We present a mass-temperature profile of gas within the central 10 kpc of a small sample of cool core clusters. The mass of the hottest gas phases, at 1.5 and 0.7 keV, is determined from X-ray spectra from the XMM Reflection Grating Spectrometers. The masses of the partially ionised atomic and the molecular phases are obtained from published H$α$ and CO measurements. We find that the mass of gas at 0.7 keV in a cluster is remarkably similar to that of the molecular gas. Assuming pressure equilibrium between the phases, this means that they occupy volumes differing by $10^5$. The molecular gas is located within the HU nebula which is often filamentary and coincides radially and in position angle with the soft X-ray emitting gas.
We present an analysis of the radial profiles of a sample of 43 HI-flux selected spiral galaxies from the Nearby Galaxies Legacy Survey (NGLS) with resolved James Clerk Maxwell Telescope (JCMT) CO $J=3-2$ and/or Very Large Array (VLA) HI maps. Comparing the Virgo and non-Virgo populations, we confirm that the HI disks are truncated in the Virgo sample, even for these relatively HI-rich galaxies. On the other hand, the H$_{2}$ distribution is enhanced for Virgo galaxies near their centres, resulting in higher H$_{2}$ to HI ratios and steeper H$_{2}$ and total gas radial profiles. This is likely…
I analyze statistics of the stellar population properties for stellar nuclei and bulges of nearby lenticular galaxies in different environments by using panoramic spectral data of the integral-field spectrograph SAURON retrieved from the open archive of Isaac Newton Group. I estimate also the fraction of nearby lenticular galaxies having inner polar gaseous disks by exploring the volume-limited sample of early-type galaxies of the ATLAS-3D survey. By inspecting the two-dimensional velocity fields of the stellar and gaseous components with running tilted-ring technique, I have found 7 new cases…
We investigate spatially resolved specific star formation rate (SSFR) in the inner $\sim$ 40 pc for a nearby Seyfert 2 galaxy, M51 (NGC 5194) by analyzing spectra obtained with the \emph{Hubble Space Telescope (HST)} Space Telescope Imaging Spectrograph (STIS). We present 24 radial spectra measured along the STIS long slit in M51, extending $\sim 1\arcsec$ from the nucleus (i.e., -41.5 pc to 39.4 pc). By the simple stellar population synthesis, the stellar contributions in these radial optical spectra are modeled. Excluding some regions with zero young flux fraction near the center (from -6 pc…
We present a uniform analysis of the integrated profile of the H I emission line of 29,958 nearby ($z < 0.06$) galaxies extracted from the ALFALFA 21 cm survey. We apply the curve-of-growth technique to derive a database of spectral parameters and robust estimates of their associated uncertainties. Besides the central velocity and total flux, the main catalog provides new measures of line width, profile asymmetry, and profile shape. For a subsample of 13,511 galaxies with optical properties available from the Sloan Digital Sky Survey, we compute inclination angle-corrected line widths, rotatio…
We explore a function with two shape parameters for the dark-matter halo density profile subject to baryonic effects, which is a special case of the general Zhao family of models applied to simulated dark matter haloes by Dekel et al. This profile has variable inner slope and concentration parameter, and analytic expressions for the gravitational potential, velocity dispersion, and lensing properties. Using the NIHAO cosmological simulations, we find that it provides better fits than the Einasto profile and the generalized NFW profile with variable inner slope, in particular towards the halo c…
We present a far-UV (FUV) study of the star-forming complexes (SFCs) in three nearby galaxies using the Ultraviolet Imaging Telescope (UVIT). The galaxies are close to face-on and show significant outer disk star formation. Two of them are isolated (NGC 628, NGC 6946), and one is interacting with distant companions (NGC 5457). We compared the properties of the SFCs inside and outside the optical radius (R$_{25}$). We estimated the sizes, star formation rates (SFRs), metallicities, and the Toomre Q parameter of the SFCs. We find that the outer disk SFCs are at least ten times smaller in area th…
High critical density molecular lines like HCN(1-0) or HCO+(1-0) represent our best tool to study currently star-forming, dense molecular gas at extragalactic distances. The optical depth of these lines is a key ingredient to estimate the effective density required to excite emission. However, constraints on this quantity are even scarcer in the literature than measurements of the high density tracers themselves. Here, we combine new observations of HCN, HCO+ and HNC(1-0) and their optically thin isotopologues H13CN, H13CO+ and HN13C(1-0) to measure isotopologue line ratios. We use IRAM 30-m o…
The Spitzer Survey of Stellar Structure in Galaxies (S4G) is a volume, magnitude, and size-limited survey of 2352 nearby galaxies with deep imaging at 3.6 and 4.5um. In this paper we describe our surface photometry pipeline and showcase the associated data products that we have released to the community. We also identify the physical mechanisms leading to different levels of central stellar mass concentration for galaxies with the same total stellar mass. Finally, we derive the local stellar mass-size relation at 3.6um for galaxies of different morphologies. Our radial profiles reach stellar m…
The stellar velocity dispersion, $σ$, is a quantity of crucial importance for spiral galaxies, where it enters fundamental dynamical processes such as gravitational instability and disc heating. Here we analyse a sample of 34 nearby spirals from the Calar Alto Legacy Integral Field Area (CALIFA) spectroscopic survey, deproject the line-of-sight $σ$ to $σ_{R}$ and present reliable radial profiles of $σ_{R}$ as well as accurate measurements of $\langleσ_{R}\rangle$, the radial average of $σ_{R}$ over one effective (half-light) radius. We show that there is a trend for $σ_{R}$ to increase with de…
We naturally obtain a power-law total mass-density profile for the inner regions (within several effective radius) of early-type galaxies(ETGs) from space-time structures, which are described by the static spherically-symmetric solutions of Einstein equations with the perfect fluid matters. We point out that, in the inner region of an early type galaxy, the average value of the equation of state $ω$ determines the power-law index $γ$ of the total mass-density profile given by \cite{2006ApJ...649..599K}. We then use 119 galaxy-galaxy strong gravitational lensing systems from SLACS, BELLS, BELLS…
Tracing Quenching in Nearby Galaxies Through Inner Surface Mass Density and Cold Gas Content
Orange Coast College（橙海岸学院）；California Institute of Technology（加州理工学院）；California State University, Long Beach（加州州立大学长滩分校）；University of California, Irvine（加州大学尔湾分校）
Gaia Data Release 2 provides a wealth of data to study the internal structure of nearby globular clusters. We use this data to investigate the internal kinematics of 11 nearby globular clusters, with a particular focus on their poorly-studied outer regions. We apply a strict set of selection criteria to remove contaminating sources and create pure cluster-member samples over a significant fraction of the radial range of each cluster. We confirm previous measurements of rotation (or a lack thereof) in the inner regions of several clusters, while extending the detection of rotation well beyond w…
We use the Gemini NIFS instrument to map the H$_2 2.1218μ$m and Br$γ$ flux distributions in the inner 0.04-2 kpc of a sample of 36 nearby active galaxies ($0.001\lesssim z\lesssim0.056$) at spatial resolutions from 4 to 250 pc. We find extended emission in 34 galaxies. In $\sim$55% of them, the emission in both lines is most extended along the galaxy major axis, while in the other 45% the extent follows a distinct orientation. The emission of H$_2$ is less concentrated than that of Br$γ$, presenting a radius that contains half of the flux 60% greater, on average. The H$_2$ emission is driven b…
We investigate the use of spiral arm pitch angles as a probe of disk galaxy mass profiles. We confirm our previous result that spiral arm pitch angles (P) are well correlated with the rate of shear (S) in disk galaxy rotation curves. We use this correlation to argue that imaging data alone can provide a powerful probe of galactic mass distributions out to large look-back times. We then use a sample of 13 galaxies, with Spitzer 3.6-$μ$m imaging data and observed H$α$ rotation curves, to demonstrate how an inferred shear rate coupled with a bulge-disk decomposition model and a Tully-Fisher-deriv…
We derive the mass weighted total density slopes within the effective (half-light) radius, $γ'$, for more than 2000 nearby galaxies from the SDSS-IV MaNGA survey using Jeans-anisotropic-models applied to IFU observations. Our galaxies span a wide range of the stellar mass ($10^9$ $M_{\rm \odot}< M_* < 10^{12}$ M$_{\odot}$) and the velocity dispersion (30 km/s $< σ_v <$ 300 km/s). We find that for galaxies with velocity dispersion $σ_v>100$ km/s, the density slope has a mean value $\langle γ^{\prime} \rangle = 2.24$ and a dispersion $σ_γ=0.22$, almost independent of velocity dispersion. A clear…
Nuclear Star Clusters (NSCs) are dense clusters of stars that reside in the centers of a majority of the galaxies. In this paper, we study the density profiles for 29 galaxies in a volume-limited survey within 10 Mpc to characterize their NSCs. These galaxies span a 3$\times$10$^8$ - 8$\times$10$^{10}$ M$_\odot$ and a wide range of Hubble types. We use high-resolution Hubble space telescope archival data to create luminosity models for the galaxies using Sérsic profiles to parameterize the NSCs. We also provide estimates for photometric masses of NSCs and their host galaxies using color-M/L re…
We present a survey of 3 mm molecular lines in IRAS 04296+2923, one of the brightest known molecular-line emitting galaxies, and one of the closest LIRGs. Data are from the Owens Valley and CARMA millimeter interferometers. Species detected at ~<4" resolution include C^18O, HCN, HCO+, HNC, CN, CH_3OH and, tentatively, HNCO. Along with existing CO, ^13CO and radio continuum data, these lines constrain the chemical properties of the inner disk. Dense molecular gas in the nucleus fuels a star formation rate ~>10 M_sun/yr and is traced by lines of HCN, HCO+, HNC, and CN. A correlation between HCN …
Long slit spectra recorded with GMOS on Gemini South are used to examine the star-forming history of the lenticular galaxy NGC 5102. Structural and supplemental photometric information are obtained from archival Spitzer [3.6] images. Comparisons with model spectra point to luminosity-weighted metallicities that are consistent with the colors of resolved red giant branch stars in the disk. The nucleus has a luminosity-weighted age at visible wavelengths of ~1 Gyr, and the integrated light is dominated by stars that formed over a time period of only a few hundred Myr. For comparison, the luminos…
Dark matter-only simulations predict that dark matter halos have steep, cuspy inner density profiles, while observations of dwarf galaxies find a range of inner slopes that are often much shallower. There is debate whether this discrepancy can be explained by baryonic feedback or if it may require modified dark matter models. In Paper 1 of this series, we obtained high-resolution integral field H$α$ observations for 26 dwarf galaxies with $M_*=10^{8.1}-10^{9.7}\textrm{M}_\odot$. We derived rotation curves from our observations, which we use here to construct mass models. We model the total mas…
We present the detection of hydrogen fluoride, HF, in two luminous nearby galaxies NGC 253 and NGC 4945 using the Heterodyne Instrument for the Far-Infrared (HIFI) on board the Herschel Space Observatory. The HF line toward NGC 253 has a P-Cygni profile, while an asymmetric absorption profile is seen toward NGC 4945. The P-Cygni profile in NGC 253 suggests an outflow of molecular gas with a mass of M(H$_2$)$_{out}$ $\sim$ 1 $\times$ 10$^7$ M$_\odot$ and an outflow rate as large as M $\sim$ 6.4 M$_\odot$ yr$^{-1}$. In the case of NGC 4945, the axisymmetric velocity components in the HF line pro…
We present our new, spatially-resolved, photometry in FUV and NUV from images obtained by GALEX, and IRAC1 (3.6 $μ$m) photometry obtained by the Spitzer Space Telescope. We analyzed the surface brightness profiles $μ_{\rm{FUV}}$, $μ_{\rm{NUV}}$, $μ_{[3.6]}$, as well as the radial evolution of the (FUV-NUV), (FUV - [3.6]), and (NUV - [3.6]) colors in the Spitzer Survey of Stellar Structures in Galaxies (S$^{4}$G) galaxies (d$<$40 Mpc) sample. We defined the GALEX Blue Sequence (GBS) and GALEX Red Sequence (GBR) from the (FUV - NUV) versus (NUV - [3.6]) color-color diagram, populated by late-typ…
In order to quantify the relationship between gas accretion and star formation, we analyse a sample of 29 nearby galaxies from the WHISP survey which contains galaxies with and without evidence for recent gas accretion. We compare combined radial profiles of FUV (GALEX) and IR 24 μm (Spitzer) characterizing distributions of recent star formation with radial profiles of CO (IRAM, BIMA, or CARMA) and HI (WSRT) tracing molecular and atomic gas contents to examine star formation efficiencies in symmetric (quiescent), asymmetric (accreting), and interacting (tidally disturbed) galaxies. In addition…
We present a detailed analysis of the inner mass structure of the Cosmic Horseshoe (J1148+1930) strong gravitational lens system observed with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). In addition to the spectacular Einstein ring, this systems shows a radial arc. We obtained the redshift of the radial arc counter image $z_\text{s,r} = 1.961 \pm 0.001$ from Gemini observations. To disentangle the dark and luminous matter, we consider three different profiles for the dark matter distribution: a power-law profile, the NFW, and a generalized version of the NFW profile. For the l…
The Spitzer Survey of Stellar Structure in Galaxies (S$^{4}$G) is a detailed study of over 2300 nearby galaxies in the near-infrared (NIR), which has been critical to our understanding of the detailed structures of nearby galaxies. Because the sample galaxies were selected only using radio-derived velocities, however, the survey favored late-type disk galaxies over lenticulars and ellipticals. A follow-up Spitzer survey was conducted to rectify this bias, adding 465 early-type galaxies (ETGs) to the original sample, to be analyzed in a manner consistent with the initial survey. We present the …
Much of the baryons in galaxy groups are thought to have been driven out to large distances ($\gtrsim$$R_{500}$) by feedback, but there are few constraining observations of this extended gas. This work presents the resolved Sunyaev--Zel'dovich (SZ) profiles for a stacked sample of 10 nearby galaxy groups within the mass range log$_{10}(M_{500}[M_{\odot}]) = 13.6 -13.9$. We measured the SZ profiles using the publicly available $y$-map from the Planck Collaboration as well as our own $y$-maps constructed from more recent versions of $Planck$ data. The $y$-map extracted from the latest data relea…
I discuss feeding and feedback processes observed in the inner few hundred parsecs of nearby active galaxies using integral field spectroscopy at spatial resolutions of a few to tens of parsecs. Signatures of feedback include outflows from the nucleus with velocities ranging from 200 to 1000km/s, with mass outflow rates between 0.5 and a few Msun/yr. Signatures of feeding include the observation of gas inflows along nuclear spirals and filaments, with velocities ranging from 50 to 100km/s and mass flow rates from 0.1 to 1 Msun/yr. These rates are 2--3 orders of magnitude larger than the mass a…
The main goal of this work is to form a large, deep and representative sample of dwarf galaxies residing in voids of the nearby Universe. The formed sample is the basement for the comprehensive mass study of the galaxy content, their evolutionary status, clustering and dynamics with respect to their counterparts residing in more typical, denser regions and for study of void small-scale substructures. We present 25 voids over the entire sky within 25 Mpc from the Local Group. They are defined as groups of lumped empty spheres bounded by `luminous' galaxies with the absolute K-band magnitudes br…
We present a study on the radial profiles of D4000,luminosity-weighted stellar ages $τ_L$,and luminosity-weighted stellar metallicities $[Z/H]_L$ of 3654 nearby galaxies($0.01<z<0.15$)using the IFU spectroscopic data from the MaNGA survey available in the SDSS DR15,in an effort to explore the connection between median stellar population radial gradients($\nabla$D4000,$\nablaτ_L,\nabla[Z/H]_L$)out to~$1.5R_e$ and various galaxy properties,including stellar mass($M_\star$),specific star formation rate(sSFR),morphologies,and local environment. We find that $M_\star$ is the single most predictive …
Using a suite of three large cosmological hydrodynamical simulations, Horizon-AGN, Horizon-noAGN (no AGN feedback) and Horizon-DM (no baryons), we investigate how a typical sub-grid model for AGN feedback affects the evolution of the inner density profiles of massive dark matter haloes and galaxies. Based on direct object-to-object comparisons, we find that the integrated inner mass and density slope differences between objects formed in these three simulations (hereafter, H_AGN, H_noAGN and H_DM) significantly evolve with time. More specifically, at high redshift (z~5), the mean central densi…
The density profiles of lensing galaxies are typically parameterised by singular power-law models with a logarithmic slope close to isothermal ($ζ=2$). This is sufficient to fit the lensed emission near the Einstein radius but may not be sufficient when extrapolated to smaller or larger radii if the large-scale density profile is more complex. Here, we consider a broken power-law model for the density profile of an elliptical galaxy at $z=1.15$ using observations with the Atacama Large (sub-)Millimetre Array of the strong gravitational lens system SPT0532$-$50. This is the first application of…
We study the velocity dispersion profiles of the nuclei of NGC 1326, 2685, 5273 and 5838 in the CO first overtone band. There is evidence for a black hole (BH) in NGC 1326 and 5838. Gas is seen flowing out of the nuclear region of NGC 5273. We put upper limits on the nuclear BHs responsible for its activity and that of NGC 2685.
We present and characterize a sample of 20 nearby Seyfert galaxies selected for having BAT 14--195keV luminosities $L_X \ge 10^{41.5}$ erg s$^{-1}$, redshift $z\le$0.015, being accessible for observations with the Gemini Near-Infrared Field Spectrograph (NIFS) and showing extended [OIII]$λ$5007 emission. Our goal is to study Active Galactic Nuclei (AGN) feeding and feedback processes from near-infrared integral-field spectra, that include both ionized (HII) and hot molecular (H$_2$) emission. This sample is complemented by other 9 Seyfert galaxies previously observed with NIFS. We show that th…
We construct two linear filtering techniques based on weak gravitational lensing to constrain the inner slope $α$ of the density profile of dark-matter halos. Both methods combine all available information into an estimate of this single number. Under idealised assumptions, $α$ is constrained to ~15% if the halo concentration c is known, and to < 30% if not. We argue that the inevitable degeneracy between density-profile slope and halo concentration cannot be lifted under realistic conditions, and show by means of Fisher-matrix methods which linear combination of $α$ and c is best constrained …
We present a useful function for describing the profiles of dark-matter haloes with a varying asymptotic inner slope -α, ranging from a cusp to a core, where the profiles of density, mass-velocity and potential are simple analytic expressions for any α. The idea is to express the mean-density profile as a simple functional form, and obtain the local density by derivative. The model involves a concentration parameter c analogous to the NFW profile. More flexibility is provided by a sum of two such functions, with concentrations c_1 and c_2. An optional additional parameter is the asymptotic out…
We report a detailed modeling of a mass profile of a $z = 0.2999$ massive elliptical galaxy using 30 milli-arcsecond resolution 1-mm Atacama Large Millimeter/submillimeter Array (ALMA) images of the galaxy-galaxy lensing system SDP.81. The detailed morphology of the lensed multiple images of the $z = 3.042$ infrared-luminous galaxy, which is found to consist of tens of $\lesssim 100$-pc-sized star-forming clumps embedded in a $\sim 2$ kpc disk, are well reproduced by a lensing galaxy modeled by an isothermal ellipsoid with a 400 pc core. The core radius is consistent with that of the visible s…
The low column density gas at the outskirts of galaxies as traced by the 21 cm hydrogen line emission (HI) represents the interface between galaxies and the intergalactic medium, i.e., where galaxies are believed to get their supply of gas to fuel future episodes of star formation. Photoionization models predict a break in the radial profiles of HI at a column density of 5x10E+19 cm^-2 due to the lack of self-shielding against extragalactic ionizing photons. To investigate the prevalence of such breaks in galactic disks and to characterize what determines the potential "edge" of the HI disks, …
We use the Made-to-Measure method to construct N-body realizations of self-similar, triaxial ellipsoidal halos having cosmologically realistic density profiles. Our implementation parallels previous work with a few numerical refinements, but we show that orbital averaging is an intrinsic feature of the force of change equation and argue that additional averaging or smoothing schemes are redundant. We present models having the Einasto radial mass profile that range from prolate to strongly triaxial. We use a least-squares polynomial fit to the expansion coefficients to obtain an analytical repr…
G79.29+0.46 is a nebula created by a Luminous Blue Variable (LBV) star candidate characterized by two almost circular concentric shells. In order to investigate whether the shells are interacting with the infrared dark cloud (IRDC) G79.3+0.3 located at the southwestern border of the inner shell, we conducted Jansky Very Large Array observations of NH3(1,1), (2,2) and c-C3H2, and combined them with previous Effelsberg data. The overall NH3 emission consists of one main clump, named G79A, elongated following the shape of the IRDC, plus two fainter and smaller cores to the north, which spatially …
The Nuker profile, characterised by an inner and outer power-law profile smoothly merged around a break radius, is a very popular model to describe the surface brightness profile of galactic nuclei. A disadvantage of this model for dynamical studies is that the spatial density distribution that corresponds to this surface brightness profile cannot be written in terms of elementary or regular special functions. We derive a compact and elegant analytical expression for the density of the Nuker model, based the Mellin integral transform method. We use this expression to discuss the general behavi…
We present the mass distribution of a sample of 121 nearby galaxies with high quality optical velocity fields and available infra-red $\it{WISE}$ 3.4 $μ$m data. Contrary to previous studies, this sample covers all morphological types and is not biased toward late-type galaxies. These galaxies are part of the Fabry-Perot kinematical $\it{GHASP}$ survey of spirals and irregular nearby galaxies. Combining the kinematical data to the $\it{WISE}$ surface brightness data probing the emission from the old stellar population, we derive mass models allowing us to compare the luminous to the dark matter…
We present new near-infrared (NIR) observations of M63 from the Extended Disk Galaxy Exploration Science (EDGES) Survey. The extremely deep 3.6 $μ$m mosaic reaches 29 AB mag arcsec$^{-2}$ at the outer reaches of the azimuthally-averaged surface brightness profile. At this depth the consequences of galactic accretion are found within a nearby tidal stream and an up-bending break in the slope of the surface brightness profile. This break occurs at a semi-major axis length of $\sim$8', and is evidence of either an enhanced outer disc or an inner stellar halo. Simulations of galaxy evolution, alon…
We present an analysis of the H2 emission-line gas kinematics in the inner < 4 arcsec radius of six nearby spiral galaxies, based on AO-assisted integral-field observations obtained in the K-band with SINFONI/VLT. Four of the six galaxies in our sample display ordered H2 velocity fields, consistent with gas moving in the plane of the galaxy and rotating in the same direction as the stars. However, the gas kinematics is typically far from simple circular motion. We can classify the observed velocity fields into four different types of flows, ordered by increasing complexity: (1) circular motion…
We analyze the velocity dispersions of individual HI and CO profiles in a number of nearby galaxies from the high-resolution HERACLES CO and THINGS HI surveys. Focusing on regions with bright CO emission, we find a CO dispersion value: 7.3 $\pm$ 1.7 km/s. The corresponding HI dispersion is 11.7 $\pm$ 2.3 km/s, yielding a mean HI/CO dispersion ratio of 1.4 $\pm$ 0.2, independent of radius. We find that the CO velocity dispersion increases towards lower peak fluxes. This is consistent with previous work where we showed that when using spectra averaged ("stacked") over large areas, larger values …
Composite Bulges -- V. Detecting signatures of gas inflows in IFU data: The MUSE view of ionised gas kinematics in nearby galaxies
Liverpool John Moores University（利物浦约翰摩尔大学）；University of Nottingham（诺丁汉大学）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）；Universitäts-Sternwarte München（慕尼黑大学天文台）；Durham University（杜伦大学）；Universidade de São Paulo, Instituto de Astronomia, Geofísica e Ciências Atmosféricas（圣保罗大学天文学、地球物理与大气科学研究所）；University of Lancashire（兰开夏大学）；Universidad de La Laguna（拉帕鲁纳大学）
Probing the Variation of the Inner Surface-Brightness Profile of Nuclear Star Clusters on the Intermediate-Mass Black Hole Mass Measurements Using Mock Observations of ELT/MICADO and HARMONI
International University, Vietnam National University in Ho Chi Minh City（越南国立大学胡志明市国际大学）；University of Michigan（密歇根大学）；University of Science, Vietnam National University in Ho Chi Minh City（越南国立大学胡志明市科学大学）
The relations between oxygen abundance and disk surface brightness (OH-SB relation) in the infrared W1 band are examined for a nearby late-type galaxies. The oxygen abundances were presented in Paper I. The photometric characteristics of the disks are inferred here using photometric maps from the literature through bulge-disk decomposition. We find evidence that the OH - SB relation is not unique but depends on the galactocentric distance r (taken as a fraction of the optical radius R_25) and on the properties of a galaxy: the disk scale length h and the morphological T-type. The parametric OH…
Based on sensitive CO measurements from HERACLES and HI data from THINGS, we show that the azimuthally averaged radial distribution of the neutral gas surface density (Sigma_HI + Sigma_H2) in 33 nearby spiral galaxies exhibits a well-constrained universal exponential distribution beyond 0.2*r25 (inside of which the scatter is large) with less than a factor of two scatter out to two optical radii r25. Scaling the radius to r25 and the total gas surface density to the surface density at the transition radius, i.e., where Sigma_HI and Sigma_H2 are equal, as well as removing galaxies that are inte…
We present a high resolution dissection of the two-dimensional total mass distribution in the core of the Hubble Frontier Fields galaxy cluster MACS J0416.1-2403, at z ~ 0.396. We exploit HST/WFC3 near-IR (F160W) imaging, VLT/MUSE spectroscopy, and Chandra data to separate the stellar, hot gas, and dark-matter mass components in the inner 300 kpc of the cluster. We combine the recent results of our refined strong lensing analysis, which includes the contribution of the intracluster gas, with the modeling of the surface brightness and stellar mass distributions of 193 cluster members, of which …
We present the molecular gas morphology and kinematics of seven nearby Seyfert galaxies obtained from our 230~GHz ALMA observations. The CO J=2-1 kinematics within the inner $\sim30$" ($\lesssim9$~kpc) reveals rotation patterns that have been explored using the Bertola rotation model and a modified version of the Kinemetry package. The latter algorithm reveals various deviations from pure circular rotation in the inner kiloparsec of all seven galaxies, including kinematic twists, decoupled and counter-rotating cores. A comparison of the global molecular gas and stellar kinematics show overall …
Universidad Técnica Federico Santa María（弗雷德里克·Santa María技术大学）；Pontificia Universidad Católica de Valparaíso（瓦爾帕萊索天主教大學）；Universidad Andres Bello（安德烈斯·貝洛大學）
Observational studies of inner-most regions of the edge-on jets in nearby active galactic nuclei (AGN) are crucial to understand their kinematics and morphology. For the inner jet of the nearby low luminosity AGN in M 84, we present new high-sensitivity observations with very long baseline interferometry since 2019, as well as archival Very Long Baseline Array observations in 2014. We find that the compact core in M 84 has an inverted-to-flat spectrum from 1.5 to 88 GHz. Based on the turnover frequency of $4.2\pm 0.2$ GHz in the spectrum, we estimated a magnetic field strength of 1-10mG and an…
The size, shape and degree of emptiness of void interiors sheds light on the details of galaxy formation. A particularly interesting question is whether void interiors are completely empty or contain a dwarf population. However the nearby voids that are most conducive for dwarf searches have large angular diameters, on the order of a steradian, making it difficult to redshift-map a statistically significant portion of their volume to the magnitude limit of dwarf galaxies. As part of addressing this problem, we investigate here the usefulness of number counts in establishing the best locations …
