SEARCH · Engineering Papers

Results for “MASS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,351 records · Page 75

All sources NASA NTRS DOE OSTI

DOE OSTI2013

Active galactic nucleus black hole mass estimates in the era of time domain astronomy

We investigate the dependence of the normalization of the high-frequency part of the X-ray and optical power spectral densities (PSDs) on black hole mass for a sample of 39 active galactic nuclei (AGNs) with black hole masses estimated from reverberation mapping or dynamical modeling. We obtained new Swift observations of PG 1426+015, which has the largest estimated black hole mass of the AGNs in our sample. We develop a novel statistical method to estimate the PSD from a light curve of photon counts with arbitrary sampling, eliminating the need to bin a light curve to achieve Gaussian statistics, and we use this technique to estimate the X-ray variability parameters for the faint AGNs in our sample. We find that the normalization of the high-frequency X-ray PSD is inversely proportional to black hole mass. We discuss how to use this scaling relationship to obtain black hole mass estimates from the short timescale X-ray variability amplitude with precision ∼0.38 dex. The amplitude of optical variability on timescales of days is also anticorrelated with black hole mass, but with larger scatter. Instead, the optical variability amplitude exhibits the strongest anticorrelation with luminosity. We conclude with a discussion of the implications of our results for estimating black hole mass from the amplitude of AGN variability.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2014

The impact of galaxy geometry and mass evolution on the survival of star clusters

Direct N-body simulations of globular clusters in a realistic Milky-Way-like potential are carried out using the code NBODY6 to determine the impact of the host galaxy disk mass and geometry on the survival of star clusters. A relation between disk mass and star-cluster dissolution timescale is derived. These N-body models show that doubling the mass of the disk from 5 × 10{sup 10} M {sub ☉} to 10 × 10{sup 10} M {sub ☉} halves the dissolution time of a satellite star cluster orbiting the host galaxy at 6 kpc from the galactic center. Different geometries in a disk of identical mass can determine either the survival or dissolution of a star cluster orbiting within the inner 6 kpc of the galactic center. Furthermore, disk geometry has measurable effects on the mass loss of star clusters up to 15 kpc from the galactic center. N-body simulations performed with a fine output time step show that at each disk crossing the outer layers of star clusters experiences an increase in velocity dispersion of ∼5% of the average velocity dispersion in the outer section of star clusters. This leads to an enhancement of mass loss—a clearly discernable effect of disk shocking. By running models with different inclinations, we determine that star clusters with an orbit that is perpendicular to the Galactic plane have larger mass loss rates than do clusters that evolve in the Galactic plane or in an inclined orbit.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2014

Magnetohydrostatic equilibrium structure and mass of filamentary isothermal cloud threaded by lateral magnetic field

Herschel observations have recently revealed that interstellar molecular clouds consist of many filaments. Polarization observations in optical and infrared wavelengths indicate that the magnetic field often runs perpendicular to the filament. In this article, we study the magnetohydrostatic configuration of isothermal gas in which the thermal pressure and the Lorentz force are balanced against the self-gravity, and the magnetic field is globally perpendicular to the axis of the filament. The model is controlled by three parameters: center-to-surface density ratio (ρ {sub c}/ρ {sub s}), plasma β of surrounding interstellar gas (β{sub 0}), and the radius of the hypothetical parent cloud normalized by the scale-height (R{sub 0}{sup ′}), although there remains freedom in how the mass is distributed against the magnetic flux (mass loading). In the case where R{sub 0}{sup ′} is small enough, the magnetic field plays a role in confining the gas. However, the magnetic field generally has the effect of supporting the cloud. There is a maximum line-mass (mass per unit length) above which the cloud is not supported against gravity. Compared with the maximum line-mass of a nonmagnetized cloud (2c{sub s}{sup 2}/G, where c{sub s} and G represent, respectively, the isothermal sound speed and the gravitational constant), that of the magnetized filament is larger than the nonmagnetized one. The maximum line-mass is numerically obtained as λ{sub max}≃0.24Φ{sub cl}/G{sup 1/2}+1.66c{sub s}{sup 2}/G, where Φ{sub cl} represents one half of the magnetic flux threading the filament per unit length. The maximum mass of the filamentary cloud is shown to be significantly affected by the magnetic field when the magnetic flux per unit length exceeds Φ{sub cl} ≳ 3 pc μG (c{sub s} /190 m s{sup –1}){sup 2}.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2014

The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet

Kepler-10b was the first rocky planet detected by the Kepler satellite and confirmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was statistically validated, but the radial velocities were only good enough to set an upper limit of 20 M{sub ⊕} for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In total, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determination for Kepler-10b to 15%. With a mass of 3.33 ± 0.49 M{sub ⊕} and an updated radius of 1.47{sub −0.02}{sup +0.03} R{sub ⊕}, Kepler-10b has a density of 5.8 ± 0.8 g cm{sup –3}, very close to the value predicted by models with the same internal structure and composition as the Earth. We were also able to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 ± 1.9 M{sub ⊕} and radius of 2.35{sub −0.04}{sup +0.09} R{sub ⊕}, Kepler-10c has a density of 7.1 ± 1.0 g cm{sup –3}. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2014

Distributed low-mass star formation in the IRDC G34.43+00.24

We have used deep near-infrared observations with adaptive optics to discover a distributed population of low-mass protostars within the filamentary Infrared Dark Cloud G34.43+00.24. We use maps of dust emission at multiple wavelengths to determine the column density structure of the cloud. In combination with an empirically verified model of the magnitude distribution of background stars, this column density map allows us to reliably determine overdensities of red sources that are due to embedded protostars in the cloud. We also identify protostars through their extended emission in the K band, which comes from excited H{sub 2} in protostellar outflows or reflection nebulosity. We find a population of distributed low-mass protostars, suggesting that low-mass protostars may form earlier than, or contemporaneously with, high-mass protostars in such a filament. The low-mass protostellar population may also produce the narrow line-width SiO emission observed in some clouds without high-mass protostars. Finally, we use a molecular line map of the cloud to determine the virial parameter per unit length along the filament and find that the highest mass protostars form in the most bound portion of the filament, as suggested by theoretical models.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2014

A spectroscopic sample of massive, quiescent z ∼ 2 galaxies: implications for the evolution of the mass-size relation

We present deep, near-infrared Hubble Space Telescope/Wide Field Camera 3 grism spectroscopy and imaging for a sample of 14 galaxies at z ≈ 2 selected from a mass-complete photometric catalog in the COSMOS field. By combining the grism observations with photometry in 30 bands, we derive accurate constraints on their redshifts, stellar masses, ages, dust extinction, and formation redshifts. We show that the slope and scatter of the z ∼ 2 mass-size relation of quiescent galaxies is consistent with the local relation, and confirm previous findings that the sizes for a given mass are smaller by a factor of two to three. Finally, we show that the observed evolution of the mass-size relation of quiescent galaxies between z = 2 and 0 can be explained by the quenching of increasingly larger star forming galaxies at a rate dictated by the increase in the number density of quiescent galaxies with decreasing redshift. However, we find that the scatter in the mass-size relation should increase in the quenching-driven scenario in contrast to what is seen in the data. This suggests that merging is not needed to explain the evolution of the median mass-size relation of massive galaxies, but may still be required to tighten its scatter, and explain the size growth of individual z = 2 galaxies quiescent galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

MASS AND ENERGY OF ERUPTING SOLAR PLASMA OBSERVED WITH THE X-RAY TELESCOPE ON HINODE

We investigate seven eruptive plasma observations by Hinode/XRT. Their corresponding EUV and/or white light coronal mass ejection features are visible in some events. Five events are observed in several passbands in X-rays, which allows for the determination of the eruptive plasma temperature using a filter ratio method. We find that the isothermal temperatures vary from 1.6 to 10 MK. These temperatures are an average weighted toward higher temperature plasma. We determine the mass constraints of eruptive plasmas by assuming simplified geometrical structures of the plasma with isothermal plasma temperatures. This method provides an upper limit to the masses of the observed eruptive plasmas in X-ray passbands since any clumping causes the overestimation of the mass. For the other two events, we assume the temperatures are at the maximum temperature of the X-ray Telescope (XRT) temperature response function, which gives a lower limit of the masses. We find that the masses in XRT, ∼3 × 10{sup 13}-5 × 10{sup 14} g, are smaller in their upper limit than the total masses obtained by LASCO, ∼1 × 10{sup 15} g. In addition, we estimate the radiative loss, thermal conduction, thermal, and kinetic energies of the eruptive plasma in X-rays. For four events, we find that the thermal conduction timescales are much shorter than the duration of eruption. This result implies that additional heating during the eruption may be required to explain the plasma observations in X-rays for the four events.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

CHARACTERIZING THE STAR FORMATION OF THE LOW-MASS SHIELD GALAXIES FROM HUBBLE SPACE TELESCOPE IMAGING

The Survey of Hi in Extremely Low-mass Dwarfs is an on-going multi-wavelength program to characterize the gas, star formation, and evolution in gas-rich, very low-mass galaxies that populate the faint end of the galaxy luminosity function. The galaxies were selected from the first ∼10% of the Hi Arecibo Legacy Fast ALFA survey based on their low Hi mass and low baryonic mass. Here, we measure the star formation properties from optically resolved stellar populations for 12 galaxies using a color–magnitude diagram fitting technique. We derive lifetime average star formation rates (SFRs), recent SFRs, stellar masses, and gas fractions. Overall, the recent SFRs are comparable to the lifetime SFRs with mean birthrate parameter of 1.4, with a surprisingly narrow standard deviation of 0.7. Two galaxies are classified as dwarf transition galaxies (dTrans). These dTrans systems have star formation and gas properties consistent with the rest of the sample, in agreement with previous results that some dTrans galaxies may simply be low-luminosity dwarf irregulars. We do not find a correlation between the recent star formation activity and the distance to the nearest neighboring galaxy, suggesting that the star formation process is not driven by gravitational interactions, but regulated internally. Further, we find a broadening in the star formation and gas properties (i.e., specific SFRs, stellar masses, and gas fractions) compared to the generally tight correlation found in more massive galaxies. Overall, the star formation and gas properties indicate these very low-mass galaxies host a fluctuating, non-deterministic, and inefficient star formation process.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Classical bulges, supermassive black holes, and AGN feedback: Extension to low-mass galaxies

The empirical model of Lu et al. for the relation between star formation rate and halo mass growth is adopted to predict the classical bulge mass (M{sub cb})–total stellar mass (M{sub ⋆}) relation for central galaxies. The assumption that the supermassive black hole (SMBH) mass (M{sub BH}) is directly proportional to the classical bulge mass, with the proportionality given by that for massive galaxies, predicts a M{sub BH}−M{sub ⋆} relation that matches well the observed relation for different types of galaxies. In particular, the model reproduces the strong transition at M{sub ⋆}=10{sup 10.5}−10{sup 11} M{sub ⊙}, below which M{sub BH} drops rapidly with decreasing M{sub ⋆}. Our model predicts a new sequence at M{sub ⋆}<10{sup 10.5} M{sub ⊙}, where M{sub BH}∝M{sub ⋆} but the amplitude is a factor of ∼50 lower than the amplitude of the sequence at M{sub ⋆}>10{sup 11} M{sub ⊙}. If all SMBHs grow through similar quasar modes with a feedback efficiency of a few percent, then the energy produced in low-mass galaxies at redshift z≳2 can heat the circumgalactic medium up to a specific entropy level that is required to prevent excessive star formation in low-mass dark matter halos.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Diversity of extrasolar planets and diversity of molecular cloud cores. II. Masses of gas giant planets

In Paper I, we suggested that the diversity of extrasolar planets might originate from the diversity of molecular cloud cores and specifically illustrated the relationship between semi-major axes of planets in a planetary system and the properties of its progenitor cloud core. In this paper, we investigate the dependence of the mass of a giant planet on the progenitor core properties. We give numerical results of planet masses as a function of the core properties by using the core accretion model of planet formation. Comparing with observations, our model could explain the range and the most frequent values of observed masses of gas giant planets. Our calculations could interpret the observed pileup of gas giants at >1 AU and the distinct deficit of gas giants from ∼0.05 to 1 AU. Our calculations indicate that it is difficult to form gas giant planets outside 20 AU and the intermediate mass planets might be found at ∼15–30 AU as the observing technique advances. We suggest a formation mechanism of super-Jupiters in the framework of the core accretion model of planet formation. A super-Jupiter can form under the condition that a disk is gravitationally unstable (high viscosity) when a protoplanet opens the deep gap. Our calculations infer that the upper limit of super-Jupiter masses, the range of semi-major axes, and the occurrence rate of super-Jupiters increase with the central star mass. We find that gas giant planets should commonly exist around various stellar masses.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Simulations of galaxies formed in warm dark matter halos of masses at the filtering scale

We present zoom-in N-body + hydrodynamic simulations of dwarf central galaxies formed in warm dark matter (WDM) halos with present-day masses of 2–4 × 10{sup 10} M{sub ⊙}. Two different cases are considered: the first one when halo masses are close to the corresponding half-mode filtering scale, M{sub f} (m{sub WDM} = 1.2 keV), and the second when they are 20 to 30 times the corresponding M{sub f} (m{sub WDM} = 3.0 keV). The WDM simulations are compared with the respective cold dark matter (CDM) simulations. The dwarfs formed in halos of masses (20–30)M{sub f} have roughly similar properties and evolution to their CDM counterparts; on the contrary, those formed in halos of masses around M{sub f}, are systematically different from their CDM counterparts. As compared to the CDM dwarfs, they assemble the dark and stellar masses later, having mass-weighted stellar ages 1.4–4.8 Gyr younger; their circular velocity profiles are shallower, with maximal velocities 20%–60% lower; their stellar distributions are much less centrally concentrated and with larger effective radii, by factors of 1.3–3. The WDM dwarfs at the filtering scale (m{sub WDM} = 1.2 keV) have disk-like structures, and end in most cases with higher gas fractions and lower stellar-to-total mass ratios than their CDM counterparts. The late halo assembly, low halo concentrations, and the absence of satellites of the former with respect to the latter are at the basis of the differences.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

A measurement of the black hole mass in NGC 1097 using ALMA

We present an estimate of the mass of the supermassive black hole (SMBH) in the nearby type-1 Seyfert galaxy NGC 1097 using Atacamma Large Millimeter/submillimeter Array (ALMA) observations of dense gas kinematics. Dense molecular gas dynamics are traced with HCN(J=1−0) and HCO{sup +}(J=1−0) emission lines. Assuming a host galaxy inclination of 46{sup ∘}, we derive an SMBH mass, M{sub BH}=1.40{sub −0.32}{sup +0.27}×10{sup 8 }M{sub ⊙}, and an I-band mass to light ratio to be 5.14{sub −0.04}{sup +0.03}, using HCN(J=1−0). The estimated parameters are consistent between the two emission lines. The measured SMBH mass is in good agreement with the SMBH mass and bulge velocity dispersion relationship. Our result showcases ALMA’s potential for deriving accurate SMBH masses, especially for nearby late-type galaxies. Larger samples and accurate SMBH masses will further elucidate the relationship between the black hole (BH) and host galaxy properties and constrain the coevolutionary growth of galaxies and BHs.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

IMAGE-PLANE ANALYSIS OF n-POINT-MASS LENS CRITICAL CURVES AND CAUSTICS

The interpretation of gravitational microlensing events caused by planetary systems or multiple stars is based on the n-point-mass lens model. The first planets detected by microlensing were well described by the two-point-mass model of a star with one planet. By the end of 2014, four events involving three-point-mass lenses had been announced. Two of the lenses were stars with two planetary companions each; two were binary stars with a planet orbiting one component. While the two-point-mass model is well understood, the same cannot be said for lenses with three or more components. Even the range of possible critical-curve topologies and caustic geometries of the three-point-mass lens remains unknown. In this paper we provide new tools for mapping the critical-curve topology and caustic cusp number in the parameter space of n-point-mass lenses. We perform our analysis in the image plane of the lens. We show that all contours of the Jacobian are critical curves of re-scaled versions of the lens configuration. Utilizing this property further, we introduce the cusp curve to identify cusp-image positions on all contours simultaneously. In order to track cusp-number changes in caustic metamorphoses, we define the morph curve, which pinpoints the positions of metamorphosis-point images along the cusp curve. We demonstrate the usage of both curves on simple two- and three-point-mass lens examples. For the three simplest caustic metamorphoses we illustrate the local structure of the image and source planes.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Initial–final mass relation for 3 to 4 M{sub ⊙} progenitors of white dwarfs from the single cluster NGC 2099

We have expanded the sample of observed white dwarfs in the rich open cluster NGC 2099 (M37) with the Keck Low Resolution Imaging Spectrometer. Of 20 white dwarf candidates, the spectroscopy shows 19 to be true white dwarfs, with 14 of these having high signal-to-noise ratio. We find 11 of these 14 to be consistent with singly evolved cluster members. They span a mass range of ∼0.7–0.95 M{sub ⊙}, excluding a low-mass outlier, corresponding to progenitor masses of ∼3–4 M{sub ⊙}. This region of the initial–final mass relation (IFMR) has large scatter and a slope that remains to be precisely determined. With this large sample of white dwarfs that belong to a single age and metallicity population, we find an IFMR of (0.171 ± 0.057)M{sub initial}+0.219±0.187M{sub ⊙}, significantly steeper than the linear relation adopted over the full observed white dwarf mass range in many previous studies. Comparison of this new relation from the solar-metallicity NGC 2099 to 18 white dwarfs in the metal-rich Hyades and Praesepe shows that their IFMR also has a consistently steep slope. This strong consistency also suggests that there is no significant metallicity dependence of the IFMR at this mass and metallicity range. As a result, the IFMR can be more reliably determined with this broad sample of 29 total white dwarfs, giving M{sub final} = (0.163 ± 0.022)M{sub initial} + 0.238 ± 0.071 M{sub ⊙} from M{sub initial} of 3–4 M{sub ⊙}. A steep IFMR in this mass range indicates that the full IFMR is nonlinear.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Probing the masses and radii of donor stars in eclipsing X-ray binaries with the Swift burst alert telescope

Physical parameters of both the mass donor and compact object can be constrained in X-ray binaries with well-defined eclipses, as our survey of wind-fed supergiant X-ray binaries IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016, and XTE J1855-026 reveals. Using the orbital period and Kepler’s third law, we express the eclipse half-angle in terms of radius, inclination angle, and the sum of the masses. Pulse-timing and radial velocity curves can give masses of both the donor and compact object as in the case of the “double-lined” binaries IGR J18027-2016 and XTE J1855-026. The eclipse half angles are 15{sub −2}{sup +3}, 31.7{sub −0.8}{sup +0.7}, 32 ± 2,34 ± 2, and 33.6±0.7 degrees for IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016, and XTE 1855-026, respectively. In wind-fed systems, the primary not exceeding the Roche-lobe size provides an upper limit on system parameters. In IGR J16393-4643, spectral types of B0 V or B0-5 III are found to be consistent with the eclipse duration and Roche-lobe, but the previously proposed donor stars in IGR J16418-4532 and IGR J16479-4514 were found to be inconsistent with the Roche-lobe size. Stars with spectral types O7.5 I and earlier are possible. For IGR J18027-2016, the mass and radius of the donor star lie between 18.6–19.4 M{sub ⊙} and 17.4–19.5 R{sub ⊙}. We constrain the neutron star mass between 1.37 and 1.43 M{sub ⊙}.We find the mass and radius of the donor star in XTE J1855-026 to lie between 19.6–20.2 M{sub ⊙} and 21.5–23.0 R{sub ⊙}. The neutron star mass was constrained to 1.77–1.82 M{sub ⊙}. Eclipse profiles are asymmetric in IGR J18027-2016 and XTE J1855-026, which we attribute to accretion wakes.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Pulsar J0453+1559: A double neutron star system with a large mass asymmetry

To understand the nature of supernovae and neutron star (NS) formation, as well as binary stellar evolution and their interactions, it is important to probe the distribution of NS masses. Until now, all double NS (DNS) systems have been measured as having a mass ratio close to unity (q ≥ 0.91). Here, we report the measurement of the individual masses of the 4.07-day binary pulsar J0453+1559 from measurements of the rate of advance of periastron and Shapiro delay: the mass of the pulsar is M{sub p} = 1.559 ± 0.005 M{sub ⊙} and that of its companion is M{sub c}=1.174±0.004 M{sub ⊙}; q = 0.75. If this companion is also an NS, as indicated by the orbital eccentricity of the system (e = 0.11), then its mass is the smallest precisely measured for any such object. The pulsar has a spin period of 45.7 ms and a spin period derivative of P-dot = (1.8616±0.0007)×10{sup −19} s s{sup −1}; from these, we derive a characteristic age of ∼ 4.1×10{sup 9} years and a magnetic field of ∼ 2.9×10{sup 9} G, i.e., this pulsar was mildly recycled by the accretion of matter from the progenitor of the companion star. This suggests that it was formed with (very approximately) its current mass. Thus, NSs form with a wide range of masses, which is important for understanding their formation in supernovae. It is also important for the search for gravitational waves released during an NS–NS merger: it is now evident that we should not assume that all DNS systems are symmetric.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2012

Measuring the neutrino mass from future wide galaxy cluster catalogues

We present forecast errors on a wide range of cosmological parameters obtained from a photometric cluster catalogue of a future wide-field Euclid-like survey. We focus in particular on the total neutrino mass as constrained by a combination of the galaxy cluster number counts and correlation function. For the latter we consider only the shape information and the Baryon Acoustic Oscillations (BAO), while marginalising over the spectral amplitude and the redshift space distortions. In addition to the cosmological parameters of the standard ΛCDM+ν model we also consider a non-vanishing curvature, and two parameters describing a redshift evolution for the dark energy equation of state. For completeness, we also marginalise over a set of ''nuisance'' parameters, representing the uncertainties on the cluster mass determination. We find that combining cluster counts with power spectrum information greatly improves the constraining power of each probe taken individually, with errors on cosmological parameters being reduced by up to an order of magnitude. In particular, the best improvements are for the parameters defining the dynamical evolution of dark energy, where cluster counts break degeneracies. Moreover, the resulting error on neutrino mass is at the level of σ(M{sub ν}) ∼ 0.9 eV, comparable with that derived from present Lyα forest measurements and Cosmic Microwave background (CMB) data in the framework of a non-flat Universe. Further adopting Planck priors and reducing the number of free parameters to a ΛCDM+ν cosmology allows to place constraints on the total neutrino mass of σ(M{sub ν}) ∼ 0.08 eV, close to the lower bound enforced by neutrino oscillation experiments. Finally, in the optimistic case where uncertainties in the calibration of the mass-observable relation were so small to be neglected, the combination of Planck priors with cluster counts and power spectrum would constrain the total neutrino mass down to σ(M{sub ν}) ∼ 0.034 eV, i.e. the minimum neutrino mass predicted by oscillation experiments would be detected in a ΛCDM framework. We thus show that galaxy clusters from future wide galaxy surveys will be an excellent tool for studying cosmology and fundamental physics.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2014

Constraining the mass-concentration relation through weak lensing peak function

Halo masses and concentrations have been studied extensively, by means of N-body simulations as well as observationally, during the last decade. Nevertheless, the exact form of the mass-concentration relation is still widely debated. One of the most promising method to estimate masses and concentrations relies on gravitational lensing from massive halos. Here we investigate the impact of the mass-concentration relation on halo peak abundance in weak lensing shear maps relying on the aperture mass method for peak detections. After providing a prescription to take into account the concentration dispersion (always neglected in previous works) in peak number counts predictions, we assess their power to constrain the mass-concentration relation by means of Fisher matrix technique. We find that, when combined with different cosmological probes, peak statistics information from near-future weak lensing surveys provides an interesting and complementary alternative method to lessen the long standing controversy about the mass-concentration relation.

79 ASTRONOMY AND ASTROPHYSICS↗