGs in S+E pairs are in rich groups/clusters (loca density N_(1Mpc)≥7),the dense environment might be the cause for their low s SFR_(enh).

Observation of HⅠaround three Satellite Galaxies of M31 with FAST:AndromedaⅡ,NGC 205,and NGC 185

With the exceptional sensitivity of the Five-hundred-meter Aperture Spherical radio Telescope,we conducted observations of the neutral hydrogen(HⅠ)in the circumgalactic medium of Andromeda’s(M31)satellite galaxies,specifically AndromedaⅡ,NGC 205,and NGC 185.Initially,three drift scans were executed for these satellites,with a detection limit of 4×10^(18)cm^(-2)(approximately 1.88×10^(3)M_Θof HⅠmass),followed by a more in-depth scan of a specific region.We discovered a C-shaped HⅠarc structure sharing a position and line-of-sight velocity similar to a stellar ring structure around AndromedaⅡ,hinting at a potential connection with AndromedaⅡ.In the context of NGC 205,we identified two mass concentrations in the northeast direction,which could be indicative of tidal streams resulting from the interaction between this galaxy and M31.These new lumps discovered could be very helpful in solving the missing interstellar medium problem for NGC 205.Observations regarding NGC 185are consistent with previous studies,and we did not detect any additional HⅠmaterial around this galaxy.These observational results enhance our understanding of the evolution of these satellite galaxies and provide insight into their historical interactions with the galaxy M31.

Four Late-type Galaxies with Double Radio Lobes and Properties of Such Galaxies

The triggering mechanism for radio lobes from late-type galaxies is not fully understood.More samples are desired for a thorough investigation and statistics.By utilizing the optical data from the newly released Dark Energy Spectroscopic Instrument imaging surveys and the radio sources from the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty-centimeter,we identify four Late-type Galaxies with double Radio Lobes(La GRLs):J0217-3645,J0947+6220,J1412+3723 and J1736+5108.Including previously known La GRLs,we confirm the correlation between radio power P_(1.4GHz)and stellar mass M_(*)of host galaxies.Most(25/35)La GRLs belong to the blue cloud galaxies,while the newly identified cases in this work are located within the region of the red sequence.We find a clear correlation between the differential radio power,i.e.,the offset from the P_(1.4GHz)-M_(*)relation,and the galaxy color,indicating that bluer galaxies at a fixed M_(*)tend to host more powerful radio lobes.Furthermore,the majority(31/36)of La GRLs are either located in a galaxy group or displaying a disturbed morphology.We suggest that all of the galaxy mass,color and surrounding environment could play important roles in triggering radio lobes in late-type galaxies.

Formation of Superthin Galaxies in IllustrisTNG

Superthin galaxies are observed to have stellar disks with extremely small minor-to-major axis ratios.In this work,we investigate the formation of superthin galaxies in the TNG100 simulation.We trace the merger history and investigate the evolution of galaxy properties of a selected sample of superthin galaxies and a control sample of galaxies that share the same joint probability distribution in the stellar-mass and color diagram.Through making comparisons between the two galaxy samples,we find that present-day superthin galaxies had similar morphologies as the control sample counterparts at higher redshifts,but have developed extended flat“superthin”morphologies since z~1.During this latter evolution stage,superthin galaxies undergo an overwhelmingly higher frequency of prograde mergers(with orbit-spin angleθ_(orb)≤40°).Accordingly the spins of their dark matter halos have grown significantly and become noticeably higher than those of their normal disk counterparts.This further results in the buildup of their stellar disks at larger distances much beyond the regimes of normal disk galaxies.We also discuss the formation scenario of those superthin galaxies that live in larger dark matter halos as satellite galaxies therein.

Morphological Classification of Infrared Galaxies Based on WISE

This study introduces a novel convolutional neural network,the WISE Galaxy Classification Network(WGC),for classifying spiral and elliptical galaxies using Wide-field Infrared Survey Explorer(WISE)images.WGC attains an accuracy of 89.03%,surpassing the combined use of K-means or SVM with the Color-Color method in more accurately identifying galaxy morphologies.The enhanced variant,WGC_mag,integrates magnitude parameters with image features,further boosting the accuracy to 89.89%.The research also delves into the criteria for galaxy classification,discovering that WGC primarily categorizes dust-rich images as elliptical galaxies,corresponding to their lower star formation rates,and classifies less dusty images as spiral galaxies.The paper explores the consistency and complementarity of WISE infrared images with SDSS optical images in galaxy morphology classification.The SDSS Galaxy Classification Network(SGC),trained on SDSS images,achieved an accuracy of 94.64%.The accuracy reached 99.30% when predictions from SGC and WGC were consistent.Leveraging the complementarity of features in WISE and SDSS images,a novel variant of a classifier,namely the Multi-band Galaxy Morphology Integrated Classifier,has been developed.This classifier elevates the overall prediction accuracy to 95.39%.Lastly,the versatility of WGC was validated in other data sets.On the HyperLEDA data set,the distinction between elliptical galaxies and Sc,Scd and Sd spiral galaxies was most pronounced,achieving an accuracy of 90%,surpassing the classification results of the Galaxy Zoo 2 labeled WISE data set.This research not only demonstrates the effectiveness of WISE images in galaxy morphology classification but also represents an attempt to integrate multi-band astronomical data to enhance understanding of galaxy structures and evolution.

The Clumpy Structure of Five Star-bursting Dwarf Galaxies in the MaNGA Survey

The star-forming clumps in star-bursting dwarf galaxies provide valuable insights into understanding the evolution of dwarf galaxies.In this paper,we focus on five star-bursting dwarf galaxies featuring off-centered clumps in the Mapping Nearby Galaxies at Apache Point Observatory survey.Using the stellar population synthesis software Fitting Analysis using Differential evolution Optimization,we obtain the spatially resolved distribution of the star formation history,which allows us to construct the g-band images of the five galaxies at different ages.These images can help us to probe the evolution of the morphological structures of these galaxies.While images of a stellar population older than 1 Gyr are typically smooth,images of a stellar population younger than 1 Gyr reveal significant clumps,including multiple clumps which appear at different locations and even different ages.To study the evolutionary connections of these five galaxies to other dwarf galaxies before their star-forming clumps appear,we construct the images of the stellar populations older than three age nodes,and define them to be the images of the"host"galaxies.We find that the properties such as the central surface brightness and the effective radii of the hosts of the five galaxies are in between those of dwarf ellipticals(dEs)and dwarf irregulars(dIrrs),with two clearly more similar to dEs and one more similar to dIrrs.Among the five galaxies,8257-3704 is particularly interesting,as it shows a previous starburst event that is not quite visible from its gri image,but only visible from images of the stellar population at a few hundred million years.The star-forming clump associated with this event may have appeared at around 600 Myr ago and disappeared at around 40 Myr ago.

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 structureΩ_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.

Stellar Populations of AGN-host Dwarf Galaxies Selected with Different Methods

In this paper we investigate the stellar populations and star formation histories of 235 active galactic nucleus(AGN)-host dwarf galaxies,consisting of four samples identified separately with different methods(i.e.,radio,X-ray,mid-IR and variability),utilizing the synthesis code STARLIGHT and spectra from the Sloan Digital Sky Survey Data Release 8.Our results show that the variability sample is the oldest,while the mid-IR sample is the youngest,for which the luminosity at 4020?is dominated(>50%)by the young population(t<10~8yr).The light-weighted mean stellar age of the whole sample is in general about 0.7 dex younger than the optical sample studied in Cai et al.We compare the population results between fitting models with and without a power-law(PL)component and find that the neglect of a PL component would lead to an under-and over-estimation by 0.2 and0.1 dex for the light-and mass-weighted mean stellar age,respectively,for our sample of dwarf galaxies,which has a mean fractional contribution of~16%from the AGN.In addition,we obtain further evidence for a possible suppression of star formation in the host galaxy by the central AGN.We also find that there exists an anticorrelation between the extinction-corrected[O III]luminosity and light-weighted mean stellar age,confirming our previous finding that there is a physical connection between AGN and star-forming activities in AGN-host dwarfs.

Low Surface Brightness Galaxies Selected by Different Model Fitting

We present a study of low surface brightness galaxies(LSBGs) selected by fitting the images for all the galaxies inα.40 SDSS DR7 sample with two kinds of single-component models and two kinds of two-component models(disk+bulge):single exponential,single sersic,exponential+deVaucular(exp+deV),and exponential+sérsic(exp+ser).Under the criteria of the B band disk central surface brightness μ_(0,disk)(B)≥22.5 mag arcsec^(-2) and the axis ratio b/a> 0.3,we selected four none-edge-on LSBG samples from each of the models which contain 1105,1038,207,and 75 galaxies,respectively.There are 756 galaxies in common between LSBGs selected by exponential and sersic models,corresponding to 68.42% of LSBGs selected by the exponential model and 72.83% of LSBGs selected by the sersic model,the rest of the discrepancy is due to the difference in obtaining μ_(0) between the exponential and sersic models.Based on the fitting,in the range of 0.5≤n≤1.5,the relation of μ_(0) from two models can be written as μ_(0,sérsic)-μ_(0,exp)=-1.34(n-1).The LSBGs selected by disk+bulge models(LSBG_(2)comps) are more massive than LSBGs selected by single-component models(LSBG_1comp),and also show a larger disk component.Though the bulges in the majority of our LSBG_(2)comps are not prominent,more than 60% of our LSBG_(2)comps will not be selected if we adopt a single-component model only.We also identified 31 giant low surface brightness galaxies(gLSBGs) from LSBG_(2)comps.They are located at the same region in the color-magnitude diagram as other gLSBGs.After we compared different criteria of gLSBGs selection,we find that for gas-rich LSBGs,M_(*)> 10^(10)M_⊙ is the best to distinguish between gLSBGs and normal LSBGs with bulge.

On the Relation Between Symmetry of Radio Galaxies and Their Physical Parameters

Gravity as a fundamental force plays a dominant role in the formation and evolution of cosmic objects and leaves its effect in the emergence of symmetric and asymmetric structures.Thus,analyzing the symmetry criteria allows us to uncover mechanisms behind the gravity interaction and understand the underlying physical processes that contribute to the formation of large-scale structures such as galaxies.We use a segmentation process using intensity thresholding and the k-means clustering algorithm to analyze radio galaxy images.We employ a symmetry criterion and explore the relation between morphological symmetry in radio maps and host galaxy properties.Optical properties(stellar mass,black hole mass,optical size(R_(50)),concentration,stellar mass surface density(μ_(50)),and stellar age)and radio properties(radio flux density,radio luminosity,and radio size)are considered.We found that there is a correlation between symmetry and radio size,indicating larger radio sources have smaller symmetry indices.Therefore,size of radio sources should be considered in any investigation of symmetry.Weak correlations are also observed with other properties,such as R_(50)for FRI galaxies and stellar age.We compare the symmetry differences between FRI and FRII radio galaxies.FRII galaxies show higher symmetry in 1.4 GHz and 150 MHz maps.Investigating the influence of radio source sizes,we discovered that this result is independent of the sizes of radio sources.These findings contribute to our understanding of the morphological properties and analyses of radio galaxies.

Cosmological Constraints on Neutrino Masses in Light of JWST Red and Massive Candidate Galaxies

The overabundance of the red and massive candidate galaxies observed by the James Webb Space Telescope(JWST)implies efficient structure formation or large star formation efficiency at high redshift z~10.In the scenario of a low or moderate star formation efficiency,because massive neutrinos tend to suppress the growth of structure of the universe,the JWST observation tightens the upper bound of the neutrino masses.Assuming A cold dark matter cosmology and a star formation efficiency∈[0.05,0.3](flat prior),we perform joint analyses of Planck+JWST and Planck+BAO+JWST,and obtain improved constraints∑m_(ν)<0.196 eV and ∑m_(ν)+<0.111 eV at 95% confidence level,respectively.Based on the above assumptions,the inverted mass ordering,which implies ∑m_(ν)≥0.1 eV,is excluded by Planck+BAO+JWST at 92.7% confidence level.

A Dark Matter Theory by Quantum Gravitation for Galaxies and Clusters

This paper develops an original theory of dark matter in the current ΛCDM framework, whose main hypothesis is that DM is generated by the own gravitational field, according to an unknown quantum gravitational phenomenon. This work is the best version of the theory, which I have been developing and publishing since 2014. The hypothesis of DM by quantum gravitation, DMbQG hereafter, has two main consequences: the first one is that the law of DM generation has to be the same, in the halo region, for all the galaxies and the second one is that the haloes are unbounded, so the total DM goes up without limit as the gravitational field is unbounded as well. The first one consequence is backed by the fact that M31 and MW has a fitted function with the same power exponent for the rotation curve at the halo region and both giant galaxies are the only ones whose rotation curves at the halo region may be studied with accuracy. This paper is firstly developed all the theory with M31 rotation curve data up to Chapter 9. The most important formula of the theory is the called Direct mass, which calculates the total mass at a specific radius into the halo region. Chapter 10 is dedicated to apply the theory to Milky Way, it is calculated its total mass at different radius into the halo and such results have been validated successfully using the data of masses at different radius published by two researcher teams. In Chapter 11, it is calculated the direct mass for the Local Group, and it is shown how the DMbQG theory is able to calculate the total mass at 770 kpc, that the dynamical methods estimate to be 5×1012MΘ. In Chapter 12, it is shown a method to estimate the Direct mass formula for a cluster of galaxies, using only its virial mass and virial radius. By this method, it is estimated the parameter a2 of the Local Group, which match with the one calculated in previous chapter by a different method. Also are calculated the parameters a2 associated to Virgo and Coma clusters. In Chapter 13, it is demonstrated how the DE is able to counterbalance the DM at cluster scale, as the Direct mass grows up with the square root of radius whereas the DE grows up with the cubic power. The chapter is an introduction to the DMbQG theory for cluster of galaxies, which has been developed fully by the author in other works. This theory aims to be a powerful method to study DM in the halo region of galaxies and cluster of galaxies and conversely the measures in galaxies and clusters offer the possibility to validate the theory.

Mock X-Ray Observations of Hot Gas with L-Galaxies Semi-analytic Models of Galaxy Formation

We create mock X-ray observations of hot gas in galaxy clusters with a new extension of the L-Galaxies semianalytic model of galaxy formation,which includes the radial distribution of hot gas in each halo.Based on the model outputs,we first build some mock light cones,then generate mock spectra with the SOXS package and derive the mock images in the light cones.Using the mock data,we simulate mock X-ray spectra for the ROSAT all-sky survey,and compare the mock spectra with the observational results.Then,we consider the design parameters of the HUBS mission and simulate the observation of the halo hot gas for HUBS as an important application of our mock work.We find:(1)our mock data match the observations by current X-ray telescopes.(2)The survey of hot baryons in resolved clusters by HUBS is effective below redshift 0.5,and the observations of the emission lines in point-like sources at z>0.5 by HUBS help us understand the hot baryons in the early universe.(3)By taking advantage of the large simulation box and flexibility in semi-analytic models,our mock X-ray observations provide the opportunity to select targets and observation strategies for forthcoming X-ray facilities.

Comparing the Structural Parameters of the Milky Way to Other Spiral Galaxies

The structural parameters of a galaxy can be used to gain insight into its formation and evolution history.In this paper,we strive to compare the Milky Way’s structural parameters to other,primarily edge-on,spiral galaxies in order to determine how our Galaxy measures up to the Local Universe.For our comparison,we use the galaxy structural parameters gathered from a variety of literature sources in the optical and near-infrared wave bands.We compare the scale length,scale height,and disk flatness for both the thin and thick disks,the thick-to-thin disk mass ratio,the bulge-to-total luminosity ratio,and the mean pitch angle of the Milky Way’s spiral arms to those in other galaxies.We conclude that many of the Milky Way’s structural parameters are largely ordinary and typical of spiral galaxies in the Local Universe,though the Galaxy’s thick disk appears to be appreciably thinner and less extended than expected from zoom-in cosmological simulations of Milky Way-mass galaxies with a significant contribution of galaxy mergers involving satellite galaxies.

The Mass Assembly History for Galaxies with MaNGA

How galaxies assemble masses through their own star formation or interaction with the external environment is still an important topic in the field of galaxy formation and evolution.We use Value Added Catalogs with galaxy features that are spatially and temporally resolved from Sloan Digital Sky Survey Data Release 17 to investigate the mass growth histories of early-type galaxies(ETGs)and late-type galaxies(LTGs).We find that the mass growth of ETGs is earlier than that of LTGs for massive galaxies(M_(*)>10^(10)M_⊙),while low-mass(M_(*)≤10^(10)M_⊙)ETGs have statistically similar mass assembly histories as low-mass LTGs.The stellar metallicity of all massive galaxies shows a negative gradient and basically does not change with time.However,in low-mass galaxies,the stellar metallicity gradient of elliptical galaxies is negative,and the stellar metallicity gradient of lenticular and spiral galaxies evolves from positive to negative.ETGs are not all in a high-density environment,but exhibit mass dependence.As the tidal strength increases,the star formation rate of low-mass ETGs rapidly decreases.These results support a picture where massive galaxies exhibit inside-out quenching mode,while low-mass galaxies show outside-in quenching mode.Environmental effects play an important role in regulating the mass assembly histories of low-mass ETGs.

Supermassive Primordial Black Holes for Nano-Hertz Gravitational Waves and High-redshift JWST Galaxies

Recently,observational hints for supermassive black holes have been accumulating,prompting the question:Can primordial black holes(PBHs)be supermassive,particularly with masses M■10^(9)M_(⊙)?A supercritical bubble,containing an inflating baby universe,that nucleated during inflation can evolve into a PBH in our observable universe.We find that when the inflaton slowly transitions past a neighboring vacuum,the nucleation rate of supercritical bubbles inevitably peaks,leading to a mass distribution of multiverse PBHs with a peak mass up to M■10^(11)M_(⊙).Thus,our mechanism naturally provides a primordial origin for supermassive black holes.

Dark Galaxies, Sun-Earth-Moon Interaction, Tunguska Event—Explained by WUM

Great experimental results and observations achieved by Astronomy in the last decades revealed new unexplainable phenomena. Astronomers have conclusive new evidence that a recently discovered “dark galaxy” is, in fact, an object the size of a galaxy, made entirely of dark matter. They found that the speed of the Earth’s rotation varies randomly each day. 115 years ago, the Tunguska Event was observed, and astronomers still do not have an explanation of It. Main results of the present article are: 1) Dark galaxies explained by the spinning of their Dark Matter Cores with the surface speed at equator less than the escape velocity. Their Rotational Fission is not happening. Extrasolar systems do not emerge;2) 21-cm Emission explained by the self-annihilation of Dark Matter particles XIONs (5.3 μeV);3) Sun-Earth-Moon Interaction explained by the influence of the Sun’s and the Moon’s magnetic field on the electrical currents of the charged Geomagma (the 660-km layer), and, as a result, the Earth’s daylength varies;4) Tunguska Event explained by a huge atmospheric explosion of the Superbolide, which was a stable Dark Matter Bubble before entering the Earth’s atmosphere.

Study of Central Intensity Ratio of Seyfert Galaxies in Nearby Universe

We use the recently discovered simple photometric parameter Central Intensity Ratio(CIR)determined for a sample of 57 nearby(z<0.02)Seyfert galaxies to explore the central features of galaxies and their possible connection with galaxy evolution.The sample of galaxies shows strong anti-correlation between CIR and mass of their central supermassive black holes(SMBHs).The SMBH masses of ellipticals are systematically higher for a given CIR value than those for lenticulars and spirals in the sample.However,the correlation between CIR and central velocity dispersion is weak.CIR appears less influenced by the excess flux produced by the central engine in these galaxies,when compared to spectroscopic parameters like velocity dispersion and OⅣflux,and proves to be a fast and reliable tool for estimating central SMBH mass.

Merging History of Massive Galaxies at 3

The observational data of high redshift galaxies become increasingly abundant,especially since the operation of the James Webb Space Telescope,which allows us to verify and optimize the galaxy formation model at high redshifts.In this work,we investigate the merging history of massive galaxies at 3<z<6 using a well-developed semi-analytic galaxy formation catalog.We find that the major merger rate increases with redshift up to 3 and then flattens.The fraction of wet mergers,during which the sum of the cold gas mass is higher than the sum of the stellar mass in two merging galaxies,also increases from~34%at z=0 to 96%at z=3.Interestingly,almost all major mergers are wet at z>3.This can be attributed to the high fraction(>50%)of cold gas at z>3.In addition,we study some special systems of massive merging galaxies at 3<z<6,including the massive gas-rich major merging systems and extreme dense proto-clusters,and investigate the supermassive black hole-dark matter halo mass relation and dual active galactic nuclei.We find that the galaxy formation model reproduces the incidence of those observed massive galaxies,but fails to reproduce the relation between the supermassive black hole mass and the dark matter halo mass at z~6.The latter requires more careful estimates of the supermassive black hole masses observationally.Otherwise,it could suggest modifications of the modeling of the supermassive black hole growth at high redshifts.

Neutral Hydrogen Content of Dwarf Galaxies in Different Environments

Environments play an important role in galaxy formation and evolution,particularly in regulating the content of neutral gas.However,current HI surveys have limitations in their depth,which prevents them from adequately studying low HI content galaxies in high-density regions.In this study,we address this issue by employing the Five-hundred-meter Aperture Spherical radio Telescope with extensive integration times to complement the relatively shallow Arecibo Legacy Fast Arecibo L-band Feed Array HI survey.This approach allows us to explore the gas content of dwarf galaxies across various environments.We observe a positive relationship between HI mass and stellar mass in dwarf galaxies,with a well-defined upper boundary for HI mass that holds true in both observations and simulations.Furthermore,we find a decrease in the H I-to-stellar mass ratio(M_(HI)/M_*)as the density of the environment increases,irrespective of whether it is determined by the proximity to the nearest group or the projected number density.Comparing our observations to simulations,we note a steeper slope in the relationship,indicating a gradual gas-stripping process in the observational data.Additionally,we find that the scaling relation between the M_(HI)/M_*and optical properties can be improved by incorporating galaxy environments.