70 research outputs found
Dynamic cosmography of the local Universe: Laniakea and five more watershed superclusters
This article delivers the dynamical cosmography of the Local Universe within
z=0.1 (1 giga light-years). We exploit the gravitational velocity field
computed using the CosmicFlows-4 catalog of galaxy distances to delineate
superclusters as watersheds, publishing for the first time their size, shape,
main streams of matter and the location of their central attractor. Laniakea,
our home supercluster's size is confirmed to be 2 (Mpc
). Five more known superclusters are now dynamically defined in the
same way: Apus, Hercules, Lepus, Perseus-Pisces and Shapley. Also, the central
repellers of the Bootes and Sculptor voids are found and the Dipole and Cold
Spot repellers now appear as a single gigantic entity. Interestingly the
observed superclusters are an order of magnitude larger than the theoretical
ones predicted by cosmological CDM simulations.Comment: 8 pages, 4 figures, 1 table, accepted in A&A (AA/2023/46802
Cosmological Simulations on a Grid of Computers
The work presented in this paper aims at restricting the input parameter
values of the semi-analytical model used in GALICS and MOMAF, so as to derive
which parameters influence the most the results, e.g., star formation, feedback
and halo recycling efficiencies, etc. Our approach is to proceed empirically:
we run lots of simulations and derive the correct ranges of values. The
computation time needed is so large, that we need to run on a grid of
computers. Hence, we model GALICS and MOMAF execution time and output files
size, and run the simulation using a grid middleware: DIET. All the complexity
of accessing resources, scheduling simulations and managing data is harnessed
by DIET and hidden behind a web portal accessible to the users.Comment: Accepted and Published in AIP Conference Proceedings 1241, 2010,
pages 816-82
The mid-infrared Tully-Fisher relation: Spitzer Surface Photometry
The availability of photometric imaging of several thousand galaxies with the
Spitzer Space Telescope enables a mid-infrared calibration of the correlation
between luminosity and rotation in spiral galaxies. The most important
advantage of the new calibration in the 3.6 micron band, IRAC ch.1, is
photometric consistency across the entire sky. Additional advantages are
minimal obscuration, observations of flux dominated by old stars, and
sensitivity to low surface brightness levels due to favorable backgrounds.
Through Spitzer cycle 7 roughly 3000 galaxies had been observed and images of
these are available at the Spitzer archive. In cycle 8 a program called Cosmic
Flows with Spitzer has been initiated that will increase by 1274 the available
sample of spiral galaxies with inclinations greater than 45 degrees from
face-on suitable for distance measurements. This paper describes procedures
based on the photometry package Archangel that are being employed to analyze
both the archival and the new data in a uniform way. We give results for 235
galaxies, our calibrator sample for the Tully-Fisher relation. Galaxy
magnitudes are determined with uncertainties held below 0.05 mag for normal
spiral systems. A subsequent paper will describe the calibration of the [3.6]
luminosity-rotation relation.Comment: Accepted for publication in The Astronomical Journal, 12 pages, 9
figure
Cosmicflows-2: SNIa Calibration and H0
The construction of the Cosmicflows-2 compendium of distances involves the
merging of distance measures contributed by the following methods: (Cepheid)
Period-Luminosity, Tip of the Red Giant Branch (TRGB), Surface Brightness
Fluctuation (SBF), Luminosity-Linewidth (TF), Fundamental Plane (FP), and Type
Ia supernova (SNIa). The method involving SNIa is at the top of an
interconnected ladder, providing accurate distances to well beyond the expected
range of distortions to Hubble flow from peculiar motions. In this paper, the
SNIa scale is anchored by 36 TF spirals with Cepheid or TRGB distances, 56 SNIa
hosts with TF distances, and 61 groups or clusters hosting SNIa with Cepheid,
SBF, TF, or FP distances. With the SNIa scale zero point set, a value of the
Hubble Constant is evaluated over a range of redshifts 0.03 < z < 0.5, assuming
a cosmological model with Omega_m = 0.27 and Omega_Lambda = 0.73. The value
determined for the Hubble Constant is H0 = 75.9 \pm 3.8 km s-1 Mpc-1.Comment: Accepted for publication in The Astrophysical Journal. 11 pages,
8Figures, 5 Table
Our Peculiar Motion Away from the Local Void
The peculiar velocity of the Local Group of galaxies manifested in the Cosmic
Microwave Background dipole is found to decompose into three dominant
components. The three components are clearly separated because they arise on
distinct spatial scales and are fortuitously almost orthogonal in their
influences. The nearest, which is distinguished by a velocity discontinuity at
~7 Mpc, arises from the evacuation of the Local Void. We lie in the Local Sheet
that bounds the void. Random motions within the Local Sheet are small. Our
Galaxy participates in the bulk motion of the Local Sheet away from the Local
Void. The component of our motion on an intermediate scale is attributed to the
Virgo Cluster and its surroundings, 17 Mpc away. The third and largest
component is an attraction on scales larger than 3000 km/s and centered near
the direction of the Centaurus Cluster. The amplitudes of the three components
are 259, 185, and 455 km/s, respectively, adding collectively to 631 km/s in
the reference frame of the Local Sheet. Taking the nearby influences into
account causes the residual attributed to large scales to align with observed
concentrations of distant galaxies and reduces somewhat the amplitude of motion
attributed to their pull. On small scales, in addition to the motion of our
Local Sheet away from the Local Void, the nearest adjacent filament, the Leo
Spur, is seen to be moving in a direction that will lead to convergence with
our filament. Finally, a good distance to an isolated galaxy within the Local
Void reveals that this dwarf system has a motion of at least 230 km/s away from
the void center. Given the velocities expected from gravitational instability
theory in the standard cosmological paradigm, the distance to the center of the
Local Void must be at least 23 Mpc from our position. The Local Void is large!Comment: Tentatively scheduled for Astrophysical Journal, 676 (March 20),
2008. 18 figures, 3 tables including web link for 2 tables, web links to 2
video
3D Velocity and Density Reconstructions of the Local Universe with Cosmicflows-1
This paper presents an analysis of the local peculiar velocity field based on
the Wiener Filter reconstruction method. We used our currently available
catalog of distance measurements containing 1,797 galaxies within 3000 km/s:
Cosmicflows-1. The Wiener Filter method is used to recover the full 3D peculiar
velocity field from the observed map of radial velocities and to recover the
underlying linear density field. The velocity field within a data zone of 3000
km/s is decomposed into a local component that is generated within the data
zone and a tidal one that is generated by the mass distribution outside that
zone. The tidal component is characterized by a coherent flow toward the
Norma-Hydra-Centaurus (Great Attractor) region while the local component is
dominated by a flow toward the Virgo Cluster and away from the Local Void. A
detailed analysis shows that the local flow is predominantly governed by the
Local Void and the Virgo Cluster plays a lesser role. The analysis procedure
was tested against a mock catalog. It is demonstrated that the Wiener Filter
accurately recovers the input velocity field of the mock catalog on the scale
of the extraction of distances and reasonably recovers the velocity field on
significantly larger scales. The Bayesian Wiener Filter reconstruction is
carried out within the ?CDM WMAP5 framework. The Wiener Filter reconstruction
draws particular attention to the importance of voids in proximity to our
neighborhood. The prominent structure of the Local Supercluster is wrapped in a
horseshoe collar of under density with the Local Void as a major component.Comment: Accepted for ApJ, August 6, 201
Cosmicflows-2: I-band Luminosity - HI Linewidth Calibration
In order to measure distances with minimal systematics using the correlation
between galaxy luminosities and rotation rates it is necessary to adhere to a
strict and tested recipe. We now derive a measure of rotation from a new
characterization of the width of a neutral Hydrogen line profile. Additionally,
new photometry and zero point calibration data are available. Particularly the
introduction of a new linewidth parameter necessitates the reconstruction and
absolute calibration of the luminosity-linewidth template. The slope of the new
template is set by 267 galaxies in 13 clusters. The zero point is set by 36
galaxies with Cepheid or Tip of the Red Giant Branch distances. Tentatively, we
determine H0 = 75 km s-1 Mpc-1. Distances determined using the
luminosity-linewidth calibration will contribute to the distance compendium
Cosmicflows-2.Comment: Accepted for publication in The Astrophysical Journal, 27 pages, 18
figure
The Extragalactic Distance Database: All Digital HI Profile Catalog
An important component of the Extragalactic Distance Database (EDD) at
http://edd.ifa.hawaii.edu is a group of catalogs related to the measurement of
HI line profile parameters. One of these is the All Digital HI catalog which
contains an amalgam of information from new data and old. The new data results
from observations with Arecibo and Parkes telescopes and with the Green Bank
Telescope (GBT), including continuing input since the award of the NRAO Cosmic
Flows Large Program. The old data has been collected from archives, wherever
available, particularly the Cornell University Digital HI Archive, the Nancay
Telescope extragalactic HI archive, and the Australia Telescope archive. The
catalog currently contains information on ~15,000 profiles relating to ~13,000
galaxies. The channel - flux per channel files, from whatever source, are
carried through a common pipeline. The derived parameter of greatest interest
is W_m50, the profile width at 50% of the mean flux. After appropriate
adjustment, the parameter W_mx is derived, the linewidth which statistically
approximates the peak to peak maximum rotation velocity before correction for
inclination, 2 V_max sin(i).Comment: 19 pages, 22 figures, Astronomical Journal (anticipated 2009,
December
Cosmicflows-4
With Cosmicflows-4, distances are compiled for 55,877 galaxies gathered into
38,065 groups. Eight methodologies are employed, with the largest numbers
coming from the correlations between the photometric and kinematic properties
of spiral galaxies (TF) and elliptical galaxies (FP). Supernovae that arise
from degenerate progenitors (SNIa) are an important overlapping component.
Smaller contributions come from distance estimates from the surface brightness
fluctuations of elliptical galaxies (SBF) and the luminosities and expansion
rates of core collapse supernovae (SNII). Cepheid Period-Luminosity Relation
(CPLR) and Tip of the Red Giant Branch (TRGB) observations founded on local
stellar parallax measurements along with the geometric maser distance to NGC
4258 provide the absolute scaling of distances. The assembly of galaxies into
groups is an important feature of the study in facilitating overlaps between
methodologies. Merging between multiple contributions within a methodology and
between methodologies is carried out with Bayesian Markov chain Monte Carlo
procedures. The final assembly of distances is compatible with a value of the
Hubble constant of km s Mpc with the small statistical
error km s Mpc but a large potential systematic error
~3 km s Mpc. Peculiar velocities can be inferred from the
measured distances. The interpretation of the field of peculiar velocities is
complex because of large errors on individual components and invites analyses
beyond the scope of this study.Comment: 38 pages, 24 figures. catalogs available at edd.ifa.hawaii.edu.
Accepted to Ap
Phosphorylation of p65(RelA) on Ser547 by ATM Represses NF-κB-Dependent Transcription of Specific Genes after Genotoxic Stress
The NF-κB pathway is involved in immune and inflammation responses, proliferation, differentiation and cell death or survival. It is activated by many external stimuli including genotoxic stress. DNA double-strand breaks activate NF-κB in an ATM-dependent manner. In this manuscript, a direct interaction between p65(RelA) and the N-terminal extremity of ATM is reported. We also report that only one of the five potential ATM-(S/T)Q target sites present in p65, namely Ser547, is specifically phosphorylated by ATM in vitro. A comparative transcriptomic analysis performed in HEK-293 cells expressing either wild-type HA-p65 or a non-phosphorylatable mutant HA-p65S547A identified several differentially transcribed genes after an etoposide treatment (e.g. IL8, A20, SELE). The transcription of these genes is increased in cells expressing the mutant. Substitution of Ser547 to alanine does not affect p65 binding abilities on the κB site of the IL8 promoter but reduces p65 interaction with HDAC1. Cells expressing p65S547A have a higher level of histone H3 acetylated on Lys9 at the IL8 promoter, which is in agreement with the higher gene induction observed. These results indicate that ATM regulates a sub-set of NF-κB dependent genes after a genotoxic stress by direct phosphorylation of p65
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