Beauty and Belonging: How Appearance Self-Appraisals Affect Perceived Relational Value, Relationship Standards and Desire for Interpersonal Contact

All individuals seek to develop and maintain social relationships (Baumeister & Leary, 1995). The extent to which people feel loved and accepted within their relationships is called perceived relational value (Leary, 2001). I argue that because sociocultural norms equate physical appearance and social acceptance for women (Thompson, 1999), women’s perceived relational value is inordinately linked to their self-appraisals of physical appearance. I also suggest that significant relational consequences can result from this association. In Study 1,1 demonstrated that self-appraisals of physical attractiveness and Body Mass Index predicted perceived relational value among women but not men. In Study 2,1 found that appearance self-appraisals have a causal impact on perceived relational value among women. I also demonstrated that one consequence of lowered perceived relational value is decreased romantic relationship standards. Study 3 replicated the impact of appearance self-appraisals on relationship standards. Moreover, perceived relational value within a romantic relationship mediated the relation between self-appraisals and relationship standards. Study 4 examined a second consequence of lower perceived relational value: the desire for social contact. A model delineating the relation between appearance self-appraisals, perceived relational value and desire for social contact, such that appearance self-appraisals were linked to lower perceived relational value, which, in turn was linked to a decreased desire for social contact, was tested and the model was found to be a good fit. Overall, these findings indicate that in addition to the behavioural and personal consequences of sociocultural norms for appearance, there are also relational consequences

Mass profiles and concentration-dark matter relation in X-ray luminous galaxy clusters

(Abriged) Assuming that the hydrostatic equilibrium holds between the intracluster medium and the gravitational potential, we constrain the NFW profiles in a sample of 44 X-ray luminous galaxy clusters observed with XMM-Newton in the redshift range 0.1-0.3. We evaluate several systematic uncertainties that affect our reconstruction of the X-ray masses. We measure the concentration c200, the dark mass M200 and the gas mass fraction within R500 in all the objects of our sample, providing the largest dataset of mass parameters for galaxy clusters in this redshift range. We confirm that a tight correlation between c200 and M200 is present and in good agreement with the predictions from numerical simulations and previous observations. When we consider a subsample of relaxed clusters that host a Low-Entropy-Core (LEC), we measure a flatter c-M relation with a total scatter that is lower by 40 per cent. From the distribution of the estimates of c200 and M200, with associated statistical (15-25%) and systematic (5-15%) errors, we use the predicted values from semi-analytic prescriptions calibrated through N-body numerical runs and measure sigma_8*Omega_m^(0.60+-0.03)= 0.45+-0.01 (at 2 sigma level, statistical only) for the subsample of the clusters where the mass reconstruction has been obtained more robustly, and sigma_8*Omega_m^(0.56+-0.04) = 0.39+-0.02 for the subsample of the 11 more relaxed LEC objects. With the further constraint from the fgas distribution in our sample, we break the degeneracy in the sigma_8-Omega_m plane and obtain the best-fit values sigma_8~1.0+-0.2 (0.75+-0.18 when the subsample of the more relaxed objects is considered) and Omega_m = 0.26+-0.01.Comment: 21 pages. A&A in press. Minor revisions to match accepted version. Corrected 2nd and 3rd column in Table 3, and equation (A.4

Low-Mass X-ray Binaries and Globular Clusters in Early-Type Galaxies. I. Chandra Observations

We present a Chandra survey of LMXBs in 24 early-type galaxies. Correcting for detection incompleteness, the X-ray luminosity function (XLF) of each galaxy is consistent with a powerlaw with negative logarithmic differential slope, beta~2.0. However, beta strongly correlates with incompleteness, indicating the XLF flattens at low-Lx. The composite XLF is well-fitted by a powerlaw with a break at 2.21(+0.65,-0.56)E38 erg/s and beta=1.40(+0.10,-0.13) and 2.84(+0.39,-0.30) below and above it, respectively. The break is close to the Eddington limit for a 1.4Msun neutron-star, but the XLF shape rules out its representing the division between neutron-star and black-hole systems. Although the XLFs are similar, we find evidence of some variation between galaxies. The high-Lx XLF slope does not correlate with age, but may correlate with [alpha/Fe]. Considering only LMXBs with Lx>1E37 erg/s, matching the LMXBs with globular clusters (GCs) identified in HST observations of 19 of the galaxies, we find the probability a GC hosts an LMXB is proportional to LGC^alpha ZFe^gamma} where alpha=1.01+/-0.19 and gamma=0.33+/-0.11. Correcting for GC luminosity and colour effects, and detection incompleteness, we find no evidence that the fraction of LMXBs with Lx>1e37 erg/s in GCs (40%), or the fraction of GCs hosting LMXBs (~6.5%) varies between galaxies. The spatial distribution of LMXBs resembles that of GCs, and the specific frequency of LMXBs is proportional to the GC specific luminosity, consistent with the hypothesis that all LMXBs form in GCs. If the LMXB lifetime is tau and the duty cycle is Fd, our results imply ~1.5 (tau/1E8 yr)^-1 /Fd LMXBs are formed per Gyr per GC and we place an upper limit of 1 active LMXB in the field per 3.4E9Lsun of V-band luminosity.Comment: 24 pages, 17 figures and 6 tables. Accepted for publication in the Astrophysical Journal. Expanded discussion and various minor revisions to improve robustness of results. Conclusions unchange

Oxygen Absorption in M87: Evidence for a Warm+Hot ISM

We present a re-analysis of the ROSAT PSPC data within the central 100 kpc of M87 to search for intrinsic oxygen absorption similar to that recently measured in several galaxies and groups. Using a spatial-spectral deprojection analysis we find the strongest evidence to date for intrinsic oxygen absorption in the hot gas of a galaxy, group, or cluster. Single-phase plasma models modified by intervening Galactic absorption cannot fit the 0.2-2.2 keV PSPC data as they under-predict the 0.2-0.4 keV region and over-predict the 0.5-0.8 keV region where the emission and absorption residuals are obvious upon visual inspection of the spectral fits. Since the excess emission between 0.2-0.4 keV rules out intrinsic absorption from cold gas or dust, the most reasonable model for the excess emission and absorption features is warm, collisionally ionized gas with a temperature of ~10^6 K. Simple multiphase models (cooling flow, two phases) modified by both intervening Galactic absorption and by a single oxygen edge provide good fits and yield temperatures and Fe abundances of the hot gas that agree with previous determinations by ASCA and SAX. The multiphase models of M87 inferred from the PSPC can account for the excess EUV emission observed with EUVE and the excess X-ray absorption inferred from EINSTEIN and ASCA data above 0.5 keV. Although the total mass of the warm gas implied by the oxygen absorption is consistent with the matter deposited by a cooling flow, the suppression of the mass deposition rate and the distortion of the X-ray isophotes in the region where the radio emission is most pronounced suggest some feedback effect from the AGN on the cooling gas. (Abridged)Comment: 17 pages (13 figures), Accepted for Publication in The Astrophysical Journa

Baryonically Closed Galaxy Groups

Elliptical galaxies and their groups having the largest L_x/L_B lie close to the locus in the L_x,L_B diagram expected for closed systems with baryon fractions equal to the cosmic mean value, f_b = 0.16. The estimated baryon fractions for several of these galaxies/groups are also close to 0.16 when the gas density is extrapolated to the virial radius. Evidently they are the least massive baryonically closed systems. Gas retention in these groups implies that non-gravitational heating cannot exceed about 1 keV per particle, consistent with the heating required to produce the deviation of groups from the L_x - T correlation for more massive clusters. Isolated galaxies/groups with X-ray luminosities significantly lower than baryonically closed groups may have undermassive dark halos, overactive central AGNs, or higher star formation efficiencies. The virial mass and hot gas temperatures of nearly or completely closed groups correlate with the group X-ray luminosities and the optical luminosities of the group-centered elliptical galaxy, an expected consequence of their merging history. The ratio of halo mass to the mass of the central galaxy for X-ray luminous galaxy/groups is about 80.Comment: 7 pages; Accepted by ApJ Letter

A Census of Baryons and Dark Matter in an Isolated, Milky Way-sized Elliptical Galaxy

We present a study of the dark and luminous matter in the isolated elliptical galaxy NGC720, based on deep X-ray observations made with Chandra and Suzaku. The gas is reliably measured to ~R2500, allowing us to place good constraints on the enclosed mass and baryon fraction (fb) within this radius (M2500=1.6e12+/-0.2e12 Msun, fb(2500)=0.10+/-0.01; systematic errors are <~20%). The data indicate that the hot gas is close to hydrostatic, which is supported by good agreement with a kinematical analysis of the dwarf satellite galaxies. We confirm a dark matter (DM) halo at ~20-sigma. Assuming an NFW DM profile, our physical model for the gas distribution enables us to obtain meaningful constraints at scales larger than R2500, revealing that most of the baryons are in the hot gas. We find that fb within Rvir is consistent with the Cosmological value, confirming theoretical predictions that a ~Milky Way-mass (Mvir=3.1e12+/-0.4e12 Msun) galaxy can sustain a massive, quasi-hydrostatic gas halo. While fb is higher than the cold baryon fraction typically measured in similar-mass spiral galaxies, both the gas fraction (fg) and fb in NGC720 are consistent with an extrapolation of the trends with mass seen in massive galaxy groups and clusters. After correcting for fg, the entropy profile is close to the self-similar prediction of gravitational structure formation simulations, as observed in galaxy clusters. Finally, we find a strong heavy metal abundance gradient in the ISM similar to those observed in massive galaxy groups.Comment: 23 pages, 13 figures, 4 tables. Accepted for publication in the Astrophysical Journal. Minor modifications to match accepted version. Conclusions unchange

Apparent high metallicity in 3-4 keV galaxy clusters: the inverse iron-bias in action in the case of the merging cluster Abell 2028

Recent work based on a global measurement of the ICM properties find evidence for an increase of the iron abundance in galaxy clusters with temperature around 2-4 keV up to a value about 3 times larger than that typical of very hot clusters. We have started a study of the metal distribution in these objects from the sample of Baumgartner et al. (2005), aiming at resolving spatially the metal content of the ICM. We report here on a 42ks XMM observation of the first object of the sample, the cluster Abell 2028. The XMM observation reveals a complex structure of the cluster over scale of 300 kpc, showing an interaction between two sub-clusters in cometary-like configurations. At the leading edges of the two substructures cold fronts have been detected. The core of the main subcluster is likely hosting a cool corona. We show that a one-component fit for this region returns a biased high metallicity. This inverse iron bias is due to the behavior of the fitting code in shaping the Fe-L complex. In presence of a multi-temperature structure of the ICM, the best-fit metallicity is artificially higher when the projected spectrum is modeled with a single temperature component and it is not related to the presence of both Fe-L and Fe-K emission lines in the spectrum. After accounting for the bias, the overall abundance of the cluster is consistent with the one typical of hotter, more massive clusters. We caution the interpretation of high abundances inferred when fitting a single thermal component to spectra derived from relatively large apertures in 3-4 keV clusters, because the inverse iron bias can be present. Most of the inferences trying to relate high abundances in 3-4 keV clusters to fundamental physical processes will likely have to be revised.Comment: 13 pages, 8 figures.Accepted for publication in Astronomy and Astrophysycs. Minor changes to match published versio

The X-Ray Concentration-Virial Mass Relation

We present the concentration (c)-virial mass (M) relation of 39 galaxy systems ranging in mass from individual early-type galaxies up to the most massive galaxy clusters, (0.06-20) x 10^{14} M_sun. We selected for analysis the most relaxed systems possessing the highest quality data currently available in the Chandra and XMM public data archives. A power-law model fitted to the X-ray c-M relation requires at high significance (6.6 sigma) that c decreases with increasing M, which is a general feature of CDM models. The median and scatter of the c-M relation produced by the flat, concordance LCDM model (Omega_m=0.3, sigma_8=0.9) agrees with the X-ray data provided the sample is comprised of the most relaxed, early forming systems, which is consistent with our selection criteria. Holding the rest of the cosmological parameters fixed to those in the concordance model the c-M relation requires 0.76< sigma_8 <1.07 (99% conf.), assuming a 10% upward bias in the concentrations for early forming systems. The tilted, low-sigma_8 model suggested by a new WMAP analysis is rejected at 99.99% confidence, but a model with the same tilt and normalization can be reconciled with the X-ray data by increasing the dark energy equation of state parameter to w ~ -0.8. When imposing the additional constraint of the tight relation between sigma_8 and Omega_m from studies of cluster abundances, the X-ray c-M relation excludes (>99% conf.) both open CDM models and flat CDM models with Omega_m ~1. This result provides novel evidence for a flat, low-Omega_m universe with dark energy using observations only in the local (z << 1) universe. Possible systematic errors in the X-ray mass measurements of a magnitude ~10% suggested by CDM simulations do not change our conclusions.Comment: Accepted for Publication in ApJ; 13 pages, 4 figures; minor clarifications and updates; correlation coefficients corrected in Table 1 (correct values were used in the analysis in previous versions); conclusions unchange

The Apparent and Intrinsic Shape of the APM Galaxy Clusters

We estimate the distribution of intrinsic shapes of APM galaxy clusters from the distribution of their apparent shapes. We measure the projected cluster ellipticities using two alternative methods. The first method is based on moments of the discrete galaxy distribution while the second is based on moments of the smoothed galaxy distribution. We study the performance of both methods using Monte Carlo cluster simulations covering the range of APM cluster distances and including a random distribution of background galaxies. We find that the first method suffers from severe systematic biases, whereas the second is more reliable. After excluding clusters dominated by substructure and quantifying the systematic biases in our estimated shape parameters, we recover a corrected distribution of projected ellipticities. We use the non-parametric kernel method to estimate the smooth apparent ellipticity distribution, and numerically invert a set of integral equations to recover the corresponding distribution of intrinsic ellipticities under the assumption that the clusters are either oblate or prolate spheroids. The prolate spheroidal model fits the APM cluster data best.Comment: 8 pages, including 7 figures, accepted for publication in MNRA

On The Origin of Radio Halos in Galaxy Clusters

Previously it has been recognized that radio halos in galaxy clusters are preferentially associated with merging systems as indicated by substructure in the X-ray images and temperature maps. Since, however, many clusters without radio halos also possess substructure, the role of mergers in the formation of radio halos has remained unclear. By using power ratios to relate gravitational potential fluctuations to substructure in X-ray images, we provide the first quantitative comparison of the dynamical states of clusters possessing radio halos. A correlation between the 1.4 GHz power (P_{1.4}) of the radio halo (or relic) and the magnitude of the dipole power ratio (P_1/P_0) is discovered such that approximately P_{1.4} ~ P_1/P_0; i.e., the strongest radio halos appear only in those clusters currently experiencing the largest departures from a virialized state. From additional consideration of a small number of highly disturbed clusters without radio halos detected at 1.4 GHz, and recalling that radio halos are more common in clusters with high X-ray luminosity (Giovannini, Tordi, & Feretti), we argue that radio halos form preferentially in massive (L_x >~ 0.5 x 10^{45} erg/s) clusters experiencing violent mergers (P_1/P_0 >~ 0.5 x 10^{-4}) that have seriously disrupted the cluster core. The association of radio halos with massive, large-P_1/P_0, core-disrupted clusters is able to account for both the vital role of mergers in accelerating the relativistic particles responsible for the radio emission as well as the rare occurrence of radio halos in cluster samples.Comment: 4 pages, 1 figure, Accepted for Publication in The Astrophysical Journal Letters, updated reference