Day 480

Friday.

1308.0013
Failed supernovae explain the compact remnant mass function
Kochanek

One explanation of the absence of higher mass red supergiants (16.5 Msun < M < 25 Msun) as the progenitors of Type IIP SNe is that they die in failed SNe creating black holes.  Simulations show that such failed SNe still eject their hydrogen envelopes in a weak transient, leaving a BH with the mass of the star's He core (5-8 Msun).  Show here that this naturally explains the typical masses of observed BHs and the gap between NS and BH masses without any fine-tuning of the NS mechanism beyond having it fail in a mass range where many progenitor models have density structures that make the explosions more likely to fail.  There is no difficulty including this ~20% population of failed SNe in any accounting of SN types over the progenitor mass function.  And, other than patience, there is no observational barrier to either detecting these black hole formation events or limiting their rates to be well below this prediction.

NASA PCOS Newsletter
01-08-2013
Seiffert, Rhodes

MoU with ESA's Euclid signed; Euclid scheduled for 2020 launch, ~6yr photometric and spectroscopic survey of ~1/3 of the sky.  NASA will provide detectors, associated electronics for NISP; sensor chip systems (SCS) includes Teledyne H2RG (2k x 2k) NIR detector, flexible cryogenic cable, associated cryogenic readout electronics.  20 provided by NASA, 16 for flight and 4 flight spares.  Goddard's detector characterization lab (DCL) will validate and characterize the performance of the SCSs and their components before delivery to ESA.  NASA contribution managed by JPL (PM: Ulf Israelsson).  In exchange for hardware contribution, NACA invited to nominate 40 individual scientists for membership in Euclid Consortium (EC).  EC is the scientific body set up to provide the NISP and VIS to ISA and perform the Euclid scientific analyses.  40 new US scientists joined 14 US scientists already part of EC.  3 teams led by Jason Rhodes (JPL), Alexander Kashlinsky (GSFC) and Ranga-Ram Chary (Caltech/IPAC) will pursue science programs in DE science as well as science related to galaxy evolution.  Seiffert was given the 40th NASA slot (NASA Euclid Project Scientist); Rhodes is the NASA representative on EC Board, and the 12-member ESA Euclid Science team (monitors overall implementation of Euclid).  Hardware currently on schedule for delivery; contract negotiated with Teledyne to deliver hardware to NASA for testing, successful preliminary design review (PDR) for NASA HW contribution held July 17-18 2013.  NASA studying the possibility of US joining Euclid's SGS.  Implementation of Euclid also proceeding on schedule in Europe: VIS, NISP and SGS have all passed recent detailed reviews.  ESA has also chosen Thales Alenia Space as the prime contractor for Euclid and EADS Astrium to provide the payload module (including the telescope).

1308.0021
Co-evolution of galactic nuclei and globular cluster systems
Gnedin, Ostriker, Tremaine

Revisit the hypothesis that dense galactic nuclei are formed from inspiraling globular clusters.  Recent advances in understanding of the continuous formation of globular clusters over cosmic time and the concurrent evolution of the galaxy stellar distribution allow us to construct a simple model that matches the observed spatial and mass distributions of clusters in the Galaxy and the giant elliptical galaxy M87.  In order to compare with observations, model the effects of dynamical friction and dynamical evolution, including stellar mass loss, tidal stripping of stars, and tidal disruption of clusters by the growing galactic nucleus.  Find that inspiraling globular clusters form a dense central stellar cluster with an effective radius of several pc, with mass and radius comparable to the typical values in observed nuclear star clusters in late-type and low-mass early-type galaxies.  The density contrast associated with the nuclear star cluster is less pronounced in giant elliptical galaxies.  Thus disrupted globular clusters may contribute most of the mass of nuclear star clusters (NSCs) in galaxies with stellar mass below 1e11 Msun.  Results indicate that the NSC mass as a fraction of mass of the galaxy stellar spheroid scales as M_NCS/M_sph~0.0025 M_{sph, 11}^-0.5.  However, some fraction of the accumulated stellar debris may seed the growth of a central BH via stellar dynamical core collapse, thereby relieving the problem of how to form luminous quasars at high redshift.  Both the formation time of NSC and the core collapse time are less than 1 Gyr for galaxies more massive than the MW.

1308.0054
Massive blue early-type galaxies in the SDSS.  I. A new population of recently quenced elliptical galaxies
McIntosh, ... Bell, ... van den Bosch, ... et al

Use SDSS to explore ETGs that are plausibly in transition between the red sequence and the blue cloud.  Identify 1500 unusually blue elliptical galaxies with 0.01<z<0.08 and M*>1d10 Msun/h^2.  Blue elliptical comprise 3.7% of all ETGs with 1e10<Mstar<1e11 Msun/h^2.  Using spectra diagnostics, find a unique population of 172 non-SF ellipticals with distinctly blue urn colors and <3Gyr stellar ages.  These recently quenched ellipticals (RQEs) have n=2.7-4.7e-5 h^3/Mpc^3, and sufficient numbers above 2.5e10 Msun/h^2 to account for >50% of the expected quiescent growth at z~0 assuming this phase lasts 0.5 Gyr.  Based on color, stellar M/L ratios and metallicity estimates, argue that RQEs have recent SFHs that differ from rejuvenated ETGs.  Yet, a significant but small incidence (5%) of RQEs with E+A spectra implies that the quenching of most RQEs did not involve a large starburst.  Most (90%) RQEs reside at the centers of 3e12 Msun/h groups, which agrees well with the 'small group scale' in which spiral merging onto the halo center is maximally efficient.  The preferred RQE environment rules out satellite-specific quenching processes for most.  Under the assumption that most RQEs were quenched by a hot halo atmosphere impeding efficient gas cooling, discuss the incidence of Seyfert and LINER activity with regards to the maintenance-mode feedback needed to keep SF shut off at the centers of such small haloes.

1308.0063
CLASH: photometric redshifts with 16 HST bands in galaxy cluster fields
Jouvel, Host, Lahav, Seitz, .. Coe, Benitez, Koekemoer, et al

The Cluster Lensing And Supernovae survey with Hubble (CLASH) observes 25 massive galaxy clusters with HST in 16 bands from UV to NIR to derive photos.  Present CLASH photoz and study the photometric redshift accuracy of the arcs in more detail for the case of MACS1206.2-0847.  Use the publicly available LePhare and BPZ photo-z codes on 17 CLASH clusters.  LePhare on S/N>=10 objects reach a precision of 3(1+z)% for the SL arcs; reduced to 2.4(1+z)% after removing outliers.  In the field, the corresponding values are 4(1+z)% and 3(1+z)%.  Using mock galaxy catalogues, show that 3(1+z)% precision is what one would expect from the CLASH photometry when taking into account extinction from dust, emission lines and the finite range of SEDs included in the photo-z template library.  Study photo-z results for different aperture photometry and find that the SExtractor isophotal photometry works best.  Le Phare and BPZ give similar photo-z results for the SL arcs as well as galaxies of the cluster field.  Results are improved when optimizing the photometric aperture shape showing and optimal aperture size around 1" radius giving results which are equivalent to isophtal photometry.  Tailored photometry of the arcs improve the photo-z results.
1308.0286
On the joint analysis of CMB temperature and lensing-reconstruction power spectra
Schmittfull, Challinor, Hanson, Lewis

Perform a rigorous analysis of the covariance between lensing PS and trispectrum analysis.  Find two dominant contributions coming from (i) correlations between the disconnected noise bias in the trispectrum measurement and sample variance in the temperature PS, and (ii) sample variance of the lenses themselves.  The former is naturally removed when the dominant N0 Gaussian bias in the reconstructed deflection spectrum is dealt with via a partially data-dependent correction, as advocated elsewhere for other reasons.  The remaining lens-cosmic-variance contribution is easily modeled but can safely be ignored for a Planck-like experiment, justifying treating the two observable spectra as independent.  Also test simple likelihood approximations for the deflection PS, finding that a Gaussian with a parameter-independent covariance performs well.