Day 388

Sunday.

1303.3004
Energy extraction from spinning black holes via relativistic jets
Narayan, McClintock, Tchekhovskoy

An article of faith: that BH spin energy is responsible for powering the relativistic jets seen in accreting BHs.  2 recent advances have strengthened the case.  (1) numerical GR MH sims of accreting spinning BHs show that relativistic jets form spontaneously.  In at least some of the cases, there is unambiguous evidence that much of the jet energy comes from the BH, not the disk.  (2) Spin parameters of a number of accreting SM BHs have been measured.  For ballistic jets from these systems, it is found that the radio luminosity of the jet correlates with the spin of the BH.  This suggests a causal relationship between BH spin and jet power, presumably due to a generalized Penrose process.

1303.3005
Photometric redshifts and systematic variations in the SEDs of luminous red galaxies from the SDSS DR7
Greisel, Seitz, Drory, Bender, Saglia, Snigula

Construction of a template set of SEDs for the estimation of photometric redshifts of LRGs with a Bayesian template fitting method.  Examine the color properties of several publicly available SEDs within 0<z<0.5 and compare to DR7 data, show that only some of the SEDs approximately match the colors of the LRG data throughout the redshift range, but not at the quantitative level required for precise photo-z.  Generate new SEDs by superposing model SEDs of composite stellar populations with a burst model, allowing both components to be reddened by dust, in order to match the data in 5 different z bins.  Select a set of SEDs which represents the LRG data in color space within 5 z bins, thus defining new SED template set for photoz estimates.  Results with the new template and photoz code are nearly unbiased, with a scatter of sigma(Delta z)=0.027 (incl. outliers), and a fraction of catastrophic outliers of 0.12% [outlier fraction can be limited if the photoz code is limited in redshift range...what was the range that their code used?].  Show that templates that optimally describe the brightest galaxies indeed vary from 0.1<z<0.5, consistent with aging of the stellar population.  Find that templates that optimally describe galaxies at z<0.1 strongly differ as a function of the absolute magnitude of the galaxies, indicating an increase in SF activity for less luminous galaxies.  Findings based on the photometry of the SDSS LRGs and the SED template fitting are supported by comparison to the average SDSS LRG spectra in different luminosity and z bins.

1303.3009
Toy models for galaxy formation versus simulations
Dekel, Zolotov, Tweed, Cacciato, Severino, Primack

Describe toy models for key processes of galaxy formation in its most active phase, at z>1, and test the approximate expressions against a suite of high-res hydro-cosmo simulations of massive galaxies at 1<z<4.  Address as a function of mass and z, the evolution of (a) the total mass inflow rate from the cosmic web into galactic haloes based on the EPS approximation, (b) the penetration of baryonic streams into the inner galaxy, (c) the disc size, (d) the implied steady-state gas content and SFR in the galaxy subject to mass conservation and a universal SF law, (e) the inflow rate within the disc to a central bulge and BH as derived using energy conservation and self-regulated Q~1 violent disk instability (VDI), and (f) the implied steady state in the disc and bulge.  Toy models found to provide useful approximations for the average behaviour of the simulated galaxies.  Find: (a) inflow rate propto mass and (1+z)^5/2, (b) Penetration to the inner halo is ~60% at z=2-4, (c) the disc radius is about 5% of the virial radius [are they compact/ultra-compact?  but I guess they're talking about disks, not spheroids], (d) the galaxies reach a steady state with the SFR with the SFR following the accretion rate into the galaxy, (e) There is an intense inflow through the disc, comparable to the SFR, following the predictions of VDI, and (f) the galaxies approach a steady state with the bulge mass comparable to the disk mass, where the draining of gas by SFR, outflows and inflows in the disc is replenished by fresh accretion.  Given the agreement with simulations, these toy modes are useful for understanding the complex phenomena in simple terms and for back-of-the-envelope predictions.

1303.3105
A history of the gamma-ray burst flux at the Earth from galactic globular clusters
Domainko, Bailer-Jones, Feng

Nearby GRBs are likely to have represented a significant threat to life on Earth.  Significant source of such bursts is compact binary mergers in globular clusters.  Link between globular clusters and GRBs offers the possibility to find time intervals in the past with higher probabilities of a nearby burst, by tracing globular cluster orbits back in time.  Show that the expected flux from such bursts is not flat over the past 550 Myr but rather exhibits 3 broad peaks at 70, 180 and 340 Myr ago.  The main source for nearby GRBs for all 3 time intervals is the globular cluster 47 Tuc, a consequence of its large mass and high stellar encounter rate, as well as the fact that it is one of the globular clusters which comes quite close to the Sun.  Mass extinction events indeed coincide with all 3 time intervales found in this study, although a chance coincidence is quite likely.  Nevertheless, the identified time intervas can be used as a guide to search for specific signatures of GRBs in the geological record around these times.

1303.3121
Cosmic variance and the measurement of the local Hubble parameter
Marra, et al

There is an ~7.5% discrepancy (2.0 sigma) between 2 independent constraints on the expansion rate of the universe: one from CMB and BAO, and the other from local measurements of luminosity distances.  Argue that by taking into account the local gravitational potential at the position of the observer, this tension is partially relieved and the concordance of the standard model of cosmology increased.  Estimate that present measurements of the local Hubble constant are subject to a cosmic variance of about 2.4% (limiting the local sample to z>0.010) or 1.3% (limiting to z>0.023), which should be added to the error budget of such measurements.

1303.3259
Gravitational wave constraints on the shape of neutron stars
Johnson-McDaniel

Show: direct relation between upper limits on the m=2 quadrupole moments of slowly rotating NSs and the l=m=2 deformation of the star's surface in full GR, to first order in the perturbation.  Relation only depends on the star's structure through its mass and radius.  All one has to assume about the star's constituents is that the stress-energy tensor at its surface is that of a perfect fluid, which will be true with good accuracy in almost all situations, and that the B-field configuration there is force-firee, which is likely to be a good approximation.  Then apply this relation to the stars which have direct LIGY/Virgo bounds on their l=m=2 quadrupole moment, below the spin-down limit, and compare with the expected surface deformations due to rotation.  In particular, find that LIGO observations have constrained the Crab pulsar's l=m=2 surface deformation to be smaller than tis l=2, m=0 deformation due to rotation, for all the causal equations of state considered, a statement that would not have been able to be made just using the upper bounds on the l=m=2 deformation from EM observations.

1303.3274
Masses of galaxy clusters from gravitational lensing
Hoekstra, Bartelmann, Dahle, Israel, Limousin, Meneghetti

Observational properties of galaxy clusters are difficult to predict ab initio.  Important to compare both theoretical and observational results to a direct measure of the cluster mass.  This is possible by measuring the gravitational lensing effects caused by the bending of light by the cluster has distribution.  In this review, discuss how this phenomenon can be used to determine cluster masses and study the mass distribution itself.  As sample sizes increase, the accuracy of the WL mass estimates needs to improve accordingly.  Discuss the main practical aspects of these measurements.  Review a number of applications and highlight some recent results.  [48 page review paper]

1303.3285
Internal cluster structure
Bartelmann, Limousin, Meneghetti, Schmidt

Core structure of galaxy clusters are important.  Self-gravitating systems have no stable equilibrium state due to their negative heat capacity, numerical simulations find density profiles which are universal in the sense that they are fairly flat within a scale radius and gradually steepen farther outward, asymptotically approaching a logarithmic slope of ~-3 near the virial radius.  Argue that the reason for the formation of this profile is not satisfactorily understood.  The ratio between the virial radius and the scale radius, the so-called concentration, is found in simulations to be closely related to the mass and the redshift and low and cluster-sized haloes, but observed to be substantially higher at least in a subset of observed clusters.  Haloes formed from CDM should furthermore be richly substructured.  Review theoretical and observational aspects of cluster cores here, discuss modifications by baryonic physics and observables that can provide better insight into the internal structure of clusters.

1303.3286
Outskirts of galaxy clusters
Reiprich, Basu, Ettori, Israel, Lovisari, Molendi, Pointecouteau, Roncarelli

A wide are of hot gas physics and chemistry awaits discovery in galaxy cluster outskirts.  Robust LS total mass profiles and maps are within reach.  First observational and theoretical results in this emerging field have been achieved in recent years with sometimes surprising findings.  Summarize and illustrate the relevant underlying physical and chemical processes and review the recent progress in X-ray, SZ, and WL observations of cluster outskirts, including brief discussions of technical challenges and possible future improvements.  [52 page review paper]

1303.3363
Arc statistics
Meneghetti, Bartelmann, Dahle, Limousin

The abundance and the frequency of strong lensing events like gravitational arcs turned out to be a potentially very powerful tool to trace the structure formation.  But given the limited size of observational and theoretical data-sets, the power of arc statistics as a cosmological tool has been only minimally exploited so far.  On the other hand, the last years were characterized b significant advancements in the field, and several cluster surveys that are ongoing or planned for the near future seem to have the potential to make arc statistics a competitive cosmological prove.  Recent observations of anomalously large Einstein radii and concentrations in galaxy clusters have reinvigorated the debate on the arc statistic problem.  Review the work done so far on arc statistics, focussing on what is the lesson learned and what is likely to improve in the next years.  [49 page review paper]

1303.3372
The height evolution of the 'true' CME mass derived from STEREO COR1 and COR2 observations
Bein et al

As the title says.  CME kinetic energies range between 1-66e23 J, and forces between 2-510e14 N.  Sample of 25 events between 2007 to 2011.  The mass increase ranges from 2 to 6% per Rs, and is positively correlated to the total CME mass.  Able to estimate the 'true' mass for very low coronal heights (<3Rs).  

1303.3403
ALMA observations of the galactic center: SiO outflows and high mass star formation near Sgr A*
Yusef-Zadeh et al

Detection of 11 SiO(5-4) clumps of molecular gas within 0.6 pc (15") of Sgr A*, interior to the 2-pc circumnuclear molecular ring.  The 3 SiO clumps closest to Sgr A* show the largest central velocities, 150 km/s, and broadest asymmetric linewidths with full width zero intensity (FWZI) ~110-147 km/s.  The remaining clumps, distributed mainly to the NE of the ionized mini-spiral, have narrow FWZI (18-56 km/s).  Using CARMA SiO (2-1) data, LVG modeling of the SiO line ratios for the broad velocity clumps, constrains the column density N(SiO) ~1e14/cm2, and the H2 gas density n_H2=3-9e5/cm3 for an assumed kinetic temperature of 100-200K.  The SiO clumps are interpreted as highly embedded protostellar outflows, signifying an early stage of massive SF near Sgr A* in the last 1e4-5 years.  Support for this interpretation is provided by the SiO(5-4) line luminosities and velocity withs which lie in the range measured for protostellar outflows in SF regions in the galaxy.  Furthermore, SED modeling of stellar sources shows 2 YSO candidates near SiO clumps, supporting in-situ SF near Sgr A*.  Discuss the nature of SF where the gravitational potential of the BH dominates. In particular, suggest that external radiative pressure exerted on self-shielded molecular clouds enhances the gas density, before the gas cloud become gravitationally unstable near Sgr A*.  Alternatively collisions between clumps in the ring may trigger gravitational collapse.

1303.3530
Mass profiles of galaxy clusters from X-ray analysis
Ettori, .. Reiprich, ... et al

Review methods used at the present to reconstruct the mass profiles in X-ray luminous galaxy clusters.  Discuss the limitations and the biases affecting these measurements and their cosmological implications.  [39 page review paper]

1303.3535
A measurement of the secondary-CMB and millimeter-wave-foreground bispectrum using 800 square degrees of South Pole Telescope data
Crawford ... Carlstrom, ... et al

Present angular bispectrum of mm-wave sky at 95, 150, and 220 Ghz, on angular scales of 1'<theta<10' (multipole number 1000<l<10,000).  At these frequencies and angular scales, the main contributions to the bispectrum are expected to be the thermal tSZ effect and emission from FG extragalactic sources, mostly dusty, SF galaxies (DSFGs) and AGNs.  Measure the bispectrum, use a multi-frequency fitting procedure to separate the bispectrum of the tSZ effect from the extragalactic source contribution.  Simultaneously detect the bispectrum of the tSZ effect at >10 sigma, the unclustered component of the extragalactic source bispectrum at >6 sigma in each frequency band, and the bispectrum due to the clustering of DSFGs--i.e., the clustered CIB bispectrum---at >5sigma.  First detection reported of CIB bispectrum.  Use the measured tSZ bispectrum, compare to theoretical predictions, constrain sigma_8 = 0.786 pm 0.031, and predict the tSZ PS amplitude.  This prediction imrpoves ability to separate the thermal and kinematic contributions to the total SZ PS.  Addition of bispectrum data improves constraint on the tSZ PS amplitude by x2 compared to PS measurements alone, and provides the first evidence of a nonzero kSZ power spectrum, with a derived constraint on the kSZ amplitude at l=3000 of A_kSZ = 2.9pm1.5 uK^2.

1303.3551
The different star-formation histories of blue and red spiral and elliptical galaxies
Tojeiro, .. Percival, ... Nichol, et al

Study the spectral properties of intermediate mass galaxies as a function of color and morphology.  Use galaxy zoo to define 3 morphological classes of galaxies: Ellipticals, disk-dominated face-on spirals, and bulge-dominated spirals.  Classify these galaxies as blue or red according to their SDSS g-r color and use the spectral fitting code VESPA to calculate time-resolved SFH, metallicity and total starlight dust extinction from their SDSS fibre spectra.  Find that red late-type spirals show less SF in the last 500 Myr than blue late-type spirals by x3, but share similar SFH at earlier times.  This decline in recent SF explains their redder color: their chemical and dust content are the same.  Postulate that red late-type spirals are recent descendants of blue late-type spirals, with their SF curtailed in the last 500 Myrs.  The red late-type spirals are however still forming stars approximately x17 faster than red ellipticals over the same period.  Red early-type spirals lie between red late-type spirals and red ellipticals in terms of recent-to-intermediate SF and dust content.  Therefore, it is plausible that these galaxies represent an evolutionary link between these two populations.  They are more likely to evolve directly into red ellipticals than red late-type spirals.  Blue ellipticals show similar SFH as blue spirals (regardless of type), except they have formed less stars in the last 100 Myrs.  However, blue ellipticals have different dust content, which peaks at lower extinction values than all spiral galaxies.

1303.3562
redMaPPer I: Algorithm and SDSS DR8 catalog
Rykoff, Rozo, Busha, Cunha, Finoguenov, Evrard, Hao, Koester, Leauthaud, Nord, ..Sheldon, Wechsler  et al

A new red-sequence cluster finder specifically designed to make optimal use of ongoing and near-future large-photometric surveys.  Features: (1) can iteratively self-train the red-sequence model based on minimal spectroscopic training sample (an important feature for high-z surveys), (2) can handle complex masks with varying depth, (3) produces cluster-appropriate random points to enable LSS studies, (4) clusters are assigned a full z probability distribution P(z), (5) clusters can have multiple candidate central galaxies, each with corresponding centering probabilities, (6) algorithm is parallel and numerically efficient, (7) algorithm exhibits excellent photo-z performance, the richness estimates are tightly correlated with external mass proxies, and the completeness and purity of the corresponding catalogs is superb.  Apply to 10k sq deg of SDSS DR8 data, and present the resulting catalog of 25k clusters over 0.08<z<0.55.  The photo-zs are nearly Gaussian [the errors?], with a scatter of sigma_z~0.006 at low z, increasing to 0.02 at z~0.5 due to increased photometric noise near the survey limit.  THe incidence of projection effect is low (<=5%).  Detailed performance comparisons of the redMaPPer DR8 cluster catalog to X-ray and SZ catalogs are presented in a companion paper (Rozo & Rykoff 2013).

1303.3566
Variation of the diameter of the sun as measured by the Solar Disk Sextant (SDS)
Sofia et al

At 100nm-wide passband centered at 615 nm, the angular diameter of the Sun from 1992 to 2011 varies by 200 mas, while the typical uncertainty of each measure is 20 mas.  The diameter variation appears to be cyclic, although it is not in phase with the solar activity cycle (i.e., the diameter variation is not simply an observational artifact of surface activity).