Publications (44)
Evidence for GeV Pair Halos around Low Redshift Blazars
Wenlei Chen, James H. Buckley, Francesc Ferrer
We report on the results of a search for -ray pair halos with a stacking analysis of low-redshift blazars using data from the Fermi Large Area Telescope. For this analysis we u…
Constraints on Light Hidden Sector Gauge Bosons from Supernova Cooling
James B. Dent, Francesc Ferrer, Lawrence M. Krauss
We derive new bounds on hidden sector gauge bosons which could produce new energy loss mechanisms in supernovae, enlarging the excluded region in mass-coupling space by a significa…
TeV Dark Matter detection by Atmospheric Cerenkov Telescopes
Francesc Ferrer
Ground based Atmospheric Cerenkov Telescopes have recently unveiled a TeV gamma-ray signal from the direction of the Galactic Centre. We examine whether these gamma-rays, observed…
Probing Heavy Axion-like Particles from Massive Stars with X-rays and Gamma Rays
James H. Buckley, P. S. Bhupal Dev, Francesc Ferrer +1
The hot interiors of massive stars in the later stages of their evolution provide an ideal place for the production of heavy axion-like particles (ALPs) with mass up to O(100 keV)…
Novel Search for TeV-Initiated Pair Cascades in the Intergalactic Medium
Wenlei Chen, Manel Errando, James H. Buckley +1
TeV emission from blazars can be used to probe the intergalactic magnetic fields and measure their intensity, coherence length, and helicity. Intergalactic magnetic fields deflect…
Dark energy and decompactification in string gas cosmology
Francesc Ferrer, Syksy Rasanen
We study the stability of extra dimensions in string gas cosmology at late times. Vacuum energy and, interestingly, baryons lead to decompactification after they become dynamically…
The clustering of ultra-high energy cosmic rays and their sources
N. Wyn Evans, Francesc Ferrer, Subir Sarkar
The sky distribution of cosmic rays with energies above the 'GZK cutoff' holds important clues to their origin. The AGASA data, although consistent with isotropy, shows evidence fo…
Possible Evidence for MeV Dark Matter In Dwarf Spheroidals
Dan Hooper, Francesc Ferrer, Céline Boehm +4
It has been recently proposed that the observed 511 keV emission from the Galactic bulge could be the product of very light (1-100 MeV) annihilating dark matter particles. Other po…
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
Marco Battaglieri, Alberto Belloni, Aaron Chou +248
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.
New constraints on the dark matter-neutrino and dark matter-photon scattering cross sections from TXS 0506+056
Francesc Ferrer, Gonzalo Herrera, Alejandro Ibarra
The flux of high energy neutrinos and photons produced in a blazar could get attenuated when they propagate through the dark matter spike around the central black hole and the halo…
Search for CP Violating Signature of Intergalactic Magnetic Helicity in the Gamma Ray Sky
Hiroyuki Tashiro, Wenlei Chen, Francesc Ferrer +1
The existence of a cosmological magnetic field could be revealed by the effects of non-trivial helicity on large scales. We evaluate a CP odd statistic, , using gamma ray data o…
Zero modes on cosmic strings in an external magnetic field
Francesc Ferrer, Harsh Mathur, Tanmay Vachaspati +1
A classical analysis suggests that an external magnetic field can cause trajectories of charge carriers on a superconducting domain wall or cosmic string to bend, thus expelling ch…
Dark matter spikes in the vicinity of Kerr black holes
Francesc Ferrer, Augusto Medeiros da Rosa, Clifford M. Will
The growth of a massive black hole will steepen the cold dark matter density at the center of a galaxy into a dense spike, enhancing the prospects for indirect detection. We study…
Primordial Black Holes from the QCD axion
Francesc Ferrer, Eduard Masso, Giuliano Panico +2
We propose a mechanism to generate Primordial Black Holes (PBHs) which is independent of cosmological inflation and occurs slightly below the QCD phase transition. Our setup relies…
Gravitational Waves from First-Order Phase Transition in a Simple Axion-Like Particle Model
P. S. Bhupal Dev, Francesc Ferrer, Yiyang Zhang +1
We consider a gauge-singlet complex scalar field with a global symmetry that is spontaneously broken at some high energy scale . As a result, the angular part of t…
The 511-CAM Mission: A Pointed 511 keV Gamma-Ray Telescope with a Focal Plane Detector Made of Stacked Transition Edge Sensor Microcalorimeter Arrays
Farzane Shirazi, Md. Arman Hossen, Daniel Becker +18
The 511 keV gamma-ray emission from the galactic center region may fully or partially originate from the annihilation of positrons from dark matter particles with electrons from th…
Light superconducting strings in the Galaxy
Francesc Ferrer, Tanmay Vachaspati
Observations of the Milky Way by the SPI/INTEGRAL satellite have confirmed the presence of a strong 511 KeV gamma-ray line emission from the bulge, which require an intense source…
Secular evolution of galaxies and galaxy clusters in decaying dark matter cosmology
Francesc Ferrer, Carlo Nipoti, Stefano Ettori
If the dark matter sector in the universe is composed by metastable particles, galaxies and galaxy clusters are expected to undergo significant secular evolution from high to low r…
Indirect detection of light neutralino dark matter in the NMSSM
Francesc Ferrer, Lawrence M. Krauss, Stefano Profumo
We explore the prospects for indirect detection of neutralino dark matter in supersymmetric models with an extended Higgs sector (NMSSM). We compute, for the first time, one-loop a…
Vacuum Topology and the Electroweak Phase Transition
Yiyang Zhang, Francesc Ferrer, Tanmay Vachaspati
We investigate if the topology of pure gauge fields in the electroweak vacuum can play a role in classical dynamics at the electroweak phase transition. Our numerical analysis show…
Fitting oscillating string gas cosmology to supernova data
Francesc Ferrer, Tuomas Multamaki, Syksy Rasanen
In string gas cosmology, extra dimensions are stabilised by a gas of strings. In the matter-dominated era, competition between matter pushing the extra dimensions to expand and the…
A novel approach to derive halo-independent limits on dark matter properties
Francesc Ferrer, Alejandro Ibarra, Sebastian Wild
We propose a method that allows to place an upper limit on the dark matter elastic scattering cross section with nucleons which is independent of the velocity distribution. Our app…
The Anisotropy of the Ultra-High Energy Cosmic Rays
Wyn Evans, Francesc Ferrer, Subir Sarkar
Ultra-high energy cosmic rays (UHECRs) may originate from the decay of massive relic particles in the dark halo of the Galaxy, or they may be produced by supermassive black holes i…
511 KeV photons from superconducting cosmic strings
Francesc Ferrer, Tanmay Vachaspati
We show that a tangle of light superconducting strings in the Milky Way could be the source of the observed 511 KeV emission from electron-positron annihilation in the Galactic bul…
Fast radio bursts from axion stars moving through pulsar magnetospheres
James H. Buckley, P. S. Bhupal Dev, Francesc Ferrer +1
We study the radio signals generated when an axion star enters the magnetosphere of a neutron star. As the axion star moves through the resonant region where the plasma-induced pho…
Degree-scale anomalies in the CMB: localizing the first peak dip to a small patch of the north ecliptic sky
Amanda Yoho, Francesc Ferrer, Glenn D. Starkman
Noticeable deviations from the prediction of the fiducial LCDM cosmology are found in the angular power spectrum of the CMB. Besides large-angle anomalies, the WMAP 1st year data r…
Gravitational waves from the Axiverse
Saurav Das, Francesc Ferrer
Models with axion like particles (ALPs) often predict the formation of a string-domain wall network in the early universe. We study how such networks of defects appear in the conte…
Magnetic field production at a first-order electroweak phase transition
Yiyang Zhang, Tanmay Vachaspati, Francesc Ferrer
We study the generation of magnetic field seeds during a first-order electroweak phase transition, by numerically evolving the classical equations of motion of the bosonic electrow…
Dark matter in natural supersymmetric extensions of the Standard Model
Francesc Ferrer, Christopher Spitzer
We explore the dark matter sector in extensions of the Minimal Supersymmetric Standard Model (MSSM) that can provide a good fit to the PAMELA cosmic ray positron excess, while at t…
Reply to ``Cuts and penalties: comment on `The clustering of ultra-high energy cosmic rays and their sources' ''
N. W. Evans, Francesc Ferrer, Subir Sarkar
We reiterate that there is no evidence that BL Lacs are sources of ultrahigh energy cosmic rays.
On the Galactic radio signal from stimulated decay of axion dark matter
P. S. Bhupal Dev, Francesc Ferrer, Takuya Okawa
We study the full-sky distribution of the radio emission from the stimulated decay of axions which are assumed to compose the dark matter in the Galaxy. Besides the constant extrag…
The Scientific Reach of Multi-Ton Scale Dark Matter Direct Detection Experiments
Jayden L. Newstead, Thomas D. Jacques, Lawrence M. Krauss +2
The next generation of large scale WIMP direct detection experiments have the potential to go beyond the discovery phase and reveal detailed information about both the particle phy…
Lovelock inflation and the number of large dimensions
Francesc Ferrer, Syksy Rasanen
We discuss an inflationary scenario based on Lovelock terms. These higher order curvature terms can lead to inflation when there are more than three spatial dimensions. Inflation w…
Dark Matter Boosted by Terrestrial Collisions
Zamiul Alam, Christopher V. Cappiello, Francesc Ferrer
Inelastic dark matter (IDM) models feature an energy threshold for scattering with Standard Model particles, which enables their consistency with the increasingly stringent limits…
Dark matter distributions around massive black holes: A general relativistic analysis
Laleh Sadeghian, Francesc Ferrer, Clifford M. Will
The cold dark matter at the center of a galaxy will be redistributed by the presence of a massive black hole. The redistribution may be determined using an approach pioneered by Go…
Cosmological acceleration from a gas of strings
Francesc Ferrer
In string gas cosmology, the extra dimensions of the underlying theory are kept at a microscopic scale by a gas of strings. In the matter-dominated era, however, dust pressure can…
Correlated isocurvature perturbations from mixed inflaton-curvaton decay
Francesc Ferrer, Syksy Rasanen, Jussi Valiviita
We study cosmological perturbations in the case that present-day matter consists of a mixture of inflaton and curvaton decay products. We calculate how the curvaton perturbations a…
Helical Magnetic Fields from Sphaleron Decay and Baryogenesis
Craig J. Copi, Francesc Ferrer, Tanmay Vachaspati +1
Many models of baryogenesis rely on anomalous particle physics processes to give baryon number violation. By numerically evolving the electroweak equations on a lattice, we show th…
Imprints of a Supercooled Phase Transition in the Gravitational Wave Spectrum from a Cosmic String network
Francesc Ferrer, Anish Ghoshal, Marek Lewicki
A network of cosmic strings (CS), if present, would continue emitting gravitational waves (GW) as it evolves throughout the history of the Universe. This results in a characteristi…
The impact of the phase-space density on the indirect detection of dark matter
Francesc Ferrer, Daniel R. Hunter
We study the indirect detection of dark matter when the local dark matter velocity distribution depends upon position, as expected for the Milky Way and its dwarf spheroidal satell…
Detecting Chameleon Dark Energy via Electrostatic Analogy
Katherine Jones-Smith, Francesc Ferrer
The late-time accelerated expansion of the universe could be caused by a scalar field that is screened on small scales, as in chameleon or symmetron scenarios. We present an analog…
Have Atmospheric Cerenkov Telescopes Observed Dark Matter?
Dan Hooper, Ignacio de la Calle Perez, Joseph Silk +2
Two ground-based experiments have recently independently detected TeV -rays from the direction of the Galactic center. The observations made by the VERITAS and CANGAROO collabo…
Intergalactic magnetic field spectra from diffuse gamma rays
Wenlei Chen, Borun D. Chowdhury, Francesc Ferrer +2
Non-vanishing parity-odd correlators of gamma ray arrival directions observed by Fermi-LAT indicate the existence of a helical intergalactic magnetic field (Tashiro et al.2013). We…
Cuspidal Singularities in Collapsing Domain Walls
Jose J. Blanco-Pillado, Matthew Elley, Francesc Ferrer +4
Domain wall networks have attracted renewed interest, particularly in relation to the dynamics of network collapse. Accurately describing this process is challenging and typically…