1307.0818
The Gemini NICI planet-finding campaign: the frequency of giant planets around debris disk stars
Wahhaj, ..., Kuchner, Reid (Neil), Toomey, et al
High-contrast direct imaging survey for giant planets around 57 debris disk stars; H-band contrasts of 12.4 mag at 0.5" and 14.1 mag at 1" separation; follow-up of 66 candidates with project separation < 500 AU show that all of them are BG objects. Establish statistical constraints on the underlying giant planet population based on imaging data---Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constraint the planet population. Formalism allows inclusion previously known planets. Results show at 95% CL that <13% of debris disk stars have a >5MJup planet beyond 80 AU, and <21% of debris disk stars have a >3 MJup planet outside of 40 AU, based on hot-start evolutionary models. Model the population of directly-imaged planets of d^2N/dMda ~ m^alpha a^beta, where m is planet mass and a is orbital semi-major axis (with maximum value amax). Find that beta < -0.8 and/or alpha>1.7. Likewise, find that beta < -0.8 and/or amax < 200AU. If Beta Pic and HR 8799 planets (rare and distinct group) ignored, find that <20% of debris disk stars have a > 3MJup planet beyond 10 AU, and beta < -0.8 and/or alpha < -1.5. Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet formation; non-detections at large separations show that planets with orbital separation > 40 AU and planet masses > 3 MJup do not carve the central holes in these disks.
1307.0833
The lack of star formation gradients in galaxy groups up to z~1.6
Ziparo .. Finoguenov, ... Tanaka, Ilbert, ... Genzel, et al
In cluster cores, early type galaxies dominate, whereas SF galaxies are more and more common in the outskirts. At higher redshifts and in somewhat less dense environments (galaxy groups), the situation is less clear. The open issue: how and whether the SFR of galaxies in groups depends on the distance from the centre of mass. To shed light on this topic, we have built a sample of X-ray selected galaxy groups at 0<z<1.6 in various blank fields (ECDFS, COSMOS, GOODS). We use a sample of spectroscopically confirmed group members with stellar mass M > 1e10.3 Msun in order to have a high spectroscopic completeness. As only spectroscopic redshifts are used, results are not affected by uncertainties due to projection effects. Use several SFR indicators to link the SF activity to the galaxy environment. Taking advantage of the extremely deep MIR Spitzer MIPS and FIR Herschel PACS observations, have an accurate, broad-band measure of the SFR for the bulk of the SF galaxies. Use multi-wavelength SED fitting techniques to estimate the stellar masses of all objects and the SFR of the MPIS and PACS undetected galaxies. Analyse the dependence of the SF activity, stellar mass and specific SFR on the group-centri distance, up to z~1.6, for the first time. Do not find any correlation between the mean SFR and group-centric distance at any redshift. Do not observe any strong mass segregation either, in agreement with predictions from simulations. Results suggest that either groups have a much smaller spread in accretion times with respect to the clusters and that the relaxation time is longer than the group crossing time.
1307.0971
The UV to FIR spectral energy distribution of star-forming galaxies in the redshift desert
Oteo et al
Rest-frame UV-to-NIR SED of LBGs, SF BzK (sBzK), and UV-selected galaxies at 1.5<z<2.5 in the COSMOS, GOODS-North, and GOODS-South fields. Complement the multi-wavelength coverage of the galaxies located in GOODS-North and GOODS-South fields with deep FIR data taken within the framework of the GOODS-Herschel project. According to their best-fitted SED-derived properties, find that due to their selection criterion involving UV measurements, LBGs tend to be UV-brighter, bluer, have less prominent Balmer break (are younger), and have higher dust-corrected total SFR than sBzK galaxies. In a color versus stellar mass diagram, LBGs at z~2 tend to be mostly located over the blue cloud of galaxies at their redshift, although galaxies with older ages, higher dust attenuation, and redder UV continuum slope deviate to the green valley and red sequence. Find PACS (100um or 160 um) individual detections for a subsample of 77 LBGs, 140 sBzK, and 144 UV-selected galaxies. The total SFR of the studied PACS-detected galaxies cannot be recovered with the dust-correction factors derived with their continuum slope and the IRX-beta relations for local star-burst, similar to what it happens at higher redshifts. In an SFR-mass diagram, the studied PACS-detected galaxies are located above the Dadi et al. (2007) main sequence and, therefore, their SF is likely driven by star burst. There is a subpopulation of 26 and 49 LBGs and sBzK galaxies, respectively, that are detected in SPIRE (250um, 350um, or 500um) bands. Speculate that this population of SPIRE-detected LBGs is the bridge population between sub-mm galaxies and LBGs. Finally, find that the IR properties of the dustiest LBGs have changed with redshift, indicating an evolution that is in agreement with previous results.
1307.0982
Tangential velocity of the dark matter in the Bullet Cluster from precise lensed image redshifts
Molnar, Broadhurst, Umetsu, Zitrin, Raphaeli, Shimon
The fast moving component of the gullet cluster can induce potentially resolvable redshift differences between multiply-lensed images of background galaxies. The moving cluster effect can be expressed as the scalar product of the lensing deflection angle with the tangential [tangential with respect to what?] velocity of the mass components, and it is maximal for clusters colliding in the plane of the sky with velocities boosted by their mutual gravity. ... Complements radial effect determined by the kSZ effect.
The Gemini NICI planet-finding campaign: the frequency of giant planets around debris disk stars
Wahhaj, ..., Kuchner, Reid (Neil), Toomey, et al
High-contrast direct imaging survey for giant planets around 57 debris disk stars; H-band contrasts of 12.4 mag at 0.5" and 14.1 mag at 1" separation; follow-up of 66 candidates with project separation < 500 AU show that all of them are BG objects. Establish statistical constraints on the underlying giant planet population based on imaging data---Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constraint the planet population. Formalism allows inclusion previously known planets. Results show at 95% CL that <13% of debris disk stars have a >5MJup planet beyond 80 AU, and <21% of debris disk stars have a >3 MJup planet outside of 40 AU, based on hot-start evolutionary models. Model the population of directly-imaged planets of d^2N/dMda ~ m^alpha a^beta, where m is planet mass and a is orbital semi-major axis (with maximum value amax). Find that beta < -0.8 and/or alpha>1.7. Likewise, find that beta < -0.8 and/or amax < 200AU. If Beta Pic and HR 8799 planets (rare and distinct group) ignored, find that <20% of debris disk stars have a > 3MJup planet beyond 10 AU, and beta < -0.8 and/or alpha < -1.5. Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet formation; non-detections at large separations show that planets with orbital separation > 40 AU and planet masses > 3 MJup do not carve the central holes in these disks.
1307.0833
The lack of star formation gradients in galaxy groups up to z~1.6
Ziparo .. Finoguenov, ... Tanaka, Ilbert, ... Genzel, et al
In cluster cores, early type galaxies dominate, whereas SF galaxies are more and more common in the outskirts. At higher redshifts and in somewhat less dense environments (galaxy groups), the situation is less clear. The open issue: how and whether the SFR of galaxies in groups depends on the distance from the centre of mass. To shed light on this topic, we have built a sample of X-ray selected galaxy groups at 0<z<1.6 in various blank fields (ECDFS, COSMOS, GOODS). We use a sample of spectroscopically confirmed group members with stellar mass M > 1e10.3 Msun in order to have a high spectroscopic completeness. As only spectroscopic redshifts are used, results are not affected by uncertainties due to projection effects. Use several SFR indicators to link the SF activity to the galaxy environment. Taking advantage of the extremely deep MIR Spitzer MIPS and FIR Herschel PACS observations, have an accurate, broad-band measure of the SFR for the bulk of the SF galaxies. Use multi-wavelength SED fitting techniques to estimate the stellar masses of all objects and the SFR of the MPIS and PACS undetected galaxies. Analyse the dependence of the SF activity, stellar mass and specific SFR on the group-centri distance, up to z~1.6, for the first time. Do not find any correlation between the mean SFR and group-centric distance at any redshift. Do not observe any strong mass segregation either, in agreement with predictions from simulations. Results suggest that either groups have a much smaller spread in accretion times with respect to the clusters and that the relaxation time is longer than the group crossing time.
1307.0971
The UV to FIR spectral energy distribution of star-forming galaxies in the redshift desert
Oteo et al
Rest-frame UV-to-NIR SED of LBGs, SF BzK (sBzK), and UV-selected galaxies at 1.5<z<2.5 in the COSMOS, GOODS-North, and GOODS-South fields. Complement the multi-wavelength coverage of the galaxies located in GOODS-North and GOODS-South fields with deep FIR data taken within the framework of the GOODS-Herschel project. According to their best-fitted SED-derived properties, find that due to their selection criterion involving UV measurements, LBGs tend to be UV-brighter, bluer, have less prominent Balmer break (are younger), and have higher dust-corrected total SFR than sBzK galaxies. In a color versus stellar mass diagram, LBGs at z~2 tend to be mostly located over the blue cloud of galaxies at their redshift, although galaxies with older ages, higher dust attenuation, and redder UV continuum slope deviate to the green valley and red sequence. Find PACS (100um or 160 um) individual detections for a subsample of 77 LBGs, 140 sBzK, and 144 UV-selected galaxies. The total SFR of the studied PACS-detected galaxies cannot be recovered with the dust-correction factors derived with their continuum slope and the IRX-beta relations for local star-burst, similar to what it happens at higher redshifts. In an SFR-mass diagram, the studied PACS-detected galaxies are located above the Dadi et al. (2007) main sequence and, therefore, their SF is likely driven by star burst. There is a subpopulation of 26 and 49 LBGs and sBzK galaxies, respectively, that are detected in SPIRE (250um, 350um, or 500um) bands. Speculate that this population of SPIRE-detected LBGs is the bridge population between sub-mm galaxies and LBGs. Finally, find that the IR properties of the dustiest LBGs have changed with redshift, indicating an evolution that is in agreement with previous results.
1307.0982
Tangential velocity of the dark matter in the Bullet Cluster from precise lensed image redshifts
Molnar, Broadhurst, Umetsu, Zitrin, Raphaeli, Shimon
The fast moving component of the gullet cluster can induce potentially resolvable redshift differences between multiply-lensed images of background galaxies. The moving cluster effect can be expressed as the scalar product of the lensing deflection angle with the tangential [tangential with respect to what?] velocity of the mass components, and it is maximal for clusters colliding in the plane of the sky with velocities boosted by their mutual gravity. ... Complements radial effect determined by the kSZ effect.
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