Friday. Got to catch up for the week, to be prepared for the next...Saturday. Didn't read yesterday... :(
1209.0759
The milky way's circular velocity curve between 4 and 14 kpc from APOGEE data
Bovy et al
Find MW's DM mass within the virial radius is 8e11 Msun, circular velocity at local is 218 pm 6 km/s, rotation curve approximately flat.
1209.0765
Episodic accretion, protostellar radiative feedback, and their role in low-mass star formation
Stamatellos, Whitworth, Hubber
Episodic accretion moderates the effect of radiative feedback from young protostars on their environments, and under some conditions allows the formation of low-mass stars, brown dwarfs, and planetary-mass objects by fragmentation of protostellar discs.
1209.0767
The low mass end of the fundamental relation for gravitationally lensed star forming galaxies at 1<z<6
Christensen et al
13 SL'ed galaxies at 1<z<6 of 1e7-11 Msun mass used to probe fundamental relations; those with <1e10 Msun have large scatter compared to the fundamental relation for low-mass, low-metallicity galaxies with a weaker dependence of the metallicity on either the SFR or stellar mass compared to low-mredshift, high-mass and high-metallicity SDSS galaxies.
1209.0771
Galaxy gas fractions at high-redshift: the tension between observations and cosmological simulations
Narayanan, Bothwell, Dave
z=1~4 galaxies have baryonic gas fraction significantly higher than galaxies at z=0, with values ranging from 20-80%, based on CO measurements. Suggest here that gas fractions inferred from observation of SF galaxies at high-z are overestimated, owing to the adoption of locally-calibrated CO-H2 conversion factors, Xco. Xco is lower than z=0 value; now we have better agreement with simulations.
1209.0775
Gravitationally lensed galaxies at 2<z<3.5: direct abundance measurements of Lya emitters
Christensen et al
3 galaxies at high z, observed in medium resolution spectroscopy. Have 10% solar oxygen abundances; C and N sub-solar. 2 are Lya emitters with EW of 60 and 80 A. Accurately reproduce the line profiles with radiative transfer models; show relatively small outflow.
1209.0778
Star formation rate distributions: inadequacy of the Schechter function
Salim, Lee
Optical and NIR LFs are well fit by Schechter function (power law with exponential cutoff at bright end). LFs of SFR (objects whose luminosity traces SFR) are different, shallow decline at the bright end due to large intrinsic scatter of SFRs at any given stellar mass: best described by "Saunders" function (power law with Gaussian at high end). Schechter-like appearances of UV and Halpha LFs (i.e., of the SFR type) is due to not correcting for dust, etc., i.e., systematics. So, the FIR non-schechter form observed is probably a true form, instead of the purported artifact of AGN contamination.
1209.0780
Convolution Lagrangian perturbation theory for biased tracers
Carlson, Reid, White
Accurate predictions of real- and redshift-space correlation functions of the mass field and DM haloes, with new formulation of Lagrangian perturbation theory. From Matsubara (2008). Naturally recover the Zel'dovich approximation as the lowest order of expansion for matter correlation function; includes NL bias and explains strong bias-dependence of the multiple moments of the z-space correlation function seen in N-body sims.
1209.0782
Evolution along the sequence of S0 Hubble types induced by dry minor mergers. I - Global bulge-to-disk structural relations
Eliche-Moral et al
Dry intermediate and minor mergers can induce global structural evolution within the sequence of S0 Hubble types (based on collision-less N-body simulations).
1209.0825
Is the primordial IMF controlled by dark matter haloes?
de Souza et al
Study statistical properties (shape, spin) of high-z (11<z<16) haloes hosting the first (Pop III) stars with cosmological simulations including detailed gas physics. <sphericity>=0.3; >90% haloes have triaxiality parameter T<0.4 (more oblate than prolate). But large haloes in sims more spherical and prolate. Spin distribution of DM and gas considerably different at z=16 (baryons slower than DM). At low z, spin distributions of DM and gas track each other well. Spin of both gas and DM follows a lognormal distribution. With two feedback models and mapping halo-spin distribution into a PopIII IMF; find high-z the IMF closely tracks the spin lognormal distribution. Depending on feedback model, distribution can be centered at 65 Msun or 140 Msun. Some develop into bimodal distribution (second peak at 40 Msun); result of NL relation of rotation and halo mass. DM halo properties might be a key factor shaping the IMF of the first stars.
1209.0961
Magnetic field amplification associated with the Richtmyer-Meshkov instability
Sano, et al
Amplification of B-field due to RMI in 2d MHD sims. Ambient B-field stretched by fluid motions associated with RMI; strength is amplified by >100x. Saturation level of field determined by balance between amplified B pressure and thermal pressure after shock passage. Results suggest RMI could be a robust mechanism of the amplification of interstellar B-fields and cause the localized strong fields observed at the shock of SNe remnants.
1209.0972
Plunging fireworks: why do infalling galaxies light up on the outskirts of clusters?
Mahajan, et al
Some clusters have enhanced SFR in galaxies on the cluster outskirts. These clusters tend to be unrelaxed clusters currently being assembled via galaxies falling in through stright filaments, resulting in high velocity dispersions. These clusters have higher overall SFR in the clusters compared to the other type of clusters (i.e., no enhanced SFR at outskirts). The comparison galaxies are more likely to be fed by relatively low density filaments. Find: starburst galaxies on the periphery of clusters are in a environment of higher local density than other cluster galaxies at similar radial distances from the cluster center. Conclude: relatively high galaxy density in the infalling regions of cluster promotes interactions amongst galaxies, leading to momentary bursts of SF. Such interactions play a crucial role in exhausting the fuel for SF in a galaxy, before it is expelled due to the environmental processes that are operational in the dense interiors of the cluster.
1209.1043
Measuring neutrino masses with a future galaxy survey
Hamann, Hannestad, Wong
Detailed forecast on how well a Euclid-like photmetric galaxy and cosmic shear survey will be able to constrain the absolute neutrino mass scale. Can detect Sum m_nu ~ 0.06 eV with 2.5 sigma significance; with better knowledge of galaxy bias, significance can be ~5.6 sigma. Need galaxy and cosmic shear power spectrum both to break the degeneracies between neutrino mass, Omega_m, and H0. Euclid-like obs. is not sensitive to the exact mass spectrum of the neutrino sector; no significant bias (<1 sigma) in the parameter estimation is induced by fitting inaccurate models of the neutrino mass splittings to the mock data, nor does the goodness-of-fit of these models suffer any significant degradation relative to the true one (Delta chi_eff^2 < 1).
1209.1094
The unchanging circumgalactic medium over the pst 11 billion years
Chen
Between z~2.2 and 0, the spatial extent and mean absorption equivalent width of the CGM around galaxies of comparable mass have changed little over this time interval.
1209.1095
Limits on the high redshift growth of massive black holes
Salvaterra et al
Place firm upper limits on global accretion history of MBH at z>5 from the unresolved fraction of cosmic X-ray background. From maximum allowed unresolved intensity observed at 1.5 keV, a maximum accreted-mass density onto MBH of 1.4e4 Msun/Mpc^3 implied for z>5. When lower-z AGN contribution considered, the value reduces by a half. Black holes are rare in high-z galaxies, because need rapid accretion given the observations already in place at z>7, and the strict upper limit on the accreted mass derived from X-ray BG. Or, accretion is efficient only for BH hosted by rare galaxies.
1209.1104
Accumulated tidal heating of stars over multiple pericenter passages near SgrA*
Li, Loeb
Tidal heating of stars at pericenter passage around SMBH can cause the star to disrupt 7-10 times the distance farther than the standard tidal disruption radius.
1209.1175
Jet interactions with a giant molecular cloud in the Galactic centre and ejection of hypervelocity stars
Silk, et al
Hypervelocity OB stars in MW were generated by the interactions of an AGN jet from the central BH with a dense molecular cloud. Broader implications for the possible origin of the Fermi bubbles and enrichment of the IGM.
1209.1200
An ultra fast image generator (UFig) for wide-field astronomy
Berge, Gamper, Refregier, Amara
Simulated wide-field images: want fast computation. Models of galaxies/stars and observational conditions, and state-of-the-art computational and implementation optimizations. 30 seconds on a laptop gives 0.25 degsq simulated image.
1209.1234
Clear sky fraction above Indonesia: an analysis for astronomical site selection
Hidayat et al
As the title says.
1209.1320
Effects of dynamical evolution of giant planets on survival of terrestrial planets
Matsumura, Ida, Nagasawa
Many terrestrial planet systems may not have additional planets on the "stable" orbits since past dynamical instability among giant planets could have removed them.
1209.1354
Discovery of an active supermassive black hole in the bulge-less galaxy NGC 4561
Salvo et al
Discovered by hard X-ray detection. Presence of SMBH at the center of the bulge-less galaxy shows that BH masses are not necessarily related to bulge properties.
1209.0759
The milky way's circular velocity curve between 4 and 14 kpc from APOGEE data
Bovy et al
Find MW's DM mass within the virial radius is 8e11 Msun, circular velocity at local is 218 pm 6 km/s, rotation curve approximately flat.
1209.0765
Episodic accretion, protostellar radiative feedback, and their role in low-mass star formation
Stamatellos, Whitworth, Hubber
Episodic accretion moderates the effect of radiative feedback from young protostars on their environments, and under some conditions allows the formation of low-mass stars, brown dwarfs, and planetary-mass objects by fragmentation of protostellar discs.
1209.0767
The low mass end of the fundamental relation for gravitationally lensed star forming galaxies at 1<z<6
Christensen et al
13 SL'ed galaxies at 1<z<6 of 1e7-11 Msun mass used to probe fundamental relations; those with <1e10 Msun have large scatter compared to the fundamental relation for low-mass, low-metallicity galaxies with a weaker dependence of the metallicity on either the SFR or stellar mass compared to low-mredshift, high-mass and high-metallicity SDSS galaxies.
1209.0771
Galaxy gas fractions at high-redshift: the tension between observations and cosmological simulations
Narayanan, Bothwell, Dave
z=1~4 galaxies have baryonic gas fraction significantly higher than galaxies at z=0, with values ranging from 20-80%, based on CO measurements. Suggest here that gas fractions inferred from observation of SF galaxies at high-z are overestimated, owing to the adoption of locally-calibrated CO-H2 conversion factors, Xco. Xco is lower than z=0 value; now we have better agreement with simulations.
1209.0775
Gravitationally lensed galaxies at 2<z<3.5: direct abundance measurements of Lya emitters
Christensen et al
3 galaxies at high z, observed in medium resolution spectroscopy. Have 10% solar oxygen abundances; C and N sub-solar. 2 are Lya emitters with EW of 60 and 80 A. Accurately reproduce the line profiles with radiative transfer models; show relatively small outflow.
1209.0778
Star formation rate distributions: inadequacy of the Schechter function
Salim, Lee
Optical and NIR LFs are well fit by Schechter function (power law with exponential cutoff at bright end). LFs of SFR (objects whose luminosity traces SFR) are different, shallow decline at the bright end due to large intrinsic scatter of SFRs at any given stellar mass: best described by "Saunders" function (power law with Gaussian at high end). Schechter-like appearances of UV and Halpha LFs (i.e., of the SFR type) is due to not correcting for dust, etc., i.e., systematics. So, the FIR non-schechter form observed is probably a true form, instead of the purported artifact of AGN contamination.
1209.0780
Convolution Lagrangian perturbation theory for biased tracers
Carlson, Reid, White
Accurate predictions of real- and redshift-space correlation functions of the mass field and DM haloes, with new formulation of Lagrangian perturbation theory. From Matsubara (2008). Naturally recover the Zel'dovich approximation as the lowest order of expansion for matter correlation function; includes NL bias and explains strong bias-dependence of the multiple moments of the z-space correlation function seen in N-body sims.
1209.0782
Evolution along the sequence of S0 Hubble types induced by dry minor mergers. I - Global bulge-to-disk structural relations
Eliche-Moral et al
Dry intermediate and minor mergers can induce global structural evolution within the sequence of S0 Hubble types (based on collision-less N-body simulations).
1209.0825
Is the primordial IMF controlled by dark matter haloes?
de Souza et al
Study statistical properties (shape, spin) of high-z (11<z<16) haloes hosting the first (Pop III) stars with cosmological simulations including detailed gas physics. <sphericity>=0.3; >90% haloes have triaxiality parameter T<0.4 (more oblate than prolate). But large haloes in sims more spherical and prolate. Spin distribution of DM and gas considerably different at z=16 (baryons slower than DM). At low z, spin distributions of DM and gas track each other well. Spin of both gas and DM follows a lognormal distribution. With two feedback models and mapping halo-spin distribution into a PopIII IMF; find high-z the IMF closely tracks the spin lognormal distribution. Depending on feedback model, distribution can be centered at 65 Msun or 140 Msun. Some develop into bimodal distribution (second peak at 40 Msun); result of NL relation of rotation and halo mass. DM halo properties might be a key factor shaping the IMF of the first stars.
1209.0961
Magnetic field amplification associated with the Richtmyer-Meshkov instability
Sano, et al
Amplification of B-field due to RMI in 2d MHD sims. Ambient B-field stretched by fluid motions associated with RMI; strength is amplified by >100x. Saturation level of field determined by balance between amplified B pressure and thermal pressure after shock passage. Results suggest RMI could be a robust mechanism of the amplification of interstellar B-fields and cause the localized strong fields observed at the shock of SNe remnants.
1209.0972
Plunging fireworks: why do infalling galaxies light up on the outskirts of clusters?
Mahajan, et al
Some clusters have enhanced SFR in galaxies on the cluster outskirts. These clusters tend to be unrelaxed clusters currently being assembled via galaxies falling in through stright filaments, resulting in high velocity dispersions. These clusters have higher overall SFR in the clusters compared to the other type of clusters (i.e., no enhanced SFR at outskirts). The comparison galaxies are more likely to be fed by relatively low density filaments. Find: starburst galaxies on the periphery of clusters are in a environment of higher local density than other cluster galaxies at similar radial distances from the cluster center. Conclude: relatively high galaxy density in the infalling regions of cluster promotes interactions amongst galaxies, leading to momentary bursts of SF. Such interactions play a crucial role in exhausting the fuel for SF in a galaxy, before it is expelled due to the environmental processes that are operational in the dense interiors of the cluster.
1209.1043
Measuring neutrino masses with a future galaxy survey
Hamann, Hannestad, Wong
Detailed forecast on how well a Euclid-like photmetric galaxy and cosmic shear survey will be able to constrain the absolute neutrino mass scale. Can detect Sum m_nu ~ 0.06 eV with 2.5 sigma significance; with better knowledge of galaxy bias, significance can be ~5.6 sigma. Need galaxy and cosmic shear power spectrum both to break the degeneracies between neutrino mass, Omega_m, and H0. Euclid-like obs. is not sensitive to the exact mass spectrum of the neutrino sector; no significant bias (<1 sigma) in the parameter estimation is induced by fitting inaccurate models of the neutrino mass splittings to the mock data, nor does the goodness-of-fit of these models suffer any significant degradation relative to the true one (Delta chi_eff^2 < 1).
1209.1094
The unchanging circumgalactic medium over the pst 11 billion years
Chen
Between z~2.2 and 0, the spatial extent and mean absorption equivalent width of the CGM around galaxies of comparable mass have changed little over this time interval.
1209.1095
Limits on the high redshift growth of massive black holes
Salvaterra et al
Place firm upper limits on global accretion history of MBH at z>5 from the unresolved fraction of cosmic X-ray background. From maximum allowed unresolved intensity observed at 1.5 keV, a maximum accreted-mass density onto MBH of 1.4e4 Msun/Mpc^3 implied for z>5. When lower-z AGN contribution considered, the value reduces by a half. Black holes are rare in high-z galaxies, because need rapid accretion given the observations already in place at z>7, and the strict upper limit on the accreted mass derived from X-ray BG. Or, accretion is efficient only for BH hosted by rare galaxies.
1209.1104
Accumulated tidal heating of stars over multiple pericenter passages near SgrA*
Li, Loeb
Tidal heating of stars at pericenter passage around SMBH can cause the star to disrupt 7-10 times the distance farther than the standard tidal disruption radius.
1209.1175
Jet interactions with a giant molecular cloud in the Galactic centre and ejection of hypervelocity stars
Silk, et al
Hypervelocity OB stars in MW were generated by the interactions of an AGN jet from the central BH with a dense molecular cloud. Broader implications for the possible origin of the Fermi bubbles and enrichment of the IGM.
1209.1200
An ultra fast image generator (UFig) for wide-field astronomy
Berge, Gamper, Refregier, Amara
Simulated wide-field images: want fast computation. Models of galaxies/stars and observational conditions, and state-of-the-art computational and implementation optimizations. 30 seconds on a laptop gives 0.25 degsq simulated image.
1209.1234
Clear sky fraction above Indonesia: an analysis for astronomical site selection
Hidayat et al
As the title says.
1209.1320
Effects of dynamical evolution of giant planets on survival of terrestrial planets
Matsumura, Ida, Nagasawa
Many terrestrial planet systems may not have additional planets on the "stable" orbits since past dynamical instability among giant planets could have removed them.
1209.1354
Discovery of an active supermassive black hole in the bulge-less galaxy NGC 4561
Salvo et al
Discovered by hard X-ray detection. Presence of SMBH at the center of the bulge-less galaxy shows that BH masses are not necessarily related to bulge properties.
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