Day 387

Saturday.

1303.2627
Reconnaissance of the HR 8799 Exosolar system I:  Near IR spectroscopy
Oppenhiemer et al

Obtained spectra of all 4 known planets orbiting the star HR8799 from Palomar 5-m Hale telescope; data acquired at 2 epochs.  2 different methods of speckle suppression and spectrum extraction, both yielding results that agree.  The spectra do not directly correspond to those of any known objects, although similarities with L and T-dwarfs are present, as well as some characteristics similar to planets such as Saturn.  Tentatively identify the presence of CH_4 along with NH_3 and/or C_2H_2, and possibly CO_2 or HCN in varying amounts in each component of the system.  Other studies suggest red colors for these faint companions, and data confirm these observations.  Cloudy models, based on previous photometric observations, may provide the best explanation for the new data.  Notable : the presumably co-eval objects of similar luminosity have significantly different spectra; the diversity of planets may be greater than previously thought.  The techniques and methods employed in this paper represent a new capability to observe and rapidly characterize exoplanetary systems in a routine manner over a broad range of planet masses and separations.  These are the first simultaneous spectroscopic observations of multiple planets in a planetary system other than our own.

1303.2664
Superbubble breakout and galactic winds from disk galaxies
Roy, Nath, Sharma, Shchekinov

Study conditions for disk galaxies to produce super bubble that can break out of the disk and produce a galactic wind.  The threshold surface density of SNe rate for seeding a wind depends on the ability of superbubble energetics to compensate for radiative cooling.  First adapt Kompaneets formalism for expanding bubbles in a stratified medium to the case of continuous energy injection and include the effects of radiative cooling in the shell.  With the help of hydrodynamic simulations, then study the evolution of superbubbles evolving in stratified disks with typical disk parameters.  Identify 2 crucial energy injection rates that differ in their effects, the corresponding breakout ranging from being gentle to a vigorous one. (a) Superbubbles that break out of the disk with a Mach number of order 2-3 correspond to an energy injection rate of order 1e-4 erg/cm2/s, which is relevant for disk galaxies with synchrotron emitting gas in the extra-planar regions.  (b) a larger energy injection threshold, of order 1e-3 erg/cm2/s, or equivalently, a SF surface density of ~0.1 solar mass/yr/kpc2, corresponds to superbubbles with a Mach number ~5-10.  While the milder superbubbles can be produced by large OB associations, the latter kind requires super-starclusters.  These derived conditions compare will with observations of disk galaxies with winds and the existence of multiphase halo gas.  Furthermore, find that contrary to the general belief that superbubbles fragment through RT instability when they reach a vertical height of order the scale height, the superbubbles are first affected by thermal instability for typical disk parameters and that the RT instability takes over when the shells reach a distance of approximately twice the scale height.

1303.2672
The PRIsm MUlti-obect Survey (PRIMUS).  II.  Data reduction and redshift fitting
Cool, Moustakas, Blanton, ... Coil, Eisenstein, ... Bernstein (Rebecca), Bolton, Hogg, et al

PRIMUS redshift survey to z~1 completed with a low-dispersion prism and slitmasks allowing for simultaneous observations of 2.5k objects over 0.18 sq. deg.  The final PRIMUS catalog includes 130k robust redshifts over 9.1 sq. deg.  Summarize the observational strategy and present data reduction details used to measure z, redshift precision, and survey completeness.  The survey motivation, observational techniques, fields, target selection, slitmask design, and observations are presented in Coil+2010.  Comparisons to existing higher-resolution spectroscopic measurements show a typical precision of sigma_z/(1+z) = 0.005.  PRIMUS, both in area and number of redshifts, is the largest faint galaxy redshift survey completed to date and is allowing for precise measurements of the relationship between AGNs and their hosts, the effects of environment on galaxy evolution, and the build up of galactic systems over the latter half of cosmic history.

1303.2688
Elliptical galaxies with rapidly decreasing velocity dispersion profiles: NMAGIC models and dark halo parameter estimates for NGC 4494
Morganti et al

NGC 4494 inferred to have unusually diffuse DM halo.  Use particle code NMAGIC to construct axisymmetric models of NGC 4494 from photometric and various kinematic data.  Light spectra out to 3.5 R_e, and 100s of planetary nebulae velocities out to 7R_e, thus allowing to probe the DM content and orbital structure in the halo.  Use MC simulations to estimate confidence boundaries for the halo parameters, given data and modelling set-up.  Find that the true potential of the DM halo is recovered within Delta G (merit function) < 26 at 70% CL.  These numbers are much larger than the usually assumed Delta chi^2=2.3 for 70% CL for 2 free parameters, perhaps case-dependent, but calling into question the general validity of the standard assumptions used for halo and BH mass determinations.  The best-fitting models for NGC 4494 have a DM fraction of about 0.6pm0.1 at 5 R_e (70%CL), and are embedded in DM halo with circular velocity of @200 km/s.  The total circular velocity curve (CVC) is approximately fat at v_c=220 km/s outside 0.5 R_e.  The orbital anisotropy of the stars is moderately radial.  These results are independent of the assumed inclination of the galaxy, and edge-on models are preferred.  Comparing with the haloes of NGC 3379 and 4697, whose velocity dispersion profiles also decrease rapidly from the center outwards, the outer CVCs and DM haloes are quite similar.  4494 shows a particularly high DM fraction inside ~3R_e, and a strong concentration of baryons in the center.

1303.2689
Constraining the assembly of normal and compact passively evolving galaxies from redshift z=3 to the present with CANDELS
Cassata, ... Grogin, Koekemoer, et al

Study the evolution of the number density, as a function of size, of passive galaxies with a wide range of stellar masses (1e10-11.5 Msun) from 1<z<3, exploiting the unique dataset available in GOODS-S, including WFC3 images from CANDELS; VLT, CFHT, Spitzer, Chandra, and HST ACS.  Select a sample of 107 massive (M*>1e10 Msun) passive (SSFR < 1e-2 /Gyr) and morphologically spheroidal galaxies at 1.2<z<3.  Find that at 1<z<3 the passively evolving early-type galaxies are the reddest and most massive objects in the universe, and prove that a correlation between mass, morphology, color and SF activity is already in place at that epoch.  Measure a significant evolution in the mass-size relation of passive ETGs from z~3 to 1, with galaxies growing on average by a factor of 2 in size in a 3 Gyr timescale.  Also see an increase in the number density of passive ETGs of 50x over the same time interval.  Find that the first ETGs to form at z>2 are all compact or ultra-compact, while normal (i.e., local-like) sized ETGs are the most common ETGs only at z<1.  The increase of the average size of ETGs at 0<z<1 is primarily driven by the appearance of new large ETGs rather than by the size increase of individual galaxies.

1303.2708
Quasars probing quasars IV: joint constraints on the circumgalactic medium from absorption and emission
Hennawi, Prochaska

As the title says: Much deeper integrations with upcoming integral-field spectrometers such as MUSE and KCWI will be able to routinely detect a diffuse Ly-a glow around bright quasars on scales R~100 kpc and thus directly image the CGM.

1303.2722
ALMA observations of SPT-discovered, strongly lensed, dusty, star-forming galaxies
Hezaveh ... Aguirre, ... et al

ALMA 860 um imaging of high z (2.8-5.7) dusty sources detected at SPT 1.4 mm.  Some multiple images of a submillimeter source seen (1-3 arcsec separation), consistent with SL with IR galaxy as lens.  One of the sources at z=5.7 is most luminous and intensely SF (3.7e13 Lsun and SF density of 4200 Msun/yr/kpc2.  Magnification factor of 5-22, with Einstein radii of 1.1-2.0" and enclosed mass of 1.6-7.2e11 Msun.  Observations confirm lensing origin of these objects.  [We know they are dusty because they are detected at submm, I guess]

1303.2723
Dusty starburst galaxies in the early universe as revealed by gravitational lensing
Vieira, et al

Same as above.  Spectra give redshifts of lens and source for 23/26 sources (12/26 has multiple lines and are robust); at least 10 of them are z>4, indicating that the fraction of dusty starburst galaxies at high z is greater than previously thought.  Models of lens geometries in the sample indicate that the BG objects are ultra-luminous IR galaxies, powered by extreme bursts of SF.

1303.2726
ALMA redshifts of millimeter-selected galaxies from the SPT survey: The redshift distribuiton of dusty star-forming galaxies
Weiss et al

The z distribution of the aformentioned dusty source galaxies (from lensing).  A broad distribution from z=1 to 7.

1303.2746
BSG alignment of SDSS galaxy groups
Li, Wang, Yang, Chen, Xie, Wang

Alignment signal between distribution of brightest satellite galaxies (BSGs) and the major axis of their host groups.  Correct for the effect of the group ellipticity, a statistically significant 5 sigma major-axis alignment is detected and the alignment angle is found to be 43.0 pm 0.4 degrees.  More massive and richer groups show stronger BSG alignment.  The BSG alignment around the blue BCGs is slightly stronger than that around red BCGs, and red BSGs have much stronger major-axis alignment than blue BSGs.  Unlike BSGs, other satellites do not show very significant alignment with group major axis.  Further explore in SAM; find general agreement with observations: BSGs in SAM show strong major axis alignment which depends on group mass and richness in the same way as observations; and none of other satellites exhibit prominent alignment.  However, discrepancy also exists in that the SAM shows opposite BSG color dependence, which is most probably induced by the missing of large scale environment ingredient in SAM.  The combination of two popular scenarios can explain the detected BSG alignment.  The first one: satellite merged into the group preferentially along the surrounding filaments, which is strongly aligned with the major axis of the group.  Second: BSGs enter their host group more recently than other satellites, then will preserve more information about the assembling history and so the major-axis alignment.  In SAM, find positive evidence for the second scenario by the fact that BSGs merged into groups statistically more recently than other satellites.  On the other hand, although SAM has it backwards, the BSG color dependence in observation might indicate the first scenario as well.

1303.2864
e-MERLIN resolve Betelgeuse at wavelength 5cm
Richards et al

As the title says.

1303.2928
Resonant behavior of Comet Halley and the Orionid stream
Sekhar, Asher

As the title says.  Study the 1:6 and 2:13 mean resonances with Jupiter.  2:13 libration from 240 BC to 1700 AD while stream particles can survive for timescales of order 10k years and 1k years in the 1:6 and 2:13 resonances respectively.  Influences the Orionid [meteor shower] outbursts.  Can correlate enhanced meteor phenomena seen in 3 periods with 1:6 resonance, and outburst of 1916 & 1993 with 2:13 resonance.  Ancient as well as modern observational records agree with these theoretical simulations to a very good degree.