AstroUnit

Have you ever wondered what is the biggest structure in our Universe? Well, the answer is the Hercules–Corona Borealis Great Wall. It's so massive that it takes light approximately 10 billion (10,000,000,000) years to cross it. It was first detected in 2013 by a team of astronomers while analyzing data from the Swift Gamma-Ray Burst Mission, together with other data from ground-based telescopes. Now, a new study using advanced statistical tools offered arguments that suggest that the structure may not be real and speculated about its potential origin.  This enormous image shows Hubble’s view of the massive galaxy cluster MACS J0717.5+3745. Credit:  NASA, ESA, Harald Ebeling (the University of Hawaii at Manoa) & Jean-Paul Kneib (LAM) The Hercules–Corona Borealis Great Wall is by far the largest structure in the observable Universe inferred from the clustering of gamma-ray bursts. The length of this structure is roughly 10% of the entire Universe. The structure lies in ...

On May 21, 2019, at 03:02:29 UTC the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaboration observed a short duration of the gravitational-wave signal, named GW190521. The detected signal is consistent with the merger of two black holes with masses of 85 and 66 solar masses. The mass of the remnant black hole is estimated to be around 142 solar masses, which makes the historic event GW190521 the first observational confirmation for the existence of an intermediate-mass black hole (IMBH).  Artist's impression of binary black holes about to collide. Source:  Caltech Black holes can be grouped into 4 categories depending on their masses. Firstly, there are the supermassive black holes that reside exclusively at the heart of galaxies having masses in the range from a few million to billions of solar masses. Then there are  the intermediate-mass black holes having masses between a hundred to a few thousands of solar masses. Next are  ...

  A team of cosmologists compared the theoretical predictions of the maximal abundance of massive galaxies predicted in different dynamical dark energy (DDE) models at high redshifts z ≈ 4 − 7 with the observed abundance and derived constraints for the evolution of the dark energy equation of state parameter which is complementary to the existing probes. The study employed three different, independent probes, namely the luminous end of the stellar mass function at z ≥ 6, the spatial density of luminous galaxies detected in the submillimeter range at z = 4 − 5, and the rareness of the extreme hyperluminous infrared galaxy SPT031158 at z ≈ 7. The analysis excluded a significant fraction of parameter spaces for the DDE models but interestingly does not completely exclude the possibility that dark energy may be dynamical (i.e, changing with time). Deepest visible-light image of the Universe containing nearly 10000 galaxies. Source:  Hubble According to our current understanding of...

  A team of astronomers used deep radio observations from 53 MHz to 1.5 GHz with the LOFAR Low/High Band Antenna (LBA/HBA) arrays, the Jansky Very Large Array (JVLA) and the upgraded Giant Metrewave Radio Telescope (GMRT) and discovered the existence of a giant radio bridge connecting two pre-merging galaxy clusters A1758N and A1758S that are ~ 2 Mpc apart. This is the second large-scale radio bridge observed to date in a cluster pair. By studying the radio and X-ray emissions from the radio bridge, the astronomers found clear-cut evidence that the non-thermal phenomena in the intracluster medium (ICM) can be produced in the region of compressed gas in-between infalling systems.  Cluster Merger: Galaxy Clusters Caught in a First Kiss. Source:  Chandra The existence of radio bridges connecting pre-merging galaxy clusters has been confirmed very recently. Hitherto, only two such systems, namely A1758N-A1758S situated at a redshift of z ...

  A team of astronomers used archival data from The Baryon Oscillation Spectroscopic Survey (BOSS) and the Pantheon supernovae to obtain stringent constraints on the Hubble parameter at $H_{0}=65.1^{+3.0}_{-5.4}  km/s/Mpc$ which differs from the best fit of SH0ES at 95% confidence level. This is the first time the Hubble parameter has been ascertained from the horizon scale at matter-radiation equality and therefore offers a consistency check for standard cosmological physics in the pre-recombination era.   Source:  hdqwalls.com                                                                                                                            ...

Cosmologists from Visva-Bharati University and Osmania University reported that the stellar mass of galaxies does not encode all of the information about other galactic properties, an assumption long thought to be true. The new study used archival data from the SDSS in conjunction with cosmological simulations to come to this groundbreaking conclusion.  An artist’s impression of the Milky Way galaxy. Photograph: Chen Xiaodian.                         Downloaded from:  The Guardian                            Understanding the formation and evolution of galaxies is  undoubtedly   one of the major goals of modern  cosmology. The integrated stellar mass of a galaxy is thought to be the most fundamental property which  largely influences its structure and evolution. It is often taken as an impression of its  formation h...