Friday. Violet is aliiiive.... for now. The battery charging mechanism seems to be messed up. JC yesterday was pretty lame... not enough fun topics.
1202.1822
Spatially resolved Halpha maps and sizes of 57 strongly star-forming galaxies at z~1 from 3d-HST: evidence for rapid inside-out assembly of disk galaxies
Nelson, van Dokkum, ... Franx, ... Rix, ... Kreik, ... et al
Investigate the build-up of galaxies at z~1 using maps of Halpha and stellar continuum emission for a sample of 57 galaxies with rest-frame Halpha equivalent widths >100 A. Find: Ha emission broadly follows the rest-fram R-band light, but that it is typically somewhat more extended and clumpy. Quantify the spatial distribution with the half-light radius. The median Ha effective radius r_e(Ha) is 4.2pm0.1 kpc but the sizes span a large range, from compact objects with r_e(Ha) ~1.0 kpc to extended disks with r_e(Ha)~15 kpc. Comparing Ha sizes to continuum sizes, find <r_e(Ha) / r_e(R) > = 1.3 for the full sample. That is, SF, as traced by Ha, typically occurs out to larger radii than the rest-frame R-band stellar continuum; galaxies are growing their radii and building up from the inside out. This effect appears to be somewhat more pronounced for the largest galaxies. Using the meausred Ha sizes, derive star formation rate surface densities. Find that they range from ~0.05 Msun/yr / kpc^2 for the largest galaxies to ~5 Msun/yr/kpc^2 for the smallest galaxies, implying a large range in physical conditions in rapidly SF z~1 galaxies. Finally, infer that all galaxies in the sample have very high gas mass fractions and stellar mass doubling times < 500 Myr. Although other explanations are also possible, a straightforward interpretation is that we are simultaneously witnessing the rapid formation of compact bulges and large disks at z~1.
1202.1829
A comprehensive view of a strongly lensed planck-associated submillimeter galaxy
Fu, ... Scoville, Aguirre, ... et al
Present high-res maps of stars, dust and molecular gas in a strongly lensed SMG at 3.259. Image indicates differentiated distributions of the various components: stars in 3 major kpc-scale clumps extended over 1.6 kpc, the dust in compact (~1kpc) region ~3kpc north of the stars, and the cold molecular gas in an extended (~7kpc) disk ~5kpc NE of the stars. The emission from the stars, dust, and gas are magnified by ~17, 8, and 7 times, respectively, by the 4 lensing galaxies at z~1. Intrinsically, the galaxy is a arm (T_dust~40-65K), hyper-luminous (L_IR~1.6e13 Lsun, SFR~2000Msun/yr), gas rich (M_gas/M_baryon~70%), young (M_stellar/SFR~20Myr), and short-lived (M_gas/SFR~40Myr) starburst, without a significant AGN. With physical properties imilar to unlensed z>2 SMGs, HATLAS12-00 offers a detailed view of a typical SMG through a powerful cosmic microscope.
1202.1832
Exploring halo substructure with giant stars: substructure in the local halo as seen in the Grid Giant Star Survey including extended tidal debris from Omega Centauri
Majewski, et al
Nearby halo is found to (1) exhibit significant kinematical substructure, and (2) be prominently represented by several velocity coherent structures, including a very retrograde "cloud" of stars at l~285 deg and extended, retrograde "stream" visible as relatively tight l-vb sequences. One sequence looks like a tidal disruption from wCen (it's retrograde); retrograde debris accounts for almost all fourth Galactic quadrant retrograde stars in the southern GGSS; and so it appears that wCen is a dominant contributor of retrograde giant stars in the inner galaxy.
1202.1840
Cosmological evolution of atomic gas and implications for 21cm H I absorption
Braun
Galaxy disk are shown to contain a significant population of atomic clouds of 100pc linear size which are self-opaque in the 21cm transition. These objects have HI column densities as high as 1e23 and contribute to a global opacity correction factor of 1.34 that applies to the integrated 21cm emission to obtain a total HI mass estimate. ... the incidence of deep 21 cm absorption systems is predicted to show very little evolution with redshift, while that of faint absorbers should decline by a factor of five between z=3 and the present. Explicitly consider the effects of HI absorption against BG sources that are extended relative to the 100pc intervening absorber size scale. Future surveys of 21cm absorption will require very high angular resolution, of about 15 mas, for their unambiguous interpretation.
1202.1878
Breaking the law: the M_BH-M_spheroid mass relations for core-Sersic and Sersic galaxies
Graham
The popular log-linear relation beteen SMBH mass and the dynamical mass of the host spheroid is shown to require a significant correction. Core galaxies (M_BH>2e8 Msun and thought to form in dry merger events) are shown to be well described by a linear relation for which the median BH mass is 0.36%: roughly double the old value of constancy. 'Classical' spheroids hosting a 1e6 Msun BH will have M_bh/M_sph~0.025%. Many implications.
1202.1887
Total to central luminosity ratios of quiescent galaxies in MODS as an indicator of size evolution
Akhlaghi, Ichikawa, Kajisawa
Measure Luminosity ratio (LR) of the outer to the central regions of massive (M1e10.5 Msun) galaxies at fixed radii in a single rest-frame for z<3.5 as a new approach to the problem of size evolution. Didn't observe any evolution in the median LR.
1202.1927
Towards an understanding of 3rd order gg lensing
Simon, Schneider, Kübler
Third-order gg lensing (G3L) is a next-generation gg lensing technique that either measures the excess shear about lens pairs, or the excess shear-shear correlation about lenses. It is clear that these statistics assess the 3 pt correlations between galaxy positions and projected matter density. For future applications of these novel statistics, aim at a more intuitive understanding of G3L to isolate the main features that possibly can be measured. Construct a toy model ("isolated lens model"; ILM) for the distribution of galaxies and associated matter to determine the measured quantities of the two G3L correlation functions and traditional gg lensing in a simplified context. The ILM presumes single lens galaxies to be embedded inside arbitrary matter hales that are statistically independent ("isolated") from any other halo or lens position. In the ILM, the avg mass-to-galaxy number ratio of clusters of any size cannot change. GGL and galaxy clustering alone cannot distinguish an ILM from any more complex scenario. The lens-lens-shear correlator in combination with second-order statistics enables us to detect deviations from a ILM, though. This can be quantified by a difference signal defined in the paper. We demonstrate with the ILM that this correlator picks up the excess matter distribution about galaxy pairs inside clusters. The shear-shear-lens correlator is sensitive to variations among matter haloes. In principle, it could be devised to constrain the ellipticities of haloes, without the need for luminous tracers, or maybe even random halo substructure.
1202.1929
Bar patatern speed evolution over the last 7 Gyr
Perez, Aguerri, Mendez-Abreu
The tumbling pattern of a bar is the main parameter characterising its dynamics. Evolution since bar formation is tightly linked to the dark halo in which the bar is formed through dynamical friction and angular momentum exchange. Observational measurements of the bar pattern speed with z can restrict models of galaxy formation and bar evolution. Aim to determine the bar pattern speed evolution with z based on morphological measurements. Have selected a sample of 44 low inclination ringed galaxies from the SDSS and COSMOS surveys covering the z range 0<z<0.8 to investigate the evolution of the bar pattern speed. The quantity R_CR / R_bar (ratio of outer ring radius to bar size) is used for classifying bars in slow and fast rotators. Obtain similar distribution of this ratio at all z. Implies no substantial angular momentum exchange between the bar and halo, as predicted by numerical sims. Imply that the discs of these high surface-brightness galaxies are maximal.
1202.1977
Recoiling BHs: EM signatures, candidates, and astrophysical implications
Komossa
SMBHs may not always reside right at the centers of their host galaxies. Newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of GWs. Consequence: long-lived oscillations of the SMBHs in galaxy cores, or (rarely) ejections from their host galaxies. Observationally this would appear as AGN offset from host galaxy center. some observations discussed.
1202.2005
Building a Model Astrolabe
Ford
Hands-on introduction to the medieval astrolabe. (a planisphere!)
1202.2022
Comparision of the properties of two fossil groups of galaxies with the normal group NGC 6034 based on multiband imaging and optical spectroscopy
Adami, ... Ilbert, ... et al
Fossil groups are dominated by a bright galaxy, and their luminosity functions show an absence within half the virial radus of galaxies brighter than the central galaxy magnitude +2. They are nevertheless massive with an extended X-ray halo. The formation and evolution of these structures is still widely debated. Study faint galaxy population necessary, and their LS environment, to study if they are isolated. Confirm that these two are indeed fossil groups.
1202.2046
Retrieving the 3d matter power spectrum and galaxy biasing parameters from lensing tomography
Simon
Lensing tomography can constrain spatial 3d matter power spectrum over a range in z and physical scale. By adding gg lensing and galaxy clusterin, this can be extended to probe the 3d galaxy-matter and gg power spectrum, or alternatively, galaxy biasing parameters. To achieve this aim, this paper introduces and discusses minimum variance estimators and a more general Bayesian approach to statistically invert a set of noisy tomography 2pt correlation functions, measured within a confined opening angle. Both methods are constructed such that they probe deviations of the 3d power spectrum from a fiducial power spectrum. Both methods are constructed such that they probe deviations of the 3d power spectrum from a fiducial power spectrum. A direct comparison of theory and data is achieved; the physical scale and z of deviations can in principle be identified. By devising a new MC technique the measurement noise in the correlators is quantified for a fiducial survey, and the performance of the inversion techniques is tested. Conclude that a shear tomography analysis of near future wl surveys promises insights into the effect of baryons on the NL matter power spectrum at z<0.3 around k~2h/Mpc, and into galaxy biasing (z<0.5). However, a proper treatment of anticipated systematics - not included in the mock analysis but discussed here - is likely to reduce the S/N in the analysis so that a robust assessment of the 3d matter power spectrum probably asks for a survey area of at least 1000 sq deg.
1202.2096
Driving the gaseous evolution of massive galaxies in the early universe
Riechers
Studies of molecular ISM that fuels SF and SMBH growth: based on the direction of molecular gas in >120 galaxies at z=1 to 6.4, obtain detailed insight on how the amount and physical properties of this material in a galaxy are connected to its current star formation rate over a range of galaxy populations. Studies of the gas dynamics and morphology at high spatial resolution allows distinguishing between gas-rich mergers in different stages along the "merger sequence" and disk galaxies. Observations of the most massive gas-rich SB galaxies out to z>5 provide insight into the role of cosmic environment for the early growth of present -day massive spheroidal galaxies. Large-area submillimeter surveys have revealed a rare population of extremely far-IR luminous gas-rich high-redshift objects, which is dominated by strongly lensed, massive SB galaxies. ...
1202.1829
A comprehensive view of a strongly lensed planck-associated submillimeter galaxy
Fu, ... Scoville, Aguirre, ... et al
Present high-res maps of stars, dust and molecular gas in a strongly lensed SMG at 3.259. Image indicates differentiated distributions of the various components: stars in 3 major kpc-scale clumps extended over 1.6 kpc, the dust in compact (~1kpc) region ~3kpc north of the stars, and the cold molecular gas in an extended (~7kpc) disk ~5kpc NE of the stars. The emission from the stars, dust, and gas are magnified by ~17, 8, and 7 times, respectively, by the 4 lensing galaxies at z~1. Intrinsically, the galaxy is a arm (T_dust~40-65K), hyper-luminous (L_IR~1.6e13 Lsun, SFR~2000Msun/yr), gas rich (M_gas/M_baryon~70%), young (M_stellar/SFR~20Myr), and short-lived (M_gas/SFR~40Myr) starburst, without a significant AGN. With physical properties imilar to unlensed z>2 SMGs, HATLAS12-00 offers a detailed view of a typical SMG through a powerful cosmic microscope.
1202.1832
Exploring halo substructure with giant stars: substructure in the local halo as seen in the Grid Giant Star Survey including extended tidal debris from Omega Centauri
Majewski, et al
Nearby halo is found to (1) exhibit significant kinematical substructure, and (2) be prominently represented by several velocity coherent structures, including a very retrograde "cloud" of stars at l~285 deg and extended, retrograde "stream" visible as relatively tight l-vb sequences. One sequence looks like a tidal disruption from wCen (it's retrograde); retrograde debris accounts for almost all fourth Galactic quadrant retrograde stars in the southern GGSS; and so it appears that wCen is a dominant contributor of retrograde giant stars in the inner galaxy.
1202.1840
Cosmological evolution of atomic gas and implications for 21cm H I absorption
Braun
Galaxy disk are shown to contain a significant population of atomic clouds of 100pc linear size which are self-opaque in the 21cm transition. These objects have HI column densities as high as 1e23 and contribute to a global opacity correction factor of 1.34 that applies to the integrated 21cm emission to obtain a total HI mass estimate. ... the incidence of deep 21 cm absorption systems is predicted to show very little evolution with redshift, while that of faint absorbers should decline by a factor of five between z=3 and the present. Explicitly consider the effects of HI absorption against BG sources that are extended relative to the 100pc intervening absorber size scale. Future surveys of 21cm absorption will require very high angular resolution, of about 15 mas, for their unambiguous interpretation.
1202.1878
Breaking the law: the M_BH-M_spheroid mass relations for core-Sersic and Sersic galaxies
Graham
The popular log-linear relation beteen SMBH mass and the dynamical mass of the host spheroid is shown to require a significant correction. Core galaxies (M_BH>2e8 Msun and thought to form in dry merger events) are shown to be well described by a linear relation for which the median BH mass is 0.36%: roughly double the old value of constancy. 'Classical' spheroids hosting a 1e6 Msun BH will have M_bh/M_sph~0.025%. Many implications.
1202.1887
Total to central luminosity ratios of quiescent galaxies in MODS as an indicator of size evolution
Akhlaghi, Ichikawa, Kajisawa
Measure Luminosity ratio (LR) of the outer to the central regions of massive (M1e10.5 Msun) galaxies at fixed radii in a single rest-frame for z<3.5 as a new approach to the problem of size evolution. Didn't observe any evolution in the median LR.
1202.1927
Towards an understanding of 3rd order gg lensing
Simon, Schneider, Kübler
Third-order gg lensing (G3L) is a next-generation gg lensing technique that either measures the excess shear about lens pairs, or the excess shear-shear correlation about lenses. It is clear that these statistics assess the 3 pt correlations between galaxy positions and projected matter density. For future applications of these novel statistics, aim at a more intuitive understanding of G3L to isolate the main features that possibly can be measured. Construct a toy model ("isolated lens model"; ILM) for the distribution of galaxies and associated matter to determine the measured quantities of the two G3L correlation functions and traditional gg lensing in a simplified context. The ILM presumes single lens galaxies to be embedded inside arbitrary matter hales that are statistically independent ("isolated") from any other halo or lens position. In the ILM, the avg mass-to-galaxy number ratio of clusters of any size cannot change. GGL and galaxy clustering alone cannot distinguish an ILM from any more complex scenario. The lens-lens-shear correlator in combination with second-order statistics enables us to detect deviations from a ILM, though. This can be quantified by a difference signal defined in the paper. We demonstrate with the ILM that this correlator picks up the excess matter distribution about galaxy pairs inside clusters. The shear-shear-lens correlator is sensitive to variations among matter haloes. In principle, it could be devised to constrain the ellipticities of haloes, without the need for luminous tracers, or maybe even random halo substructure.
1202.1929
Bar patatern speed evolution over the last 7 Gyr
Perez, Aguerri, Mendez-Abreu
The tumbling pattern of a bar is the main parameter characterising its dynamics. Evolution since bar formation is tightly linked to the dark halo in which the bar is formed through dynamical friction and angular momentum exchange. Observational measurements of the bar pattern speed with z can restrict models of galaxy formation and bar evolution. Aim to determine the bar pattern speed evolution with z based on morphological measurements. Have selected a sample of 44 low inclination ringed galaxies from the SDSS and COSMOS surveys covering the z range 0<z<0.8 to investigate the evolution of the bar pattern speed. The quantity R_CR / R_bar (ratio of outer ring radius to bar size) is used for classifying bars in slow and fast rotators. Obtain similar distribution of this ratio at all z. Implies no substantial angular momentum exchange between the bar and halo, as predicted by numerical sims. Imply that the discs of these high surface-brightness galaxies are maximal.
1202.1977
Recoiling BHs: EM signatures, candidates, and astrophysical implications
Komossa
SMBHs may not always reside right at the centers of their host galaxies. Newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of GWs. Consequence: long-lived oscillations of the SMBHs in galaxy cores, or (rarely) ejections from their host galaxies. Observationally this would appear as AGN offset from host galaxy center. some observations discussed.
1202.2005
Building a Model Astrolabe
Ford
Hands-on introduction to the medieval astrolabe. (a planisphere!)
1202.2022
Comparision of the properties of two fossil groups of galaxies with the normal group NGC 6034 based on multiband imaging and optical spectroscopy
Adami, ... Ilbert, ... et al
Fossil groups are dominated by a bright galaxy, and their luminosity functions show an absence within half the virial radus of galaxies brighter than the central galaxy magnitude +2. They are nevertheless massive with an extended X-ray halo. The formation and evolution of these structures is still widely debated. Study faint galaxy population necessary, and their LS environment, to study if they are isolated. Confirm that these two are indeed fossil groups.
1202.2046
Retrieving the 3d matter power spectrum and galaxy biasing parameters from lensing tomography
Simon
Lensing tomography can constrain spatial 3d matter power spectrum over a range in z and physical scale. By adding gg lensing and galaxy clusterin, this can be extended to probe the 3d galaxy-matter and gg power spectrum, or alternatively, galaxy biasing parameters. To achieve this aim, this paper introduces and discusses minimum variance estimators and a more general Bayesian approach to statistically invert a set of noisy tomography 2pt correlation functions, measured within a confined opening angle. Both methods are constructed such that they probe deviations of the 3d power spectrum from a fiducial power spectrum. Both methods are constructed such that they probe deviations of the 3d power spectrum from a fiducial power spectrum. A direct comparison of theory and data is achieved; the physical scale and z of deviations can in principle be identified. By devising a new MC technique the measurement noise in the correlators is quantified for a fiducial survey, and the performance of the inversion techniques is tested. Conclude that a shear tomography analysis of near future wl surveys promises insights into the effect of baryons on the NL matter power spectrum at z<0.3 around k~2h/Mpc, and into galaxy biasing (z<0.5). However, a proper treatment of anticipated systematics - not included in the mock analysis but discussed here - is likely to reduce the S/N in the analysis so that a robust assessment of the 3d matter power spectrum probably asks for a survey area of at least 1000 sq deg.
1202.2096
Driving the gaseous evolution of massive galaxies in the early universe
Riechers
Studies of molecular ISM that fuels SF and SMBH growth: based on the direction of molecular gas in >120 galaxies at z=1 to 6.4, obtain detailed insight on how the amount and physical properties of this material in a galaxy are connected to its current star formation rate over a range of galaxy populations. Studies of the gas dynamics and morphology at high spatial resolution allows distinguishing between gas-rich mergers in different stages along the "merger sequence" and disk galaxies. Observations of the most massive gas-rich SB galaxies out to z>5 provide insight into the role of cosmic environment for the early growth of present -day massive spheroidal galaxies. Large-area submillimeter surveys have revealed a rare population of extremely far-IR luminous gas-rich high-redshift objects, which is dominated by strongly lensed, massive SB galaxies. ...
1202.1672
Galactic cold cores III. general cloud properties
Juvela, ... Marshcall, ... et al
Examine the cloud structure around the Planck detections on 71 field observed with the Herschel SPIRE instrument. Look for signs of coreshine (enhanced mid-IR scattering), an indication of growth of the dust grains, and examine the star formation activity associated with the cold clumps. Size range: 100pc to few kpc; mass range: 10 Msun to 1e4 Msun. Most contain some filamentary structures in about half of the cases filament dominates morphology. Some show cometary shape, have sharp boundaries indicative of compression by an extrenal force. Width of filaments is typically 0.2-0.3 pc. Singifnicant variation from 0.1pc to 1pc and the estimates are sensitive to the methods used and the very definition of a filament. Enhanced mid-IR scattering, coreshine was detected on 4(+6)/71 clouds. About half of the fields are associated with active SF as indicated by the presence of mid-IR point sources. The mid-IR sources often coincide with structures whose sub-millimeter spectra are still dominated by the cold dust.
1202.1763
Survival of molecular gas in Virgo's hot intracluster medium: CO near M86
Dasyra, Combes, Salome, Braine
CO observations of 21 different regions around M86, NGC4438, and along the 120 kpc-long, Ha-emitting filamentary trail that connects them, aiming to test whether molecular gas can survive to be transferred from a spiral to an elliptical galaxy in Virgo's 1e7K ICM. Target Ha-emitting regions that could be associated with the interface between cold molecular clouds and the hot ionized ICM. Data led to the detection of molecular gas close to M86. CO gas with a recession velocity that is similar to that of the stars (-265 km/s), and with a corresponding H2 mass of 2e7 Msun, was detected 10kpc SE of the nucleus of M86, near the peak of its HI emission. Argue that it is possible for this molecular gas either to have formed in situ from HI, or to have been stripped from NGC 4438 directly in molecular form. In situ formation is nonetheless negligible for the 7e6 Msun of gas detected at ~10 kpc NE of M86, where no (storng) HI emission is present. This detection provides evidence for the survival of molecular gas in flilaments for timescales of ~100 Myr. An amount equivalent to 5e7 Msun of H2 gas that could be lost to the ICM or to neighboring galaxies was also discovered in the tidal tail NW of NGC4438. A scenario of gas being alternatively rought to M86 from NGC4388 on its south was also examined bit it was considered unlikely due to the non detection of CO below or at the HI stream velocities, 2000-2700 km/s.
1202.1776
On the unification of the AGN
Elitzur
Meaningful studies of unification statistics cannot be conducted without first determining the intrinsic distribution function of torus covering factors.
1201.5383
Growth of early SMBH and the high-z Eddington ratio distribution
DeGraf, Di Matteo, Khandai, Croft
Large-scale hydrosim: investigate the growth rate of SMBH in z>4.75. Find a clear peak in the typical Eddington ratio at BH masses of 4-8e7 Msun (typically in halos of 1e12 Msun), independent of z and indicative that most BH growth occurs in the cold-flow dominated regime. BH growth is by and large regulated by the evolution of gas density. The typical Eddington ratio at a given mass scales simply as cosmological density (1+z)^3 and the peak is caused by the competition between increased gas density available in more massive hosts, and a decrease due to strong AGN feedback. In addition to evolution in the mean Edington ratio, show that the distribution of Eddington ratio among both mass-selected and luminosity-selected samples is approximately log-normal. Combine these findings into a single log-normal fitting formula for the distribution of Eddington ratios as a function of (M_BH,z).
1201.5384
The dust budget of the SMC: are AGB stars the primary dust source at low metallicity?
Boyer, et al
Estimate the total dust input from the cool evolved stars in the SMC, using 8 micron excess as a proxy for the dust-production rate. Find AGB and RSG (red supergiant) stars produce 1e8 Msun/yr of dust, depending on the fraction of far-IR sources that belong to the evolved star population. RSGs contribute the least (<4%), while carbon-rich AGB stars (especially the so-called "extreme" AGB stars) account for 90% of the total dust input from cool evolved stars. Also estimate the dust input from hot stars and SNe, and find that if SNe produce 1e-3 solar masses of dust each, then the total SN dust input and AGB input are roughly equivalent. Consider several scenarios of SNe dust production and destruction and find that the ISM dust can be accounted for solely by stellar sources if all SNe produce dust in the quantities seen around the dustiest examples and if most SNe explode in dense regions where much of the ISM dust is shielded from the shocks. Find that AGB stars contribute only 2% of the ISM dust. Without a net positive contribution from SNe to the dust budget, this suggest that dust must grow in the ISM or be formed by another unknown mechanism.
1201.5491
The radial distribution of galaxies in groups and clusters
Budzynski, Kpopsov, McCarthy, McGee, Belokurov
New group/cluster (centered on LRG) catalog of SDSS DR7 in 0.15<z<0.4. Provide halo mass estimates for each of these groups derived from a calibration between the otpical richness of bright galaxies (M_r<-20.5) within 1Mpc. Find that derived profile can be well described by a projected NFW profile with a concentration parameter (2.6) that is approximately a factor of two lower tan that of the DM, predicted from N-body simulations, and nearly independent of halo mass. In spite of the difference in shape between the galaxy and DM radial distributions, both exhibit a high degree of self-similarity. Beyond 0.3 r_500, models can reproduce both the shape and normalization of the satellite profiles, and within 0.3 r_500 the predicted profiles are sensitive to the details of the satellite-BCG merger timescale calculation. The former is a direct result of the models being tuned to match the global galaxy luminosity function combined with the assumption that the satellite galaxies do not suffer significant tidal stripping, even though their surrounding DM haloes can be removed through this process. Combining results with measurements of the IC light should provide a way to inform theoretical models on the efficacy of the tidal stripping and merging processes.
1201.5571
Relativistic cosmology number densities and the luminosity function
Iribarrem, Lopes, Ribeiro, Stoeger
Increased relevance of the relativistic effects of expansion when compared to the evolution of the LF at the higher z. ...
1201.5583
Galaxy scale lenses in the RCS2: I. first catalog of candidate strong lenses
Anguita, Barrientos, Gladderes, Faure, Yee, Gilbank
First galaxy-scale lens catalog from RCS2, using color-gradient as a search criteria (red lens, blue Einstein ring/arcs).
1201.5591
Measuring the 3d shape of x-ray clusters
Samsing, Skielboe, Hansen
Spatial shape of the gas itself also carries useful information: x-ray gas shape in the inner parts of the galaxy clusters is greatly affected by feedback mechanisms, cooling and rotation, and measuring this shape can indirectly provide information on these mechanisms. Present a novel mothod to measure the 3d shape of the intracluster x-ray gas from x-ray observation only, which is possible when using the full spectral information contained in the observed spectra. Demonstrate the method by measuring radial dependent shapes along the line of sight for CHANDRA mock data. Find that at least 1e6 photons required to get 5 sigma detection of shape having e.g., cool core and a double powerlaw for the density profile. Illustrate how Bayes' theorem is used to find the best fitting model of the x-ray gas, an analysis that is very important in a real observational scenario where the true spatial shape is unknown. Not including a shape in the fit may propagate to a mass bias if the xray is used to estimate the total cluster mass. Discuss this mass bias for a class of spacial shapes.
1201.5617
New measurements of the CIB fluctuations in deep Spitzer/IRAC survey data and their cosmological implications
Kashlinsky, Arendt, Ashby, Fazio, Mather, Moseley
Extend the measurement of fluctuatons to angular scales of 1 deg using new data obtained in the course of the 2000+ hr Spitzer Extended Deep Survey, find that the CIB fluctuations continue to diverge more than 10 times those of ordinary galaxies. The detected CIB anisotropies are found to be significantly in excess of random instrument noise and known galaxy contributions on angular scales out to 1 deg. The low shot noise levels remaining in the diffuse maps indicate that the large scale fluctuations is in reasonable agreement with simple fitting assuming that they originate in early populations spatially distributed according to the standard cosmological model (LCDM) at epochs coinciding with the first stars era. The alternative to this identification would require a new population never observed before, nor expected on theoretical grounds, but if true this would represent an important discovery in its own right.
1201.5630
Stacked rest-frame UV spectra of Lya-emitting and continuum-selected galaxies at 2<z<3.5
Berry, Gawiser, ... et al
Present properties of individual and composite rest-UV spectra of continuum- and narrowband-selected SF galaxies at 2<z<3.5 in MUSYC collaboration in the ECDF-S. Among 81 UV-bright SFGs, 59 have R20A, the limit to be classified as LAE. Divide dataset into subsamples based on properties, we are able to measure for each individual galaxy: Lya EW, rest-fram UV colors, and z. ....
1202.1763
Survival of molecular gas in Virgo's hot intracluster medium: CO near M86
Dasyra, Combes, Salome, Braine
CO observations of 21 different regions around M86, NGC4438, and along the 120 kpc-long, Ha-emitting filamentary trail that connects them, aiming to test whether molecular gas can survive to be transferred from a spiral to an elliptical galaxy in Virgo's 1e7K ICM. Target Ha-emitting regions that could be associated with the interface between cold molecular clouds and the hot ionized ICM. Data led to the detection of molecular gas close to M86. CO gas with a recession velocity that is similar to that of the stars (-265 km/s), and with a corresponding H2 mass of 2e7 Msun, was detected 10kpc SE of the nucleus of M86, near the peak of its HI emission. Argue that it is possible for this molecular gas either to have formed in situ from HI, or to have been stripped from NGC 4438 directly in molecular form. In situ formation is nonetheless negligible for the 7e6 Msun of gas detected at ~10 kpc NE of M86, where no (storng) HI emission is present. This detection provides evidence for the survival of molecular gas in flilaments for timescales of ~100 Myr. An amount equivalent to 5e7 Msun of H2 gas that could be lost to the ICM or to neighboring galaxies was also discovered in the tidal tail NW of NGC4438. A scenario of gas being alternatively rought to M86 from NGC4388 on its south was also examined bit it was considered unlikely due to the non detection of CO below or at the HI stream velocities, 2000-2700 km/s.
1202.1776
On the unification of the AGN
Elitzur
Meaningful studies of unification statistics cannot be conducted without first determining the intrinsic distribution function of torus covering factors.
1201.5383
Growth of early SMBH and the high-z Eddington ratio distribution
DeGraf, Di Matteo, Khandai, Croft
Large-scale hydrosim: investigate the growth rate of SMBH in z>4.75. Find a clear peak in the typical Eddington ratio at BH masses of 4-8e7 Msun (typically in halos of 1e12 Msun), independent of z and indicative that most BH growth occurs in the cold-flow dominated regime. BH growth is by and large regulated by the evolution of gas density. The typical Eddington ratio at a given mass scales simply as cosmological density (1+z)^3 and the peak is caused by the competition between increased gas density available in more massive hosts, and a decrease due to strong AGN feedback. In addition to evolution in the mean Edington ratio, show that the distribution of Eddington ratio among both mass-selected and luminosity-selected samples is approximately log-normal. Combine these findings into a single log-normal fitting formula for the distribution of Eddington ratios as a function of (M_BH,z).
1201.5384
The dust budget of the SMC: are AGB stars the primary dust source at low metallicity?
Boyer, et al
Estimate the total dust input from the cool evolved stars in the SMC, using 8 micron excess as a proxy for the dust-production rate. Find AGB and RSG (red supergiant) stars produce 1e8 Msun/yr of dust, depending on the fraction of far-IR sources that belong to the evolved star population. RSGs contribute the least (<4%), while carbon-rich AGB stars (especially the so-called "extreme" AGB stars) account for 90% of the total dust input from cool evolved stars. Also estimate the dust input from hot stars and SNe, and find that if SNe produce 1e-3 solar masses of dust each, then the total SN dust input and AGB input are roughly equivalent. Consider several scenarios of SNe dust production and destruction and find that the ISM dust can be accounted for solely by stellar sources if all SNe produce dust in the quantities seen around the dustiest examples and if most SNe explode in dense regions where much of the ISM dust is shielded from the shocks. Find that AGB stars contribute only 2% of the ISM dust. Without a net positive contribution from SNe to the dust budget, this suggest that dust must grow in the ISM or be formed by another unknown mechanism.
1201.5491
The radial distribution of galaxies in groups and clusters
Budzynski, Kpopsov, McCarthy, McGee, Belokurov
New group/cluster (centered on LRG) catalog of SDSS DR7 in 0.15<z<0.4. Provide halo mass estimates for each of these groups derived from a calibration between the otpical richness of bright galaxies (M_r<-20.5) within 1Mpc. Find that derived profile can be well described by a projected NFW profile with a concentration parameter (2.6) that is approximately a factor of two lower tan that of the DM, predicted from N-body simulations, and nearly independent of halo mass. In spite of the difference in shape between the galaxy and DM radial distributions, both exhibit a high degree of self-similarity. Beyond 0.3 r_500, models can reproduce both the shape and normalization of the satellite profiles, and within 0.3 r_500 the predicted profiles are sensitive to the details of the satellite-BCG merger timescale calculation. The former is a direct result of the models being tuned to match the global galaxy luminosity function combined with the assumption that the satellite galaxies do not suffer significant tidal stripping, even though their surrounding DM haloes can be removed through this process. Combining results with measurements of the IC light should provide a way to inform theoretical models on the efficacy of the tidal stripping and merging processes.
1201.5571
Relativistic cosmology number densities and the luminosity function
Iribarrem, Lopes, Ribeiro, Stoeger
Increased relevance of the relativistic effects of expansion when compared to the evolution of the LF at the higher z. ...
1201.5583
Galaxy scale lenses in the RCS2: I. first catalog of candidate strong lenses
Anguita, Barrientos, Gladderes, Faure, Yee, Gilbank
First galaxy-scale lens catalog from RCS2, using color-gradient as a search criteria (red lens, blue Einstein ring/arcs).
1201.5591
Measuring the 3d shape of x-ray clusters
Samsing, Skielboe, Hansen
Spatial shape of the gas itself also carries useful information: x-ray gas shape in the inner parts of the galaxy clusters is greatly affected by feedback mechanisms, cooling and rotation, and measuring this shape can indirectly provide information on these mechanisms. Present a novel mothod to measure the 3d shape of the intracluster x-ray gas from x-ray observation only, which is possible when using the full spectral information contained in the observed spectra. Demonstrate the method by measuring radial dependent shapes along the line of sight for CHANDRA mock data. Find that at least 1e6 photons required to get 5 sigma detection of shape having e.g., cool core and a double powerlaw for the density profile. Illustrate how Bayes' theorem is used to find the best fitting model of the x-ray gas, an analysis that is very important in a real observational scenario where the true spatial shape is unknown. Not including a shape in the fit may propagate to a mass bias if the xray is used to estimate the total cluster mass. Discuss this mass bias for a class of spacial shapes.
1201.5617
New measurements of the CIB fluctuations in deep Spitzer/IRAC survey data and their cosmological implications
Kashlinsky, Arendt, Ashby, Fazio, Mather, Moseley
Extend the measurement of fluctuatons to angular scales of 1 deg using new data obtained in the course of the 2000+ hr Spitzer Extended Deep Survey, find that the CIB fluctuations continue to diverge more than 10 times those of ordinary galaxies. The detected CIB anisotropies are found to be significantly in excess of random instrument noise and known galaxy contributions on angular scales out to 1 deg. The low shot noise levels remaining in the diffuse maps indicate that the large scale fluctuations is in reasonable agreement with simple fitting assuming that they originate in early populations spatially distributed according to the standard cosmological model (LCDM) at epochs coinciding with the first stars era. The alternative to this identification would require a new population never observed before, nor expected on theoretical grounds, but if true this would represent an important discovery in its own right.
1201.5630
Stacked rest-frame UV spectra of Lya-emitting and continuum-selected galaxies at 2<z<3.5
Berry, Gawiser, ... et al
Present properties of individual and composite rest-UV spectra of continuum- and narrowband-selected SF galaxies at 2<z<3.5 in MUSYC collaboration in the ECDF-S. Among 81 UV-bright SFGs, 59 have R20A, the limit to be classified as LAE. Divide dataset into subsamples based on properties, we are able to measure for each individual galaxy: Lya EW, rest-fram UV colors, and z. ....
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