Thursday. Missed reading yesterday. Back from hiking, exhausted.
1209.0225
Galaxy clusters as reservoirs of heavy dark matter and high energy cosmic rays: constraints from neutrino observations
Murase, Beacom
Expect (with DM self-annihilation) enhancement of DM clustering sources of gamma rays and neutrinos. Hadronic CR interactions can also lead to high luminosity in gamma rays and neutrinos, enhanced from cluster accretion/merger shocks and AGN. IceCube/KM3Net can separate DM and CR emission processes. Neutrino processes important at high energy (>10TeV). Include gamma-ray results, can lead to comparable constraints.
1209.0247
CMB photons shedding light on dark matter
Giesen, Lesgourgues, Audren, Ali-Haimoud
The annihilation or decay of DM particles could affect the thermal history of the universe and leave an observable signature in CMB anisotropies. Update constraints on the annihilation rate of DM particles on the smooth cosmological background. Also show DM annihilation in halos at small redshift may explain entirely the reionization patterns observed in the CMB. Mixed reionization models with DM annihilation in halos as well as SF at z~6.5 could simultaneously account for CMB observations and satisfy constraints inferred from the Gunn-Peterson effect. But these models tend to reheat the IGM well above observational bounds. Use IGM temperature at low-z as prior; find stronger bounds on the annihilation cross-section of DM.
1209.0256
The gravitational potential near the sun from SEGUE K-dwarf kinematics
Zhang, Rix, van de Ven, Bovy, Liu, Zhao
Constrain the potential ~1.5kpc from the sun; derive and model the spatial and velocity distribution for a sample of 9000 K-dwarfs with spectra that yields radial velocities and abundances ([Fe/H] and [alpha/Fe]). Derive spatial density distribution: vertical profile are exponentials, profile nearly isothermal. Disk scale height < 300pc, total surface mass density 67 Msun/pc^2 (42 at |z|=1.0 kpc, with contribution of 13 from cold gas). Local DM density 0.0065 Msun/pc^3; consistent with global fits of approximately round DM haloes to kinematic data in the outskirts of the galaxy.
1209.0272
The GALEX ultraviolet virgo cluster survey (GUViCS). II. Constraints on star formation in ram-pressure stripped gas
Boisser et al
Find: level of SF in gas stripped from galaxies by ram-pressure is low wrt the available amount of gas; SF low by at least 10x compared to Schmidt Law as determined in regular spiral galaxy disks. Also lower than measured in dwarfs.
1209.0306
The opacity of spiral galaxy disks IX; dust and gas surface densities
Holwerda et al
Opacity does not correlate will with HI or H2 alone, implying that dust is not only associated with molecular clouds, but also the diffuse atomic disk in these disk galaxies. Typical dust-to-gas ratio of 0.04 (high compared to other measurements, but consistent with metallicity at measured radii), ratio declines with galactocentric radius.
1209.0225
Galaxy clusters as reservoirs of heavy dark matter and high energy cosmic rays: constraints from neutrino observations
Murase, Beacom
Expect (with DM self-annihilation) enhancement of DM clustering sources of gamma rays and neutrinos. Hadronic CR interactions can also lead to high luminosity in gamma rays and neutrinos, enhanced from cluster accretion/merger shocks and AGN. IceCube/KM3Net can separate DM and CR emission processes. Neutrino processes important at high energy (>10TeV). Include gamma-ray results, can lead to comparable constraints.
1209.0247
CMB photons shedding light on dark matter
Giesen, Lesgourgues, Audren, Ali-Haimoud
The annihilation or decay of DM particles could affect the thermal history of the universe and leave an observable signature in CMB anisotropies. Update constraints on the annihilation rate of DM particles on the smooth cosmological background. Also show DM annihilation in halos at small redshift may explain entirely the reionization patterns observed in the CMB. Mixed reionization models with DM annihilation in halos as well as SF at z~6.5 could simultaneously account for CMB observations and satisfy constraints inferred from the Gunn-Peterson effect. But these models tend to reheat the IGM well above observational bounds. Use IGM temperature at low-z as prior; find stronger bounds on the annihilation cross-section of DM.
1209.0256
The gravitational potential near the sun from SEGUE K-dwarf kinematics
Zhang, Rix, van de Ven, Bovy, Liu, Zhao
Constrain the potential ~1.5kpc from the sun; derive and model the spatial and velocity distribution for a sample of 9000 K-dwarfs with spectra that yields radial velocities and abundances ([Fe/H] and [alpha/Fe]). Derive spatial density distribution: vertical profile are exponentials, profile nearly isothermal. Disk scale height < 300pc, total surface mass density 67 Msun/pc^2 (42 at |z|=1.0 kpc, with contribution of 13 from cold gas). Local DM density 0.0065 Msun/pc^3; consistent with global fits of approximately round DM haloes to kinematic data in the outskirts of the galaxy.
1209.0272
The GALEX ultraviolet virgo cluster survey (GUViCS). II. Constraints on star formation in ram-pressure stripped gas
Boisser et al
Find: level of SF in gas stripped from galaxies by ram-pressure is low wrt the available amount of gas; SF low by at least 10x compared to Schmidt Law as determined in regular spiral galaxy disks. Also lower than measured in dwarfs.
1209.0306
The opacity of spiral galaxy disks IX; dust and gas surface densities
Holwerda et al
Opacity does not correlate will with HI or H2 alone, implying that dust is not only associated with molecular clouds, but also the diffuse atomic disk in these disk galaxies. Typical dust-to-gas ratio of 0.04 (high compared to other measurements, but consistent with metallicity at measured radii), ratio declines with galactocentric radius.
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