No, This Isn’t a Doorway on Mars A Mastcam image from the Mars Curiosity rover captures what looks like a doorway into a rock ledge. It was formed when layered rock cracked and eroded away. Courtesy NASA Mars Curiosity Rover team. The planet Mars has a lot of intriguing geological features, but a doorway in the side of some sedimentary rock on the flank of Mount Sharp (Aeolis Mons) isn’t one of them. In fact, no such doorway on Mars (supposedly created by aliens) exists. But, there is a break in the rock that really, really does look like one. The fact that it isn’tRead More →

Constraining Fundamental Constant Variations from Ultralight Dark Matter with Pulsar Timing Arrays. (arXiv:2205.06817v1 [hep-ph]) <a href="">David E. Kaplan</a>, <a href="">Andrea Mitridate</a>, <a href="">Tanner Trickle</a> Pulsar Timing Arrays (PTAs) are exceptionally sensitive detectors in the frequency band $text{nHz} lesssim f lesssim mutext{Hz}$. Ultralight dark matter (ULDM), with mass in the range $10^{-23},text{eV} lesssim m_phi lesssim 10^{-20},text{eV}$, is one class of DM models known to generate signals in this frequency window. While purely gravitational signatures of ULDM have been studied previously, in this work we consider two signals in PTAs which arise in presence of direct couplings between ULDM and ordinary matter. These couplings induce variations inRead More →

The angular scale of homogeneity with SDSS-IV DR16 Luminous Red Galaxies. (arXiv:2205.07819v1 [astro-ph.CO]) <a href="">Uendert Andrade</a>, <a href="">Rodrigo S. Gon&#xe7;alves</a>, <a href="">Gabriela C. Carvalho</a>, <a href="">Carlos A. P. Bengaly</a>, <a href="">Joel C. Carvalho</a>, <a href="">Jailson Alcaniz</a> We report measurements of the angular scale of cosmic homogeneity ($theta_{h}$) using the recently released luminous red galaxy sample of the sixteenth data release of the Sloan Digital Sky Survey (SDSS-IV LRG DR16). This consists on a model-independent method, as we only use the celestial coordinates of these objects to carry out such an analysis. The observational data is divided in thin redshift bins, namely $0.67<z<0.68$, $0.70<z<0.71$, and $0.73<z<0.74$,Read More →

Scintillation yield from electronic and nuclear recoils in superfluid $^4$He. (arXiv:2108.02176v2 [physics.ins-det] UPDATED) <a href="">SPICE/HeRALD Collaboration</a>: <a href="">A. Biekert</a>, <a href="">C. Chang</a>, <a href="">C. W. Fink</a>, <a href="">M. Garcia-Sciveres</a>, <a href="">E. C. Glazer</a>, <a href="">W. Guo</a>, <a href="">S. A. Hertel</a>, <a href="">S. Kravitz</a>, <a href="">J. Lin</a>, <a href="">M. Lisovenko</a>, <a href="">R. Mahapatra</a>, <a href="">D. N. McKinsey</a>, <a href="">J. S. Nguyen</a>, <a href="">V. Novosad</a>, <a href="">W. Page</a>, <a href="">P. K. Patel</a>, <a href="">B. Penning</a>, <a href="">H. D. Pinckney</a>, <a href="">M. Pyle</a>, <a href="">R. K. Romani</a>, <a href="">A. S. Seilnacht</a>, <a href="">A. Serafin</a>, <a href="">R. J. Smith</a>, <a href="">P. Sorensen</a>, <a href="">B. Suerfu</a>, <a href="">A. Suzuki</a>, <aRead More →

The primordial black hole from running curvaton. (arXiv:2107.07310v3 [astro-ph.CO] UPDATED) <a href="">Lei-Hua Liu</a> In light of our previous work cite{Liu:2019xhn}, we investigate the possibility of the formation of a primordial black-hole during preheating period, in which we have implemented the instability of the Mathieu equation. For generating sufficient enough enhanced power spectrum, we choose some proper parameters belonging to the narrow resonance. To characterize the full power spectrum, the enhanced part of the power spectrum is depicted by the $delta$ function at some specific scales, which is highly relevant to the mass of the inflaton due to the explicit coupling between the curvaton and inflaton.Read More →

Interstellar Gas Heating by Primordial Black Holes. (arXiv:2105.06099v2 [astro-ph.GA] UPDATED) <a href="">Volodymyr Takhistov</a>, <a href="">Philip Lu</a>, <a href="">Graciela B. Gelmini</a>, <a href="">Kohei Hayashi</a>, <a href="">Yoshiyuki Inoue</a>, <a href="">Alexander Kusenko</a> Interstellar gas heating is a powerful cosmology-independent observable for exploring the parameter space of primordial black holes (PBHs) formed in the early Universe that could constitute part of the dark matter (DM). We provide a detailed analysis of the various aspects for this observable, such as PBH emission mechanisms. Using observational data from the Leo T dwarf galaxy, we constrain the PBH abundance over a broad mass-range, $M_{rm PBH} sim mathcal{O}(1) M_{odot}-10^7 M_{odot}$, relevant for theRead More →

On the origin of observed cosmic ray spectrum below 100 TV. (arXiv:2105.04630v2 [astro-ph.HE] UPDATED) <a href="">Mikhail A. Malkov</a>, <a href="">Igor V. Moskalenko</a> Recent precise measurements of primary and secondary cosmic rays (CRs) in the TV rigidity domain have unveiled a bump in their spectra, located between 0.5-50 TV. We argue that a local shock may generate such a bump by increasing the rigidity of the preexisting CRs below 50 TV by a mere factor of ~1.5. Reaccelerated particles below ~0.5 TV are convected with the interstellar medium (ISM) flow and do not reach the Sun, thus creating the bump. This single universal process is responsibleRead More →

House UFO Hearing Brings a Few Answers and More Questions For the first time in more than half a century, Congress conducted a public hearing into the state of the Pentagon’s study of unidentified aerial phenomena — which is the new name for mysteries once known as unidentified flying objects, or UFOs. Scott Bray, deputy director of naval intelligence, told a hearing organized by the House Intelligence subcommittee on counterterrorism, counterintelligence and counterproliferation that military reports about UFOs — sorry, I mean UAPs — have been “frequent and continuing.” Today’s hearing follows up on a Pentagon report that was issued last year and listed 144Read More →

Carbon-12 is an Essential Building Block for Life and Scientists Have Finally Figured Out How it Forms in Stars Artist’s impression of a red giant star. Their cores are cauldrons where carbon-12 is produced. Credit:NASA/ Walt Feimer Each of us is, as it says in Max Ehrmann’s famous poem “Desiderata”, a child of the universe. It speaks metaphorically about our place in the cosmos, but it turns out to be a very literal truth. Our bodies contain the stuff of stars and galaxies, and that makes us children of the cosmos. To be more precise, we are carbon-based life forms. All life on Earth isRead More →

Image: Hubble reveals a river of star formation This newly revised NASA Hubble Space Telescope image of the Hickson Compact Group 31 (HCG 31) of galaxies highlights streams of star-formation as four dwarf galaxies interact. The bright, distorted clump of young blue-white stars (top-right of center) is NGC 1741. Although it appears to be a single galaxy, NGC 1741 is actually a pair of colliding dwarf galaxies. Another dwarf, cigar-shaped galaxy to the pair’s right joins their dance with a thin, blue stream of stars that connects the trio. HGC 31’s fourth member is revealed by a stream of young blue stars that point toRead More →

Merging Supermassive Black Holes Gives us a New Way to Measure the Universe The study of black holes has advanced immensely in the past few years. In 2015, the first gravitational waves were observed by scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO). This finding confirmed what Einstein predicted a century before with General Relativity and offered new insight into black hole mergers. In 2019, scientists with the Event Horizon Telescope (EHT) Collaboration shared the first image of a supermassive black hole (SMBH), which resides at the center of the M87 galaxy. Earlier this month, the EHT announced that they had also acquired the firstRead More →

Mysterious nuclear transient AT2019pev inspected in X-rays Astronomers from the Ohio State University (OSU) and elsewhere have performed a detailed X-ray observational campaign of a mysterious nuclear transient event known as AT2019pev. Results of the study, published May 10 on the arXiv pre-print server, offer more clues into the nature of this peculiar object. Go to SourceRead More →

Triboelectric Backgrounds to radio-based UHE Neutrino Exeperiments. (arXiv:2103.06079v2 [astro-ph.IM] UPDATED) <a href="">J. A. Aguilar</a>, <a href="">A. Anker</a>, <a href="">P. Allison</a>, <a href="">S. Archambault</a>, <a href="">P. Baldi</a>, <a href="">S. W. Barwick</a>, <a href="">J. J. Beatty</a>, <a href="">J. Beise</a>, <a href="">D. Besson</a>, <a href="">A. Bishop</a>, <a href="">E. Bondarev</a>, <a href="">O. Botner</a>, <a href="">S. Bouma</a>, <a href="">S. Buitink</a>, <a href="">M. Cataldo</a>, <a href="">C.C. Chen</a>, <a href="">C.H. Chen</a>, <a href="">P. Chen</a>, <a href="">Y.C. Chen</a>, <a href="">B. A. Clark</a>, <a href="">W. Clay</a>, <a href="">Z. Curtis-Ginsberg</a>, <a href="">A. Connolly</a>, <a href="">P. Dasgupta</a>, <a href="">S. de Kockere</a>, <a href="">K. D. de Vries</a>, <a href="">C. Deaconu</a>, <a href="">M. A. DuVernois</a>, <a href="">J. Flaherty</a>,Read More →

First-Order Quantum Correction in Coherent State Expectation Value of Loop-Quantum-Gravity Hamiltonian: Overview and Results. (arXiv:2012.14242v4 [gr-qc] UPDATED) <a href="">Cong Zhang</a>, <a href="">Shicong Song</a>, <a href="">Muxin Han</a> Given the Loop-Quantum-Gravity (LQG) non-graph-changing Hamiltonian $widehat{H[N]}$, the coherent state expectation value $langlewidehat{H[N]}rangle$ admits an semiclassical expansion in $ell^2_{rm p}$. In this paper, we compute explicitly the expansion of $langlewidehat{H[N]}rangle$ on the cubic graph to the linear order in $ell^2_{rm p}$, when the coherent state is peaked at the homogeneous and isotropic data of cosmology. In our computation, a powerful algorithm is developed to overcome the complexity in computing $langle widehat{H[N]} rangle$. In particular, some key innovations in ourRead More →

Turning in the landscape: a new mechanism for generating Primordial Black Holes. (arXiv:2004.08369v3 [hep-th] UPDATED) <a href="">Jacopo Fumagalli</a>, <a href="">S&#xe9;bastien Renaux-Petel</a>, <a href="">John W. Ronayne</a>, <a href="">Lukas T. Witkowski</a> We propose a new model-independent mechanism for producing primordial black holes from a period of multi-field inflation. This requires an enhancement of primordial fluctuations at short scales compared to their value at CMB scales. We show that such an amplification naturally occurs when the inflationary trajectory exhibits a strong turn, that is a limited period during which the trajectory strongly deviates from a geodesic in field space, and is sufficient for subsequently producing primordial black holesRead More →

Runko: Modern multiphysics toolbox for plasma simulations. (arXiv:1906.06306v3 [physics.comp-ph] UPDATED) <a href="">J. N&#xe4;ttil&#xe4;</a> Runko is a new open-source plasma simulation framework implemented in C++ and Python. It is designed to function as an easy-to-extend general toolbox for simulating astrophysical plasmas with different theoretical and numerical models. Computationally intensive low-level kernels are written in modern C++ taking advantage of polymorphic classes, multiple inheritance, and template metaprogramming. High-level functionality is operated with Python scripts. The hybrid program design ensures good code performance together with ease of use. The framework has a modular object-oriented design that allows the user to easily add new numerical algorithms to the system.Read More →

Understanding the relativistic overdensity of galaxy surveys. (arXiv:1606.00712v5 [astro-ph.CO] UPDATED) <a href="">Didam Duniya</a> (BIUST, Cape Town, AIMS, Western Cape) The main goal of galaxy surveys is to map the distribution of the galaxies, for the purpose of understanding the properties of this distribution and its implications for the content and the evolution of the universe. However, in order to realise the full potential of these surveys, we need to ensure that we are using the correct analysis: a relativistic analysis, which has been widely studied recently. In this work, the known relativistic overdensity of galaxy surveys is re-examined. Unlike in previous works, a consistent approachRead More →

Cosmological Bound on the QCD Axion Mass, Redux. (arXiv:2205.07849v1 [astro-ph.CO]) <a href="">Francesco D&#x27;Eramo</a>, <a href="">Eleonora Di Valentino</a>, <a href="">William Giar&#xe8;</a>, <a href="">Fazlollah Hajkarim</a>, <a href="">Alessandro Melchiorri</a>, <a href="">Olga Mena</a>, <a href="">Fabrizio Renzi</a>, <a href="">Seokhoon Yun</a> We revisit the joint constraints in the mixed hot dark matter scenario in which both thermally produced QCD axions and relic neutrinos are present. Upon recomputing the cosmological axion abundance via recent advances in the literature, we improve the state-of-the-art analyses and provide updated bounds on axion and neutrino masses. By avoiding approximate methods, such as the instantaneous decoupling approximation, and limitations due to the limited validity of the perturbativeRead More →

Non-Universal Stellar Initial Mass Functions: Large Uncertainties in Star Formation Rates at $zapprox 2-4$ and Other Astrophysical Probes. (arXiv:2205.07845v1 [astro-ph.GA]) <a href="">Joshua J. Ziegler</a>, <a href="">Thomas D. P. Edwards</a>, <a href="">Anna M. Suliga</a>, <a href="">Irene Tamborra</a>, <a href="">Shunsaku Horiuchi</a>, <a href="">Shin&#x27;ichiro Ando</a>, <a href="">Katherine Freese</a> We explore the assumption, widely used in many astrophysical calculations, that the stellar initial mass function (IMF) is universal across all galaxies. By considering both a canonical Salpeter-like IMF and a non-universal IMF, we are able to compare the effect of different IMFs on multiple observables and derived quantities in astrophysics. Specifically, we consider a non-universal IMF which varies asRead More →

Patchy nightside clouds on ultra-hot Jupiters: General Circulation Model simulations with radiatively active cloud tracers. (arXiv:2205.07834v1 [astro-ph.EP]) <a href="">Thaddeus D. Komacek</a>, <a href="">Xianyu Tan</a>, <a href="">Peter Gao</a>, <a href="">Elspeth K.H. Lee</a> The atmospheres of ultra-hot Jupiters have been characterized in detail through recent phase curve and low- and high-resolution emission and transmission spectroscopic observations. Previous numerical studies have analyzed the effect of the localized recombination of hydrogen on the atmospheric dynamics and heat transport of ultra-hot Jupiters, finding that hydrogen dissociation and recombination lead to a reduction in the day-to-night contrasts of ultra-hot Jupiters relative to previous expectations. In this work, we add to previousRead More →