Search Publications
Test of consistency between Planck and WMAP
Hazra, Dhiraj Kumar; Shafieloo, Arman
Within the context of the concordance model of cosmology we test the consistency of the angular power spectrum data from WMAP and Planck looking for possible systematics. The best fit concordance model to each observation is used as a mean function along with a Crossing function with an orthogonal basis to fit the data from the other observation s…
Statistically anisotropic Gaussian simulations of the CMB temperature field
Souradeep, Tarun; Mukherjee, Suvodip
Although theoretically expected to be statistically isotropic (SI), the observed cosmic microwave background (CMB) temperature and polarization field would exhibit SI violation due to various inevitable effects like weak lensing, Doppler boost, and practical limitations of observations like noncircular beam, masking, etc. However, the presence of …
Current constraints on early and stressed dark energy models and future 21 cm perspectives
Mena, Olga; Archidiacono, Maria; Lopez-Honorez, Laura
Despite the great progress of current cosmological measurements, the nature of the dominant component of the Universe, coined dark energy, is still an open question. Early dark energy is a possible candidate which may also alleviate some fine-tuning issues of the standard paradigm. Using the latest available cosmological data, we find that the 95%…
Confronting dark energy anisotropic stress
Xu, Lixin; Chang, Baorong
We use currently available cosmic observations to probe and constrain an imperfect dark-energy fluid that is characterized by a constant equation of state w and a constant speed of viscosity cvis2. The model parameter space was scanned using the Markov chain Monte Carlo method. The results show that the speed of viscosity cvis2
Effects of cosmic strings with delayed scaling on CMB anisotropy
Yokoyama, Jun'ichi; Kamada, Kohei; Miyamoto, Yuhei +1 more
The network of cosmic strings generated in a phase transition during inflation enters the scaling regime later than that of usual strings. If it occurs after the recombination, temperature anisotropies of the cosmic microwave background (CMB) at high multipole moments are significantly reduced. In this paper, we study such effects qualitatively an…
Modulated inflation models and primordial black holes
Erfani, Encieh
For the first time, the running of the running of the spectral index βs has been measured by Planck. This parameter is crucial for dark matter primordial black holes (PBHs) formation. We study the PBHs formation in inflation potentials with superimposed periodic oscillations. We show that the value of βs suggested by the rece…
Large tensor-to-scalar ratio from composite inflation
Channuie, Phongpichit; Karwan, Khamphee
The claimed detection of the BICEP2 experiment on the primordial B-mode of cosmic microwave background polarization suggests that cosmic inflation possibly takes place at the energy around the grand unified theory scale given a constraint on the tensor-to-scalar ratio, i.e., r≃0.20. In this report, we revisit single-field (slow-roll) composite inf…
Effects of mass varying neutrinos on cosmological parameters as determined from the cosmic microwave background
Ghalsasi, Akshay; Nelson, Ann E.
In models with a light scalar field (the "acceleron") coupled to neutrinos, neutrino masses depend on neutrino density. The resulting coupled system of mass varying neutrinos (MaVaNs) and the acceleron can act as a negative pressure fluid and is a candidate for dark energy [R. Fardon et al. J. Cosmol. Astropart. Phys. 10 (2004) 005]. MaVaNs also a…
Quantum collapse as a source of the seeds of cosmic structure during the radiation era
Landau, Susana J.; León, Gabriel; Piccirilli, María Pía
The emergence of the seeds of cosmic structure, from a perfect isotropic and homogeneous Universe, has not been clearly explained by the standard version of inflationary models as the dynamics involved preserve the homogeneity and isotropy at all times. A proposal that attempts to deal with this problem, by introducing "the self-induced collapse h…
Secondary CMB anisotropies from bulk motions in the presence of stochastic magnetic fields
Kunze, Kerstin E.
Bulk motions of electrons along the line of sight induce secondary temperature fluctuations in the postdecoupling, reionized Universe. In the presence of a magnetic field not only the scalar mode but also the vector mode act as a source for the bulk motion. The resulting angular power spectrum of temperature anisotropies of the cosmic microwave ba…