相关论文: A rapid occultation event in NGC 3227

We report recent Chandra observations of the ULX in the elliptical galaxy NGC3379 that clearly detect two flux variability cycles. Comparing these data with the Chandra observation of ~5yr ago, we measure a flux modulation with a period of…

We report on the detection of a remarkable new fast high-energy transient found in the Chandra Deep Field-South, robustly associated with a faint ($m_{\rm R}=27.5$ mag, $z_{\rm ph}$$\sim$2.2) host in the CANDELS survey. The X-ray event is…

Context: In April 2013, the nearby (z=0.031) TeV blazar, Mkn 421, showed one of the largest flares in X-rays since the past decade. Aim: To study all multiwavelength data available during MJD 56392 to 56403, with special emphasis on X-ray…

We use X-ray monitoring data obtained over a broad range of time-scales to measure the broadband power spectral density functions (PSDs) of two Seyfert galaxies, the broad line Seyfert 1 NGC 3227 and the Seyfert 2 NGC 5506, which has…

We describe extensive synoptic multi-wavelength observations of the transition disk LRLL 31 in the young cluster IC 348. We combined four epochs of IRS spectra, nine epochs of MIPS photometry, seven epochs of cold-mission IRAC photometry…

We systematically analyzed about a terabyte of data from Galactic binary systems to characterize how these spectra change as a function of mass accretion rate. With this volume of data we are able to identify the differences in behaviour of…

We have observed four low-luminosity active galactic nuclei classified as Type 1 LINERs with the X-ray Telescope (XRT) and the UltraViolet-Optical Telescope (UVOT) onboard Swift, in an attempt to clarify the main powering mechanism of this…

The globular cluster NGC 6440 is known to harbor a bright neutron-star X-ray transient. We observed the globular cluster with Chandra on two occasions when the bright transient was in its quiescent state in July 2000 and June 2003 (both…

In the last few years, a few supermassive black holes (SMBHs) have shown short-term (of the order of hours) X-ray variability. Given the limited size of the sample, every new addition to this class of SMBHs can bring invaluable information.…

The particular giant X-ray bump of GRB 121027A triggered by \emph{Swift} is quite different from the typical X-ray flares in gamma-ray bursts. There exhibit four parts of the observed structural variabilities in the rise and decay phase of…

We report on the X-ray time resolved spectral analysis of XMM-Newton observations of NGC 3783. The main goal is to detect transient features in the Fe K line complex, in order to study the dynamics of the innermost accretion flow. We…

We present an update of 3C 273's database hosted by the ISDC, completed with data from radio to gamma-ray observations over the last 10 years. We use this large data set to study the multiwavelength properties of this quasar,especially…

We report on the detection of flaring activity from the Fanaroff-Riley I radio galaxy NGC 1275 in very-high-energy (VHE, E $>$ 100 GeV) gamma rays with the MAGIC telescopes. Observations were performed between 2016 September and 2017…

Chandra observations of 17 nearby galaxies were analysed and 166 bright sources with X-ray counts > 100, were chosen for temporal analysis. Fractional root mean square variability amplitudes were estimated for lightcurves binned at ~ 4 ksec…

Mrk 590 is a Changing Look AGN currently in an unusual repeat X-ray and UV flaring state. Here, we report on deep X-ray observations with XMM-Newton, NuSTAR, and NICER, obtained at a range of X-ray flux levels. We detect a prominent soft…

We present the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 galaxy NGC 4151, as part of an effort to study its short time-scale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed…

We present NGC 6221 as a case study of ``X-ray loud composite galaxies,'' which appear similar to starbursts at optical wavelengths and resemble traditional active galactic nuclei in X-rays. The net optical spectrum of NGC 6221 is properly…

We present a detailed analysis of the intrinsic X-ray absorption in the Seyfert 1 galaxy NGC 4151 using Chandra/HETGS data obtained 2002 May, as part of a program which included simultaneous UV spectra using HST/STIS and FUSE. NGC 4151 was…

We report on the first near-simultaneous X-ray and optical observations of RX J0806.3+1527. The source is believed to be a 321s orbital period ultra-compact binary system hosting an X-ray emitting white dwarf. Data were obtained with…

We describe the results of a new reverberation mapping program focused on the nearby Seyfert galaxy NGC 3227. Photometric and spectroscopic monitoring were carried out from 2022 December to 2023 June with the Las Cumbres Observatory network…