Galactic Center Research Papers - Academia.edu (original) (raw)

he emission of gravitational waves from a system of massive objects interacting on hyperbolic orbits is studied in the quadrupole approximation. Analytic expressions are derived for the gravitational radiation luminosity, the total energy output and the gravitational radiation amplitude. An estimation of the expected number of events towards different targets (i.e. globular clusters and the center of the Galaxy) is also given. In particular, for a dense stellar cluster at the galactic center, a rate up to one event per year is obtained.

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- Approximation Theory, Gravitational Wave Detectors, Galactic Center

The 1st book of Ra-Ah-Si-Rus, This was originally published as a draft copy in 2015 ( * total solar eclipse at the Spring equinox ) ... and then as its 1st photographic edition in 2016. Since then, 60+ signed copies have been printed and posted around the world. The most up to date version can be downloaded @ www.Infinity-codes.net. All work is done by donation, as I have explained in the book, the world Maths situation, shows that we can't seem to Add up very well as a species, Peace

- by Raahsirus Hun Kukum
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- Fractal Geometry, Earth Sciences, Climate Change, Alchemy
- by J. Auffenberg
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- Quantum Physics, Dark Matter, Prey Choice Model, Galactic halo

The gravitational-wave (GW) sky may include nearby pointlike sources as well as astrophysical and cosmological stochastic backgrounds. Since the relative strength and angular distribution of the many possible sources of GWs are not well constrained, searches for GW signals must be performed in a model-independent way. To that end we perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. The latter result is the first of its kind. Finding no evidence to support the detection of GWs, we present 90% confidence level (CL) upper-limit maps of GW strain power with typical values between 2-20x10^-50 strain^2 Hz^-1 and 5-35x10^-49 strain^2 Hz^-1 sr^-1 for pointlike and extended sources respectively. The limits on pointlike sources constitute a factor of 30 improvement over the previous best limits. We also set 90% CL limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN1987A and the Galactic Center as low as ~7x10^-25 in the most sensitive frequency range near 160 Hz. These limits are the most constraining to date and constitute a factor of 5 improvement over the previous best limits.

To date, the most precise tests of general relativity have been achieved through pulsar timing, albeit in the weak-field regime. Since pulsars are some of the most precise and stable "clocks" in the Universe, present observational efforts are focused on detecting pulsars in the vicinity of supermassive black holes (most notably in our Galactic Centre), enabling pulsar timing to be used as an extremely precise probe of strong-field gravity. In this paper a mathematical framework to describe test-particle dynamics in general black hole spacetimes is presented, and subsequently used to study a binary system comprising a pulsar orbiting a black hole. In particular, taking into account the parameterization of a general spherically symmetric black hole metric, general analytic expressions for both the advance of the periastron and for the orbital period of a massive test particle are derived. Furthermore, these expressions are applied to four representative cases of solutions arising in both general relativity and in alternative theories of gravity. Finally, this framework is applied to the Galactic Centre S-stars and four distinct pulsar toy models. It is shown that by adopting a fully general-relativistic description of test-particle motion which is independent of any particular theory of gravity, observations of pulsars can help impose better constraints on alternative theories of gravity than is presently possible.

- by Mariafelicia De Laurentis
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- Pulsars, Extended theories of gravity, Galactic Center

There is compelling observational evidence for the existence of dark matter. Although knowledge of its underlying nature remains elusive, a variety of theories provide candidate particles [1]. Among those are supersymmetry [2] and universal extra dimensions [3], both of which predict new physics at the electro-weak scale and, in most scenarios, introduce a light, and stable (or long lived) particle that exhibits the properties of a weakly interacting massive particle (WIMP)[4]. WIMPs are an ideal dark matter candidate, predicted to have ...

- by J. Auffenberg
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- Quantum Physics, Dark Matter, Prey Choice Model, Galactic halo

We used both radial-velocity and proper-motion data to perform a rotation-curve solution on a combined sample of about 700 Population-I objects including young open clusters (lg A < 8.1), classical Cepheids, and red supergiants. The distances of all objects are derived on a homogenized scale based on Kholopov's (1980) ZAMS, M_V (B-V)_0, PL relation for classical Cepheids by Berdnikov &

- by L. Salotti and +2
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- Dust (Astronomy & Astrophysics), X Rays, Spectrum, Broad Line Region
- by Tom Jarrett
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- Data Analysis, Statistical Analysis, Object Classification, Decision Tree
- by Tiberiu Harko
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- Dark Matter, Gravitational Lensing, Dwarf Galaxies, Bose-Einstein Condensate
- by Daniel Pfenniger
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- Dust (Astronomy & Astrophysics), Dynamics, Models, Kinematics
- by Roland Crocker
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- Organic Chemistry, Oscillations, Spectrum, Next Generation
- by Yazan Momany
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- Organic Chemistry, Astrophysical Plasma, High Resolution, Galactic Center
- by Leonardo Bronfman
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- Mechanical Engineering, Aerospace Engineering, Physics, Space
- by Deborah Padgett
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- Mechanical Engineering, Aerospace Engineering, Physics, Space
- by Remon Cornelisse
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- X-ray Binaries, Dust (Astronomy & Astrophysics), X Rays, Galactic Center
- by Luis Acedo
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- Dark Matter, Early Universe, Kinetic Theory, Galaxy evolution
- by Frederick K Baganoff
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- Physics, Dust (Astronomy & Astrophysics), Stellar Dynamics, Near Infrared

If the present dark matter in the Universe annihilates into Standard Model particles, it must contribute to the gamma ray fluxes detected on the Earth. The magnitude of such contribution depends on the particular dark matter candidate, but certain features of the produced spectra may be analyzed in a rather model-independent fashion. In this communication we briefly revise the complete photon spectra coming from WIMP annihilation into Standard Model particle-antiparticle pairs obtained by extensive Monte Carlo simulations and consequent fitting functions presented by Dombriz et al. in a wide range of WIMP masses. In order to illustrate the usefulness of these fitting functions, we mention how these results may be applied to the so-called brane-world theories whose fluctuations, the branons, behave as WIMPs and therefore may spontaneously annihilate in SM particles. The subsequent gamma\gammagamma-rays signal in the framework of dark matter indirect searches from Milky Way dSphs and Galactic...

- by Alvaro de la Cruz-Dombriz
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- Physics, Monte Carlo Simulation, Dark Matter, High Energy Physics
- by Claudio Maccone
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- Mechanical Engineering, Aerospace Engineering, General Relativity, Black Hole
- by Josh Walawender
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- Organic Chemistry, Astrophysical Plasma, Star Formation, Surveys
- by C. Alcock and +2
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- Organic Chemistry, Astrophysical Plasma, Dwarf Galaxies, Cataclysmic Variable Stars
- by Miles Blanton
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- Physics, Astronomy, Galactic Center
- by Christophe Jean
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- Gravitational Lensing, Image Quality, High Redshift Universe, Galactic Center
- by Daniele Fargion
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- Organic Chemistry, Astrophysical Plasma, X Rays, Ultra High Energy Cosmic Rays
- by Ed Wetherell and +2
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- Milky Way, Galactic Center
- by Martin muños
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- Mechanical Engineering, Aerospace Engineering, Space, Synchrotron Radiation

We present an overview of the design of IRIS, an infrared (0.84 - 2.4 micron) integral field spectrograph and imaging camera for the Thirty Meter Telescope (TMT). With extremely low wavefront error (<30 nm) and on-board wavefront sensors, IRIS will take advantage of the high angular resolution of the narrow field infrared adaptive optics system (NFIRAOS) to dissect the sky at the diffraction limit of the 30-meter aperture. With a primary spectral resolution of 4000 and spatial sampling starting at 4 milliarcseconds, the instrument will create an unparalleled ability to explore high redshift galaxies, the Galactic center, star forming regions and virtually any astrophysical object. This paper summarizes the entire design and basic capabilities. Among the design innovations is the combination of lenslet and slicer integral field units, new 4Kx4k detectors, extremely precise atmospheric dispersion correction, infrared wavefront sensors, and a very large vacuum cryogenic system.

- by Elliot Meyer
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- Galactic Astronomy, Adaptive Optics, Sensors, Dispersion
- by Aigen Li
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- Earth Sciences, Interstellar Medium, Mathematical Sciences, Physical sciences

We describe the test planet and photon orbits of the third kind inside a
rotating and electrically charged Kerr-Newman black hole, which are stable, periodic and neither come out of the black hole nor terminate at the singularity. The third kind orbits exist in between the central singularity and the Cauchy horizon. Interiors of supermassive black holes may be inhabited by advanced civilizations living on the planets with third-kind orbits.

- by D. Bini
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- Physics, Cosmology, Models, Mathematical Sciences
- by Mustafa Amin
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- Quantum Physics, Dark Matter, Supersymmetric Models, Cross Section
- by David Stiff
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- Quantum Physics, Dark Matter, Galactic halo, Hierarchical Clustering
- by Fulvio Melia
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- Masers, Spatial Distribution, Spatial Correlation, Galactic Center
- by Ashley Pagnotta
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- Spectrum, Infrared, Population Study, Galactic Center

We modeled the evolution of the Milky Way to trace the distribution in space and time of four prerequisites for complex life: the presence of a host star, enough heavy elements to form terrestrial planets, sufficient time for biological evolution and an environment free of life-extinguishing supernovae. We identified the Galactic habitable zone (GHZ) as an annular region between 7 and 9 kiloparsecs from the Galactic center that widens with time and is composed of stars that formed between 8 and 4 billion years ago. This GHZ yields an age distribution for the complex life that may inhabit our Galaxy. We found that 75% of the stars in the GHZ are older than the Sun.

- by Charles Lineweaver
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- Molecular Evolution, Science, Chemical Evolution, Multidisciplinary
- by JoAnn O'Linger
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- Mechanical Engineering, Aerospace Engineering, Space, Ir

In the indirect detection of dark matter through its annihilation products, the signals depend on the square of the dark matter density, making precise knowledge of the distribution of dark matter in the Universe critical for robust predictions. Many studies have focused on regions where the dark matter density is greatest, e.g., the Galactic Center, as well as on the cosmic signal arising from all halos in the Universe. We focus on the signal arising from the whole Milky Way halo; this is less sensitive to uncertainties in the dark matter distribution, and especially for flatter profiles, this halo signal is larger than the cosmic signal. We illustrate this by considering a dark matter model in which the principal annihilation products are neutrinos. Since neutrinos are the least detectable Standard Model particles, a limit on their flux conservatively bounds the dark matter total self-annihilation cross section from above. By using the Milky Way halo signal, we show that previous constraints using the cosmic signal can be improved on by 1-2 orders of magnitude; dedicated experimental analyses should be able to improve both by an additional 1-2 orders of magnitude.

- by Hasan yüksel
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- Quantum Physics, Dark Matter, Cosmic Rays, Galactic halo

A new type of high-energy binary system has been revealed by the INTEGRAL satellite. These sources are being unveiled by means of multi-wavelength optical, near- and midinfrared observations. Among these sources, two distinct classes are appearing: the first one is constituted of intrinsically obscured high-energy sources, of which IGR J16318-4848 seems to be the most extreme example. The second one

- by Sylvain Chaty
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- X-ray Binaries, X Rays, Mid-Infrared, Galactic Center
- by Mark Krumholz and +1
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- Astrophysical Plasma, HII Regions, Solar Radiation Pressure, Star Clusters
- by Christopher Stubbs
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- Organic Chemistry, Astrophysical Plasma, Galactic halo, Galactic Center
- by J. Tavernet
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- Organic Chemistry, Astrophysical Plasma, X Rays, Gamma Ray Burst

The SOFIA airborne observatory will provide a high spatial resolution, low background telescope for farinfrared astrophysical investigations. Selected as a PI instrument for SOFIA, SAFIRE is an imaging Fabry-Perot spectrograph covering 145mum-655mum, with spectral resolving power of ~1500 (200km/s). This resolution is well matched to extragalactic emission lines and yields the greatest sensitivity for line detection. SAFIRE will make important

- by Dominic Benford
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- Star Formation, Early Universe, Imaging Mass Spectrometry, Imaging spectroscopy