Raul Jimenez

Harvard University, Cambridge, Massachusetts, United States

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Publications (181)1000.74 Total impact

  • Emilio Bellini · Antonio J. Cuesta · Raul Jimenez · Licia Verde ·
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    ABSTRACT: Recent anomalies found in cosmological datasets such as the low multipoles of the Cosmic Microwave Background or the low redshift amplitude and growth of clustering measured by e.g., abundance of galaxy clusters and redshift space distortions in galaxy surveys, have motivated explorations of models beyond standard {\Lambda}CDM. Of particular interest are models where general relativity (GR) is modified on large cosmological scales. Here we consider deviations from {\Lambda}CDM+GR within the context of Horndeski gravity, which is the most general theory of gravity with second derivatives in the equations of motion. We adopt a parametrization in which the four additional Horndeski functions of time {\alpha}_i(t) are proportional to the cosmological density of dark energy {\Omega}_DE(t). Constraints on this extended parameter space using a suite of state-of-the art cosmological observations are presented for the first time. Although the theory is able to accommodate the low multipoles of the Cosmic Microwave Background and the low amplitude of fluctuations from redshift space distortions, we find no significant tension with {\Lambda}CDM+GR when performing a global fit to recent cosmological data and thus there is no evidence against {\Lambda}CDM+GR from an analysis of the value of the Bayesian evidence ratio of the modified gravity models with respect to {\Lambda}CDM, despite introducing extra parameters. The posterior distribution of these extra parameters that we derive return strong constraints on any possible deviations from {\Lambda}CDM+GR in the context of Horndeski gravity. We illustrate how our results can be applied to a more general frameworks of modified gravity models.
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    ABSTRACT: Galactic Gamma-Ray Bursts (GRBs) are copious sources of gamma-rays that can pose a threat to complex life. Using recent determinations of their rate and the probability of GRBs causing massive extinction, we explore what type of universes are most likely to harbour advanced forms of life. For this purpose we use cosmological N-body simulations to determine at what time and for what value of the cosmological constant ($\Lambda$) the chances of life being unaffected by cosmic explosions are maximised. We find that $\Lambda-$dominated universes favour the survival of life against GRBs. Within a $\Lambda$CDM cosmology, the parameters that govern the likelihood of life survival to GRBs are dictated by the value of $\Lambda$ and the age of the Universe. We find that we seem to live in a favorable point in this parameter phase space which minimises the exposure to cosmic explosions, yet maximises the number of main sequence (hydrogen-burning) stars around which advanced life forms can exist.
  • Michele Trenti · Paolo Padoan · Raul Jimenez ·
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    ABSTRACT: Old globular clusters (GCs) in the Milky Way have ages of about 13 Gyr, placing their formation time in the reionization epoch. We propose a novel scenario for the formation of these systems based on the merger of two or more atomic cooling halos at high redshift (z > 6). First-generation stars are formed as an intense burst in the center of a minihalo that grows above the threshold for hydrogen cooling (halo mass ∼Mh 10 8M⊙ ) by undergoing a major merger within its cooling timescale (∼150 Myr). Subsequent minor mergers and sustained gas infall bring a new supply of pristine gas to the halo center, creating conditions that can trigger new episodes of star formation. The dark-matter halo around the GC is then stripped during assembly of the host-galaxy halo. Minihalo merging is efficient only in a short redshift window, set by the LCDM parameters, allowing us to make a strong prediction on the age distribution for old GCs. From cosmological simulations, we derive an average merging redshift 〈z〉= 9 and a narrow distribution δz = 2, implying average GC age 〈átage 〉ñ = 13.0 ± 0.2 Gyr including ∼0.2 Gyr of star formation delay. Qualitatively, our scenario reproduces other general old GC properties (characteristic masses and number of objects, metallicity versus galactocentric radius anticorrelation, radial distribution), but unlike age, these generally depend on details of baryonic physics. In addition to improved age measurements, direct validation of the model at z ∼10 may be within reach with ultradeep gravitationally lensed observations with the James Webb Space Telescope. © 2015. The American Astronomical Society. All rights reserved.
    07/2015; 808(2):L35. DOI:10.1088/2041-8205/808/2/L35
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    ABSTRACT: Applying a transformation to a non-Gaussian field can enhance the information content of the resulting power spectrum, by reducing the correlations between Fourier modes. In the context of weak gravitational lensing, it has been shown that this gain in information content is significantly compromised by the presence of shape noise. We apply clipping to mock convergence fields, a technique which is known to be robust in the presence of noise and has been successfully applied to galaxy number density fields. When analysed in isolation the resulting convergence power spectrum returns degraded constraints on cosmological parameters. However substantial gains can be achieved by performing a combined analysis of the power spectra derived from both the original and transformed fields. Even in the presence of realistic levels of shape noise, we demonstrate that this approach is capable of reducing the area of likelihood contours within the $\Omega_m - \sigma_8$ plane by more than a factor of three.
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    Emilio Bellini · Raul Jimenez · Licia Verde ·
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    ABSTRACT: We present a detailed study of second-order matter perturbations for the general Horn- deski class of models. Being the most general scalar-tensor theory having second-order equations of motion, it includes many known gravity and dark energy theories and General Relativity with a cosmological constant as a specific case. This enables us to estimate the leading order dark matter bispectrum generated at late-times by gravitational instability. We parametrize the evolution of the first and second-order equations of motion as proposed by Bellini and Sawicki (2014), where the free functions of the theory are assumed to be proportional to the dark energy density. We show that it is unnatural to have large 10% ( 1%) deviations of the bispectrum introducing even larger ~ 30% (~ 5%) deviations in the linear growth rate. Considering that measurements of the linear growth rate have much higher signal-to-noise than bispectrum measurements, this indicates that for Horndeski models which reproduce the expansion history and the linear growth rate as predicted by GR the dark matter bispectrum kernel can be effectively modelled as the standard GR one. On the other hand, an observation of a large bispectrum deviation that can not be explained in terms of bias would imply either that the evolution of perturbations is strongly different than the evolution predicted by GR or that the theory of gravity is exotic (e.g., breaks the weak equivalence principle) and/or fine-tuned.
    Journal of Cosmology and Astroparticle Physics 04/2015; 2015(05). DOI:10.1088/1475-7516/2015/05/057 · 5.81 Impact Factor
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    Michele Trenti · Paolo Padoan · Raul Jimenez ·
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    ABSTRACT: We propose a novel scenario for the formation of Globular Clusters (GCs) based on the merger of two or more atomic cooling halos at high-redshift (z>6). The model naturally fulfills several key observational constraints on GCs that have emerged in the last decade. Specifically, absolute and relative ages, widespread presence of multiple stellar populations, spatial distribution around host galaxies, and correlations between galactocentric radius and metallicity. In our framework, the oldest globular clusters form the first generation stars as an intense burst in the center of a minihalo that grows above the threshold for hydrogen cooling (halo mass M_h~1e8 Msun) and undergoes a major merger within the cooling timescale (~150 Myr). Subsequent minor mergers and sustained gas infall bring new supply of pristine gas at the halo center, diluting AGB ejecta, and triggering additional bursts of star formation which form multiple generation of stars in the majority of the clusters. The DM halo around the GC is then stripped during assembly of the host galaxy halo. Our modeling is based on the merging history of dark-matter halos, and thus has no free adjustable parameters within the concordance LCDM cosmology. As a first application, based on a high-resolution cosmological simulation, we make quantitative predictions for the age distribution of the old GC population (Age=13.0+/-0.2 Gyr). We suggest that a similar merging mechanism is responsible for forming the sequence of younger and progressively metal richer clusters, through subhalo-subhalo merging in the later stages of massive halo assembly.
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    Tsvi Piran · Raul Jimenez ·
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    ABSTRACT: As a copious source of gamma rays, a nearby galactic gamma ray burst (GRB) can be a threat to life. Using recent determinations of the rate of GRBs, their luminosity function, and properties of their host galaxies, we estimate the probability that a life-threatening (lethal) GRB would take place. Amongst the different kinds of GRBs, long ones are most dangerous. There is a very good chance (but no certainty) that at least one lethal GRB took place during the past 5 gigayears close enough to Earth as to significantly damage life. There is a 50% chance that such a lethal GRB took place during the last 500×10^{6} years, causing one of the major mass extinction events. Assuming that a similar level of radiation would be lethal to life on other exoplanets hosting life, we explore the potential effects of GRBs to life elsewhere in the Galaxy and the Universe. We find that the probability of a lethal GRB is much larger in the inner Milky Way (95% within a radius of 4 kpc from the galactic center), making it inhospitable to life. Only at the outskirts of the Milky Way, at more than 10 kpc from the galactic center, does this probability drop below 50%. When considering the Universe as a whole, the safest environments for life (similar to the one on Earth) are the lowest density regions in the outskirts of large galaxies, and life can exist in only ≈10% of galaxies. Remarkably, a cosmological constant is essential for such systems to exist. Furthermore, because of both the higher GRB rate and galaxies being smaller, life as it exists on Earth could not take place at z>0.5. Early life forms must have been much more resilient to radiation.
    Physical Review Letters 12/2014; 113(23):231102. DOI:10.1103/PhysRevLett.113.231102 · 7.51 Impact Factor
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    Antonio J. Cuesta · Licia Verde · Adam Riess · Raul Jimenez ·
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    ABSTRACT: We exploit cosmological model-independent measurements of the expansion history of the Universe to provide a cosmic distance ladder. These are supernovae Type Ia used as standard candles (at redshift between 0.01 and 1.3) and baryon acoustic oscillations (at redshifts between 0.1 and 0.8) as standard rulers. We calibrate (anchor) the ladder in two ways: first using the local H0 value as an anchor at z = 0 (effectively calibrating the standard candles) and secondly using the cosmic microwave background-inferred sound-horizon scale as an anchor (giving the standard ruler length) as an inverse distance ladder. Both methods are consistent, but the uncertainty in the expansion history H(z) is smaller if the sound-horizon scale is used. We present inferred values for the sound horizon at radiation drag rd which do not rely on assumptions about the early expansion history nor on cosmic microwave background measurements but on the cosmic distance ladder and baryon acoustic oscillations measurements. We also present derived values of H0 from the inverse distance ladder and we show that they are in very good agreement with the extrapolated value in a Λ cold dark matter model from Planck cosmic microwave background data.
    Monthly Notices of the Royal Astronomical Society 11/2014; 448(4). DOI:10.1093/mnras/stv261 · 5.11 Impact Factor
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    ABSTRACT: In order to elucidate the origin of spin in both dark matter and baryons in galaxies, we have performed hydrodynamical simulations from cosmological initial conditions. We study atomic cooling haloes in the redshift range $100 > z > 9$ with masses of order $10^9{\rm M_{\odot}}$ at redshift $z=10$. We assume that the gas has primordial composition and that ${\rm H_2}$-cooling and prior star-formation in the haloes have been suppressed. We present a comprehensive analysis of the gas and dark matter properties of four halos with very low ($\lambda \approx 0.01$), low ($\lambda \approx 0.04$), high ($\lambda \approx 0.06$) and very high ($\lambda \approx 0.1$) spin parameter. Our main conclusion is that the spin orientation and magnitude is initially well described by tidal torque linear theory, but later on is determined by the merging and accretion history of each halo. We provide evidence that the topology of the merging region, i.e. the number of colliding filaments, gives an accurate prediction for the spin of dark matter and gas: halos at the center of knots will have low spin while those in the center of filaments will have high spin. The spin of a halo is given by $\lambda \approx 0.05 \times \left(\frac{7.6}{\rm number\,\,\, of \,\,\, filaments}\right)^{5.1}$.
    Monthly Notices of the Royal Astronomical Society 10/2014; 452(1). DOI:10.1093/mnras/stv1234 · 5.11 Impact Factor
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    Alan Heavens · Raul Jimenez · Licia Verde ·
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    ABSTRACT: Assuming the existence of standard clocks, standard candles and standard rulers, we determine the length of the Baryon Acoustic Oscillation (BAO) feature, and the expansion history of the recent Universe, from low-redshift data only, in a relatively model-independent way. In this process we assume as little as possible, requiring only the cosmological principle, a metric theory of gravity, a smooth expansion history, and the existence of these standard objects; the rest is determined by the data. The data we use are a compilation of recent BAO data, Type \OneA supernov\ae\ and ages of early-type galaxies. Making only these assumptions, we find for the first time that the standard ruler has a largely model-independent length of $101.9 \pm 1.9 h^{-1}$ Mpc. We also find that the standard candle has a brightness consistent with determinations from supernov\ae\ alone, and that the inverse curvature radius of the Universe is weakly constrained and consistent with zero, independently of the gravity model, provided it is metric. The most notable result is that of the standard ruler; we determine it without using the cosmic microwave background (CMB), and with an error which is marginally smaller than the model-dependent CMB determination from Planck data ($99.3 \pm 2.1 \, h^{-1}$Mpc), which assumes it is the sound horizon at radiation drag in a $\Lambda$CDM universe.
    Physical Review Letters 09/2014; 113(24). DOI:10.1103/PhysRevLett.113.241302 · 7.51 Impact Factor
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    ABSTRACT: We show that modifications of Einstein gravity during inflation could leave potentially measurable imprints on cosmological observables in the form of non-Gaussian perturbations. This is due to the fact that these modifications appear in the form of an extra field that could have non-trivial interactions with the inflaton. We show it explicitly for the case $R+\alpha R^2$, where nearly scale-invariant non-Gaussianity at the level of $f_{\rm NL} \approx -(1$ to $30)$ can be obtained, in a quasi-local configuration.
    Physical Review Letters 07/2014; 113(16). DOI:10.1103/PhysRevLett.113.161303 · 7.51 Impact Factor
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    Michele Trenti · Rosalba Perna · Raul Jimenez ·
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    ABSTRACT: [Abridged] Long-Duration Gamma-Ray Bursts (GRBs) are powerful probes of the star formation history of the Universe, but the correlation between the two depends on the highly debated presence and strength of a metallicity bias. To investigate this correlation, we use a phenomenological model that successfully describes star formation rates, luminosities and stellar masses of star forming galaxies, and apply it to GRB production. We predict the comoving GRB rate and luminosities/stellar masses of host galaxies depending on the presence (or absence) of a metallicity bias, highlighting that apparent conflicts among previous studies might disappear following a comprehensive data-model comparison. We conclude that: (1) Our best fitting model includes a moderate metallicity bias, broadly consistent with the large majority of the long-duration GRBs in metal-poor environments originating from a collapsar (~83%), but with a secondary contribution from a metal-independent production channel, such as binary evolution; (2) Because of the mass-metallicity relation of galaxies, the metal-independent channel becomes dominant at z<2, where hosts have higher metallicities and collapsars are suppressed. This possibly explains studies that find no clear evidence of a metal-bias based on low-z samples; (3) Lower, but non-zero, efficiencies of the metal-independent GRB channel might be preferred following a comprehensive fit that includes metallicity of GRB hosts; (4) Overall, the optimal redshift range to investigate the GRB metallicity bias is 1.5<z<4, when the majority of star forming galaxies have metallicities in the range ~0.1-1 Zsun; (5) Careful data-model comparison is critical, and complicated by dust-absorption, which may hide star formation in the most massive galaxies, but not necessarily the GRB explosion. Our findings are limited by the small size of complete samples of GRB host observations.
    The Astrophysical Journal 06/2014; 802(2). DOI:10.1088/0004-637X/802/2/103 · 5.99 Impact Factor
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    ABSTRACT: We give an analytical form for the weighted correlation function of peaks in a Gaussian random field. In a cosmological context, this approach strictly describes the formation bias and is the main result here. Nevertheless, we show its validity and applicability to the evolved cosmological density field and halo field, using Gaussian random field realisations and dark matter N-body numerical simulations. Using this result from peak theory we compute the bias of peaks (and dark matter halos) and show that it reproduces results from the simulations at the ${\mathcal O}(10\%)$ level. Our analytical formula for the bias predicts a scale-dependent bias with two characteristics: a broad band shape which, however, is most affected by the choice of weighting scheme and evolution bias, and a more robust, narrow feature localised at the BAO scale, an effect that is confirmed in simulations. This scale-dependent bias smooths the BAO feature but, conveniently, does not move it. We provide a simple analytic formula to describe this effect. We envision that our analytic solution will be of use for galaxy surveys that exploit galaxy clustering.
    Monthly Notices of the Royal Astronomical Society 04/2014; 443(1). DOI:10.1093/mnras/stu1164 · 5.11 Impact Factor
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    Licia Verde · Pavlos Protopapas · Raul Jimenez ·
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    ABSTRACT: We use cosmology-independent measurements of the expansion history in the redshift range 0.1 < z <1.2 and compare them with the Cosmic Microwave Background-derived expansion history predictions. The motivation is to investigate if the tension between the local (cosmology independent) Hubble constant H0 value and the Planck-derived H0 is also present at other redshifts. We conclude that there is no tension between Planck and cosmology independent-measurements of the Hubble parameter H(z) at 0.1 < z < 1.2 for the LCDM model (odds of tension are only 1:15, statistically not significant). Considering extensions of the LCDM model does not improve these odds (actually makes them worse), thus favouring the simpler model over its extensions. On the other hand the H(z) data are also not in tension with the local H0 measurements but the combination of all three data-sets shows a highly significant tension (odds ~ 1:400). Thus the new data deepen the mystery of the mismatch between Planck and local H0 measurements, and cannot univocally determine wether it is an effect localised at a particular redshift. Having said this, we find that assuming the NGC4258 maser distance as the correct anchor for H0, brings the odds to comfortable values. Further, using only the expansion history measurements we constrain, within the LCDM model, H0 = 68.5 +- 3.5 and Omega_m = 0.32 +- 0.05 without relying on any CMB prior. We also address the question of how smooth the expansion history of the universe is given the cosmology independent data and conclude that there is no evidence for deviations from smoothness on the expansion history, neither variations with time in the value of the equation of state of dark energy.
    Physics of the Dark Universe 03/2014; 5-6. DOI:10.1016/j.dark.2014.09.003 · 8.57 Impact Factor
  • Joaquin Prieto · Raul Jimenez · Zoltan Haiman ·
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    ABSTRACT: We have performed hydrodynamical simulations from cosmological initial conditions using the Adaptive Mesh Refinement (AMR) code RAMSES to study atomic cooling haloes (ACHs) at z = 10 with masses in the range 5 × 107 M⊙ ≲ M ≲ 2 × 109 M⊙. We assume the gas has primordial composition and H2-cooling and prior star formation in the haloes have been suppressed. We present a comprehensive analysis of the gas and dark matter (DM) properties of 19 haloes at a spatial resolution of ˜10 (proper) pc, selected from simulations with a total volume of ˜2000 (comoving) Mpc3. This is the largest statistical hydro-simulation study of ACHs at z > 10 to date. We examine the morphology, angular momentum, thermodynamical state and turbulent properties of these haloes, in order to assess the prevalence of discs and massive overdensities that may lead to the formation of supermassive black holes (SMBHs). We find no correlation between either the magnitude or the direction of the angular momentum of the gas and its parent DM halo. Only three of the haloes form rotationally supported cores. Two of the most massive haloes, however, form massive, compact overdense blobs, which migrate to the outer region of the halo. These blobs have an accretion rate between ˜10-1 and 10-3 M⊙ yr-1 (at a distance of 100 pc from their centre), and are possible sites of SMBH formation. Our results suggest that the degree of rotational support and the fate of the gas in a halo is determined by its large-scale environment and merger history. In particular, the two haloes that form overdense blobs are located at knots of the cosmic web, cooled their gas early on (z > 17) and experienced many mergers. The gas in these haloes is thus lumpy and highly turbulent, with Mach numbers M≳ 5. In contrast, the haloes forming rotationally supported cores are relatively more isolated, located mid-way along filaments of the cosmic web, cooled their gas more recently and underwent fewer mergers. As a result, the gas in these haloes is less lumpy and less turbulent (Mach numbers M≲ 4), and could retain most of its angular momentum. The remaining 14 haloes have a diverse range of intermediate properties. If verified in a larger sample of haloes and with additional physics to account for metals and star formation, our results will have implications for observations of the highest redshift galaxies and quasars with James Web Space Telescope.
    Monthly Notices of the Royal Astronomical Society 12/2013; 436(3):2301-2325. DOI:10.1093/mnras/stt1730 · 5.11 Impact Factor
  • Raul Jimenez · Tsvi Piran ·
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    ABSTRACT: While there are numerous indications that gamma-ray bursts (GRBs) arise from the deaths of massive stars, the GRB rate does not follow the global cosmic star formation rate and, within their hosts, GRBs are more concentrated in regions of very high star formation. We explain both puzzles here. Using the publicly available VESPA database of the Sloan Digital Sky Survey (SDSS) Data Release 7 spectra, we explore a multi-parameter space in galaxy properties such as stellar mass, metallicity, and dust to find the subset of galaxies that reproduces the GRB rate recently obtained by Wanderman & Piran. We find that only galaxies with present stellar masses below <1010M ☉ and low metallicity reproduce the observed GRB rate. This is consistent with direct observations of GRB hosts and provides an independent confirmation of the nature of GRB hosts. Because of the significantly larger sample of SDSS galaxies, we compute their correlation function and show that they are anti-biased with respect to dark matter: they are in filaments and voids. Using recent observations of massive stars in local dwarfs we show how the fact that GRB host galaxies are dwarfs can explain the observation that GRBs are more concentrated in regions of high star formation than are supernovae. Finally, we explain these results using new theoretical advances in the field of star formation.
    The Astrophysical Journal 08/2013; 773(2):126. DOI:10.1088/0004-637X/773/2/126 · 5.99 Impact Factor
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    Raul Jimenez ·
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    ABSTRACT: There has been significant recent progress in observational cosmology. This, in turn, has provided an unprecedented picture of the early universe and its evolution. In this review I will present a (biased) view of how one can use these observational results to constraint fundamental physics and in particular physics beyond the standard model.
    07/2013; DOI:10.1063/1.4891122
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    Joaquin Prieto · Raul Jimenez · Licia Verde ·
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    ABSTRACT: It has been shown by Shchekinov & Vasiliev2006 (SV06) that HD molecules can be an important cooling agent in high redshift z >10 haloes if they undergo mergers under specific conditions so suitable shocks are created. Here we build upon Prieto et al. (2012) who studied in detail the merger-generated shocks, and show that the conditions for HD cooling can be studied by combining these results with a suite of dark-matter only simulations. We have performed a number of dark matter only simulations from cosmological initial conditions inside boxes with sizes from 1 to 4 Mpc. We look for haloes with at least two progenitors of which at least one has mass M > M_cr (z), where M_cr (z) is the SV06 critical mass for HD over-cooling. We find that the fraction of over-cooled haloes with mass between M_cr (z) and 10^{0.2} M_cr (z), roughly below the atomic cooling limit, can be as high as ~ 0.6 at z ~ 10 depending on the merger mass ratio. This fraction decreases at higher redshift reaching a value ~0.2 at z ~ 15. For higher masses, i.e. above 10^{0.2} M_cr (z) up to 10^{0.6} M_cr (z), above the atomic cooling limit, this fraction rises to values ~ 0.8 until z ~ 12.5. As a consequence, a non negligible fraction of high redshift z > 10 mini-haloes can drop their gas temperature to the Cosmic Microwave Background temperature limit allowing the formation of low mass stars in primordial environments.
    Monthly Notices of the Royal Astronomical Society 07/2013; 437(3). DOI:10.1093/mnras/stt2049 · 5.11 Impact Factor
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    Luis Alvarez-Gaume · Cesar Gomez · Raul Jimenez ·
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    ABSTRACT: We show how general initial conditions for small field inflation can be obtained in multi-field models. This is provided by non-linear angular friction terms in the inflaton that provide a phase of non-slow-roll inflation before the slow-roll inflation phase. This in turn provides a natural mechanism to star small-field slow-roll at nearly zero velocity for arbitrary initial conditions. We also show that there is a relation between the scale of SUSY breaking sqrt (f) and the amount of non-gaussian fluctuations generated by the inflaton. In particular, we show that in the local non-gaussian shape there exists the relation sqrt (f) = 10^{13} GeV sqrt (f_NL). With current observational limits from Planck, and adopting the minimum amount of non-gaussian fluctuations allowed by single-field inflation, this provides a very tight constraint for the SUSY breaking energy scale sqrt (f) = 3-7 x 10^{13} GeV at 95% confidence. Further limits, or detection, from next year's Planck polarisation data will further tighten this constraint by a factor of two. We highlight that the key to our approach is to identify the inflaton with the scalar component of the goldstino superfield. This superfield is universal and implements the dynamics of SUSY breaking as well as superconformal breaking.
    07/2013; DOI:10.1063/1.4891111
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    Licia Verde · Pavlos Protopapas · Raul Jimenez ·
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    ABSTRACT: We use the latest Planck constraints, and in particular constraints on the derived parameters (Hubble constant and age of the Universe) for the local universe and compare them with local measurements of the same quantities. We propose a way to quantify whether cosmological parameters constraints from two different experiments are in tension or not. Our statistic, T, is an evidence ratio and therefore can be interpreted with the widely used Jeffrey's scale. We find that in the framework of the LCDM model, the Planck inferred two dimensional, joint, posterior distribution for the Hubble constant and age of the Universe is in "strong" tension with the local measurements; the odds being ~ 1:50. We explore several possibilities for explaining this tension and examine the consequences both in terms of unknown errors and deviations from the LCDM model. In some one-parameter LCDM model extensions, tension is reduced whereas in other extensions, tension is instead increased. In particular, small total neutrino masses are favored and a total neutrino mass above 0.15 eV makes the tension "highly significant" (odds ~ 1:150). A consequence of accepting this interpretation of the tension is that the degenerate neutrino hierarchy is highly disfavoured by cosmological data and the direct hierarchy is slightly favored over the inverse.
    Physics of the Dark Universe 06/2013; 2(3). DOI:10.1016/j.dark.2013.09.002 · 8.57 Impact Factor

Publication Stats

6k Citations
1,000.74 Total Impact Points


  • 2014
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2009-2013
    • CERN
      • Physics Department (PH)
      Genève, Geneva, Switzerland
    • University of Barcelona
      • Instituto de Ciencias del Cosmos (ICCUB)
      Barcino, Catalonia, Spain
  • 2012
    • Institut Marqués, Spain, Barcelona
      Barcino, Catalonia, Spain
  • 2009-2012
    • Catalan Institution for Research and Advanced Studies
      Barcino, Catalonia, Spain
  • 2010
    • University of California, Berkeley
      Berkeley, California, United States
  • 2007-2009
    • IEEC Institute of Space Studies of Catalonia
      Barcino, Catalonia, Spain
    • Princeton University
      • Department of Astrophysical Sciences
      Princeton, New Jersey, United States
    • William Penn University
      Filadelfia, Pennsylvania, United States
  • 1996-2009
    • The Royal Observatory, Edinburgh
      Edinburgh, Scotland, United Kingdom
  • 2008
    • National Institute of Standards and Technology
      Maryland, United States
    • Universidad Autónoma de Madrid
      Madrid, Madrid, Spain
  • 2003-2008
    • University of Pennsylvania
      • Department of Physics and Astronomy
      Philadelphia, PA, United States
  • 2000-2008
    • Rutgers, The State University of New Jersey
      • Department Physics and Astronomy
      New Brunswick, NJ, United States
  • 1998-2008
    • The University of Edinburgh
      • Institute for Astronomy (IfA)
      Edinburgh, SCT, United Kingdom
  • 2006
    • Carnegie Institution for Science
      Вашингтон, West Virginia, United States