15997425
A Multiwavelength Study of 1WGA J1346.5-6255: A New γ Cas Analog Unrelated to the Background Supernova Remnant G309.2-00.6
WGA J1346.5-6255 is a ROSAT X-ray source found within the radio lobes of the supernova remnant (SNR) G309.2-00.6. This source also appears to coincide with the bright and early-type star HD 119682, which is in the middle of the galactic open cluster NGC 5281. The radio morphology of the remnant, consisting of two brightened and distorted arcs of emission on opposite sides of the 1WGA J1346.5-6255 source and of a jet-like feature and break in the shell, led to the suggestion that 1WGA J1346.5-6255/G309.2-00.6 is a young analog of the microquasar SS 433 powering the W50 nebula. This motivated us to study this source at X-ray and optical wavelengths. We here present new Chandra observations of 1WGA J1346.5-6255, archival XMM- Newton observations of G309.2-00.6, and optical spectroscopic observations of HD 119682, in order to search for X-ray jets from 1WGA J1346.5-6255, study its association with the SNR, and test for whether HD 119682 represents its optical counterpart. We do not nd evidence for jets from 1WGA J1346.5-6255 down to an unabsorbed ux of 2.6 10 -13 ergs cm -2 s (0.5n7.5 keV), we rule out its association with G309.2-00.6, and we conrm that HD 119682 is its optical counterpart. We derive a distance of 1.2 0.3 kpc, which is consistent with the distance estimate to NGC 5281 (1.3 0.3 kpc), and much smaller than the distance derived to the SNR G309.2-00.6. We discuss the nature of the source, unveil that HD 119682 is a Be star and suggest it is a new member of the recently proposed group of -Cas analogs. The Chandra and XMM-Newton X-ray lightcurves show variability on timescales of hundreds of seconds, and the presence of a possible period of 1500 s that could be the rotational period of an accreting neutron star or white dwarf in this -Cas analog.
119385026
Distribution of Spectral Lags in Gamma-Ray Bursts
Using the data acquired in the time-to-spill (TTS) mode for long gamma-ray bursts (GRBs) by the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO), we have carefully measured spectral lags in time between the low (25-55 keV) and high (110-320 keV) energy bands of individual pulses contained in 64 multipeak GRBs. We find that a temporal lead by higher energy gamma-ray photons (i.e., positive lags) is the norm in this selected sample set of long GRBs. While relatively few in number, some pulses of several long GRBs do show negative lags. This distribution of spectral lags in long GRBs is in contrast to that in short GRBs. This apparent difference poses challenges to and places constraints on the physical mechanism(s) for producing long and short GRBs. The relation between the pulse peak count rates and the spectral lags is also examined. Observationally, there seems to be no clear evidence for a systematic spectral lag-luminosity connection for pulses within a given long GRB.
14404489
XMM-Newton studies of a massive cluster of galaxies: RXC J2228.6+2036
We present the X-ray properties of a massive cluster of galaxies (RXC J2228.6+2036 at z = 0.421) using XMM-Newton data. The X-ray mass modeling is based on the temperature and density distributions of the intracluster medium derived using a deprojection method. We find that RXC J2228.6+ 2036 is a hot cluster (T(500) = 8.92(-1.32)(+1.78) keV) showing a cooling flow rate of 12.0(-12.0)(+56.0) M(circle dot) yr(-1) based on spectral fitting within the cooling flow radius (r(cool) = 147 +/- 10 kpc). The total cluster mass is M(500) = (1.19 +/- 0.35) x 10(15) M(circle dot) and the mean gas mass fraction is f(gas) = 0.165 +/- 0.045 at r(500) = 1.61 +/- 0.16 Mpc. We discuss the PSF-correction effect on the spectral analysis and find that, for the selected annular width, the PSF-corrected temperatures are consistent with those without PSF-correction. We observe remarkable agreement between X-ray and SZ results, which is of prime importance for future SZ surveys. RXC J2228.6+ 2036 obeys the empirical scaling relations found in general massive galaxy clusters (e. g. S-T, M-T, L-T and M-Y), after accounting for self-similar evolution.
14245903
Deprojection technique for galaxy cluster considering the point spread function
We present a new method for the analysis of Abell 1835 observed by XMM-Newton. The method is a combination of the Direct Demodulation technique and deprojection. We eliminate the effects of the point spread function (PSF) with the Direct Demodulation technique. We then use a traditional deprojection technique to study the properties of Abell 1835. Compared to only using a deprojection method, the central electron density derived from this method increases by 30%, while the temperature profile is similar.
119242733
A GOOD MASS PROXY FOR GALAXY CLUSTERS WITH XMM-NEWTON
We use a sample of 39 galaxy clusters at redshift z < 0.1 observed by XMM-Newton to investigate the relations between X-ray observables and total mass. Based on central cooling time and central temperature drop, the clusters in this sample are divided into two groups: 25 cool core clusters and 14 non-cool core clusters, respectively. We study the scaling relations of L bol-M 500, M 500-T, M 500-M g, and M 500-Y X, and also the influences of cool core on these relations. The results show that the M 500-Y X relation has a slope close to the standard self-similar value, has the smallest scatter and does not vary with the cluster sample. Moreover, the M 500-Y X relation is not affected by the cool core. Thus, the parameter of YX may be the best mass indicator.
16367305
The analysis of Abell 1835 using a deprojection technique
We present the results from a detailed deprojection analysis of Abell 1835 as observed by XMM-Newton .I f we fi t the spectra with an isothermal plasma model, the deprojected temperature profile is flat in the outer region around 7.6 keV and decreases to ∼5.6 keV in the center, which may be connected with the gas cooling. In the central part, a two-component thermal plasma model can fit the spectrum significantly better. Moreover, the cool component (T ∼ 1.8 keV) has a much lower metal abundance than the hot component (T ∼ 8 keV), which may be due to the longer cooling time for the cool gas with lower abundance. In addition, it was found that without a main isothermal component, the standard cooling flow model cannot fit the spectrum satisfactorily. From the isothermal model fitting results we also derived the electron density ne, and fitted its radial distribution with a double-β model. The ne profile inferred with the double-β model and the deprojected X-ray gas temperature profile were then combined to derive the total mass and the total projected mass of the cluster. The projected mass is lower than that derived from the weak lensing method. However, assuming that the cluster extends to a larger radius ∼15 � as found by Clowe & Schneider (2002), the two results are consistent within the error bars. Furthermore, we calculated the projected mass within the radius of ∼153 kpc implied by the presence of a gravitational lensing arc, which is about half of the mass determined from the optical lensing.
118403311
Geometry and optics calibration of WFCTA prototype telescopes using star light
The Large High Altitude Air Shower Observatory project is proposed to study high energy gamma ray astronomy ( 40 GeV-1 PeV ) and cosmic ray physics ( 20 TeV-1 EeV ). The wide field of view Cherenkov telescope array, as a component of the LHAASO project, will be used to study energy spectrum and compositions of cosmic ray by measuring the total Cherenkov light generated by air showers and shower maximum depth. Two prototype telescopes have been in operation since 2008. The pointing accuracy of each telescope is crucial to the direction reconstruction of the primary particles. On the other hand the primary energy reconstruction relies on the shape of the Cherenkov image on the camera and the unrecorded photons due to the imperfect connections between photomultiplier tubes. UV bright stars are used as point-like objects to calibrate the pointing and to study the optical properties of the camera, the spot size and the fractions of unrecorded photons in the insensitive areas of the camera.
119287365
Geodetic precession and strong gravitational lensing in dynamical Chern–Simons-modified gravity
We have investigated the geodetic precession and the strong gravitational lensing in the slowly rotating black hole in the dynamical Chern–Simons-modified gravity theory. We present the formulas of the orbital period T and the geodetic precession angle ΔΘ for the timelike particles in the circular orbits around the black hole, which shows that the change of the geodetic precession angle with the Chern–Simons coupling parameter ξ is converse to the change of the orbital period with ξ for fixed a. We also discuss the effects of the Chern–Simons coupling parameter on the strong gravitational lensing when the light rays pass close to the black hole and obtain that for the stronger Chern–Simons coupling the prograde photons may be captured more easily, and conversely, the retrograde photons are harder to capture in the slowly rotating black hole in the dynamical Chern–Simons-modified gravity. Supposing that the gravitational field of the supermassive central object of the Galaxy can be described by this metric, we estimated the numerical values of the main observables for gravitational lensing in the strong field limit.
119252617
Holographic superconductor models with $RF^{2}$ corrections
We investigate the effect of the RF 2 correction on the holographic superconductor model in the background of AdS black hole. We find that, similar to the effect caused by the Weyl correction, the higher RF 2 correction term can make it easier for the scalar operator to condense and result in the larger deviations from the expected relation in the gap frequency. However, if a non-trivial hair for the black hole has been triggered, we observe that the RF 2 correction and the Weyl correction do play different roles in the behavior of the condensation, which can be used to support the existing findings. PACS numbers: 11.25.Tq, 04.70.Bw, 74.20.-z ∗ panqiyuan@126.com † csb3752@hunnu.edu.cn ‡ jljing@hunnu.edu.cn
118628016
Is the CMB asymmetry due to the kinematic dipole
Parity violation found in the Cosmic Microwave Background (CMB) radiation is a crucial clue for the non-standard cosmological model or the possible contamination of various foreground residuals and/or calibration of the CMB data sets. In this paper, we study the directional properties of the CMB parity asymmetry by excluding the $m=0$ modes in the definition of parity parameters. We find that the preferred directions of the parity parameters coincide with the CMB kinematic dipole, which implies that the CMB parity asymmetry may be connected with the possible contamination of the residual dipole component. We also find that such tendency is not only localized at $l=2,3$, but in the extended multipole ranges up to $l\sim 22$.
119110851
THE PULSAR SEARCH COLLABORATORY: DISCOVERY AND TIMING OF FIVE NEW PULSARS
We present the discovery and timing solutions of five new pulsars by students involved in the Pulsar Search Collaboratory, a NSF-funded joint program between the National Radio Astronomy Observatory and West Virginia University designed to excite and engage high-school students in Science, Technology, Engineering, and Mathematics (STEM) and related fields. We encourage students to pursue STEM fields by apprenticing them within a professional scientific community doing cutting edge research, specifically by teaching them to search for pulsars. The students are analyzing 300?hr of drift-scan survey data taken with the Green Bank Telescope at 350?MHz. These data cover 2876?deg2 of the sky. Over the course of five years, more than 700 students have inspected diagnostic plots through a web-based graphical interface designed for this project. The five pulsars discovered in the data have spin periods ranging from 3.1?ms to 4.8?s. Among the new discoveries are PSR?J1926?1314, a long period, nulling pulsar; PSR?J1821+0155, an isolated, partially recycled 33?ms pulsar; and PSR?J1400?1438, a millisecond pulsar in a 9.5?day orbit whose companion is likely a white dwarf star.