#LiteBIRD

[thxnews]

LiteBIRD Mission Unveils Cosmic Secrets Worldwide

  UK's Role in Cosmic Exploration

In a pivotal contribution to the quest for understanding the origins of the universe, the United Kingdom is set to play a crucial role in the pioneering LiteBIRD mission. Led by Japan, this ambitious mission aims to trace patterns in light from space, taking us on a journey back to the very birth of the cosmos, a monumental leap in our comprehension of the universe's beginnings.   Probing the Big Bang The LiteBIRD mission, short for 'Light satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection,' focuses on analyzing variations in the light that was left behind after the Big Bang. Its primary mission is to scrutinize the prevailing cosmological inflation theory, which describes the rapid expansion of the universe immediately following its creation.  

A section of a detailed representation of the distribution of CMB radiation density. Photo by NASA - WMAP Science Team.  

UK's Investment and Contributions

The UK Space Agency has committed an initial investment of £2.7 million to support the LiteBIRD mission. This financial backing will serve two primary purposes:   UK Scientists at the Helm Firstly, it will enable a group of UK scientists to engage in designing critical components of LiteBIRD's specialized science instruments and analyzing their findings.   Cardiff University's Unique Expertise Secondly, Cardiff University, renowned for its unique expertise, will produce the lenses and filters required for the telescopes. This distinct capability positions the university as the sole institution worldwide capable of creating these specialized components.  

Future Commitments

The UK Space Agency's commitment doesn't stop here. It intends to inject a total of £17 million throughout the mission's lifespan, slated for launch before 2030. This reaffirms the UK's dedication to pushing the boundaries of space exploration and deepening its collaborations, particularly with Japan.  

A Growing UK-Japan Partnership

The LiteBIRD mission is but one facet of the growing partnership between the UK and Japan in the field of space exploration. The commitment to this mission was unveiled during the International Astronautical Congress in Baku, Azerbaijan, where the UK pledged £1.7 million from its £20 million International Bilateral Fund to support Viasat's In-Range telemetry relay service, designed for Mitsubishi Heavy Industry's H3 launch vehicle, scheduled for liftoff in 2025. George Freeman MP, Minister for Space at the Department for Science, Innovation, and Technology, expressed his enthusiasm, stating, "This initial £2.7 million investment... is a great moment for both UK space science and technology and our deepening science, technology, and innovation collaboration with Japan."  

A Game-Changing Mission

Dr. Paul Bate, Chief Executive of the UK Space Agency, anticipates that LiteBIRD will be a game-changer in the field of cosmology, enabling scientists to put prevailing theories about the universe's origins to the test. He described it as: "incredibly exciting for the UK to be at the forefront of this mission."   Challenging Cosmological Inflation At the heart of LiteBIRD's mission is the challenge to the cosmological inflation theory. This theory postulates the existence of "primordial gravitational waves" observable within the cosmic microwave background (CMB), the lingering light from the early universe. LiteBIRD intends to examine the pattern of B-mode polarization in the CMB to either confirm or disprove this influential theory.  

JAXA Exhibiting at the Berlin ExpoCenter Airport. Photo by DLR German Aerospace. Flickr.  

A Multinational Endeavor

Coordinated by the Japanese Aerospace Exploration Agency (JAXA), the LiteBIRD mission is poised to deploy a combination of high-, mid-, and low-frequency telescopes. These advanced instruments aim to detect B-mode signals in the cosmic microwave background (CMB) with an unparalleled level of sensitivity. The UK's active involvement is seamlessly integrated into this collaborative effort. This partnership operates through a European Consortium, masterfully led by the French space agency CNES. Notably, CNES holds the responsibility for delivering the high and mid-frequency telescopes, further enhancing the mission's scientific capabilities.   Leading Optical Development Cardiff University takes the lead in optical design and component development. Additionally, they receive support from other prominent UK universities, including Cambridge, Mullard Space Science Laboratory, University College London, Oxford, Manchester, and Sussex. Professors Peter Hargrave and Erminia Calabrese will spearhead the UK's contribution from Cardiff University. Their primary focus will be on designing and building optics for two telescopes and filters for the third, which is Japanese-built.   The Search for Gravitational Waves Professor Hargrave, LiteBIRD UK Consortium Principal Investigator, shared his excitement, noting that LiteBIRD's mission will "confirm or rule out broad classes of inflation models, and greatly enhance our understanding of the origins of our Universe." Dr. Kuninaka Hitoshi, DG, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), highlighted the international cooperation behind the mission and the invaluable contributions of the UK, including Cardiff University's unique technology.  

Beyond LiteBIRD

In addition to its role in the LiteBIRD mission, the UK Space Agency is also supporting experts at the University of Aberdeen in designing an instrument for a future JAXA Mars rover. Named "Habit," this device will explore the habitability of the landing site, provide environmental information, and demonstrate In-Situ Resource Utilization technology for future Mars exploration.  

Looking for Traces of Cosmological Inflation

The concept of cosmological inflation and its connection to LiteBIRD's mission is a fascinating area of study. The theory asserts that immediately after the Big Bang, the universe underwent exponential expansion, leaving traces observable in the cosmic microwave background (CMB) as "primordial gravitational waves."   The Cosmic Microwave Background The CMB, composed of remnant light from the early universe when it was a hot plasma, appears largely uniform but contains subtle variations. These variations, corresponding to gravitational waves imprinted on B-mode polarization signals in the CMB, hold the potential to shed light on the universe's immediate post-Big Bang history.  

UK Space Agency's Support and Engagement

The UK Space Agency's involvement in the LiteBIRD mission extends beyond financial support. It encompasses a group of UK scientists tasked with designing the mission's specialized telescope optical instruments. Moreover, Cardiff University's unique expertise comes into play as it manufactures the lenses and filters essential for LiteBIRD's telescopes.   Collaboration in Action The mission operates within a European Consortium, led by France's CNES, with the UK taking a prominent role. Much of the optical design and component development are overseen by Cardiff University, with support from various UK institutions.   Optics and Filters Cardiff University's team will design and construct optics for two telescopes and filters for the third, all of which are pivotal for LiteBIRD's success.  

The SpaceX Dragon spacecraft is pictured docked to the space-facing port on the International Space Station. Photo by NASA.  

Unveiling LiteBIRD's Mission

LiteBIRD, a mission led by the Japanese Aerospace Exploration Agency (JAXA), has a noble aim: to uncover compelling evidence that supports the cosmological inflation theory. Crafted and meticulously manufactured by the Institute of Space and Astronautical Science (ISAS) in Japan, this spacecraft will carry a weight of approximately 450 kg. Furthermore, it will be launched into the cosmos using the powerful H3 launch vehicle.   Detecting B-Mode Signals LiteBIRD's primary objective is to detect B-mode signals within the CMB. This data will provide conclusive evidence regarding the nature of the universe's expansion in the moments following the Big Bang.  

The Telescopes of LiteBIRD

LiteBIRD will execute a comprehensive three-year full-sky survey from the Sun-Earth Lagrangian point (L2). In order to achieve this ambitious goal, it will employ three telescopes. Moreover, each of these telescopes will cover a range of light frequencies: the Japanese-delivered Low-Frequency Telescope (LFT) and the European-delivered Medium-High Frequency Telescope (MHFT). Furthermore, these telescopes will utilize cutting-edge technology, including around 4,500 transition edge sensors spread across 15 observational frequency bands.   Cutting-Edge Technology LiteBIRD's telescopes are equipped with state-of-the-art lenses and specialized frequency filters. Consequently, they will operate at a cryogenic temperature of around 100 mK to minimize thermal noise and employ superconducting polarimeters for exceptionally sensitive measurements of B-mode signals' polarization. In a groundbreaking cosmic exploration endeavor, the UK's involvement in the LiteBIRD mission signifies a significant leap forward in our understanding of the universe's birth and early evolution. Furthermore, as the mission sets its sights on the cosmic microwave background and the traces of cosmological inflation, the UK's scientific and technical contributions play a pivotal and indispensable role in advancing our knowledge of the cosmos. With a mission launch anticipated before 2030, the world eagerly awaits the revelations that LiteBIRD will bring to the forefront of cosmological research.   Sources: THX News & UK Space Agency. Read the full article

[astroblogs]

Is 'dubbele breking' ontdekt in de kosmische microgolf-achtergrondstraling?

Is ‘dubbele breking’ ontdekt in de kosmische microgolf-achtergrondstraling?

De CMB, waargenomen door Planck. (Credit: ESA/Planck) De kosmische microgolf-achtergrondstraling (Engels: CMB) is het oudste licht van het heelal, het is de straling die afkomstig is van de hete oerknal, waarmee 13,8 miljard jaar geleden het heelal onstond. Vandaag de dag is de straling van de CMB afgekoeld tot 2,7K, ietsje boven het absolute nulpunt dus, maar toen de fotonen van de CMB zich…

[adrianusv61]

Is 'dubbele breking' ontdekt in de kosmische microgolf-achtergrondstraling?

Is ‘dubbele breking’ ontdekt in de kosmische microgolf-achtergrondstraling?

De CMB, waargenomen door Planck. (Credit: ESA/Planck) De kosmische microgolf-achtergrondstraling (Engels: CMB) is het oudste licht van het heelal, het is de straling die afkomstig is van de hete oerknal, waarmee 13,8 miljard jaar geleden het heelal onstond. Vandaag de dag is de straling van de CMB afgekoeld tot 2,7K, ietsje boven het absolute nulpunt dus, maar toen de fotonen van de CMB zich…

[astroimages]

QUINTESSÊNCIA - A NATUREZA DA ENERGIA ESCURA NO UNIVERSO? | SPACE TODAY ...

PASSE LÁ NA SPACE TODAY STORE, A PATROCINADORA OFICIAL DO CANAL SPACE TODAY: https://spacetodaystore.com Em 1998, os pesquisadores tiveram a primeira evidência de algo que mudou o nosso entendimento do universo, havia alguma força puxando a expansão cósmica, ou melhor dizendo acelerando a expansão do universo. Essa pista veio de dois estudos separados que foram feitos usando dados de supernovas. Desde então, muitos outros estudos confirmaram essa expansão acelerada do universo, ou seja, mostrando que havia mesmo uma força aí, força essa que foi chamada de energia escura. Primeiro, os pesquisadores pensaram que a energia escura seria uma propriedade intrínseca do espaço, mas depois outros pesquisadores sugeriram que não, e eles chamaram a energia escura de quintessência, ou seja, algo relacionado     o quinto elemento. A quintessência poderia ter propriedades mensuráveis pelos pesquisadores, e isso foi muito animador, pois seria então possível entender a natureza da energia escura. Então, em 1998 mesmo, um pesquisadores propôs um teste experimental para a quintessência, baseada na previsão que ela altera como a luz se propaga no espaço. Esse efeito poderia ser medido na CMB. CMB para quem não sabe é a radiação cósmica de microondas de fundo, ou apenas radiação de fundo, a radiação lá do Big Bang que os pesquisadores conseguem medir usando o Planck, por exemplo, entre outros observatórios espaciais especializados. A ideia era, nos mapas da CMB detectar luz polarizada, ou seja, quando o campo elétrico acaba alinhando a propagação da luz numa direção preferencial. A teoria diz que a quintessência muda a direção na qual a polarização aponta, de modo que seria possível detectar isso nos dados. Agora, outro grupo de pesquisadores, desenvolveu uma nova técnica de análise de dados aplicou nos dados do Planck e conseguiram medir a polarização da radiação. Antes de mais nada, e para não ter problema algum, já vale dizer que a análise não atingiu o que chamamos de 5 sigma, ou seja, ainda tem uma incerteza muito grande. Essas análises atingiram os 2.5 sigma. O próprio editor da Physical Reviews Letter disse que o trabalho é bom, mas precisa ser julgado por todos. O problema principal é que o dado do Planck é muito ruidoso e isso pode ser um fator decisivo na análise. Mas o trabalho aponta uma pista interessante. Tão interessante que novos projetos de detecção da CMB já estão em andamento como o Observatório Simons e o LiteBIRD no Deserto do Atacama. Se a quintessência for mesmo a explicação para a energia escura, seria um efeito em cascata muito lindo. Teríamos uma melhor estimativa da idade do universo. Poderíamos explicar melhor a CMB. Resolveria o problema da energia escura e poderíamos definir melhor o destino do universo. A quintessência como explicação da energia escura, poderia fazer com que em um certo momento, a expansão tivesse uma velocidade reduzida, desaparecer e o universo começar a contrair levando o universo ao Big Crunch. Ou seja, seriam muitos efeitos!! E aí, será que a quintessência é a explicação para a energia escura? Fontes: https://www.nature.com/articles/d41586-020-03201-8 https://arxiv.org/pdf/2011.11254.pdf #QUINTESSENCE #DARKENERGY #SPACETODAY

[arxt1]

Non-Gaussianity constraints from Planck spectral distortion cross-correlations. (arXiv:2205.15971v1 [astro-ph.CO])

Primordial non-Gaussianity can source $\mu$-distortion anisotropies that are correlated with the large-scale temperature and polarization signals of the cosmic microwave background (CMB). A measurement of $\mu T$ and $\mu E$ correlations can therefore be used to constrain it on wavelengths of perturbations not directly probed by the standard CMB anisotropies. In this work, we carry out a first rigorous search for $\mu$-type spectral distortion anisotropies with \Planck data, applying the well-tested constrained ILC component-separation method combined with the needlet framework. We reconstruct a $\mu$ map from \Planck data, which we then correlate with the CMB anisotropies to derive constraints on the amplitude $\fNL$ of the local form bispectrum, specifically on the highly squeezed configurations with effective wavenumbers $k_s \simeq \SI{740}{Mpc^{-1}}$ and $k_L \simeq \SI{0.05}{Mpc^{-1}}$. We improve previously estimated constraints by more than an order of magnitude. This enhancement is owing to the fact that for the first time we are able to use the full multipole information by carefully controlling biases and systematic effects in the final analysis. We also for the first time incorporate constraints from measurements of $\mu E$ correlations, which further tighten the limits. A combination of the derived \Planck $\mu T$ and $\mu E$ power spectra yields $|\fNL| \lesssim 6800$ (95\% c.l.) on this highly squeezed bispectrum. This is only $\simeq 3$ times weaker than the anticipated constraint from \LiteBIRD alone. We show that a combination of \LiteBIRD with \Planck will improve the expected future constraint by $\simeq 20\%$ over \LiteBIRD alone. These limits can be used to constrain multi-field inflation models and primordial black hole formation scenarios, thus providing a promising novel avenue forward in CMB cosmology.

from gr-qc updates on arXiv.org https://ift.tt/PH3IQWS

[kathleenseiber]

Quantum cosmology explains anomalies beyond Einstein’s physics

Quantum cosmology accounts for two major mysteries about the properties of the universe at the largest-scales, researchers report.

Quantum cosmology is a theory that uses quantum mechanics to extend gravitational physics beyond Einstein’s theory of general relativity.

While Einstein’s theory of general relativity can explain a large array of fascinating astrophysical and cosmological phenomena, some aspects of the properties of the universe remain puzzling.

While the differences in the theories occur at the tiniest of scales—much smaller than even a proton—they have consequences at the largest of accessible scales in the universe.

The study in Physical Review Letters also provides new predictions about the universe that future satellite missions could test.

Quantum cosmology and going beyond the Big Bang

While a zoomed-out picture of the universe looks fairly uniform, it does have a large-scale structure, for example because galaxies and dark matter are not uniformly distributed throughout the universe.

The origin of this structure has been traced back to the tiny inhomogeneities observed in the Cosmic Microwave Background (CMB)—radiation that was emitted when the universe was 380 thousand years young that we can still see today. But the CMB itself has three puzzling features that are considered anomalies because they are difficult to explain using known physics.

“While seeing one of these anomalies may not be that statistically remarkable, seeing two or more together suggests we live in an exceptional universe,” says coauthor Donghui Jeong, associate professor of astronomy and astrophysics at Penn State.

“A recent study in the journal Nature Astronomy proposed an explanation for one of these anomalies that raised so many additional concerns, they flagged a ‘possible crisis in cosmology.’ Using quantum loop cosmology, however, we have resolved two of these anomalies naturally, avoiding that potential crisis.”

Research over the last three decades has greatly improved our understanding of the early universe, including how the inhomogeneities in the CMB were produced in the first place. These inhomogeneities are a result of inevitable quantum fluctuations in the early universe. During a highly accelerated phase of expansion at very early times—known as inflation—these primordial, miniscule fluctuations were stretched under gravity’s influence and seeded the observed inhomogeneities in the CMB.

“To understand how primordial seeds arose, we need a closer look at the early universe, where Einstein’s theory of general relativity breaks down,” says Abhay Ashtekar, professor of physics, chair in physics, and director of the Penn State Institute for Gravitation and the Cosmos.

“The standard inflationary paradigm based on general relativity treats space time as a smooth continuum. Consider a shirt that appears like a two-dimensional surface, but on closer inspection you can see that it is woven by densely packed one-dimensional threads,” Ashtekar says. “In this way, the fabric of space time is really woven by quantum threads. In accounting for these threads, loop quantum cosmology allows us to go beyond the continuum described by general relativity where Einstein’s physics breaks down—for example beyond the Big Bang.”

The researchers’ previous investigation into the early universe replaced the idea of a Big Bang singularity, where the universe emerged from nothing, with the Big Bounce, where the current expanding universe emerged from a super-compressed mass that was created when the universe contracted in its preceding phase. They found that all of the large-scale structures of the universe accounted for by general relativity are equally explained by inflation after this Big Bounce using equations of loop quantum cosmology.

Resolving anomalies in Einstein’s General Relativity

In the new study, the researchers determined that inflation under loop quantum cosmology also resolves two of the major anomalies that appear under general relativity.

“The primordial fluctuations we are talking about occur at the incredibly small Planck scale,” says Brajesh Gupt, a postdoctoral researcher at Penn State at the time of the research and currently at the Texas Advanced Computing Center of the University of Texas at Austin.

“A Planck length is about 20 orders of magnitude smaller than the radius of a proton. But corrections to inflation at this unimaginably small scale simultaneously explain two of the anomalies at the largest scales in the universe, in a cosmic tango of the very small and the very large.”

The researchers also produced new predictions about a fundamental cosmological parameter and primordial gravitational waves that could be tested during future satellite missions, including LiteBird and Cosmic Origins Explorer, which will continue improve our understanding of the early universe.

Additional researchers from the National Institute of Technology Karnataka in Surathkal, India contributed to the work. Support for the research came from the National Science Foundation; NASA; the Penn State Eberly College of Science; and the Inter-University Center for Astronomy and Astrophysics in Pune, India.

Source: Penn State

The post Quantum cosmology explains anomalies beyond Einstein’s physics appeared first on Futurity.

Quantum cosmology explains anomalies beyond Einstein’s physics published first on https://triviaqaweb.weebly.com/

[scienceblogtumbler]

Cosmic tango between the very small and the very large

While Einstein’s theory of general relativity can explain a large array of fascinating astrophysical and cosmological phenomena, some aspects of the properties of the universe at the largest-scales remain a mystery. A new study using loop quantum cosmology — a theory that uses quantum mechanics to extend gravitational physics beyond Einstein’s theory of general relativity — accounts for two major mysteries. While the differences in the theories occur at the tiniest of scales — much smaller than even a proton — they have consequences at the largest of accessible scales in the universe. The study, which appears online July 29 in Physical Review Letters, also provides new predictions about the universe that future satellite missions could test.

While a zoomed-out picture of the universe looks fairly uniform, it does have a large-scale structure, for example because galaxies and dark matter are not uniformly distributed throughout the universe. The origin of this structure has been traced back to the tiny inhomogeneities observed in the Cosmic Microwave Background (CMB) — radiation that was emitted when the universe was 380,000 years young that we can still see today. But the CMB itself has three puzzling features that are considered anomalies because they are difficult to explain using known physics.

“While seeing one of these anomalies may not be that statistically remarkable, seeing two or more together suggests we live in an exceptional universe,” said Donghui Jeong, associate professor of astronomy and astrophysics at Penn State and an author of the paper. “A recent study in the journal Nature proposed an explanation for one of these anomalies that raised so many additional concerns, they flagged a ‘possible crisis in cosmology.’ Using quantum loop cosmology, however, we have resolved two of these anomalies naturally, avoiding that potential crisis.”

Research over the last three decades has greatly improved our understanding of the early universe, including how the inhomogeneities in the CMB were produced in the first place. These inhomogeneities are a result of inevitable quantum fluctuations in the early universe. During a highly accelerated phase of expansion at very early times — known as inflation — these primordial, miniscule fluctuations were stretched under gravity’s influence and seeded the observed inhomogeneities in the CMB.

“To understand how primordial seeds arose, we need a closer look at the early universe, where Einstein’s theory of general relativity breaks down,” said Abhay Ashtekar, Evan Pugh Professor of Physics, holder of the Eberly Family Chair in Physics, and director of the Penn State Institute for Gravitation and the Cosmos. “The standard inflationary paradigm based on general relativity treats space time as a smooth continuum. Consider a shirt that appears like a two-dimensional surface, but on closer inspection you can see that it is woven by densely packed one-dimensional threads. In this way, the fabric of space time is really woven by quantum threads. In accounting for these threads, loop quantum cosmology allows us to go beyond the continuum described by general relativity where Einstein’s physics breaks down — for example beyond the Big Bang.”

The researchers’ previous investigation into the early universe replaced the idea of a Big Bang singularity, where the universe emerged from nothing, with the Big Bounce, where the current expanding universe emerged from a super-compressed mass that was created when the universe contracted in its preceding phase. They found that all of the large-scale structures of the universe accounted for by general relativity are equally explained by inflation after this Big Bounce using equations of loop quantum cosmology.

In the new study, the researchers determined that inflation under loop quantum cosmology also resolves two of the major anomalies that appear under general relativity.

Diagram showing evolution of the Universe according to the paradigm of Loop Quantum Origins, developed by scientists at Penn State.

IMAGE: ALAN STONEBRAKER. P. SINGH, PHYSICS 5, 142 (2012); APS/A. STONEBRAKER

“The primordial fluctuations we are talking about occur at the incredibly small Planck scale,” said Brajesh Gupt, a postdoctoral researcher at Penn State at the time of the research and currently at the Texas Advanced Computing Center of the University of Texas at Austin. “A Planck length is about 20 orders of magnitude smaller than the radius of a proton. But corrections to inflation at this unimaginably small scale simultaneously explain two of the anomalies at the largest scales in the universe, in a cosmic tango of the very small and the very large.”

The researchers also produced new predictions about a fundamental cosmological parameter and primordial gravitational waves that could be tested during future satellite missions, including LiteBird and Cosmic Origins Explorer, which will continue to improve our understanding of the early universe.

In addition to Jeong, Ashtekar and Gupt, the research team includes V. Sreenath at the National Institute of Technology Karnataka in Surathkal, India. This work was supported by the National Science Foundation, NASA, the Penn State Eberly College of Science, and the Inter-University Center for Astronomy and Astrophysics in Pune, India.

source https://scienceblog.com/517673/cosmic-tango-between-the-very-small-and-the-very-large/

[astroblogs]

Komende LiteBIRD missie zou zelfs signalen van de inflatie in het vroegste heelal kunnen detecteren

Komende LiteBIRD missie zou zelfs signalen van de inflatie in het vroegste heelal kunnen detecteren

Impressie van zwaartekrachtgolven die de ruimtetijd doen verbuigen. Credit: Kavli IPMU De Japanse LiteBIRD ((Dat staat voor de Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection.)) missie staat gepland voor lancering in 2028 – oooohhh, nog maar zes jaar wachten – en vanuit Lagrangepunt 2, waar de Webb ruimtetelescoop nu ook…

[adrianusv61]

Komende LiteBIRD missie zou zelfs signalen van de inflatie in het vroegste heelal kunnen detecteren

Komende LiteBIRD missie zou zelfs signalen van de inflatie in het vroegste heelal kunnen detecteren

Impressie van zwaartekrachtgolven die de ruimtetijd doen verbuigen. Credit: Kavli IPMU De Japanse LiteBIRD ((Dat staat voor de Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection.)) missie staat gepland voor lancering in 2028 – oooohhh, nog maar zes jaar wachten – en vanuit Lagrangepunt 2, waar de Webb ruimtetelescoop nu ook…

[astroblogs]

Bouw van LiteBIRD, de satelliet die zwaartekrachtgolven van de oerknal gaat opsporen, is goedgekeurd

Bouw van LiteBIRD, de satelliet die zwaartekrachtgolven van de oerknal gaat opsporen, is goedgekeurd

De Japanse ruimtevaartorganisatie JAXA en het Institute for Space and Astronautical Science (ISAS) hebben deze week de bouw goedgekeurd van LiteBIRD (‘Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection’), een satelliet die op zoek gaat naar de zogeheten primordiale zwaartekrachtgolven. Dat zijn zwaartekrachtgolven die niet…

[adrianusv61]

Bouw van LiteBIRD, de satelliet die zwaartekrachtgolven van de oerknal gaat opsporen, is goedgekeurd

Bouw van LiteBIRD, de satelliet die zwaartekrachtgolven van de oerknal gaat opsporen, is goedgekeurd

De Japanse ruimtevaartorganisatie JAXA en het Institute for Space and Astronautical Science (ISAS) hebben deze week de bouw goedgekeurd van LiteBIRD (‘Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection’), een satelliet die op zoek gaat naar de zogeheten primordiale zwaartekrachtgolven. Dat zijn zwaartekrachtgolven die niet…

[arxt1]

Cosmic Birefringence: Cross-Spectra and Cross-Bispectra with CMB Anisotropies. (arXiv:2202.04584v3 [astro-ph.CO] UPDATED)

Parity-violating extensions of Maxwell electromagnetism induce a rotation of the linear polarization plane of photons during propagation. This effect, known as cosmic birefringence, impacts on the Cosmic Microwave Background (CMB) observations producing a mixing of $E$ and $B$ polarization modes which is otherwise null in the standard scenario. Such an effect is naturally parametrized by a rotation angle which can be written as the sum of an isotropic component $\alpha_0$ and an anisotropic one $\delta\alpha(\hat{\mathbf{n}})$. In this paper we compute angular power spectra and bispectra involving $\delta\alpha$ and the CMB temperature and polarization maps. In particular, contrarily to what happens for the cross-spectra, we show that even in absence of primordial cross-correlations between the anisotropic birefringence angle and the CMB maps, there exist non-vanishing three-point correlation functions carrying signatures of parity-breaking physics. Furthermore, we find that such angular bispectra still survive in a regime of purely anisotropic cosmic birefringence, which corresponds to the conservative case of having $\alpha_0=0$. These bispectra represent an additional observable aimed at studying cosmic birefringence and its parity-violating nature beyond power spectrum analyses. They provide also a way to perform consistency checks for specific models of cosmic birefringence. Moreover, we estimate that among all the possible birefringent bispectra, $\langle\delta\alpha\, TB\rangle$ and $\langle\delta\alpha\,EB\rangle$ are the ones which contain the largest signal-to-noise ratio. Once the cosmic birefringence signal is taken to be at the level of current constraints, we show that these bispectra are within reach of future CMB experiments, as LiteBIRD.

from gr-qc updates on arXiv.org https://ift.tt/NEzcvHy

[arxt1]

Cosmic Birefringence: Cross-Spectra and Cross-Bispectra with CMB Anisotropies. (arXiv:2202.04584v1 [astro-ph.CO])

Parity-violating extensions of Maxwell electromagnetism induce a rotation of the linear polarization plane of photons during propagation. This effect, known as cosmic birefringence, impacts on the Cosmic Microwave Background (CMB) observations producing a mixing of $E$ and $B$ polarization modes which is otherwise null in the standard scenario. Such an effect is naturally parametrized by a rotation angle which can be written as the sum of an isotropic component $\alpha_0$ and an anisotropic one $\delta\alpha(\hat{\mathbf{n}})$. In this paper we compute angular power spectra and bispectra involving $\delta\alpha$ and the CMB temperature and polarization maps. In particular, contrarily to what happens for the cross-spectra, we show that even in absence of primordial cross-correlations between the anisotropic birefringence angle and the CMB maps, there exist non-vanishing three-point correlation functions carrying signatures of parity-breaking physics. Furthermore, we find that such angular bispectra still survive in a regime of purely anisotropic cosmic birefringence, which corresponds to the conservative case of having $\alpha_0=0$. These bispectra represent an additional observable aimed at studying cosmic birefringence and its parity-violating nature beyond power spectrum analyses. They provide also a way to perform consistency checks for specific models of cosmic birefringence. Moreover, we estimate that among all the possible birefringent bispectra, $\langle\delta\alpha\, TB\rangle$ and $\langle\delta\alpha\,EB\rangle$ are the ones which contain the largest signal-to-noise ratio. Once the cosmic birefringence signal is taken to be at the level of current constraints, we show that these bispectra are within reach of future CMB experiments, as LiteBIRD.

from gr-qc updates on arXiv.org https://ift.tt/XQsNdlU

[arxt1]

Spinning Guest Fields during Inflation: Leftover Signatures. (arXiv:2108.06722v1 [astro-ph.CO])

We consider the possibility of extra spinning particles during inflation, focussing on the spin-2 case. Our analysis relies on the well-known fully non-linear formulation of interacting spin-2 theories. We explore the parameter space of the corresponding inflationary Lagrangian and identify regions therein exhibiting signatures within reach of upcoming CMB probes. We provide a thorough study of the early and late-time dynamics ensuring that stability conditions are met throughout the cosmic evolution. We characterise in particular the gravitational wave spectrum and three-point function finding a local-type non-Gaussianity whose amplitude may be within the sensitivity range of both the LiteBIRD and CMB-S4 experiments.

from gr-qc updates on arXiv.org https://ift.tt/3xXiSn7

[arxt1]

Measuring the spectrum of primordial gravitational waves with CMB, PTA and Laser Interferometers. (arXiv:2007.04241v1 [astro-ph.CO])

We investigate the possibility of measuring the primordial gravitational wave (GW) signal across 23 decades in frequencies, using the cosmic microwave background (CMB), pulsar timing arrays (PTA), and direct detection with laser and atomic interferometers. For the CMB and PTA experiments we consider the LiteBIRD mission and the Square Kilometer Array (SKA), respectively. For the interferometers we consider space mission proposals including the Laser Interferometer Space Antenna (LISA), the Big Bang Observer (BBO), the Deci-hertz Interferometer Gravitational wave Observatory (DECIGO), the $\mu$Ares experiment, the Decihertz Observatory (DO), and the Atomic Experiment for Dark Matter and Gravity Exploration in Space (AEDGE), as well as the ground-based Einstein Telescope (ET) and Cosmic Explorer (CE) proposals. We implement the mathematics needed to compute sensitivities for both CMB and interferometers, and derive the response functions for the latter from the first principles. We also evaluate the effect of the astrophysical foreground contamination in each experiment. We present binned sensitivity curves and error bars on the energy density parameter, $\Omega_{GW}h^2$, as a function of frequency for two representative classes of models for the stochastic background of primordial GW: the quantum vacuum fluctuation in the metric from single-field slow-roll inflation, and the source-induced tensor perturbation from the spectator axion-SU(2) inflation models. We find excellent prospects for joint measurements of the GW spectrum by CMB and space-borne direct detection mission proposals.

from gr-qc updates on arXiv.org https://ift.tt/3iTDcjg

[arxt1]

Constraining graviton non-Gaussianity through the CMB bispectra. (arXiv:1908.00366v2 [astro-ph.CO] UPDATED)

Tensor non-Gaussianities are a key ingredient to test the symmetries and the presence of higher spin fields during the inflationary epoch. Indeed, the shape of the three point correlator of the graviton is totally fixed by the symmetries of the de Sitter stage and, in the case of parity conservation, gets contributions only from the ordinary gravity action plus a higher derivative term called the (Weyl)$^3$ action. We discuss current and future bounds on the three point tensor contribution from the (Weyl)$^3$ term using cosmic microwave background (CMB) bispectra. Our results indicate that forthcoming experiments, such as LiteBIRD, CMB-S4 and CORE, will detect the presence of the (Weyl)$^3$ term if $M_p^4 L^4 \sim 10^{17} r^{-4}$, where $L$ parametrizes the strength of the (Weyl)$^3$ term and $r$ is the tensor-to-scalar ratio, which corresponds to $L\gtrsim 3.2 \times 10^5 M_p^{-1}$, while the current upper limit is $M_p^4 L^4 = (1.1 \pm 4.0) \times 10^{19} r^{-4}$ (68%CL).

from gr-qc updates on arXiv.org https://ift.tt/2Yx8aSQ