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First search for gravitational waves from known pulsars with advanced LIGO

We present the result of searches for gravitational waves from 200 pulsars using data from the first observing run of the Advanced LIGO detectors. We find no significant evidence for a gravitational-wave signal from any of these pulsars, but we are able to set the most constraining upper limits yet on their gravitational-wave amplitudes and ellipticities. For eight of these pulsars, our upper limits give bounds that are improvements over the indirect spin-down limit values. For another 32, we are within a factor of 10 of the spin-down limit, and it is likely that some of these will be reachable in future runs of the advanced detector. Taken as a whole, these new results improve on previous limits by more than a factor of two.

Author: Powell, J.
Publication year: 2017
Publication type: Journal article
Source: The Astrophysical Journal
Status: Live|Last updated:7 December 2017 6:32 PM
Relevance: 0.23
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Polarimetry of the Eclipsing Pulsar PSR J1748–2446A

Observations with the Parkes radio telescope of the eclipsing millisecond binary pulsar PSR J1748-2446A, which is in the globular cluster Terzan 5, are presented. These include the first observations of this pulsar in the 3 GHz frequency band, along with simultaneous observations in the 700 MHz band, and new observations around 1400 MHz. We show that the pulsar signal is not eclipsed in the 3 GHz band and observe the known eclipses in the lower-frequency bands. We find that the observed pulse signal becomes depolarized during particular orbital phases and postulate that this depolarization occurs because of rotation-measure fluctuations resulting from turbulence in the stellar wind responsible for the eclipses.

Author: You, X. P., Manchester, R. N., Coles, W. A., Hobbs, G. B., Shannon, R.
Publication year: 2018
Publication type: Journal article
Source: The Astrophysical Journal
Status: Live|Last updated:13 November 2018 5:32 PM
Relevance: 0.23
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The influence of host galaxies in type Ia supernova cosmology

We use a sample of 1338 spectroscopically confirmed and photometrically classified Type Ia supernovae (SNe Ia) sourced from Carnegie Supernova Project, Center for Astrophysics Supernova Survey, Sloan Digital Sky Survey-II, and SuperNova Legacy Survey SN samples to examine the relationships between SNe Ia and the galaxies that host them. Our results provide confirmation with improved statistical significance that SNe Ia, after standardization, are on average more luminous in massive hosts (significance >5σ), and decline more rapidly in massive hosts (significance >9σ) and in hosts with low specific star formation rates (significance >8σ). We study the variation of these relationships with redshift and detect no evolution. We split SNe Ia into pairs of subsets that are based on the properties of the hosts and fit cosmological models to each subset. Including both systematic and statistical uncertainties, we do not find any significant shift in the best-fit cosmological parameters between the subsets. Among diff…

Author: Uddin, Syed A., Mould, Jeremy, Lidman, Chris, Ruhlmann-Kleider, Vanina...
Publication year: 2017
Publication type: Journal article
Source: Astrophysical Journal
Status: Live|Last updated:1 November 2017 1:32 PM
Relevance: 0.215|Keywords found in attachment content
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Galaxy and mass assembly (gama): Impact of the group environment on galaxy star formation

We explore how the group environment may affect the evolution of star-forming galaxies. We select 1197 Galaxy And Mass Assembly groups at 0.05 ≤ z ≤ 0.2 and analyze the projected phase space (PPS) diagram, i.e., the galaxy velocity as a function of projected group-centric radius, as a local environmental metric in the low-mass halo regime 1012 ≤ (M 200/M o) < 1014. We study the properties of star-forming group galaxies, exploring the correlation of star formation rate (SFR) with radial distance and stellar mass. We find that the fraction of star-forming group members is higher in the PPS regions dominated by recently accreted galaxies, whereas passive galaxies dominate the virialized regions. We observe a small decline in specific SFR of star-forming galaxies toward the group center by a factor ∼1.2 with respect to field galaxies. Similar to cluster studies, we conclude for low-mass halos that star-forming group galaxies represent an infalling population from the field to the halo and show suppressed star for…

Author: Barsanti, S., Owers, M. S., Brough, S., Davies, L. J.M., Driver, S. P....
Publication year: 2018
Publication type: Journal article
Source: Astrophysical Journal
Status: Live|Last updated:26 April 2018 4:32 PM
Relevance: 0.215|Keywords found in attachment content
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Binary pulsar distances and velocities from Gaia Data Release 2

The second data release from the Gaia mission (Gaia DR2) includes, among its billion entries, astrometric parameters for binary companions to a number of known pulsars, including white dwarf companions to millisecond pulsars (MSPs) and the non-degenerate components of so-called "black widow" and "redback" systems. We find 22 such counterparts in DR2, of which 12 have statistically significant measurements of parallax. These DR2 optical proper motions and parallaxes provide new measurements of the distances and transverse velocities of the associated pulsars. For the most part, the results agree with existing radio interferometric and pulsar timing-based astrometry, as well as other distance estimates based on photometry or associations, and for some pulsars they provide the best known distance and velocity estimates. In particular, two of these pulsars have no previous distance measurement: PSR. J1227-4853, for which Gaia measures a parallax of 0.62 +/- 0.16 mas, and PSR. J1431-4715, with a Gaia parallax of 0…

Author: Jennings, Ross J., Kaplan, David L., Chatterjee, Shami, Cordes, James ...
Publication year: 2018
Publication type: Journal article
Source: The Astrophysical Journal
Status: Live|Last updated:13 September 2018 5:32 PM
Relevance: 0.189|Keywords found in attachment content
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The AGN ionization cones of NGC 5728. I. Excitation and nuclear structure

We explore the gas morphology and excitation mechanisms of the ionization cones of the Type II Seyfert galaxy NGC 5728. Near-IR and optical data from the SINFONI and MUSE integral field units on the Very Large Telescope are combined with Hubble Space Telescope optical images, Chandra X-ray data, and Very Large Array radio observations. The complex nuclear structure has a star-forming (SF) ring with a diameter of 2 kpc. A radio jet impacts on the interstellar medium at about 200 pc from the nucleus, with the supernova remnants in the SF ring also present. Emission-line ratios of [Fe ii] and H ii show heavy extinction toward the nucleus, moderate extinction in the SF ring, and reduced extinction in the ionization cones. The active galactic nucleus (AGN) is hidden by a dust bar with up to 19 mag of visual extinction; the dust temperature at the nuclear position is ∼870 K. An X-ray jet is aligned with the ionization cones and associated with high-excitation emission lines of [Si vi] in a coronal line region exten…

Author: Durre, Mark, Mould, Jeremy
Publication year: 2018
Publication type: Journal article
Source: The Astrophysical Journal
Status: Live|Last updated:28 November 2018 11:32 AM
Relevance: 0.183|Keywords found in attachment content
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Unique tracks drive the scatter of the spatially resolved star formation main sequence

The scatter of the spatially resolved star formation main sequence (SFMS) is investigated in order to reveal signatures about the processes of galaxy formation and evolution. We have assembled a sample of 355 nearby galaxies with spatially resolved H and mid-infrared fluxes from the Survey for Ionized Neutral Gas in Galaxies and the Wide-field Infrared Survey Explorer, respectively. We examine the impact of various star formation rate (SFR) and stellar mass transformations on the SFMS. Ranging from 106 to 1011.5 M o and derived from color to mass-to-light ratio methods for mid-infrared bands, the stellar masses are internally consistent within their range of applicability and inherent systematic errors; a constant mass-to-light ratio also yields representative stellar masses. The various SFR estimates show intrinsic differences and produce noticeable vertical shifts in the SFMS, depending on the timescales and physics encompassed by the corresponding tracer. SFR estimates appear to break down on physical scal…

Author: Hall, Christine, Courteau, Stephane, Jarrett, Thomas, Cluver, Michelle...
Publication year: 2018
Publication type: Journal article
Source: The Astrophysical Journal
Status: Live|Last updated:24 October 2018 10:32 AM
Relevance: 0.183|Keywords found in attachment content
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Search for gravitational waves associated with gamma-ray bursts during the first advanced LIGO observing run and implications for the origin of GRB 150906B

We present the results of the search for gravitational waves (GWs) associated with γ-ray bursts detected during the first observing run of the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO). We find no evidence of a GW signal for any of the 41 γ-ray bursts for which LIGO data are available with sufficient duration. For all γ-ray bursts, we place lower bounds on the distance to the source using the optimistic assumption that GWs with an energy of ${10}^{-2}{M}_{\odot }{c}^{2}$ were emitted within the $16$–$500$ Hz band, and we find a median 90% confidence limit of 71 Mpc at 150 Hz. For the subset of 19 short/hard γ-ray bursts, we place lower bounds on distance with a median 90% confidence limit of 90 Mpc for binary neutron star (BNS) coalescences, and 150 and 139 Mpc for neutron star–black hole coalescences with spins aligned to the orbital angular momentum and in a generic configuration, respectively. These are the highest distance limits ever achieved by GW searches. We also discuss in d…

Author: Powell, J.
Publication year: 2017
Publication type: Journal article
Source: The Astrophysical Journal
Status: Live|Last updated:7 December 2017 5:32 PM
Relevance: 0.183|Keywords found in attachment content
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ZFIRE: the evolution of the stellar mass Tully-Fisher relation to redshift ∼2.2

Using observations made with MOSFIRE on Keck I as part of the ZFIRE survey, we present the stellar mass TullyFisher relation at 2.0 < z < 2.5. The sample was drawn from a stellar-mass-limited, Ks-band-selected catalog from ZFOURGE over the CANDELS area in the COSMOS field. We model the shear of the Hα emission line to derive rotational velocities at 2.2 the scale radius of an exponential disk (V2.2). We correct for the blurring effect of a 2D point-spread function (PSF) and the fact that the MOSFIRE PSF is better approximated by a Moffat than a Gaussian, which is more typically assumed for natural seeing. We find for the Tully-Fisher relation at 2.0 < z < 2.5 that log V2.2 = (2.18 ± 0.051)+(0.193 ± 0.108)(logM/M -10) and infer an evolution of the zero-point of DM/M = -0.25 ± 0.16 dex or DM M = -0.39 ± 0.21 dex compared to z = 0 when adopting a fixed slope of 0.29 or 1/4.5, respectively. We also derive the alternative kinematic estimator S0.5, with a best-fit relation log S0.5 = (2.06 ± 0.032) + (0.211 ± 0.086…

Author: Straatman, Caroline M. S., Glazebrook, Karl, Kacprzak, Glenn G., Labbe...
Publication year: 2017
Publication type: Journal article
Source: The Astrophysical Journal
Status: Live|Last updated:29 March 2018 10:14 AM
Relevance: 0.183|Keywords found in attachment content
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The SLUGGS Survey: The inner dark matter density slope of the Massive Elliptical Galaxy NGC 1407

We investigate the dark matter density profile of the massive elliptical galaxy, NGC 1407, by constructing spherically symmetric Jeans models of its field star and globular cluster systems. Two major challenges in such models are the degeneracy between the stellar mass and the dark matter halo profiles, and the degeneracy between the orbital anisotropy of the tracer population and the total mass causing the observed motions. We address the first issue by using new measurements of the mass-to-light ratio profile from stellar population constraints that include a radially varying initial mass function. To mitigate the mass-anisotropy degeneracy, we make use of multiple kinematic tracers, including two subpopulations of globular clusters in addition to the galaxys field stars. We create a hierarchical Bayesian model that addresses several often-neglected systematic uncertainties, such as the statistical weight given to various data sets and the adopted distance. After sampling the posterior probability distribut…

Author: Wasserman, Asher, Romanowsky, Aaron J., Brodie, Jean, Dokkum, Pieter V...
Publication year: 2018
Publication type: Journal article
Source: Astrophysical Journal
Status: Live|Last updated:3 September 2018 5:32 PM
Relevance: 0.183|Keywords found in attachment content
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