1203.1330
The WISE gamma-ray strip parameterization: the nature of the gamma-ray AGN of uncertain type
Massaro, et al
Origins of "unidentified gamma-ray sources" remain unknown. Find that, 54 out of 60 Fermi's "AGN of uncertain types (AGUs)" have IR colors consistent with "WISE gamma-ray strip"--i.e., blazars. 90% of AGUs from Fermi are blazar candidates.
1203.1334
Deep Chandra x-ray imaging of nearby radio galaxy 4C+29.30: X-ray/radio connection
Siemiginowska, et al
Chandra observations of z=0.0647 radio galaxy, structures on sub-arcsec/arcsec scales; nucleus, jet, hotspots, and lobes detected. Nucleus has strong absorption (1e23 atoms/cm^2 of H), unabsorbed luminosity (2-10 keV) 5e43 erg/s; type 2 AGN. Soft (<2keV) emission traces ISM, correlated with radio structures along the main radio axis. X-ray emission beyond radio source correlates with the morphology of optical line-emitting regions. ISM at 0.5 keV, slightly higher at the center, and around radio hotspots. If region heated by shocks, then Mach number is 1.6. Thermal pressure of x-ray gas suggest hot ISM is slightly under-pressured wrt the cold optical-line emitting gas and radio-emitting plasma (both seem to be in a rough pressure equilibrium). Complex system: jet-driven radio outflow, feedback processes closely associated with the central active nucleus.
1203.1342
Models of accretion disks
Siemiginowska
Accretion flow onto a SMBH: primary process powering quasars, but geometry of the flow not well constrained. Several emission components present in the nucleus: accretion disk, hot plasma (corona or sphere) with electrons scattering the optical and UV photons, and an outflow (wind/jet). Relative location and size of these emission and their interaction affect the quasar spectrum. Briefly review standard accretion disk models and recent progress.
1203.1343
The flying spaghetti monster: impact of magnetic fields on ram pressure stripping in disk galaxies
Ruszkowski, Bruggen, Lee, Shin
* ram pressure: pressure exerted on a body which is moving through a fluid medium. Causes a strong drag force on the body: P= rho v^2. Also applicable to stationary body, flowing fluid.
Ram pressure stripping can remove significant amounts of gas from galaxies in clusters; has a large impact on the evolution of cluster galaxies. Simulate disk galaxy exposed face-on to a uniformly magnetized wind including radiative cooling and self-gravity of the gas. Find: magnetic fields have a strong effect on the morphology of the gas in the tail of the galaxy. Purely hydrodynamic case: tail is very clumpy. MHD case: filamentary structures in the tail. Filaments strongly supported by magnetic pressure; B-fields tend to be aligned with the filaments. Observe formation of two dominant magnetized density tails behind the galaxy resembling the double tail, observed in ESO 137-001. In the sim, the double tail results from the folding of the ambient B-field around the galaxy. Detectability of such structures depends on the time since the beginning of the stripping process, the length scale of the B-field fluctuations in the ICM, the orientation of the galaxy wrt the LoS, and the relative emissivities of the tail and ambient ICM. B-field affect the tail morphology, but magnetic draping does not suppress the rate of gas stripping; in fact, B-field may enhance it. In combination with the buildup of the magnetic pressure in front of the galaxy, this undoes the protective effect of this layer and allows the gas to leak out of the galaxy.
1203.1344
Timing properties of gamma-ray bursts detected by SPI-ACS detector on board of INTEGRAL
Savchenko, Neronov, Courvoisier
Compare INTEGRAL GRB detection with BATSE. ~1500 GRB-like events in 10 years. Peak of distribution of Long GRBs are ~20s, somewhat shorter than BATSE. Unlike BATSE, the short GRBs do not have a characteristic time scale, but is a power law down to the detection resolution (<50 ms). Large fraction of long GRBs have a characteristic variability timescale of 1s.
1203.1356
Co-evolution of galaxies and central BHs: observational evidence on the trigger of AGN feedback
Matsuoka
Comprehensive analysis of extended emission line region (EELR) around quasars, based on 81 EELR for type-1 and type-2 quasars with associated with AGN and host galaxy properties. AGN emission principle component 1 linked to Eddington ratio [direct or inverse relation?!?]; EELR is preferentially associated with gas-rich, massive blue galaxies, supporting the idea that the primary determinant of EELR creation is the gas availability, and that the gas may be brought in by galaxy merger triggering the current SF as well as AGN activity, and also give an explanation for the fact that most luminous EELR is found around radio-loud sources with low Eddington ratio. EELR quasars occupy the massive blue corner of the green valley, the AGN realm, on the galaxy color-stellar mass diagram. Once a galaxy is pushed to this corner, activated AGN would create EELR by the energy injection into the interstellar gas and eventually blow it away, leading to SF quenching. The results presented here provide a piece of evidence for the presence of such AGN feedback process, which may be playing a leading role in the co-evolution of galaxies and SMBHs.
* this abstract doesn't clearly state the physical processes; only names the associations. This is a frustrating abstract to read (because I don't want to have to read the paper!).
1203.1379
Multimessenger astronomy and astrophysics synergies
van Putten (Maurice!), Rossi (Graziano...)
Propose to include the multi messenger dimension (EM, hadronic and gravitational radiation) in the ranking of proposals submitted under existing NSF programs.
1203.1388
Are planetary nebulae derived from multiple evolutionary scenarios?
Frew, Parker
PNs more heterogeneous than previously understood; a surprising diversity in the population of PNe and their central stars exist. Stellar evolution theory and population synthesis models must be confronted with local PNe census.
1203.1473
Abell 1758N from an optical point of view: new insights on a merging cluster with diffuse radio emission
Boschin, Girardi, Barrena, Nonino
Abell 1758N hosts a radio halo and two relics; is a merging bimodal cluster. Analysis based on new redshift data for 137 galaxies (4 previously known). Photometric data from SDSS and CFHT. Combine galaxy velocities and positions to select 92 cluster galaxies and analyze the internal cluster dynamics. Cluster redshift z=0.2782; LoS velocity dispersion of 1300 km/s. Two sub clusters cannot be separated in the velocity analysis; small LOS velocity difference of 300 km/s in the cluster rest-frame. Velocity info shows: A1758N is surrounded by two small groups and active galaxies infalling onto, or escaping from, the cluster. Remove the two groups, estimate 1000 km/s and 800 km/s for velocity dispersion for NW and SE. Very massive clutter with a range of 2-3e15 Msun. A1758N is a major cluster merger just forming a massive system.
1203.1519
Probabilistic positional association of astrophysical sources between catalogs
Fioc
Describe a simple probabilistic method to cross-identify astrophysical sources from different catalogs and provide the probability that a source is associated with a source from another catalog, or that it has no counterpart.
* This seems important to understand, but it's also really hard to read an all-equation paper...
1203.1529
Hot-star models from 100 to 10000 Angstroms
Leitherer
Spectral libraries of hot, massive stars are challenging: they are rare, have an intense radiation field and strong stellar winds, and a luminosity bias towards UV wavelengths. These properties require the utilization of theoretical libraries. Starburst 99: static non-LTE models in optical, specially extended, expanding models; blanketed, low-resolution radiation-hydrodynamical models in the UV to X-ray.
1203.1545
Statistical and systematic errors in redshift-space distortion measurements from large surveys
Bianchi, et al
Statistical and systematic errors on linear redshift-space distortions in cosmological surveys, using large catalogues of DM haloes from BASICC simulation. Estimate dependence of errors on typical survey properties, such as volume, galaxy density, and mass (bias factor) of the adopted tracer. Beta estimated from harmonic expansion of xi on scales >3Mpc are typically under-estimated by up to 10% for galaxy-sized haloes---significantly larger than the corresponding statistical errors (a few percent). Important to improve non-linear Kaiser model to obtain accurate measurement of growth rate. Compare statistical errors to predictions from Fisher matrix; parameter errors generated are similar to the std deviations from the halo catalogues, but only if applied to strictly linear scales in Fourier space (<0.2 h/Mpc).
* the abstract doesn't say what observation parameters are assumed.
1203.1559
Molecules in eta Carinae
Loinard et al
* Homunculus ("little man") nebula: Light from an ejection event arrived Earth in 1841 ("Great Eruption"), at which point it became the 2nd brightest star in the sky after Sirius, but ejected gas and dust have since obscured much of its light. The massive (near SNe) explosion produced two polar lobes and a large but thin equatorial disk, all moving outward at 670 km/s. 7.5 ly away. Apparently there is relatively little dust-debris between the lobes, as most of the blue light is able to escape. However, the lobes contain large amounts of dust, causing the lobes to appear reddish. A binary star system.
Detection of CO, CN, HCO+, HCN, HNC, and N2H+ molecules toward eta Carinae, as well as 13Co and H13CN. Line profiles moderately broad (100km/s): emission originates in the fence, possibly clumpy, central arc second of the Homunculus Nebula. Molecules containing N and 13C isotope are overabundant by one order of magnitude. Mulecules detected here must have formed in situ out of CNO-processed stellar material.
1203.1626
Characterizing CR-propagation in a massive star-forming regions: the case of 30 Doradus and the LMC
Murphy et al
* 30 Doradus (Tarantula Nebula): a bright H II region in LMC; apparent magnitude of 8; distance of 49 kpc; estimated diameter 200pc; most active starburst region known in the local group of galaxies. At leading edge of LMC: ram pressure stripping and compression of ISM is at maximum at this location. Compact star cluster R136 lies within. Estimated mass of the cluster is 4.5e5 Msun, probably will become a globular cluster in the future. SN 1987A was observed in the outskirts of this nebula.
Investigate CR electron and nuclei in the 30 Doradus region using a phenomenological model based on the radio-far-IR correlation within galaxies. Average propagation length of ~100-140 pc for ~3 GeV CR electrons resident in 30 Dor. If observed gamma-ray emission is associated with the SF region, estimate a ~20GeV propagation length of 200-320 pc for the CR nuclei. In agreement with the results found by extending the correlation analysis to include ~70 GeV CR nuclei traced by the 3-10 GeV gamma-ray data. Use mean age of stellar populations in 30 Dor and the results from correlation analysis, estimate diffusion coefficient ~1d27 (R/GV)^0.8 cm^2/s. Compare values of CR electron propagation length and surface brightness for 30 Dor and the LMC; find that the trend of decreasing average CR propagation distance with increasing disk-averaged star formation activity holds for the LMC, and extends down to single SF regions for 30 Dor.
1203.1627
X-ray spectral curvature of high frequency peaked BL Lacs: a predictor for the TeV flux
Massaro, Paggi, Elvis, Cavaliere
* BL Lac objects: a type of AGN, characterized by rapid and large-amplitude flux variability and significant optical polarization. Compared to more luminous quasars with strong emission lines, BL Lac objects have spectra dominated by a featureless non-themral continuum. Interpreted as being due to the effects of the relativistic jet that is closely aligned to the LoS; believed to be intrinsically identical to low-power radio galaxies. Hosted in massive spheroidal galaxies; are a blazer subtype; core-dominated radio sources.
Most of the extragalactic sources detected at TeV energies are BL Lac objects. They belong to the subclass of "high frequency peaked BL Lacs" (HBLs) exhibiting spectral energy distributions with a lower energy peak in the X-ray band; this is widely interpreted as synchrotron emission from relativistic electrons. The X-ray spectra are generally curved, and well described in terms of a log-parabolic shape. Found two corrections in TeV HBLs: (1) the synchrotron peak luminosity L_p increases with its peak energy E_p; (2) the curvature parameter b decreases as E_p increases. The first is consistent with the synchrotron scenario, while the second is expected from statistical/stochastic acceleration mechanisms for the emitting electrons. Present an x-ray analysis of a sample of HBLs observed with XMM-Newton and SWIFT but undetected at TeV energies (UBLs), to compare their spectral behavior with TBLs. Develop a criterion to select the best HBL candidates for future TeV observations.
1203.1628
Force-feeding BHs
Begelman
Growth of SMBH associated mainly with brief episodes of highly super-Eddington infall of gas ("hyper accretion"), which is not immediately swallowed, but forms an envelope of matter around the BH that can be swallowed gradually, over a much longer timescale. Only a small fraction of the BH mass can be stored in the envelope at any one time. Any infalling matter above a few % of the hole's mass is ejected as a result of the plunge in opacity at temperatures below a few thousand degrees K, corresponding to the Hayashi track. The speed of ejection of this matter, compared to the velocity dispersion of the host galaxy's core, determines whether the ejected matter is lost or returns to the envelope. The threshold between matter recycling and permanent loss defines a relationship between the maximum BH mass and sigma that resembles the empirical M_BH-sigma relation.
* theory on the origin of M_BH-sigma relation.
1203.1637
Diffusive shock acceleration and B-field amplification
Schure, Bell, Drury, Bykov
Diffusive shock acceleration: theory of particle acceleration through multiple shock crossings. In order for this process to proceed at a rate that can be reconciled with observations of high-energy electrons in the vicinity of the shock, and for CR protons to be accelerated to energies up to observed galactic values, significant B-field amplification is required. Discuss various theory on how B-field amplification can proceed in the presence of CR population. On both long and short scales, CR streaming can induce instabilities that act to amplify the B-field. Developments in this area that have occurred over the past decade are the main focus of this paper.
1203.1641
Exploring the unusually high BH-to-bulge mass rations in NGC4342 and NGC 4291: the asynchronous growth of bulges and BHs
Bogdan, et al
Two nearby early-type galaxies. The observed BH-to-bulge mass ratios are 7% and 2%, respectively, which significantly exceed the typical observed ratio of 0.2% (5 sigma and 3 sigma outliers from the M_BH-M_bulge relation). Origin of the unusually high ratio: Based on hot gas content, compute gravitating mass profiles, and conclude that both galaxies reside in massive DM haloes, which extend well beyond the stellar light. The presence of DM haloes and a deep optical mage of the environment of 4342 indicate that tidal stripping, in which >90% of the stellar mass was lost, cannot explain the observed high BH-to-bulge mass ratios. Conclude that these galaxies formed with low stellar masses, implying that the bulge and BH did not grow in tandem. Also find that the BH mass correlates well with the properties of the DM halo, suggesting that DM haloes may play a major role in regulating the growth of SMBH.
1203.1642
Chandra observations of NGC4342, an optically faint, X-ray gas-rich early-type galaxy
Bogdan, et al
Low stellar mass (M_K--22.8 mag) early type galaxy show luminous, diffuse x-ray emission from hot gas with T~0.56 keV. Hot gas as a significantly broader distribution than stellar light, show strong disturbances. A cold-front edge; morphology comes from ram-pressure. From the thermal pressure ratios inside and outside the cold front, estimate the velocity of 4342 and find that it moves spersonically (M~2.6). Resolve 8 bright point sources within the D_25 ellipse, most of them being low-mass x-ray binaries, located in the center of 4342, associate it with the SMBH of 4342. Outside the optical extent of the galaxy, detect 17 luminous excess x-ray sources, origin uncertain, but possibly LMXBs located in metal-oor globular clusters in the extended DM halo of 4342. Based on the number of excess sources, estimate that 4342 may host roughly 1k globular clusters.
[ in Milky Way, 152 globular clusters discovered ]
1203.1651
The advanced camera for surveys general catalog: structural parameters for approximately half a million galaxies
Griffith, Cooper, Newman, Moustakas, Stern, Comerford, Davids, ... Capak, Faber, ..Koekemoer, Koo, Noeske, Scoville, Sheth,... et al
ACS-GC: a photometric and morphological database using publicly available data obtained with HST/ACS. Provide large statistical sample of galaxies with reliable structural and distance measurements to probe the evolution of galaxies over a wide range of look-back times. ACS-GC includes 490l astronomical sources (stars + galaxies) from AEGIS, COSMOS, GEMS and GOODS surveys. Photometric (SExtractor) and morphological (Galfit) catalogs. Assume a single Sersic model for each object to derive quantitative structural parameters. Include publicly available redshift from DEEP2, COMBO-17, TKRS, PEARS, ACES, CFHTLS, and zCOSMOS (spectro- and photometric) for 71% of the imaging sample. Includes color postage stamps, Galfit residual images, and photometry, structural parameters, and redshifts combined into a single catalog.
1203.1664
Data and 2d scaling relations for galaxies in Abell 1689: a hint of size evolution at z~0.2
Houghton, Davies, Bonta, Masters
* Kormendy relation: correlation in an elliptical galaxy of the half-light radius to the surface brightness at that radius.
* Faber-Jackson relation: Early empirical power law relation between the luminosity L and the central stellar velocity dispersion sigma of elliptical galaxies: L propto sigma^4
Imaging and spectroscopy of Abell1689 (z=0.183) from GEMINI and HST. GMOS g and r (531 galaxies), HST F625W (43 galaxies), and GMOS spectra (71 galaxies). Construct Kormendy relation, FJ relation, and color-mag relation for early-type galaxies; compare with Coma cluster. Intrinsic scatter of CMR in 1689 is 0.05 mag (degenerate constraints on the ratio of the assembly timescale to the time available, "beta", and the age of the population). Assume that galaxies in abell1689 will evolve into those of Coma over an interval of 2.26 Gyr breaks this degeneracy and limits beta to be >0.6 and the age of the red sequence to be >5.5 Gyr (formed at z>0.55). Without corrections for size evolution but accounting for magnitude cuts and selection effects, the eKR & FJR are inconsistent and diagree at the 2 sigma level, regarding the amount of luminosity evolution in the last 2.26 Gyr. However, after correcting for size evolution the KR&FJR show similar changes in luminosity that are consistent with passive evolution of the stellar populations from a single burst of SF 10Gyr ago (z=1.8 with large error). Thus the changes n the KR, FJR & CMR of Abell1689 relative to Coma all agree and suggest old galaxy populations with little or no synchronization in the SF histories. Weak evidence for size evolution in the cluster environment in the last 2.26 Gyr places interesting constraints on the possible mechanisms at work, favoring harassment or secular processes over merger scenarios.
1203.1668
SFR indicators in wide-field IR survey preliminary release
Shi, Kong, Wicker, Chen, Gong, Xin, Fan
Analyze 3.4, 4.6, 12 and 22 um data in a sample of 140k SF galaxies or SF regions covering a wide range in metallicity 7.66 < 12+ log(O/H) < 9.46, with redshift z<0.4. Study relationship between the IR luminosities, and Halpha luminosity in SDSS DR8; derive reference SFR indicators. Find linear relation; dispersion in the SFR-IR luminosity relation relates to galaxy's properties (4000A break, galaxy color).
1203.1679
A Spitzer study of interacting luminous and ultra-luinous IR galaxies
Leao, Leitherer
Spitzer survey of 28 LIRGS and ULIRGS: many of these galaxies are found in pairs or associations, and are powered either by nuclear activity or SF. Main goal: understand the relative importance of starbursts and AGNs in interacting systems. Compare IR data with optical-only.
1203.1693
Do bars trigger activity in galactic nuclei?
Lee, Woo, Lee, Hwang, Lee, Sohn, Lee
Connection of bars and AGN activity, with 9k late-tupe galaxies with b/a>0.6 and Mr<-19.5+5 log h at low z (0.02<z<0.055) from SDSS DR7. Bar fraction in AGN-host galaxies is 42%, 2.5x higher than non-AGN galaxies (15.6%); AGN fraction is a factor of two higher in strong-barred galaxies (35%) than in non-barred galaxies (15%). These trends simply caused by AGN-host galaxies are on average more massive and redder than non-AGN galaxies, because the fraction of stron-barred galaxies increases with u-r color and stellar velocity dispersion. When U-r color and velocity dispersion (or stellar mass) are fixed, bot the strong-bar excess in AGN-host galaxies and the enhanced AGN fraction in strong-barred galaxies disappears. Among AGN-host galaxies, find no strong difference of the Eddington ratio distributions between barred and non-barred systems. Results indicate that AGN activity is not dominated by the presence of bars, and that AGN power is not enhanced by bars. Conclusion: no clear evidence that bars trigger AGN activity.
1203.1695
PkANN I: on-linear matter power spectrum estimation through artificial neural networks (ANN)
Agarwal, Abdalla, Feldman, Lahav, Thomas
Show that an optimally trained ANN, when presented with a set of cosmo parameters, can provide a worst case accuracy fit to the non-linear power spectrum deduced through N-body simulations, for modes up to k<0.7 h/Mpc. Power spectrum predictor is accurate over the entire parameter space for z<2; a significant improvement over some of the current matter power spectrum calculators. Detail how an accurate prediction of matter power spectrum is achievable with only a sparkly sampled grid of cosmological parameters. A well-trained ANN can be an extremely quick and reliable tool in interpreting cosmological observations and parameter estimation. This is paper I: generate NL P(k) using halo fit and use them as mock observations to train ANN. In Paper II, a suite of N-body simulations will be used to compute the NL P(k) at sub percent accuracy, in the quasi NL regimes (0.1 < k < 0.9 h/Mpc) for redshifts between z=0 and 2.
1203.1800
Filaments and sheets of the warm-hot intergalactic medium
Klar, Mücket
Filaments are not only supposed to host the majority of the baryons at low redshifts in the form of WHIM, but also to supply forming galaxies at higher redshifts with a substantial amount of cold gas via cold streams. Hydrosim to investigate hydrodynamics and thermodynamics of filaments (and sheets and haloes). State and evolution of gas inside filament: for L>4Mpc, filaments fully confined by an accretion shock; exhibit isothermal core, temperature balanced by radiative cooling and heating due to UV background; a multiphase structure for the medium temperature WHIM. Obtain scaling relations for the main quantities of this core. In the vicinity of the halo, the filament's core can be attributed to the cold streams found in cosmological hydro-sims. Thermal conduction can lead to a complete evaporation of the cold stream for L>6 Mpc/h, corresponding to halos more massive than M_h = 1e13 Msun, and implies that SF in more massive galaxies can not be supplied by cold streams. For perturbations on scales L>6Mpc/h, the filament no longer exhibit a cold core.
1203.1825
Measuring the redshift dependence of the CMB monopole temperature with PLANCK data
de Martino, Atrio-Barandela, da Silva, Ebeling, Kashlinsky, Kocevski, Martins
Study the power of PLANCK data to constrain deviations of the CMB BB temperature from adiabatic evolution using thermal SZ anisotropy induced by clusters of galaxies. Consider two types of data sets (cosmo signal removed from time-ordered information or from the final maps); and two different statistical estimators (ratio of T anisotropy at two different frequencies and on a fit to the spectral variation of the cluster signal with frequency). Demonstrate: using X-ray selected cluster catalog with measured redshifts, e- densities and x-ray temperatures, can constrain deviations of adiabatic evolution, measured by the parameter alpha in the redshift scaling T(z) = T_0 (1+x)^(1-alpha), with accuracy of sigma_alpha=0.011 in the most optimal case (0.016 for less optimal). Results represent a factor 2-3 improvement over similar measurements carried out using quasar spectral lines and a factor 6-20 with respect to earlier results using smaller cluster samples.
1203.1831
GALAPAGOS: from pixels to parameters
Barden Häußler, Peng, McIntosh, Guo
Software pipeline in IDL that combines SExtractor and Galfit.
1203.1840
Star formation activities in early-type brightest cluster galaxies
Liu, Mao, Meng
120 BCGs at 0.1<z<0.4 in two recent large cluster catalogues from SDSS, with strong Halpha and O II (3727) line emission, which indicates significant ongoing SF. Constitute about 0.5% of the largest, optically-seleted, low-redshift BCG sample; fraction a strong function of cluster richness. SFH well described by a recent minor and short starburst superimposed o an old stellar component, with the recent episode of SF contributing on average only less than 1% of the total stellar mass. Show that the more massive star forming BCGs in richer clusters tend to have higher SFR and sSFR (SFR/unit galaxy stellar mass). Compare statistical properties with Xray luminous clusters; show fraction of SF BCGs in x-ray luminous clusters is almost one order of magnitude larger than in optically-selected clusters [why?]. BCGs with SF in cooling flow clusters usually have very flat optical spectra and show the most active SF.
1203.1863
The degeneracy between star-formation parameters in dwarf galaxy simulations and the Mstar-Mhalo relation
Cloet-Osselaer, De Rijcke, Schroyen, Dury
N-body/SPH sims of isolated dwarf galaxies: SF, stellar feedback, radiative cooling and metal enrichment accounted. DM halo initially cuspy, but (starting from spherically symmetric initial conditions) a natural conversion to a core is observed due to gas dynamics and stellar feedback. A degeneracy between the efficiency : the ISM absorbing energy feedback from SNe and stellar winds on one hand, and the density threshold for SF on the other, is found. Perform a parameter survey to determine, with the aid of observed kinematic and photometric scaling relations, which combinations of these 2 parameters produce simulated galaxies that are in agreement with the observations. With the implemented physics, unable to reproduce the relation between the stellar mass and the halo mass as determined by Guo+ (2010), but do reproduce the slope of this relation.
* Rachel's 2006 paper referenced. I could probably use this for comparison with mine.
1203.1864
On the environment of short gamma-ray bursts
Kopac et al
11 short GRBs with robust z determined: measure x-ray absorbing column densities, collect data on the host galaxy offsets. Find evidence for intrinsic absorption and weak correlation between intrinsic absorbing column density and the projected offset of the GRB from its host galaxy center. Find properties in the gamma regime (T90, fluence and 1-s peak photon flux) of short GRBs with "bright" and "faint" x-ray afterglow disfavor different prompt emission mechanisms, and that the (normalized) host galaxy offset and GRB duration (T90) do not correlate significantly. Examine the existence of short-lived and long-lived X-ray afterglows in short GRBs and find that some short GRBs with short-lived X-ray afterglows have their optical afterglow detected. Suggests that the X-ray afterglow duration does not seem to be a unique indicator of a specific progenitor and /or environment for short GRBs.
1203.1877
Host fast BHs spin in quasars
Maio, Dotti, Petova, Perego, Volonteri
Explore the interaction between SMBH and their environment during active phases through simulations of circum-nuclear disks around BHs in quasars host in the remnants of galaxy mergers; explicitly include effects of SF, stellar winds, SNe feedback, and radiative transfer. Approach crucial to investigate the angular momentum of the material that is accreted by the hole. Find that maximally rotating BHs are slightly spun down, and slow-rotating holes are spun-up, leading to upper-intermediate equilibrium values of the spin parameter (0.7-0.9). Suggests: when quasar activity is driven by mergers of galaxies of similar sizes, stellar feedback does not induce strong chaos in the gas inflow, and that most SMBHs at the end of the quasar epoch have substantial spins.
1203.1919
The metal-enriched host of an energetic gamma-ray burst at z~1.6
Krühler, et al
GRB hosts are not necessarily metal-poor, based on IR observation of GRB host galaxy at z=1.6. High SFR (34 Msun/yr). GRB hosts could be fair tracers of the population of ordinary star-forming galaxies as a whole at z>1.
Characterizing CR-propagation in a massive star-forming regions: the case of 30 Doradus and the LMC
Murphy et al
* 30 Doradus (Tarantula Nebula): a bright H II region in LMC; apparent magnitude of 8; distance of 49 kpc; estimated diameter 200pc; most active starburst region known in the local group of galaxies. At leading edge of LMC: ram pressure stripping and compression of ISM is at maximum at this location. Compact star cluster R136 lies within. Estimated mass of the cluster is 4.5e5 Msun, probably will become a globular cluster in the future. SN 1987A was observed in the outskirts of this nebula.
Investigate CR electron and nuclei in the 30 Doradus region using a phenomenological model based on the radio-far-IR correlation within galaxies. Average propagation length of ~100-140 pc for ~3 GeV CR electrons resident in 30 Dor. If observed gamma-ray emission is associated with the SF region, estimate a ~20GeV propagation length of 200-320 pc for the CR nuclei. In agreement with the results found by extending the correlation analysis to include ~70 GeV CR nuclei traced by the 3-10 GeV gamma-ray data. Use mean age of stellar populations in 30 Dor and the results from correlation analysis, estimate diffusion coefficient ~1d27 (R/GV)^0.8 cm^2/s. Compare values of CR electron propagation length and surface brightness for 30 Dor and the LMC; find that the trend of decreasing average CR propagation distance with increasing disk-averaged star formation activity holds for the LMC, and extends down to single SF regions for 30 Dor.
1203.1627
X-ray spectral curvature of high frequency peaked BL Lacs: a predictor for the TeV flux
Massaro, Paggi, Elvis, Cavaliere
* BL Lac objects: a type of AGN, characterized by rapid and large-amplitude flux variability and significant optical polarization. Compared to more luminous quasars with strong emission lines, BL Lac objects have spectra dominated by a featureless non-themral continuum. Interpreted as being due to the effects of the relativistic jet that is closely aligned to the LoS; believed to be intrinsically identical to low-power radio galaxies. Hosted in massive spheroidal galaxies; are a blazer subtype; core-dominated radio sources.
Most of the extragalactic sources detected at TeV energies are BL Lac objects. They belong to the subclass of "high frequency peaked BL Lacs" (HBLs) exhibiting spectral energy distributions with a lower energy peak in the X-ray band; this is widely interpreted as synchrotron emission from relativistic electrons. The X-ray spectra are generally curved, and well described in terms of a log-parabolic shape. Found two corrections in TeV HBLs: (1) the synchrotron peak luminosity L_p increases with its peak energy E_p; (2) the curvature parameter b decreases as E_p increases. The first is consistent with the synchrotron scenario, while the second is expected from statistical/stochastic acceleration mechanisms for the emitting electrons. Present an x-ray analysis of a sample of HBLs observed with XMM-Newton and SWIFT but undetected at TeV energies (UBLs), to compare their spectral behavior with TBLs. Develop a criterion to select the best HBL candidates for future TeV observations.
1203.1628
Force-feeding BHs
Begelman
Growth of SMBH associated mainly with brief episodes of highly super-Eddington infall of gas ("hyper accretion"), which is not immediately swallowed, but forms an envelope of matter around the BH that can be swallowed gradually, over a much longer timescale. Only a small fraction of the BH mass can be stored in the envelope at any one time. Any infalling matter above a few % of the hole's mass is ejected as a result of the plunge in opacity at temperatures below a few thousand degrees K, corresponding to the Hayashi track. The speed of ejection of this matter, compared to the velocity dispersion of the host galaxy's core, determines whether the ejected matter is lost or returns to the envelope. The threshold between matter recycling and permanent loss defines a relationship between the maximum BH mass and sigma that resembles the empirical M_BH-sigma relation.
* theory on the origin of M_BH-sigma relation.
1203.1637
Diffusive shock acceleration and B-field amplification
Schure, Bell, Drury, Bykov
Diffusive shock acceleration: theory of particle acceleration through multiple shock crossings. In order for this process to proceed at a rate that can be reconciled with observations of high-energy electrons in the vicinity of the shock, and for CR protons to be accelerated to energies up to observed galactic values, significant B-field amplification is required. Discuss various theory on how B-field amplification can proceed in the presence of CR population. On both long and short scales, CR streaming can induce instabilities that act to amplify the B-field. Developments in this area that have occurred over the past decade are the main focus of this paper.
1203.1641
Exploring the unusually high BH-to-bulge mass rations in NGC4342 and NGC 4291: the asynchronous growth of bulges and BHs
Bogdan, et al
Two nearby early-type galaxies. The observed BH-to-bulge mass ratios are 7% and 2%, respectively, which significantly exceed the typical observed ratio of 0.2% (5 sigma and 3 sigma outliers from the M_BH-M_bulge relation). Origin of the unusually high ratio: Based on hot gas content, compute gravitating mass profiles, and conclude that both galaxies reside in massive DM haloes, which extend well beyond the stellar light. The presence of DM haloes and a deep optical mage of the environment of 4342 indicate that tidal stripping, in which >90% of the stellar mass was lost, cannot explain the observed high BH-to-bulge mass ratios. Conclude that these galaxies formed with low stellar masses, implying that the bulge and BH did not grow in tandem. Also find that the BH mass correlates well with the properties of the DM halo, suggesting that DM haloes may play a major role in regulating the growth of SMBH.
1203.1642
Chandra observations of NGC4342, an optically faint, X-ray gas-rich early-type galaxy
Bogdan, et al
Low stellar mass (M_K--22.8 mag) early type galaxy show luminous, diffuse x-ray emission from hot gas with T~0.56 keV. Hot gas as a significantly broader distribution than stellar light, show strong disturbances. A cold-front edge; morphology comes from ram-pressure. From the thermal pressure ratios inside and outside the cold front, estimate the velocity of 4342 and find that it moves spersonically (M~2.6). Resolve 8 bright point sources within the D_25 ellipse, most of them being low-mass x-ray binaries, located in the center of 4342, associate it with the SMBH of 4342. Outside the optical extent of the galaxy, detect 17 luminous excess x-ray sources, origin uncertain, but possibly LMXBs located in metal-oor globular clusters in the extended DM halo of 4342. Based on the number of excess sources, estimate that 4342 may host roughly 1k globular clusters.
[ in Milky Way, 152 globular clusters discovered ]
1203.1651
The advanced camera for surveys general catalog: structural parameters for approximately half a million galaxies
Griffith, Cooper, Newman, Moustakas, Stern, Comerford, Davids, ... Capak, Faber, ..Koekemoer, Koo, Noeske, Scoville, Sheth,... et al
ACS-GC: a photometric and morphological database using publicly available data obtained with HST/ACS. Provide large statistical sample of galaxies with reliable structural and distance measurements to probe the evolution of galaxies over a wide range of look-back times. ACS-GC includes 490l astronomical sources (stars + galaxies) from AEGIS, COSMOS, GEMS and GOODS surveys. Photometric (SExtractor) and morphological (Galfit) catalogs. Assume a single Sersic model for each object to derive quantitative structural parameters. Include publicly available redshift from DEEP2, COMBO-17, TKRS, PEARS, ACES, CFHTLS, and zCOSMOS (spectro- and photometric) for 71% of the imaging sample. Includes color postage stamps, Galfit residual images, and photometry, structural parameters, and redshifts combined into a single catalog.
1203.1664
Data and 2d scaling relations for galaxies in Abell 1689: a hint of size evolution at z~0.2
Houghton, Davies, Bonta, Masters
* Kormendy relation: correlation in an elliptical galaxy of the half-light radius to the surface brightness at that radius.
* Faber-Jackson relation: Early empirical power law relation between the luminosity L and the central stellar velocity dispersion sigma of elliptical galaxies: L propto sigma^4
Imaging and spectroscopy of Abell1689 (z=0.183) from GEMINI and HST. GMOS g and r (531 galaxies), HST F625W (43 galaxies), and GMOS spectra (71 galaxies). Construct Kormendy relation, FJ relation, and color-mag relation for early-type galaxies; compare with Coma cluster. Intrinsic scatter of CMR in 1689 is 0.05 mag (degenerate constraints on the ratio of the assembly timescale to the time available, "beta", and the age of the population). Assume that galaxies in abell1689 will evolve into those of Coma over an interval of 2.26 Gyr breaks this degeneracy and limits beta to be >0.6 and the age of the red sequence to be >5.5 Gyr (formed at z>0.55). Without corrections for size evolution but accounting for magnitude cuts and selection effects, the eKR & FJR are inconsistent and diagree at the 2 sigma level, regarding the amount of luminosity evolution in the last 2.26 Gyr. However, after correcting for size evolution the KR&FJR show similar changes in luminosity that are consistent with passive evolution of the stellar populations from a single burst of SF 10Gyr ago (z=1.8 with large error). Thus the changes n the KR, FJR & CMR of Abell1689 relative to Coma all agree and suggest old galaxy populations with little or no synchronization in the SF histories. Weak evidence for size evolution in the cluster environment in the last 2.26 Gyr places interesting constraints on the possible mechanisms at work, favoring harassment or secular processes over merger scenarios.
1203.1668
SFR indicators in wide-field IR survey preliminary release
Shi, Kong, Wicker, Chen, Gong, Xin, Fan
Analyze 3.4, 4.6, 12 and 22 um data in a sample of 140k SF galaxies or SF regions covering a wide range in metallicity 7.66 < 12+ log(O/H) < 9.46, with redshift z<0.4. Study relationship between the IR luminosities, and Halpha luminosity in SDSS DR8; derive reference SFR indicators. Find linear relation; dispersion in the SFR-IR luminosity relation relates to galaxy's properties (4000A break, galaxy color).
1203.1679
A Spitzer study of interacting luminous and ultra-luinous IR galaxies
Leao, Leitherer
Spitzer survey of 28 LIRGS and ULIRGS: many of these galaxies are found in pairs or associations, and are powered either by nuclear activity or SF. Main goal: understand the relative importance of starbursts and AGNs in interacting systems. Compare IR data with optical-only.
1203.1693
Do bars trigger activity in galactic nuclei?
Lee, Woo, Lee, Hwang, Lee, Sohn, Lee
Connection of bars and AGN activity, with 9k late-tupe galaxies with b/a>0.6 and Mr<-19.5+5 log h at low z (0.02<z<0.055) from SDSS DR7. Bar fraction in AGN-host galaxies is 42%, 2.5x higher than non-AGN galaxies (15.6%); AGN fraction is a factor of two higher in strong-barred galaxies (35%) than in non-barred galaxies (15%). These trends simply caused by AGN-host galaxies are on average more massive and redder than non-AGN galaxies, because the fraction of stron-barred galaxies increases with u-r color and stellar velocity dispersion. When U-r color and velocity dispersion (or stellar mass) are fixed, bot the strong-bar excess in AGN-host galaxies and the enhanced AGN fraction in strong-barred galaxies disappears. Among AGN-host galaxies, find no strong difference of the Eddington ratio distributions between barred and non-barred systems. Results indicate that AGN activity is not dominated by the presence of bars, and that AGN power is not enhanced by bars. Conclusion: no clear evidence that bars trigger AGN activity.
1203.1695
PkANN I: on-linear matter power spectrum estimation through artificial neural networks (ANN)
Agarwal, Abdalla, Feldman, Lahav, Thomas
Show that an optimally trained ANN, when presented with a set of cosmo parameters, can provide a worst case accuracy fit to the non-linear power spectrum deduced through N-body simulations, for modes up to k<0.7 h/Mpc. Power spectrum predictor is accurate over the entire parameter space for z<2; a significant improvement over some of the current matter power spectrum calculators. Detail how an accurate prediction of matter power spectrum is achievable with only a sparkly sampled grid of cosmological parameters. A well-trained ANN can be an extremely quick and reliable tool in interpreting cosmological observations and parameter estimation. This is paper I: generate NL P(k) using halo fit and use them as mock observations to train ANN. In Paper II, a suite of N-body simulations will be used to compute the NL P(k) at sub percent accuracy, in the quasi NL regimes (0.1 < k < 0.9 h/Mpc) for redshifts between z=0 and 2.
1203.1800
Filaments and sheets of the warm-hot intergalactic medium
Klar, Mücket
Filaments are not only supposed to host the majority of the baryons at low redshifts in the form of WHIM, but also to supply forming galaxies at higher redshifts with a substantial amount of cold gas via cold streams. Hydrosim to investigate hydrodynamics and thermodynamics of filaments (and sheets and haloes). State and evolution of gas inside filament: for L>4Mpc, filaments fully confined by an accretion shock; exhibit isothermal core, temperature balanced by radiative cooling and heating due to UV background; a multiphase structure for the medium temperature WHIM. Obtain scaling relations for the main quantities of this core. In the vicinity of the halo, the filament's core can be attributed to the cold streams found in cosmological hydro-sims. Thermal conduction can lead to a complete evaporation of the cold stream for L>6 Mpc/h, corresponding to halos more massive than M_h = 1e13 Msun, and implies that SF in more massive galaxies can not be supplied by cold streams. For perturbations on scales L>6Mpc/h, the filament no longer exhibit a cold core.
1203.1825
Measuring the redshift dependence of the CMB monopole temperature with PLANCK data
de Martino, Atrio-Barandela, da Silva, Ebeling, Kashlinsky, Kocevski, Martins
Study the power of PLANCK data to constrain deviations of the CMB BB temperature from adiabatic evolution using thermal SZ anisotropy induced by clusters of galaxies. Consider two types of data sets (cosmo signal removed from time-ordered information or from the final maps); and two different statistical estimators (ratio of T anisotropy at two different frequencies and on a fit to the spectral variation of the cluster signal with frequency). Demonstrate: using X-ray selected cluster catalog with measured redshifts, e- densities and x-ray temperatures, can constrain deviations of adiabatic evolution, measured by the parameter alpha in the redshift scaling T(z) = T_0 (1+x)^(1-alpha), with accuracy of sigma_alpha=0.011 in the most optimal case (0.016 for less optimal). Results represent a factor 2-3 improvement over similar measurements carried out using quasar spectral lines and a factor 6-20 with respect to earlier results using smaller cluster samples.
1203.1831
GALAPAGOS: from pixels to parameters
Barden Häußler, Peng, McIntosh, Guo
Software pipeline in IDL that combines SExtractor and Galfit.
1203.1840
Star formation activities in early-type brightest cluster galaxies
Liu, Mao, Meng
120 BCGs at 0.1<z<0.4 in two recent large cluster catalogues from SDSS, with strong Halpha and O II (3727) line emission, which indicates significant ongoing SF. Constitute about 0.5% of the largest, optically-seleted, low-redshift BCG sample; fraction a strong function of cluster richness. SFH well described by a recent minor and short starburst superimposed o an old stellar component, with the recent episode of SF contributing on average only less than 1% of the total stellar mass. Show that the more massive star forming BCGs in richer clusters tend to have higher SFR and sSFR (SFR/unit galaxy stellar mass). Compare statistical properties with Xray luminous clusters; show fraction of SF BCGs in x-ray luminous clusters is almost one order of magnitude larger than in optically-selected clusters [why?]. BCGs with SF in cooling flow clusters usually have very flat optical spectra and show the most active SF.
1203.1863
The degeneracy between star-formation parameters in dwarf galaxy simulations and the Mstar-Mhalo relation
Cloet-Osselaer, De Rijcke, Schroyen, Dury
N-body/SPH sims of isolated dwarf galaxies: SF, stellar feedback, radiative cooling and metal enrichment accounted. DM halo initially cuspy, but (starting from spherically symmetric initial conditions) a natural conversion to a core is observed due to gas dynamics and stellar feedback. A degeneracy between the efficiency : the ISM absorbing energy feedback from SNe and stellar winds on one hand, and the density threshold for SF on the other, is found. Perform a parameter survey to determine, with the aid of observed kinematic and photometric scaling relations, which combinations of these 2 parameters produce simulated galaxies that are in agreement with the observations. With the implemented physics, unable to reproduce the relation between the stellar mass and the halo mass as determined by Guo+ (2010), but do reproduce the slope of this relation.
* Rachel's 2006 paper referenced. I could probably use this for comparison with mine.
1203.1864
On the environment of short gamma-ray bursts
Kopac et al
11 short GRBs with robust z determined: measure x-ray absorbing column densities, collect data on the host galaxy offsets. Find evidence for intrinsic absorption and weak correlation between intrinsic absorbing column density and the projected offset of the GRB from its host galaxy center. Find properties in the gamma regime (T90, fluence and 1-s peak photon flux) of short GRBs with "bright" and "faint" x-ray afterglow disfavor different prompt emission mechanisms, and that the (normalized) host galaxy offset and GRB duration (T90) do not correlate significantly. Examine the existence of short-lived and long-lived X-ray afterglows in short GRBs and find that some short GRBs with short-lived X-ray afterglows have their optical afterglow detected. Suggests that the X-ray afterglow duration does not seem to be a unique indicator of a specific progenitor and /or environment for short GRBs.
1203.1877
Host fast BHs spin in quasars
Maio, Dotti, Petova, Perego, Volonteri
Explore the interaction between SMBH and their environment during active phases through simulations of circum-nuclear disks around BHs in quasars host in the remnants of galaxy mergers; explicitly include effects of SF, stellar winds, SNe feedback, and radiative transfer. Approach crucial to investigate the angular momentum of the material that is accreted by the hole. Find that maximally rotating BHs are slightly spun down, and slow-rotating holes are spun-up, leading to upper-intermediate equilibrium values of the spin parameter (0.7-0.9). Suggests: when quasar activity is driven by mergers of galaxies of similar sizes, stellar feedback does not induce strong chaos in the gas inflow, and that most SMBHs at the end of the quasar epoch have substantial spins.
1203.1919
The metal-enriched host of an energetic gamma-ray burst at z~1.6
Krühler, et al
GRB hosts are not necessarily metal-poor, based on IR observation of GRB host galaxy at z=1.6. High SFR (34 Msun/yr). GRB hosts could be fair tracers of the population of ordinary star-forming galaxies as a whole at z>1.
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