B. W. Holwerda, W. J. G. de Blok, A. Bouchard, S-L. Blyth, K. van der Heyden, N. Prizkal
备注：
6 pages, 3 figures, proceeding of the conference "Panoramic Radio Astronomy: Wide-field 1-2 GHz research on galaxy evolution", June 02 - 05 2009, Groningen, update after small edits
he upcoming new perspective of the high redshift Universe in the 21 cm line of atomic hydrogen opens possibilities to explore topics of spiral disk evolution, hitherto reserved for the optical regime. The growth of spiral gas disks over Cosmic time can be explored with the new generation of radio telescopes, notably the SKA, and its precursors, as accurately as with the Hubble Space Telescope for stellar disks. Since the atomic hydrogen gas is the building block of these disks, it should trace their formation accurately. Morphology of HI disks can now equally be quantified over Cosmic time. In studies of HST deep fields, the optical or UV morphology of high-redshift galaxy disks have been characterized using a few quantities: concentration (C), asymmetry (A), smoothness (S), second-order-moment (M20), the GINI coefficient (G), and Ellipticity (E). We have applied these parameters across wavelengths and compared them to the HI morphology over the THINGS sample. NGC 3184, an unperturbed disk, and NGC 5194, the canonical 3:1 interaction, serve as examples for quantified morphology. We find that morphology parameters determined in HI are as good or better a tracer of interaction compared to those in any other wavelength, notably in Asymmetry, Gini and M20. This opens the possibility of using them in the parameterization pipeline for SKA precursor catalogues to select interacting or harassed galaxies from their HI morphology. Asymmetry, Gini and M20 may be redefined for use on data-cubes rather than HI column density image.
Extended UltraViolet (xuv) disks have been found in a substantial fraction of late-type --S0, spiral and irregular-- galaxies. Similarly, most late-type spirals have an extended gas disk, observable in the 21cm radio line (HI). The morphology of galaxies can be quantified well using a series of scale-invariant parameters; Concentration- Asymmetry-Smoothness (CAS), Gini, M20, and GM parameters. In this paper, we compare the quantified morphology and effective radius (R50) of the Westerbork observations of neutral Hydrogen in Irregular and Spiral galaxies Project (WHISP) HI maps to those of far-…
Galaxy evolution is driven to a large extent by interactions and mergers with other galaxies and the gas in galaxies is extremely sensitive to the interactions. One method to measure such interactions uses the quantified morphology of galaxy images. Well-established parameters are Concentration, Asymmetry, Smoothness, Gini, and M20 of a galaxy image. Thus far, the application of this technique has mostly been restricted to restframe ultra-violet and optical images. However, with the new radio observatories being commissioned (MeerKAT, ASKAP, EVLA, WSRT/APERTIF, and ultimately SKA), a new windo…
Scale-invariant morphology parameters applied to atomic hydrogen maps (HI) of galaxies can be used to quantify the effects of tidal interaction or star-formation on the ISM. Here we apply these parameters, Concentration, Asymmetry, Smoothness, Gini, M20, and the GM parameter, to two public surveys of nearby dwarf galaxies, the VLA-ANGST and LITTLE-THINGS survey, to explore whether tidal interaction or the ongoing or past star-formation is a dominant force shaping the HI disk of these dwarfs. Previously, HI morphological criteria were identified for ongoing spiral-spiral interactions. When we a…
Lopsidedness of the gaseous disk of spiral galaxies is a common phenomenon in disk morphology, profile and kinematics. Simultaneously, the asymmetry of a galaxy's stellar disk, in combination with other morphological parameters, has seen extensive use as an indication of recent merger or interaction in galaxy samples. Quantified morphology of stellar spiral disks is one avenue to determine the merger rate over much of the age of the Universe. In this paper, we measure the quantitative morphology parameters for the HI column density maps from the Westerbork observations of neutral Hydrogen in I…
The morphology of the atomic hydrogen (HI) disk of a spiral galaxy is the first component to be disturbed by a gravitational interaction such as a merger between two galaxies. We use a simple parametrisation of the morphology of HI column density maps of Westerbork HI Spiral Project (WHISP) to select those galaxies that are likely undergoing a significant interaction. Merging galaxies occupy a particular part of parameter space defined by Asymmetry (A), the relative contribution of the 20% brightest pixels to the second order moment of the column density map (M20) and the distribution of the s…
We explore the quantified morphology of atomic hydrogen (HI) disks in the Virgo cluster. These galaxies display a wealth of phenomena in their Hi morphology, e.g., tails, truncation and warps. These morphological disturbances are related to the ram-pressure stripping and tidal interaction that galaxies undergo in this dense cluster environment. To quantify the morphological transformation of the HI disks, we compute the morphological parameters of CAS, Gini, and M20 and our own GM for 51 galaxies in 48 HI column density maps from the VIVA project. Some morphological phenomena can be identified…
Major mergers of disk galaxies are thought to be a substantial driver in galaxy evolution. To trace the fraction and the rate galaxies are in mergers over cosmic times, several observational techniques, including morphological selection criteria, have been developed over the last decade. We apply this morphological selection of mergers to 21 cm radio emission line (HI) column density images of spiral galaxies in nearby surveys. In this paper, we investigate how long a 1:1 merger is visible in HI from N-body simulations. We evaluate the merger visibility times for selection criteria based on fo…
We present an analysis of the z ~ 0 morphology-environment relation for 911 bright (M_B < -19) galaxies, matching classical RC3 morphologies to the SDSS-based group catalog of Yang et al. We study how the relative fractions of spirals, lenticulars, and ellipticals depend on halo mass over a range of 10^11.7-10^14.8 h^-1 Msol. We pay particular attention to how morphology relates to central (most massive) vs satellite galaxy status. The fraction of galaxies which are elliptical is a strong function of stellar mass; it is also a strong function of halo mass, but only for central galaxies. We int…
(Abridged) We present a non-parametric cell-based method of selecting highly pure and largely complete samples of spiral galaxies using photometric and structural parameters as provided by standard photometric pipelines and simple shape fitting algorithms, demonstrably superior to commonly used proxies. Furthermore, we find structural parameters derived using passbands longwards of the $g$ band and linked to older stellar populations, especially the stellar mass surface density $μ_*$ and the $r$ band effective radius $r_e$, to perform at least equally well as parameters more traditionally link…
The standard disc formation scenario postulates that disc forms as the gas cools and flows into the centre of the dark matter halo, conserving the specific angular momentum. Major mergers have been shown to be able to destroy or highly perturb the disc components. More recently, the alignment of the material that is accreted to form the galaxy has been pointed out as a key ingredient to determine galaxy morphology. However, in a hierarchical scenario galaxy formation is a complex process that combines these processes and others in a non-linear way so that the origin of galaxy morphology remain…
The morphology of galaxies can be quantified to some degree using a set of scale-invariant parameters. Concentration (C), Asymmetry (A), Smoothness (S), the Gini index (G), relative contribution of the brightest pixels to the second order moment of the flux (M20), ellipticity (E), and the Gini index of the second order moment (GM) have all been applied to morphologically classify galaxies at various wavelengths. Here we present a catalog of these parameters for the Spitzer Survey of Stellar Structure in Galaxies (S4G), a volume-limited near-infrared imaging survey of nearby galaxies using the …
Closing the Observational Gap in Cosmic Dynamics: AI-Enabled Reconstruction of the Universe's Vorticity and Rotational Flow Morphology
School of Physics and Astronomy, Sun Yat-Sen University（中山大学物理学院）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；School of Astronomy and Space Sciences, University of Science and Technology of China（中国科学技术大学天文与空间科学学院）；South-Western Institute for Astronomy Research, Yunnan University（云南大学西南天文研究所）；Korea Institute of Advanced Studies (KIAS)（韩国高等科学研究院）；Institute for Astronomy, University of Edinburgh（爱丁堡大学天体物理研究所）；Peng Cheng Laboratory（鹏城实验室）；Institute for Astronomy, The school of Physics, Zhejiang University（浙江大学物理学院天体物理研究所）；Center for Cosmology and Computational Astrophysics, Zhejiang University（浙江大学宇宙学与计算天体物理学中心）；CSST Science Center for the Guangdong–Hong Kong–Macau Greater Bay Area, SYSU（中山大学粤港澳大湾区嫦娥科学中心）
We review the analysis of the Cosmic Web by means of an extensive toolset based on the use of Delaunay and Voronoi tessellations. The Cosmic Web is the salient and pervasive foamlike pattern in which matter has organized itself on scales of a few up to more than a hundred Megaparsec. First, we describe the Delaunay Tessellation Field Estimator (DTFE). The DTFE formalism is shown to recover the hierarchical nature and the anisotropic morphology of the cosmic matter distribution. The Multiscale Morphology Filter (MMF) uses the DTFE density field to extract the diverse morphological elements - fi…
We calculated morphological parameters for 70821 galaxies from VIPERS (spectroscopic galaxy survey performed on VIMOS spectroscope at VLT). These parameters includes Gini, M20, Concentration, Asymmetry and Smoothness. Results correlate with the distribution of these parameters for other simulated and observed samples. We also studied dependence of these parameters with Sersic power index of radial distribution of surface brightness of galaxy image. Our aim was to find a clear separation of VIPERS galaxies on elliptical and spiral. This is necessary for testing the method of Sersic index (ns) c…
We present, for the first time, a Local Universe (LU) characterization using high precision constrained $N$-body simulations based on self-consistent phase-space reconstructions of the large-scale structure in the Two-Micron All-Sky Galaxy Redshift Survey. We analyse whether we live in a special cosmic web environment by estimating cosmic variance from a set of unconstrained $Λ$CDM simulations as a function of distance to random observers. By computing volume and mass filling fractions for voids, sheets, filaments and knots, we find that the LU displays a typical scatter of about $1σ$ at scale…
For more than two decades we have known that galaxy morphological segregation is present in the Local Universe. It is important to see how this relation evolves with cosmic time. To investigate how galaxy assembly took place with cosmic time, we explore the evolution of the morphology-density relation up to redshift z~1 using about 10000 galaxies drawn from the zCOSMOS Galaxy Redshift Survey. Taking advantage of accurate HST/ACS morphologies from the COSMOS survey, of the well-characterised zCOSMOS 3D environment, and of a large sample of galaxies with spectroscopic redshift, we want to study …
We present a search for FRI radio galaxies between 1 < z < 2 in the COSMOS field. In absence of spectroscopic redshift measurements, the selection method is based on multiple steps which make use of both radio and optical constraints. The basic assumptions are that 1) the break in radio power between low-power FRIs and the more powerful FRIIs does not change with redshift, and 2) that the photometric properties of the host galaxies of low power radio galaxies in the distant universe are similar to those of FRIIs in the same redshift bin, as is the case for nearby radio galaxies. We describe th…
Substructure in redMaPPer clusters and its impact on X-ray morphology and scaling relations
University of Helsinki（赫尔辛基大学）；Univ. Grenoble Alpes（格勒诺布尔阿尔卑斯大学）；CNRS（法国国家科学研究中心）；Grenoble INP（格勒诺布尔理工学院）；LPSC-IN2P3（格勒诺布尔粒子与核物理实验室）；Instituto de Astronomia, Geofísica e Ciências Atmosféricas da USP（圣保罗大学天文、地球物理和大气科学研究所）
We have used Virtual Observatory technology to analyse the disk scale length and central surface brightness for a sample of 29955 bright disk galaxies from the Sloan Digital Sky Survey. We use the results in the r-band and revisit the relation between these parameters and the galaxy morphology, and find the average disk surface brightness of 20.2(0.7) mag/arcsec^2. We confirm that late type spirals populate the lower left corner of the scale length-mu0 plane and that the early and intermediate spirals are mixed in this diagram, with disky ellipticals at the top left corner. We further investig…
