We reach more than 65,000 registered users in Dec!!

Business Medical Psychology Astronomy Biology Science News
Discussion with Santanu Das on Statistical Isotropy (SI) violation in the Cosmic Microwave Background (CMB)
Like  Save

SIToolBox, a new software package developed for estimating the isotropy violation in the CMB sky.

Can you please describe the broad field of your research?

Cosmology is the study of a combination of the natural sciences, particularly astronomy and physics, to understand the universe as a whole. In the standard model of cosmology, all the matter and energy were created during an event called Big Bang about 14 billion years ago. Then the universe started expanding and slowly created all the structures within. The universe almost took 371 000 years to cool down. The matter became neutral, and it allowed the light to travel freely through the Universe.

Over the period of time the primeval intensity of radiation has considerably weakened and the energy of the radiation decreased. Today we can detect the light in the microwave and it is known as Cosmic Microwave Background (CMB).

CMB was first theoretically predicted by Ralph Alpher and Robert Herman in 1948. Later, in 1964, US physicist Arno Penzias and radio-astronomer Robert Woodrow Wilson accidentally observed CMB while they were working on Holmdel Horn Antenna. They estimated its temperature to be around 3.5 K. Today the most accurate measurement of CMB places the CMB temperature to 2.726K.

CMB provides astronomers the earliest blueprint of the universe, the closest possible time to the Big Bang detectable through electromagnetic radiation (light). It is currently one of the most promising ways we have for understanding the birth and evolution of our Universe. This makes the research in CMB challenging and equally exciting.

The 15 meter Holmdel horn antenna at Bell Telephone Laboratories in Holmdel, New Jersey is shown in the left bottom. Arno Penzias and Robert Wilson accidentally discovered the cosmic microwave background radiation in 1962 while trying to remove a constant noise background from the signal. They were awarded the 1978 Nobel prize in physics. In the left top, right top and the right bottom shows COBE, WMAP and Planck satellite which are the milestones in the history of CMB observation. In the middle, we have shown the expansion history of the universe - starting from Big Bang to the Present time.

Describe the problem that you are solving?

The modern cosmological models relay on the Copernican principle, which says that the universe is considered as homogeneous and isotropic. Homogeneous means that the universe presents the same properties everywhere on a cosmological scale, whereas isotropy means if you look at the different directions of the universe it will look the same.

Theory predicts that CMB is statistically isotropic (SI), which means the intensity of CMB is statistically the same from all the direction of the sky. The standard model of cosmology relays on this assumption. Therefore, the SI properties of CMB have been under intense scrutiny. NASA's WMAP-7 mission detected some SI violations in CMB. However, later it was found to be an instrumental artifact.

Even if the intrinsic CMB is SI, there can be various sources of SI violations in measured CMB. Firstly, we are measuring CMB from our solar system in our galaxy, which has a velocity with respect to the CMB rest frame. Therefore, the Doppler boost of the CMB will introduce SI violation. Different observational artifacts like scan patterns of the CMB experiments; asymmetric beam patterns due to unavoidable side lobes; masking of point sources, galactic plane, a bright region like LMC, SMC; anisotropic noise patterns of the detector, may introduce the isotropy violation in CMB. SI violations in the CMB sky may also arise due to non-standard theoretical models. Whatever be the source of SI violation, its important to develop a proper data analysis technique that can measure the SI violation in CMB.

We are working on developing of a software package, names as SIToolBox that can calculate the isotropy violation in the CMB sky. This is the first-ever such a software package developed for CMB data analysis.

The graphs show statistical isotropy (SI) violation signals discovered by different instruments in WMAP-7 year data. If there were no SI violation then all the points would have been zero. Later it was found that the signal that was detected actually came from some observational artifact.

What are the new results from your research?

Presently there are multiple methods for measuring the SI violation in the CMB sky. One of the highly recognized techniques is the Bipolar Spherical Harminics (BipoSH) method proposed by Hajian, Souradeep in a 2003 Astrophysical Journal (ApJ) paper. Since then several developments have been done in the BipoSH formalism.

In this particular research, we develop the CMB SI violation measurement package, known as SIToolBox, which can estimate the isotropy violation in CMB sky using BipoSH formalism. Previous SI violation detection algorithms used bias subtraction methods while accounting for the masking and anisotropic noise, etc. However, those may lead to errors. SIToolBox, uses a completely Baysian technique to measure the SI violation in CMB sky, which is very accurate than the previous techniques.

We use SIToolBox for measuring the isotropy violation on different simulated data set where a very small amount of SI violation signal has been injected in the presence of high instrumental noise and masking. Our algorithm can very accurately estimate the injected signal. This shows the efficacy of the algorithm.

SIToolBox also contains modules to predict the dipole modulation and the Doppler boost signal from the CMB sky. The package has been made public through github.

An application of SIToolBox for Dipole modulation estimation. The red solid line shows the injected signals and the dotted lines show that recovered signal from the noisy skymap. In the bottom, we have shown the input map to SIToolBox. Some of the parts are masked there. In the output, we can also recover the masked parts of the input maps.

Say something about your team who were involved in developing SIToolox?

The package has been developed by myself, Santanu Das. The project was started while I was in a Ph.D. The initial algorithm of the project was proposed by prof. Benjamin Wandelt at IAP and coordinated by prof Tarun Souradeep. We work on the algorithm and the first article on this research was published in the Journal of Cosmology and Astroparticle Physics (JCAP) in 2015.

After Ph.D., I joined in a joint position of the University of Wisconsin, Madison and Fermilab as a postdoctoral researcher for Tianlai project. While in postdoc I also worked on CMB SI violation and developed the algorithm further. The code is restricted and rewritten to create SIToolBox. The work is published in Monthly Notice of Royal Astronomical Society (MNRAS). This is the first software developed for measuring the isotropy violation of the CMB sky using a completely Bayesian technique.

The software package is written in Fortran 90. Initially, the parallelization was done using a distributed architecture in Mpi. However, later it was replaced using an OpenMP architecture. The package contains different standalone codes and callable subroutines which can be run directly or used by software developers as a function in their codes.

What is your future goal?

Presently SIToolBox can only be used for testing the isotropy violation in CMB temperature on simulated maps. Measuring the SI violation from the real cosmological data using SIToolBox is an interesting and important future project.

However, recently we also got the CMB polarization maps. SIToolBox package can be used for testing the SI violation in CMB polarization, and many other fields of astronomy. In most of the cases, we either need a very little or no modification in the present version of SIToolBox.

Different intensity mapping surveys, like Tianlai, HIRAX, FAST, GBT, etc. are either mapping or planning to map the 21 cm sky signal. Therefore, SIToolBox can be used directly to analyze the intensity mapping data in the future, which will help astronomers to understand the true shape of the universe.

Different upcoming CMB and HI intensity mapping experiments, where SIToolBox can be used for testing the SI violation in the universe.

List of References

    Cite this Page as

    Santanu Das, "Could simple anger have taught people to cooperate?", MachPrinciple, June 21, 2011, https://machprinciple.com/post/could-simple-anger-have-taught-people-to-cooperate

    Keywords

    CMB Statistical Isotropy Violation SIToolBox Cosmology Astrophysics Data Analysis Cosmological software

    0Likes

    0Comments

    Like   Share Share

    Authors Involved

      Institutes Involved

        Throat microbiome holds clues to older Australians’ health

        New research by Flinders University has uncovered a potential marker that could provide valuable insights into the overall health of older adults......

        New Research: Strong Link Between Western Diet During Pregnancy and ADHD

        Diet New research from Denmark reveals that a mother’s diet during pregnancy—characterised by a Western dietary pattern high in fat and sugar......

        Exercise and healthy eating behaviour together provide the best protection against cardiovascular diseases

        Body fat distribution changes as menopause progresses and estrogen levels decrease, causing the adipose tissue concentrated in the hips and thighs......

        Breakthrough study challenges long-held beliefs about the shape of atomic nuclei

        Lead-208 is exceptionally stable due to being a "doubly magic" nucleus – and is the heaviest that we know of. However, a new study published in......

        UK peatland fires are supercharging carbon emissions as climate change causes hotter, drier summers

        A new study led by the University of Cambridge has revealed that as our springs and summers get hotter and drier, the UK wildfire season is being......

        USC study shows proteins and pathways involved in inflammation are associated with changes in bone mineral density over time

        In one of the first studies of its kind, a team of researchers from Keck School of Medicine of USC has found that proteins and pathways involved......

        New Research Shows Neonatal HSV Infections May Lead to Long-Term Cognitive Impairment

        Very early exposure to even a very small dose of herpes simplex virus (HSV) in infant mice can lead to cognitive decline later in life, according......

        New Therapy May Effectively Control HIV in Uganda

        Transmission electron micrograph of HIV-1 virus particles (teal) exiting an infected immune cell after replicating inside the cell. Inset: Interio......

        uOttawa scientists use light to unlock secret of atoms

        A team of researchers from the University of Ottawa has made significant strides in understanding the ionization of atoms and molecules, a fundame......

        Structure of Supercritical Water Decoded

        When exposed to high temperatures and pressure, water enters a state in which liquid and gas can no longer be distinguished. For a long time......

        UC Irvine study shines headlights on consumer driverless vehicle safety deficiencies

        For the first time, researchers at the University of California, Irvine have demonstrated that multicolored stickers applied to stop or speed......

        Impacts of workplace bullying on sleep can be “contagious” between partners

        Workplace bullying affects not only the employee’s sleep but their partner’s too, according to new research published today.Exposure to bullyi......

        Common approaches for assessing business impact on biodiversity are powerful, but often insufficient for strategy design

        A new study has determined that the widely used tools available to businesses for assessing their biodiversity impacts depend on broad assumptions......

        ‘Glacial fracking’: A hidden source of Arctic greenhouse gas emissions

        They found that glacial melt rivers and groundwater springs are transporting large volumes of methane from beneath the ice to the atmosphere. This......

        AI accelerates discovery of neurodevelopmental disorder-associated genes

        Researchers have developed an artificial intelligence (AI) approach that accelerates the identification of genes that contribute to neurodevelopme......

        Catching Aromaticity in the Act: Direct Real-Time Tracking of How ‘Excited-State Aromaticity’ Drives Molecular Shape Changes

        Scientists have achieved the first real-time visualization of how "excited-state aromaticity" emerges within just hundreds of femtoseconds and......

        Topological quantum processor marks breakthrough in computing

        In a leap forward for quantum computing, a Microsoft team led by UC Santa Barbara physicists on Wednesday unveiled an eight-qubit topological......

        Quantum dot discovery for LEDs brings brighter, more eco-friendly displays

        New research by Curtin University has achieved a breakthrough in eco-friendly display technology, creating highly efficient and stable blue quantu......

        Chip-based system for terahertz waves could enable more efficient, sensitive electronics

        The use of terahertz waves, which have shorter wavelengths and higher frequencies than radio waves, could enable faster data transmission, more......

        Novel Bone Marrow Transplant Can Cure Sickle Cell Disease

        A bone marrow transplant process co-developed by investigators at the Johns Hopkins Kimmel Cancer Center is safe and curative for adults with......

        It's free and it will always be

        © machprinciple.com