Wednesday. One week behind.
1350.3020
Turbulence in the SuperModel: mass reconstruction with nonthermal pressure for Abell 1835
Fusco-Femiano, Lapi
Total mass derived from X-ray is biased low in a large number of clusters when compared with the mass estimated via SL and WL. Some Suzaku and Chandra observation show steep temperature gradients in relaxed clusters that, assuming hydrostatic equilibrium, imply an unphysical decreasing mass profile; the gas mass fraction appears to be inconsistent with cosmic value. Such findings can be interpreted as an evidence for an additional nonthermal pressure in the outskirts of these clusters. This nonthermal component may be due to turbulence stirred by residual bulk motions of extragalactic gas infalling into the cluster. SuperModel formalism can include in the equilibrium a nonthermal component whose level and distribution are derived imposing that the gas mass fraction f_gas equals the cosmic value at the virial radius. including such a nonthermal component, and reconstruct from X-rays an increasing mass profile consistent with the hydrostatic equilibrium also in the cluster outskirts and in agreement at the virial boundary with the WL value. The increasing f_gas profile confirms that the baryons are not missing but located at the cluster outskirts.
1305.4633
Evolution of giant molecular clouds in nearby galaxies
Koda
GMC evolution appears different between the local, predominantly atom-rich small galaxies and a typical spiral galaxy with a rich molecular content. GMCs exist almost exclusively along HI spiral arms and filaments in the disks of local small galaxies, suggesting that GMCs form and end their short lives there. In a more molecular rich environment, GMCs are present everywhere independent of HI structures. The molecular gas fraction remains high and almost constant during arm passage into the next inter-arm region. The gas remains molecular, presumably in GMCs for a long time. A transitional case has been found recently in the central regions of the atom-rich galaxy M33; GMCs do not coincide with HI there. Evolution of the physical conditions of molecular gas from spiral arms to inter-arm regions is also being revealed in molecule-rich galaxies. An increase of the CO J=2-1 and 1-0 line ratio in spiral arms in M51 suggests density and/or temperature increases by a factor of 2-3 in GMCs in the arms, compared to their counterparts in the inter-arm regions. An analysis of high-resolution MW survey data revealed that the fraction of dense (or warm) clumps increases dramatically in the spiral arms.
1305.4641
Third-epoch Magellatnic cloud proper motions II: the Large Magellanic Cloud rotation field in three dimensions
van der Marel, Kallivayalil
LMC large-scale rotation on full 3-dimensional velocity measurements, based on HST proper motion (PM) measurements for stars in 22 fields, with existing LoS velocity measurements of 6790 stars. Interpret these data with a model of circular rotation in a flat disk. PM and LoS data paint a consistent picture of the LMC rotation and their combination yields several new insights. The PM data imply a stellar dynamical center that coincides with the HI dynamical center, and a rotation curve amplitude consistent with that inferred from LoS velocity studies. The implied disk viewing angles agree with the range of values found in the literature, but continue to indicate variations with stellar population and/or radius. Young (RSG) stars rotate faster than old (RGB/AGB) stars due to asymmetric drift. Outside the central region, the circular velocity is approximately flat at 91pm19 km/s. This is consistent with baryonic TF relation, and implies an enclosed mass M(8.7 kpc)=1.7e10 Msun. The virial mass is larger and depends on the full extent of the dark halo. The tidal radius is 22.3 kpc (24 deg). Combination of the PM and LoS data yields kinematic distance estimates for the LMC, but these are not yet competitive with other methods.
1305.4642
One-point remapping of Lagrangian perturbation theory in the mildly non-linear regime of cosmic structure formation
Leclercq et al
Remap by replacing the one-point distribution of a relevant quantity (the Eulerian density contrast of the Lagrangian divergence of the displacement field) by one which accounts for the full gravitational dynamics. Obtain a physically more pertinent density field on a point-by-point basis, while also improving higher-order statistics as predicted by LPT. Improves one-, two- and three-point statistics at scales smaller than 60 Mpc/h.
1305.4768
The host haloes of OI absorbers in the reionization epoch
Finlator, Munoz, Oppenheimer, Oh, Özel, Dave
Radiation hydrodynamic simulation that models the growth of galaxies and the extragalactic UV ionizing background (EUVB) self-consistently to study the sources of OI absorption during the H reionization epoch. Diffuse regions in the IGM are reionzed before they are enriched; hence OI absorption is closely associated with DM haloes. At z=10, all haloes above the hydrogen cooling limit [10^4 K?] produce visible absorption out to a substantial fraction of the virial radius. As reionization proceeds, the nascent EUVB ionized and removes gas from low-mass haloes, leading to a cutoff mass below which the geometric cross section for producing observable absorption vanishes. The cutoff grows from 1e8 at z=10 to 1e8.4 at z=5. This is 10-100 times less massive than the host haloes of LBGs and LAEs, suggesting that OI absorption probes the mass scale of ionizing sources that drove reionization more directly. OI absorbers are predicted to have neutral hydrogen columns of 1e19-21 cm^-2 suggesting a close resemblance between objects selected in OI and HI. The predicted abundance of OI absorbers at z=6 is in reasonable agreement with observations although in detail it may be slightly low, consistent with evidence from the Lya forest that the predicted EUVB is slightly too strong. Also consider the upper limits on the OI column density of the absorber in the FG of the z=7.085 quasar and find that they cannot be satisfied by halo gas because gas at the observed HI column density enriches too quickly. By contrast, gas at less than one third the mean density readily satisfies the constraints at z>=7. Hence the FG absorption in this quasar likely originates in the diffuse IGM rather than in a discrete system.
1305.3269
Detection of X-rays from the jet-driving symbiotic star Hen 3-1341
Stute
Hen 3 is a symbiotic binary system consisting of a WD and a RG star that is one of about 10 symbiotics that show hints of jets. The bipolar jets have been detected through displaced components of emission lines during its outburst from 1998 to 2004, but these components disappeared when Hen 3 reached quiescence. In 2012, Hen 3 started a new outburst with the emergence of new bipolar jets. ToO observations with 10 ks exposure to probe the interaction of the jet with the ambient medium and also the accretion onto the WD, as well as quiescence observation of 10 ks in 2010. Detect X-ray emission during quiescence from Hen 3 with XMM-Newton. Spectrum fitting with an absorbed one-temperature plasma or an absorbed BB. Did not detect Hen 3 during the short Swift exposure. Neither periodic or aperiodic X-ray nor UV variability were found XMM-Newton data suggest that interaction of the residual jet with the ISM might survive for a long time after outbursts and might be responsible for the observed X-ray emission during quiescence. Additional data are strongly needed to confirm these suggestions.
1305.3276
Hybrid cosmological simulations with stream velocities
Richardson, Scannapieco, Thacker
Relative "stream" velocities between the gas and DM arise due to radiation pressure and persist after recombination. High-res AMR cosmo sims, which use SPH datasets as initial conditions; resolves 100 Msun mass, focus on 1e6 Msun mini-haloes at high z in which the first stars formed. At z=17, the presence of stream velocities has only a minor effect on the number density of haloes below 1e6 Msun, but it greatly suppresses gas accretion onto all halos and the DM structures around them. Stream velocities lead to significantly lower halo gas fractions, especially for ~1e5 Msun objects, and effect that is likely to depend on the orientation of a halo's accretion lanes. This reduction in gas density leads to colder, more compact radial profiles, and it substantially delays the redshift of collapse of the largest haloes, leading to delayed star formation and possibly delayed reionization. These many differences suggest that future simulations of early cosmological structure formation should include stream velocities to properly predict gas evolution, SF, and the epoch of reionization.
1305.3277
Discovery of an intermediate mass black hole at the center of the starburst/Seyfert composite galay IRAS 01072+4954
Valencia-S.
As the title says.
1305.3286
Scaling relations for galaxy clusters: properties and evolution
Giodini, .. Reiprich, Hoekstra, et al
[Review paper.] Need well-calibrated scaling relations between observables and the total masses of clusters, to understand the physical processes that give rise to these relations. They are also a critical ingredient for studies that aim to constrain cosmological parameters using galaxy clusters. For this reason, much effort has been spent during the last decade to better understand and interpret relations of the properties of the ICM. Improved X-ray data have expanded the mass range down to galaxy groups, whereas SZ surveys have opened a new observational window on the ICM. In addition, continued progress in the performance of cosmological sims has allowed a better understanding of the physical processes and selection effects affecting the observed scaling relations. Here we review the recent literature on various scaling relations, focussing on the latest observational measurements and the progress in the understanding of the deviations from self similarity.
1305.3348
Full-sky formulae for weak lensing power spectra from total angular momentum method
Yamauchi, Namikawa, Taruya
Systematically derive full-sky formulae for the WL PS generated by scalar, vector and tensor perturbations from the total angular momentum (TAM) method. Based on both the geodesic and geodesic deviation equations, first give the gauge-invariant expressions for the deflection angle and Jacobi map as observables of the CMB lensing and cosmic shear experiments. Then apply the TAM method, originally developed in theoretical studies of CMB, to a systematic derivation of the angular power spectra. The TAM representation, which characterizes the total angular dependence of the spatial modes projected along the LoS, can carry all the information of the lensing modes generated by scalar, vector, and tensor metric perturbations. This greatly simplifies the calculation, and present a complete set of the full-sky formulae for angular PS in both the E-/B-mode cosmic shear and gradient-/curl-mode lensing potential of deflection angle. Based on the formulae, give illustrative examples of non-vanishing B-mode cosmic shear and curl-mode of deflection angle in the presence of the vector and tensor perturbations, and explicitly compute the PS.
1305.3436
The progenitor of supernova 2011dh has vanished
Van Dyk, ... Filippenko, Cenko, Smith, .... Ganeshalingam et al
Observation at age ~641 days after SN type IIb show that the yellow supergiant star, clearly detected in pre-SN HST images, has disappeared, implying that this star was almost certainly the progenitor of the SN, hence ruling out compact progenitor and the yellow supergiant survival. Also present ground-based UBVRI light curves obtained with KAIT up to SN age ~70 days. From the light-curve shape including the very late-time HST data, and from recent interacting binary models for SN 2011dh, estimate that a putative surviving companion star to the now deceased yellow supergiant could be detectable by late 2013, especially in the UV.
1305.3516
Testing MOND with galaxy-galaxy gravitational lensing
Milgrom
As the title says. [Why did you vote for this, E?!] Compare MOND predictions with recent results of gg lensing, and find agreement on all counts, through MOND's phi(R) lensing signal generation (due solely to baryons).
1305.3576
WFC3 grism confirmation of the distant cluster Cl J1449+0856 at z=2.00: Quiescent and star-forming galaxy populations
Gobat ... Finoguenov, et al
Spectroscopically confirm 10 early-type galaxies in the field up to z~3, 5 of which in the cluster core; first direct spectroscopic confirmation of passive galaxies in a z=2 cluster environment. 140 redshifts in a 6 arcmin^2 field, trace the spatial and redshift galaxy distribution in the cluster core and background field. Find two strong peaks at z=2.00 and 2.07, where only one was seen in the previously published ground-based data. Now the cluster redshift is re-evaluated at z=2.00, with the background overdensity being revealed to be sparse and "sheet"-like. ...
1305.3577
Galaxy evolution in overdense environments at high redshift: passive early-type galaxies in a cluster at redshift 2
Strazzullo, et al
[Related to the paper above] Investigate stellar populations and morphological structure of cluster galaxies over an area of ~0.7Mpc^2 around the cluster core. The cluster stands out as a clear overdensity both in redshift space, and in the spatial distribution of galaxies close to the center of the extended X-ray emission. The cluster core region (r<200 kpc) shows a clearly enhanced passive fraction with respect to field levels. However, together with a population of massive passive galaxies mostly with early-type morphologies, it also hosts massive actively star-forming, often highly dust-reddened sources. Close to the cluster center, a multi-component system of passive and SF galaxies could be the future BCG still assembling. Observe a clear correlation between passive stellar populations and an early-type morphology, in agreement with field studies at similar redshift. Passive early-type galaxies in this cluster are typically a factor 2-3 smaller than similarly massive early-types at z~0, but also on average larger by a factor ~2 than their field analogs at z~2, lending support to recent claims of an accelerated structural evolution in high-redshift dense environments. These results point towards the early formation of a population of massive galaxies, already evolved both in their structure and stellar populations, coexisting with still-actively forming massive galaxies in the central regions of young clusters 10 billion years ago.
1350.3020
Turbulence in the SuperModel: mass reconstruction with nonthermal pressure for Abell 1835
Fusco-Femiano, Lapi
Total mass derived from X-ray is biased low in a large number of clusters when compared with the mass estimated via SL and WL. Some Suzaku and Chandra observation show steep temperature gradients in relaxed clusters that, assuming hydrostatic equilibrium, imply an unphysical decreasing mass profile; the gas mass fraction appears to be inconsistent with cosmic value. Such findings can be interpreted as an evidence for an additional nonthermal pressure in the outskirts of these clusters. This nonthermal component may be due to turbulence stirred by residual bulk motions of extragalactic gas infalling into the cluster. SuperModel formalism can include in the equilibrium a nonthermal component whose level and distribution are derived imposing that the gas mass fraction f_gas equals the cosmic value at the virial radius. including such a nonthermal component, and reconstruct from X-rays an increasing mass profile consistent with the hydrostatic equilibrium also in the cluster outskirts and in agreement at the virial boundary with the WL value. The increasing f_gas profile confirms that the baryons are not missing but located at the cluster outskirts.
1305.4633
Evolution of giant molecular clouds in nearby galaxies
Koda
GMC evolution appears different between the local, predominantly atom-rich small galaxies and a typical spiral galaxy with a rich molecular content. GMCs exist almost exclusively along HI spiral arms and filaments in the disks of local small galaxies, suggesting that GMCs form and end their short lives there. In a more molecular rich environment, GMCs are present everywhere independent of HI structures. The molecular gas fraction remains high and almost constant during arm passage into the next inter-arm region. The gas remains molecular, presumably in GMCs for a long time. A transitional case has been found recently in the central regions of the atom-rich galaxy M33; GMCs do not coincide with HI there. Evolution of the physical conditions of molecular gas from spiral arms to inter-arm regions is also being revealed in molecule-rich galaxies. An increase of the CO J=2-1 and 1-0 line ratio in spiral arms in M51 suggests density and/or temperature increases by a factor of 2-3 in GMCs in the arms, compared to their counterparts in the inter-arm regions. An analysis of high-resolution MW survey data revealed that the fraction of dense (or warm) clumps increases dramatically in the spiral arms.
1305.4641
Third-epoch Magellatnic cloud proper motions II: the Large Magellanic Cloud rotation field in three dimensions
van der Marel, Kallivayalil
LMC large-scale rotation on full 3-dimensional velocity measurements, based on HST proper motion (PM) measurements for stars in 22 fields, with existing LoS velocity measurements of 6790 stars. Interpret these data with a model of circular rotation in a flat disk. PM and LoS data paint a consistent picture of the LMC rotation and their combination yields several new insights. The PM data imply a stellar dynamical center that coincides with the HI dynamical center, and a rotation curve amplitude consistent with that inferred from LoS velocity studies. The implied disk viewing angles agree with the range of values found in the literature, but continue to indicate variations with stellar population and/or radius. Young (RSG) stars rotate faster than old (RGB/AGB) stars due to asymmetric drift. Outside the central region, the circular velocity is approximately flat at 91pm19 km/s. This is consistent with baryonic TF relation, and implies an enclosed mass M(8.7 kpc)=1.7e10 Msun. The virial mass is larger and depends on the full extent of the dark halo. The tidal radius is 22.3 kpc (24 deg). Combination of the PM and LoS data yields kinematic distance estimates for the LMC, but these are not yet competitive with other methods.
1305.4642
One-point remapping of Lagrangian perturbation theory in the mildly non-linear regime of cosmic structure formation
Leclercq et al
Remap by replacing the one-point distribution of a relevant quantity (the Eulerian density contrast of the Lagrangian divergence of the displacement field) by one which accounts for the full gravitational dynamics. Obtain a physically more pertinent density field on a point-by-point basis, while also improving higher-order statistics as predicted by LPT. Improves one-, two- and three-point statistics at scales smaller than 60 Mpc/h.
1305.4768
The host haloes of OI absorbers in the reionization epoch
Finlator, Munoz, Oppenheimer, Oh, Özel, Dave
Radiation hydrodynamic simulation that models the growth of galaxies and the extragalactic UV ionizing background (EUVB) self-consistently to study the sources of OI absorption during the H reionization epoch. Diffuse regions in the IGM are reionzed before they are enriched; hence OI absorption is closely associated with DM haloes. At z=10, all haloes above the hydrogen cooling limit [10^4 K?] produce visible absorption out to a substantial fraction of the virial radius. As reionization proceeds, the nascent EUVB ionized and removes gas from low-mass haloes, leading to a cutoff mass below which the geometric cross section for producing observable absorption vanishes. The cutoff grows from 1e8 at z=10 to 1e8.4 at z=5. This is 10-100 times less massive than the host haloes of LBGs and LAEs, suggesting that OI absorption probes the mass scale of ionizing sources that drove reionization more directly. OI absorbers are predicted to have neutral hydrogen columns of 1e19-21 cm^-2 suggesting a close resemblance between objects selected in OI and HI. The predicted abundance of OI absorbers at z=6 is in reasonable agreement with observations although in detail it may be slightly low, consistent with evidence from the Lya forest that the predicted EUVB is slightly too strong. Also consider the upper limits on the OI column density of the absorber in the FG of the z=7.085 quasar and find that they cannot be satisfied by halo gas because gas at the observed HI column density enriches too quickly. By contrast, gas at less than one third the mean density readily satisfies the constraints at z>=7. Hence the FG absorption in this quasar likely originates in the diffuse IGM rather than in a discrete system.
1305.3269
Detection of X-rays from the jet-driving symbiotic star Hen 3-1341
Stute
Hen 3 is a symbiotic binary system consisting of a WD and a RG star that is one of about 10 symbiotics that show hints of jets. The bipolar jets have been detected through displaced components of emission lines during its outburst from 1998 to 2004, but these components disappeared when Hen 3 reached quiescence. In 2012, Hen 3 started a new outburst with the emergence of new bipolar jets. ToO observations with 10 ks exposure to probe the interaction of the jet with the ambient medium and also the accretion onto the WD, as well as quiescence observation of 10 ks in 2010. Detect X-ray emission during quiescence from Hen 3 with XMM-Newton. Spectrum fitting with an absorbed one-temperature plasma or an absorbed BB. Did not detect Hen 3 during the short Swift exposure. Neither periodic or aperiodic X-ray nor UV variability were found XMM-Newton data suggest that interaction of the residual jet with the ISM might survive for a long time after outbursts and might be responsible for the observed X-ray emission during quiescence. Additional data are strongly needed to confirm these suggestions.
1305.3276
Hybrid cosmological simulations with stream velocities
Richardson, Scannapieco, Thacker
Relative "stream" velocities between the gas and DM arise due to radiation pressure and persist after recombination. High-res AMR cosmo sims, which use SPH datasets as initial conditions; resolves 100 Msun mass, focus on 1e6 Msun mini-haloes at high z in which the first stars formed. At z=17, the presence of stream velocities has only a minor effect on the number density of haloes below 1e6 Msun, but it greatly suppresses gas accretion onto all halos and the DM structures around them. Stream velocities lead to significantly lower halo gas fractions, especially for ~1e5 Msun objects, and effect that is likely to depend on the orientation of a halo's accretion lanes. This reduction in gas density leads to colder, more compact radial profiles, and it substantially delays the redshift of collapse of the largest haloes, leading to delayed star formation and possibly delayed reionization. These many differences suggest that future simulations of early cosmological structure formation should include stream velocities to properly predict gas evolution, SF, and the epoch of reionization.
1305.3277
Discovery of an intermediate mass black hole at the center of the starburst/Seyfert composite galay IRAS 01072+4954
Valencia-S.
As the title says.
1305.3286
Scaling relations for galaxy clusters: properties and evolution
Giodini, .. Reiprich, Hoekstra, et al
[Review paper.] Need well-calibrated scaling relations between observables and the total masses of clusters, to understand the physical processes that give rise to these relations. They are also a critical ingredient for studies that aim to constrain cosmological parameters using galaxy clusters. For this reason, much effort has been spent during the last decade to better understand and interpret relations of the properties of the ICM. Improved X-ray data have expanded the mass range down to galaxy groups, whereas SZ surveys have opened a new observational window on the ICM. In addition, continued progress in the performance of cosmological sims has allowed a better understanding of the physical processes and selection effects affecting the observed scaling relations. Here we review the recent literature on various scaling relations, focussing on the latest observational measurements and the progress in the understanding of the deviations from self similarity.
1305.3348
Full-sky formulae for weak lensing power spectra from total angular momentum method
Yamauchi, Namikawa, Taruya
Systematically derive full-sky formulae for the WL PS generated by scalar, vector and tensor perturbations from the total angular momentum (TAM) method. Based on both the geodesic and geodesic deviation equations, first give the gauge-invariant expressions for the deflection angle and Jacobi map as observables of the CMB lensing and cosmic shear experiments. Then apply the TAM method, originally developed in theoretical studies of CMB, to a systematic derivation of the angular power spectra. The TAM representation, which characterizes the total angular dependence of the spatial modes projected along the LoS, can carry all the information of the lensing modes generated by scalar, vector, and tensor metric perturbations. This greatly simplifies the calculation, and present a complete set of the full-sky formulae for angular PS in both the E-/B-mode cosmic shear and gradient-/curl-mode lensing potential of deflection angle. Based on the formulae, give illustrative examples of non-vanishing B-mode cosmic shear and curl-mode of deflection angle in the presence of the vector and tensor perturbations, and explicitly compute the PS.
1305.3436
The progenitor of supernova 2011dh has vanished
Van Dyk, ... Filippenko, Cenko, Smith, .... Ganeshalingam et al
Observation at age ~641 days after SN type IIb show that the yellow supergiant star, clearly detected in pre-SN HST images, has disappeared, implying that this star was almost certainly the progenitor of the SN, hence ruling out compact progenitor and the yellow supergiant survival. Also present ground-based UBVRI light curves obtained with KAIT up to SN age ~70 days. From the light-curve shape including the very late-time HST data, and from recent interacting binary models for SN 2011dh, estimate that a putative surviving companion star to the now deceased yellow supergiant could be detectable by late 2013, especially in the UV.
1305.3516
Testing MOND with galaxy-galaxy gravitational lensing
Milgrom
As the title says. [Why did you vote for this, E?!] Compare MOND predictions with recent results of gg lensing, and find agreement on all counts, through MOND's phi(R) lensing signal generation (due solely to baryons).
1305.3576
WFC3 grism confirmation of the distant cluster Cl J1449+0856 at z=2.00: Quiescent and star-forming galaxy populations
Gobat ... Finoguenov, et al
Spectroscopically confirm 10 early-type galaxies in the field up to z~3, 5 of which in the cluster core; first direct spectroscopic confirmation of passive galaxies in a z=2 cluster environment. 140 redshifts in a 6 arcmin^2 field, trace the spatial and redshift galaxy distribution in the cluster core and background field. Find two strong peaks at z=2.00 and 2.07, where only one was seen in the previously published ground-based data. Now the cluster redshift is re-evaluated at z=2.00, with the background overdensity being revealed to be sparse and "sheet"-like. ...
1305.3577
Galaxy evolution in overdense environments at high redshift: passive early-type galaxies in a cluster at redshift 2
Strazzullo, et al
[Related to the paper above] Investigate stellar populations and morphological structure of cluster galaxies over an area of ~0.7Mpc^2 around the cluster core. The cluster stands out as a clear overdensity both in redshift space, and in the spatial distribution of galaxies close to the center of the extended X-ray emission. The cluster core region (r<200 kpc) shows a clearly enhanced passive fraction with respect to field levels. However, together with a population of massive passive galaxies mostly with early-type morphologies, it also hosts massive actively star-forming, often highly dust-reddened sources. Close to the cluster center, a multi-component system of passive and SF galaxies could be the future BCG still assembling. Observe a clear correlation between passive stellar populations and an early-type morphology, in agreement with field studies at similar redshift. Passive early-type galaxies in this cluster are typically a factor 2-3 smaller than similarly massive early-types at z~0, but also on average larger by a factor ~2 than their field analogs at z~2, lending support to recent claims of an accelerated structural evolution in high-redshift dense environments. These results point towards the early formation of a population of massive galaxies, already evolved both in their structure and stellar populations, coexisting with still-actively forming massive galaxies in the central regions of young clusters 10 billion years ago.
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