1212.3610
The 6dF galaxy survey: dependence of halo occupation on stellar mass
Beutler, Blake, ... et al
NIR selection of 6dFGS gives more reliable stellar mass estimates compared to optical band. Use HOD to investigate the trend of DM halo mass and satellite fraction with M* by measuring the projected correlation function w_p(r_p). Find that the typical halo mass as well as the satellite power law index increase with stellar mass. This indicates (1) that galaxies with higher stellar mass sit in more massive DM haloes and (2) that these more massive DM haloes accumulate satellites faster with growing mass compared to halos occupied by low stellar mass galaxies. Find a relation between typical halo mass and the minimum DM halo mass relation of M ~ 22xM_min, in agreement with similar findings by SDSS. Satellite fraction of 6dFGS galaxies declines with increasing M* from 21% at M*=2.6e10 Msun/h^2 to 12% at M*=5.4e10Msun/h^2, indicating that high M* galaxies are more likely to be central galaxies. Compare results to 2 different SAM derived from Millennium simulation, finding some disagreement. Data can be used to constrain SAM, particularly that of LRG satellites. Compare results of HOD studies with gg WL studies. Find good overall agreement, representing a valuable Xcheck for these two different tools for studying the matter distribution in the Universe.
1212.3615
Reconstructing the distribution of haloes and mock galaxies below the resolution limit in cosmological simulations
de la Torre, Peacock
Present a method for populating DM simulations with haloes of mass below the resolution limit. Based on stochastically sampling a field derived from the density field of the halo catalogue, using constraints from the conditional halo mass function n(m|delta). Test the accuracy of the method and show its application in the context of building mock galaxy samples. Find that this technique allows precise reproduction of the 2-pt statistics of galaxies in mock samples constructed with this method. Results demonstrate that the full information content of a simulation can be communicated efficiently using only a catalogue of the more massive halos.
1212.3642
A joint model of the X-ray and infrared extragalacitic backgrounds: I. Model construction and first results
Shi, et al
Model incorporates SF and SMBH accretion in a co-evolution scenario to fit simultaneously 617 data points of number counts, z distributions and local luminosity functions with 19 free parameters. ... All variants of the model require that Compton-thick AGN fraction decrease with SMBH luminosity but increase with z while the type-1 AGN fraction has the reverse trend.
1212.3670
The local dark matter density
Nesti, Salucci
This method is based on the local equation of centrifugal equilibrium and depends on local and quite well known quantities such as the angular Sun's elocity, the disk to dark contribution to the circular velocity at the Sun and the think stellar disk scale length. Result: rho = 0.43 GeV/cm^3.
1212.3691
Constraints on anisotropic cosmic expansion from supernovae
Kalus et al
The fastest expansion is in the direction of (l,b) = (-35, -19) degrees with delta H/H ~0.026.
1212.3755
Signature of outflows in strong MgII absorbers in quasar sightlines
Sharma, et al
Velocity offset v/c = beta shows a power law increase with L_bol with a slope of 1/4. Find that such a relation of beta with L_bol is expected for outflows driven by scattering of BH radiation by dust grains, and which are launched from the innermost dust survival radius. Results indicate that a significant fraction of the strong MgII absorbers, in the range of beta = (0-0.4) are associated with the quasars themselves.
1212.3869
Evolution of the sizes of galaxies over 7<z<12 revealed by the 2012 Hubble Ultra Deep Field campaign
Ono, Ouchi, ... et al
Analyze the z- and L- dependent sizes of dropout galaxy candidates in 7<z<12 using deep images from the UDF12 campaign, data which offers two distinct advantages over that used in earlier work. Provide improved size measurements for known galaxies at 6.5<z<8 in the HUDF. Stack the new deep F140W image with the existing F125W data in order to provde improved measurements of the half-light radii of z-dropouts. Similarly stack this image with the new deep UDF12 F160W image to obtain new size measurements for a sample of Y-dropouts. Due to new data, sample at z>8 have been extended reliably to higher z. For >15 sigma detections, confirm earlier indications that the average half-light of 7<z<12 galaxies are extremely small, 0.3-0.4 kpc, comparable to the sizes of gian moleular associations in local SF galaxies. Also conform that there is a clear trend of decreasing half-light radius with increasing redshift, and provide the first evidence that this trend continues beyond z~8. Modeling the evolution of the average half-light radius as a power-law (1+z)^s, obtain a best-fit index of s=-1.28pm0.13 over 4<z<12, mid-way between the physically expected evolution for baryons embedded in dark halos of constant mass (s=-1) and constant velocity (s=-1.5). A clear size-luminosity relation, such as that found at lower redshift, is also evident in both our z- and Y-dropout sample. This realization can be interpreted in terms of a constant surface density of SF over a range in luminosity of 0.05-1.0L*_z=3.
1212.3907
Gravitational lensing properties of isothermal universal halo profile
Er
N-body simulations predict that DM haloes with different mass scales are described by a universal model, the NFW density profiles. As a consequence of baryonic cooling effects, the halos will become more concentrated, and similar to an isothermal sphere over large range in radii (~300 kpc/h). The singular isothermal sphere model however has to be truncated artificially at large radii since it extends to infinity. Model a massive galaxy halo as a combination of an isothermal sphere and an NFW density profile. Give an approximation for the mass concentration at different baryon fractions and present exact expressions for the WL shear and flexion for such a halo. Compare lensing properties with SIS and NFW profiles. Find that the combined profile can generate higher order lensing signals at small radii and is more efficient in generating SL events. In order to distinguish such a halo profile from the SIS or NFW profiles, one needs to combine strong and weak lensing constraints on small and large radii.
1212.4025
Perturbation theory for nonlinear halo power spectrum: the renormalized bias and halo bias
NIshizawa, Takada, Nishimichi
Revisit an analytical model to describe the halo-matter cross-power spectrum and the halo auto-power spectrum in the weakly NL regime, by combining the PT for matter clustering, the local bias model, and the halo bias. Non-linearities in the power spectra arise from the NL clustering of matter as well as the NL relation between the matter and halo density fields. By using the "renormalization" approach, express the NL power spectra by a sum of the two contributions: the NL matter PS with the effective linear bias parameter, and the higher-order PT spectra having the halo bias parameters as the coefficients. The halo auto-power spectrum includes the residual shot noise contamination that needs to be treated as additional free parameter. The terms of the higher-order PT spectra and the residual shot noise cause the scale-dependent bias function relative to the NL matter PS in the weakly NL regime. Show that the model predictions are in good agreement with the spectra measured from a suit of high-resolution N-body simulations up to k~0.2 h/Mpc at z=0.35, for different halo mass bins.
1212.4097
Search for dark matter annihilations in the Sun with the 79-string IceCube detector
IceCube collaboration
Search for muon neutrinos from DM annihilation in the center of the Sun. 317 days of data, consistent with expected BG from atmospheric muons and neutrinos. Upper limits set on hte DM annihilation rate, with conversions to limits on spin-dependent and spin-indepenednet WIMP-proton cross-sections for WIMP masses in the range 20-5000 GeV. These are the most stringent limits to date above 35 GeV.
1212.4131
Planck intermediate results. XI: the gas content of dark matter halos: the Sunyaev-Zeldovich-stellar mass relation for locally brightest galaxies
Planck Collaboration
Scaling relation between SZ signal and M* for 260k locally brightest galaxies from SDSS. These are predominantly the central galaxies of their DM haloes. Calibrate the stellar-t-halo mass conversion using realistic mock catalogues based on Millennium. Measure the mean SZ signal down to M*~2e11 Msun, with a clear indication of signal at even lower stellar mass. Derive the scaling relation between SZ signal and halo mass by assigning halo properties from mock catalogues to the real LBGs and simulation the Planck observation process. This relation shows no evidence for deviation from a power law over a halo mass range extending from rich clusters down to M500~2e13 Msun, and there is a clear indication of signal down to M500 ~ 4e12 Msun. Planck's SZ detections in such low-mass halos imply that about a quarter of all baryons have now been seen in the form of hot halo gas, and that this gas must be less concentrated than the DM in such halos in order to remain consistent with X-ray observations. At the high-mass end, the measured SZ signal is 20% lower than found from observations of X-ray clusters, a difference consistent with Malmquist bias effects in the X-ray sample.
1212.3608
Neutrino physics from future weak lensing surveys
Vanderveld, Hu
Shear deficit in 20-40% range, or rexcess in the 20-80% range cannot be explained by varioations in parameters of the flat LCDM model that are allowed by current observations of the expansion history from SNIa, BAO, and local measures of H0, coupled with WMAP and SPT. Such a shear deficit or excess would indicate large masses or extra species, respectively, and find this to be independent of the flatness assumption [because it's matter clustering, I think]. Also discuss the robustness of these predictions to cosmic acceleration physics and the mans by which shear degeneracies in joint variation of mass and species can be broken.
1212.3612
Ripping apart at the seams: the network of stripped gas surrounding M86
Ehlert et al
Robust measurements of the temperature and metallicity structure of each galaxy along with the entire ~1 deg region between these galaxies. Data suggest all 4 of these galaxies are undergoing ram pressure stripping by ICM, though manner of interaction is observationally distinct. Nature of ram pressure stripping can vary significantly from site to site.
1212.3792
Limits in late time conversion of cold dark matter into hot dark matter
Motta, Boriero, de Holanda
Structure formation can generate a late time conversion of CDM into a relativistic form of DM (e.g., SNe event converts 99% of binding energy into relativistic neutrinos). Alternative to the pure CDM model.
The 6dF galaxy survey: dependence of halo occupation on stellar mass
Beutler, Blake, ... et al
NIR selection of 6dFGS gives more reliable stellar mass estimates compared to optical band. Use HOD to investigate the trend of DM halo mass and satellite fraction with M* by measuring the projected correlation function w_p(r_p). Find that the typical halo mass as well as the satellite power law index increase with stellar mass. This indicates (1) that galaxies with higher stellar mass sit in more massive DM haloes and (2) that these more massive DM haloes accumulate satellites faster with growing mass compared to halos occupied by low stellar mass galaxies. Find a relation between typical halo mass and the minimum DM halo mass relation of M ~ 22xM_min, in agreement with similar findings by SDSS. Satellite fraction of 6dFGS galaxies declines with increasing M* from 21% at M*=2.6e10 Msun/h^2 to 12% at M*=5.4e10Msun/h^2, indicating that high M* galaxies are more likely to be central galaxies. Compare results to 2 different SAM derived from Millennium simulation, finding some disagreement. Data can be used to constrain SAM, particularly that of LRG satellites. Compare results of HOD studies with gg WL studies. Find good overall agreement, representing a valuable Xcheck for these two different tools for studying the matter distribution in the Universe.
1212.3615
Reconstructing the distribution of haloes and mock galaxies below the resolution limit in cosmological simulations
de la Torre, Peacock
Present a method for populating DM simulations with haloes of mass below the resolution limit. Based on stochastically sampling a field derived from the density field of the halo catalogue, using constraints from the conditional halo mass function n(m|delta). Test the accuracy of the method and show its application in the context of building mock galaxy samples. Find that this technique allows precise reproduction of the 2-pt statistics of galaxies in mock samples constructed with this method. Results demonstrate that the full information content of a simulation can be communicated efficiently using only a catalogue of the more massive halos.
1212.3642
A joint model of the X-ray and infrared extragalacitic backgrounds: I. Model construction and first results
Shi, et al
Model incorporates SF and SMBH accretion in a co-evolution scenario to fit simultaneously 617 data points of number counts, z distributions and local luminosity functions with 19 free parameters. ... All variants of the model require that Compton-thick AGN fraction decrease with SMBH luminosity but increase with z while the type-1 AGN fraction has the reverse trend.
1212.3670
The local dark matter density
Nesti, Salucci
This method is based on the local equation of centrifugal equilibrium and depends on local and quite well known quantities such as the angular Sun's elocity, the disk to dark contribution to the circular velocity at the Sun and the think stellar disk scale length. Result: rho = 0.43 GeV/cm^3.
1212.3691
Constraints on anisotropic cosmic expansion from supernovae
Kalus et al
The fastest expansion is in the direction of (l,b) = (-35, -19) degrees with delta H/H ~0.026.
1212.3755
Signature of outflows in strong MgII absorbers in quasar sightlines
Sharma, et al
Velocity offset v/c = beta shows a power law increase with L_bol with a slope of 1/4. Find that such a relation of beta with L_bol is expected for outflows driven by scattering of BH radiation by dust grains, and which are launched from the innermost dust survival radius. Results indicate that a significant fraction of the strong MgII absorbers, in the range of beta = (0-0.4) are associated with the quasars themselves.
1212.3869
Evolution of the sizes of galaxies over 7<z<12 revealed by the 2012 Hubble Ultra Deep Field campaign
Ono, Ouchi, ... et al
Analyze the z- and L- dependent sizes of dropout galaxy candidates in 7<z<12 using deep images from the UDF12 campaign, data which offers two distinct advantages over that used in earlier work. Provide improved size measurements for known galaxies at 6.5<z<8 in the HUDF. Stack the new deep F140W image with the existing F125W data in order to provde improved measurements of the half-light radii of z-dropouts. Similarly stack this image with the new deep UDF12 F160W image to obtain new size measurements for a sample of Y-dropouts. Due to new data, sample at z>8 have been extended reliably to higher z. For >15 sigma detections, confirm earlier indications that the average half-light of 7<z<12 galaxies are extremely small, 0.3-0.4 kpc, comparable to the sizes of gian moleular associations in local SF galaxies. Also conform that there is a clear trend of decreasing half-light radius with increasing redshift, and provide the first evidence that this trend continues beyond z~8. Modeling the evolution of the average half-light radius as a power-law (1+z)^s, obtain a best-fit index of s=-1.28pm0.13 over 4<z<12, mid-way between the physically expected evolution for baryons embedded in dark halos of constant mass (s=-1) and constant velocity (s=-1.5). A clear size-luminosity relation, such as that found at lower redshift, is also evident in both our z- and Y-dropout sample. This realization can be interpreted in terms of a constant surface density of SF over a range in luminosity of 0.05-1.0L*_z=3.
1212.3907
Gravitational lensing properties of isothermal universal halo profile
Er
N-body simulations predict that DM haloes with different mass scales are described by a universal model, the NFW density profiles. As a consequence of baryonic cooling effects, the halos will become more concentrated, and similar to an isothermal sphere over large range in radii (~300 kpc/h). The singular isothermal sphere model however has to be truncated artificially at large radii since it extends to infinity. Model a massive galaxy halo as a combination of an isothermal sphere and an NFW density profile. Give an approximation for the mass concentration at different baryon fractions and present exact expressions for the WL shear and flexion for such a halo. Compare lensing properties with SIS and NFW profiles. Find that the combined profile can generate higher order lensing signals at small radii and is more efficient in generating SL events. In order to distinguish such a halo profile from the SIS or NFW profiles, one needs to combine strong and weak lensing constraints on small and large radii.
1212.4025
Perturbation theory for nonlinear halo power spectrum: the renormalized bias and halo bias
NIshizawa, Takada, Nishimichi
Revisit an analytical model to describe the halo-matter cross-power spectrum and the halo auto-power spectrum in the weakly NL regime, by combining the PT for matter clustering, the local bias model, and the halo bias. Non-linearities in the power spectra arise from the NL clustering of matter as well as the NL relation between the matter and halo density fields. By using the "renormalization" approach, express the NL power spectra by a sum of the two contributions: the NL matter PS with the effective linear bias parameter, and the higher-order PT spectra having the halo bias parameters as the coefficients. The halo auto-power spectrum includes the residual shot noise contamination that needs to be treated as additional free parameter. The terms of the higher-order PT spectra and the residual shot noise cause the scale-dependent bias function relative to the NL matter PS in the weakly NL regime. Show that the model predictions are in good agreement with the spectra measured from a suit of high-resolution N-body simulations up to k~0.2 h/Mpc at z=0.35, for different halo mass bins.
1212.4097
Search for dark matter annihilations in the Sun with the 79-string IceCube detector
IceCube collaboration
Search for muon neutrinos from DM annihilation in the center of the Sun. 317 days of data, consistent with expected BG from atmospheric muons and neutrinos. Upper limits set on hte DM annihilation rate, with conversions to limits on spin-dependent and spin-indepenednet WIMP-proton cross-sections for WIMP masses in the range 20-5000 GeV. These are the most stringent limits to date above 35 GeV.
1212.4131
Planck intermediate results. XI: the gas content of dark matter halos: the Sunyaev-Zeldovich-stellar mass relation for locally brightest galaxies
Planck Collaboration
Scaling relation between SZ signal and M* for 260k locally brightest galaxies from SDSS. These are predominantly the central galaxies of their DM haloes. Calibrate the stellar-t-halo mass conversion using realistic mock catalogues based on Millennium. Measure the mean SZ signal down to M*~2e11 Msun, with a clear indication of signal at even lower stellar mass. Derive the scaling relation between SZ signal and halo mass by assigning halo properties from mock catalogues to the real LBGs and simulation the Planck observation process. This relation shows no evidence for deviation from a power law over a halo mass range extending from rich clusters down to M500~2e13 Msun, and there is a clear indication of signal down to M500 ~ 4e12 Msun. Planck's SZ detections in such low-mass halos imply that about a quarter of all baryons have now been seen in the form of hot halo gas, and that this gas must be less concentrated than the DM in such halos in order to remain consistent with X-ray observations. At the high-mass end, the measured SZ signal is 20% lower than found from observations of X-ray clusters, a difference consistent with Malmquist bias effects in the X-ray sample.
1212.3608
Neutrino physics from future weak lensing surveys
Vanderveld, Hu
Shear deficit in 20-40% range, or rexcess in the 20-80% range cannot be explained by varioations in parameters of the flat LCDM model that are allowed by current observations of the expansion history from SNIa, BAO, and local measures of H0, coupled with WMAP and SPT. Such a shear deficit or excess would indicate large masses or extra species, respectively, and find this to be independent of the flatness assumption [because it's matter clustering, I think]. Also discuss the robustness of these predictions to cosmic acceleration physics and the mans by which shear degeneracies in joint variation of mass and species can be broken.
1212.3612
Ripping apart at the seams: the network of stripped gas surrounding M86
Ehlert et al
Robust measurements of the temperature and metallicity structure of each galaxy along with the entire ~1 deg region between these galaxies. Data suggest all 4 of these galaxies are undergoing ram pressure stripping by ICM, though manner of interaction is observationally distinct. Nature of ram pressure stripping can vary significantly from site to site.
1212.3792
Limits in late time conversion of cold dark matter into hot dark matter
Motta, Boriero, de Holanda
Structure formation can generate a late time conversion of CDM into a relativistic form of DM (e.g., SNe event converts 99% of binding energy into relativistic neutrinos). Alternative to the pure CDM model.
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