1308.0336
The DiskMass survey. VII. The distribution of luminous and dark matter in spiral galaxies
Martinsson, et al
Present dynamically-determined rotation-curve mass decompositions of 30 spiral galaxies, which were carried out to test the maximum-disk hypothesis [*] and to quantify properties of their DM haloes. Used measured vertical velocity dispersions of the disk stars to calculate dynamical mass surface densities. Together with atomic and molecular gas mass surface densities, derived the stellar mass surface densities, and thus have absolute measurements of all dominant baryonic components. Using K-band surface brightness profiles, calculate the K-band M/L ratio of the stellar disks. Result consistent with all galaxies in the sample having equal M/L, with a sample average and scatter of <M/L>=0.31 pm 0.07. Rotation-curves of the baryonic components calculated from their mass surface densities, and used with circular-speed measurements to derive the structural parameters of the DM haloes, modeled as either a pseudo-isothermal sphere (pISO) or NFW. All galaxies in sample are submaximal, such that at 2.2 disk scale lengths (hR) the ratios between the baryonic and total rotation curves are less than 0.75. Find this ratio to be nearly constant between 1-6 hR within individual galaxies. Find a sample average and scatter of <Fb^{2.2 hR}> = 0.57pm0.07, with trends of larger Fb^{2.2 hR} for more luminous and higher-surface-brightness galaxies. To enforce these being maximal, need to scale M/L by a factor 3.6 on average. The DM rotation curves are marginally better fit by a pISO than by an FNW halo. For the nominal-M/L (submaximal) case, the derived NFW-halo parameters have values consistent with LCDM N-body simulations, suggesting that the baryonic matter has only had a minor effect on the DM distribution. In contrast, maximum-M/L decompositions yield halo concentrations that are too low compared to the LCDM simulations.
* In the 'maximum disk hypothesis' the disk contribution is optimized such that the amplitude of the disk-alone rotation curve is as large as the observations allow. In a maximal disk, the ratio between the disk-alone rotation curve and the observed one will be a bit lower than unity to allow a bulge contribution and let dark haloes have a low density core. A working definition is Vdisk/Vrot = 0.85 pm 0.10 (Sackett 1997). Most galaxies are not 'maximum-disk'. The ones that may be maximum disk have a high surface density. Disk that are maximal appear to have more anisotropic velocity distributions or are less stable according to Toomre Q.
1308.0458
The effects of dust on the photometric parameters of decomposed disks and bulges
Pastrav, et al
Quantify the effects of dust on the derived photometric parameters of disk and bulges obtained from bulge-disk decomposition: scale-length, effective radius, Sersic index, disk axis-ratio, and bulge-to-disk ratio. The dust induced changes in these parameters were obtained by fitting simulated images of composite systems (containing a disk and a bulge) produced using radiative transfer calculations. The simulations were fitted with GALFIT, with combination of exponential plus a variable-index Sersic, as well as a combination of two variable-index Sersic. Find that dust is biasing the derived exponential scale-length of decomposed disks towards smaller values than otherwise if the galaxy were to have no bulge. Similarly, the derived bulge-to-disk ratio is biased towards smaller values [why?]. However, the derived axis-ratio of the disk is not changed in the decomposition process. The derived effective radius of decomposed disks of systems having exponential bulges is found to be less affected by dust when fits are done with two variable-index Sersic functions. For the same type of fits dust is found to bias the value of the derived effective radius of decomposed disks towards lower values for systems having de Vaucouleurs bulges. All corrections derived in this paper are made available in electronic form.
1308.0604
Recovering galaxy stellar population properties from broad-band spectral energy distribution fitting II. The case with unknown redshift
Pforr, Maraston, Tonini
Dependence of galaxy stellar population properties from broad-band SED fitting on the fitting parameters, e.g. SFH, age grid, metallicity, IMF, dust reddening, reddening law, filter setup and wavelength coverage. Consider also redshift as a free parameter in the fit and study whether one can obtain reasonable estimates of photo-z and stellar population properties at once. Use mock SF as well as passive galaxies placed at various z (0.5 to 3) as test particles. Mock SF galaxies extracted from SAM. Show that for high-z SF galaxies, photo-z, stellar masses and reddening can be determined simultaneously when using a broad wavelength coverage and a wide template setup in the fit. Masses similarly well recovered as as at fixed z. For old galaxies with little recent SF masses are better recovered than in the fixed z case, such that the median recovered stellar mass improves by up to 0.3 dex whereas the uncertainty in the z accuracy increases by only ~0.05. However, a railure in z recovery also means a failure in mass recovery. As at fixed z mismatches in SFH and degeneracies between age, dust and now also z cause underestimated ages, overestimated reddening and underestimated masses. Stellar masses are best determined at low z without reddening in the fit (median underestimation ~ 0.1 dex for similarly well recovered redshifts). The recovery of properties is substantially better for passive galaxies. In all cases, the recovery of physical parameters is crucially dependent on the wavelength coverage adopted in the fitting. Scaling relations for the transformation of stellar masses provided.
1308.0616
A proposal for new definitions of solar system bodies - Planet, Moon and satellite
Russell
A new classification system for Solar System bodies proposed, which takes into account both physical and dynamical perspectives, as well as critiques of the IAU resolutions for the definitions of planet, dwarf planet, and small solar system bodies. In this proposal there are 4 classes of planets which correspond with environments of planetary formation in the early history of the Solar System: Terrestrial, Cerian, Jovian, and Kuiperian. Specific physical criteria are adopted for identifying an object as a planet and the four classes naturally address dynamical concerns. The proposal also addresses the problem of calling all satellites in the growing list of objects discovered orbiting the Jovian planets as moons by defining two classes of satellites: moons and satellites. Advantages of the new system over the current IAU definitions discussed.
1308.0630
Large-scale analysis of the SDSS-III DR8 photometric luminous galaxies angular correlation function
de Simoni et al
Large-scale angular correlation function (ACF) of CMASS LGs, a photo-z catalog based on DR8. Contains 600k LGs in 0.45<z<0.65, split into 4 z shells of constant width. Estimate the constraints on RSD parameters b*sigma_8 and f*sigma_8, where b is the galaxy bias, f the growth rate and sigma_8 the perturbation normalization, finding that they vary appreciably among different redshift shells, in agreement with previous results using DR7 data. When assuming constant RSD parameters over the survey redshift range, obtain f*sigma_8=0.69pm0.21, which agrees at the 1.5 sigma level with BOSS DR9 spec-z results. Next, perform 2 cosmo analysis, where relevant parameters not fitted were kept fixed at their fiducial values. In the first analysis, extracted the BAO peak position for the 4 z shells, and combined with the WMAP7 sound horizon scale to constrain Omega_m=0.249pm0.031 and w=-0.885pm0.145. In the second analysis, used the ACF full shape information to constrain cosmology using real data for the first time, finding Omega_m=0.280pm0.022 and f_b=Omega_b/Omega_m=0.211pm0.026. These results are in good agreement with WMAP7 findings, showing that the ACF can be efficiently applied to constrain cosmology in future photometric galaxy surveys.
1308.0847
The DESI experiment, a whitepaper for Snowmass 2013
Levi, ... et al
The Dark Energy Spectroscopic Instrument (DESI) is a massively multiplexed fiber-fed spectrograph that will make the next major advance in DE in the timeframe 2018-2022. On the Mayall telescope, DESI will obtain spectra and redshifts for at least 18 M emission-line galaxies, 4M LRGs and 3M QSOs. In order to probe the effects of DE on the expansion history using BAO, measure the gravitational growth history through RSD, measure the sum of neutrino masses, and investigate the signatures of primordial inflation. The resulting 3-d galaxy maps at z<2 and Lya forest at z>2 will make 1%-level measurements of the distance scale in 35 z bins, thus providing unprecedented constraints on cosmological models.
1308.0970
Weighing the Local Group in the presence of dark energy
Partridge, Lahav, Hoffman
Revise the mass estimate of LG when DE is incorporated into the timing argument (TA) mass estimator [?] for the LG. Assuming the age of the universe and the cosmological constant according to the recent values from the Planck CMB experiment, find the mass of the LG to be M_TAL=4.7e12 Msun, which is 13% higher than the classical TA mass estimate. This partly explains the discrepancy between earlier results from LCDM simulations and the classical TA. When a similar analysis is performed on 16 LG-like galaxy pairs from the CLUES simulations, find that the scatter in the ratio of the virial to the TA estimated mass is given by M_vir/M_TAL=1.04. Applying it to the LG mass estimation find a calibrated M_vir=4.9e12 Msun.
1308.1029
The physics of neutrinos
Funchal, Schmauch, Giesen
Lecture notes based on a course given at CEA/Saclay in Jan/Feb 2013.
A proposal for new definitions of solar system bodies - Planet, Moon and satellite
Russell
A new classification system for Solar System bodies proposed, which takes into account both physical and dynamical perspectives, as well as critiques of the IAU resolutions for the definitions of planet, dwarf planet, and small solar system bodies. In this proposal there are 4 classes of planets which correspond with environments of planetary formation in the early history of the Solar System: Terrestrial, Cerian, Jovian, and Kuiperian. Specific physical criteria are adopted for identifying an object as a planet and the four classes naturally address dynamical concerns. The proposal also addresses the problem of calling all satellites in the growing list of objects discovered orbiting the Jovian planets as moons by defining two classes of satellites: moons and satellites. Advantages of the new system over the current IAU definitions discussed.
1308.0630
Large-scale analysis of the SDSS-III DR8 photometric luminous galaxies angular correlation function
de Simoni et al
Large-scale angular correlation function (ACF) of CMASS LGs, a photo-z catalog based on DR8. Contains 600k LGs in 0.45<z<0.65, split into 4 z shells of constant width. Estimate the constraints on RSD parameters b*sigma_8 and f*sigma_8, where b is the galaxy bias, f the growth rate and sigma_8 the perturbation normalization, finding that they vary appreciably among different redshift shells, in agreement with previous results using DR7 data. When assuming constant RSD parameters over the survey redshift range, obtain f*sigma_8=0.69pm0.21, which agrees at the 1.5 sigma level with BOSS DR9 spec-z results. Next, perform 2 cosmo analysis, where relevant parameters not fitted were kept fixed at their fiducial values. In the first analysis, extracted the BAO peak position for the 4 z shells, and combined with the WMAP7 sound horizon scale to constrain Omega_m=0.249pm0.031 and w=-0.885pm0.145. In the second analysis, used the ACF full shape information to constrain cosmology using real data for the first time, finding Omega_m=0.280pm0.022 and f_b=Omega_b/Omega_m=0.211pm0.026. These results are in good agreement with WMAP7 findings, showing that the ACF can be efficiently applied to constrain cosmology in future photometric galaxy surveys.
1308.0847
The DESI experiment, a whitepaper for Snowmass 2013
Levi, ... et al
The Dark Energy Spectroscopic Instrument (DESI) is a massively multiplexed fiber-fed spectrograph that will make the next major advance in DE in the timeframe 2018-2022. On the Mayall telescope, DESI will obtain spectra and redshifts for at least 18 M emission-line galaxies, 4M LRGs and 3M QSOs. In order to probe the effects of DE on the expansion history using BAO, measure the gravitational growth history through RSD, measure the sum of neutrino masses, and investigate the signatures of primordial inflation. The resulting 3-d galaxy maps at z<2 and Lya forest at z>2 will make 1%-level measurements of the distance scale in 35 z bins, thus providing unprecedented constraints on cosmological models.
1308.0970
Weighing the Local Group in the presence of dark energy
Partridge, Lahav, Hoffman
Revise the mass estimate of LG when DE is incorporated into the timing argument (TA) mass estimator [?] for the LG. Assuming the age of the universe and the cosmological constant according to the recent values from the Planck CMB experiment, find the mass of the LG to be M_TAL=4.7e12 Msun, which is 13% higher than the classical TA mass estimate. This partly explains the discrepancy between earlier results from LCDM simulations and the classical TA. When a similar analysis is performed on 16 LG-like galaxy pairs from the CLUES simulations, find that the scatter in the ratio of the virial to the TA estimated mass is given by M_vir/M_TAL=1.04. Applying it to the LG mass estimation find a calibrated M_vir=4.9e12 Msun.
1308.1029
The physics of neutrinos
Funchal, Schmauch, Giesen
Lecture notes based on a course given at CEA/Saclay in Jan/Feb 2013.
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