相关论文: Complex Optical-X-ray Correlations in the Narrow-L…

We discuss the origin of the optical variations in the Narrow line Seyfert 1 galaxy NGC 4051 and present the results of a cross-correlation study using X-ray and optical light curves spanning more than 12 years. The emission is highly…

We report on the results of a three-year program of coordinated X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051. The rapid continuum variations observed in the X-ray spectra are not detected in the optical,…

We report on a three-year program of coordinated X-ray and optical monitoring of the Narrow-Line Seyfert 1 galaxy NGC 4051. The rapid continuum variations observed in the X-ray spectra are not detected in the optical, although the X-ray and…

NGC 4051 is one of the X-ray brightest and most variable Seyfert galaxies. During 2009 NGC 4051 was caught at its lowest state ever observed by $XMM-Newton$. The low source continuum emission allows a clear measurement of the He-like…

We present optical observations of the low-luminosity Seyfert 1 nucleus of NGC 4395, as part of a multiwavelength reverberation-mapping program. Observations were carried out over two nights in 2004 April at Lick, Wise, and Kitt Peak…

We present a comprehensive examination of the X-ray variability of the narrow line Seyfert 1 (NLS1) galaxy NGC4051. We combine over 6.5 years of frequent monitoring observations by RXTE with a >100ks continuous observation by XMM-Newton and…

We report on the X-ray spectral variability of the Seyfert 1 galaxy NGC 4051 observed with the Rossi X-ray Timing Explorer (RXTE) during a 1000 day period between May 1996 and March 1999. The spectra were obtained as part of monitoring…

We present intensive quasi-simultaneous X-ray and radio monitoring of the narrow line Seyfert 1 galaxy NGC 4051, over a 16 month period in 2000-2001. Observations were made with the Rossi Timing X-ray Explorer (RXTE) and the Very Large…

Archival XMM-Newton data on the nearby Seyfert galaxy NGC 4051, taken in relatively high and low flux states, offer a unique opportunity to explore the complexity of its X-ray spectrum. We find the hard X-ray band to be significantly…

An extended component of X-ray emission has been detected in Seyfert galaxies - NGC 1365 and NGC 4051, using the ROSAT HRI. Its size is about 2 kpc and it contains 56% +- 8% of the total observed flux in NGC 1365, and 21% +- 6% in NGC 4051.…

We examine simultaneous X-ray and UV light curves from multi-epoch 8 day XMM Newton observations of the narrow line Seyfert 1 galaxy 1H 0707-495. The simultaneous observations reveal that both X-ray and UV emission are variable and that the…

We present a detailed multi-frequency analysis of an intense monitoring programme of Seyfert 1 galaxy NGC 4593 over a duration of nearly for a month with Swift observatory. We used 185 pointings to study the variability in six…

We present the first results from a high sampling rate, multi-month reverberation mapping campaign undertaken primarily at MDM Observatory with supporting observations from telescopes around the world. The primary goal of this campaign was…

On 9-11 May 1998, the highly-variable, low luminosity Seyfert 1 galaxy NGC4051 was observed in an unusual low flux state by BeppoSAX (Guainazzi et al. 1998) RXTE and EUVE. We present fits of the 4-15 keV RXTE spectrum and BeppoSAX MECS…

The Narrow Line Seyfert 1 galaxy NGC4051 shows unusual low flux states, lasting several months, when the 2-10 keV X-ray spectrum becomes unusually hard (photon index<1) while the spectrum at lower X-ray energies is dominated by a large soft…

We report the results from a Chandra TOO observation of the low-luminosity Narrow Line Seyfert 1 galaxy NGC 4051, obtained during a 6-week duration low-flux state in 2001 February. During the Chandra observation, the 2-10 keV source flux…

We present the long term, frequency-dependent, X-ray time lags of the Seyfert galaxy NGC 4051. We used Rossi X-ray Timing Explorer light curves in the 2-4, 4-7 and 7-10 keV bands and we measured the time-lags at $10^{-7}-10^{-6}$ Hz. This…

We present the results of a two-year long optical monitoring program of the narrow-line Seyfert 1 galaxy Akn 564. The majority of this monitoring project was also covered by X-ray observations (RXTE) and for a period of ~50 days, we…

We performed a detailed broadband spectral and timing analysis of a small flaring event of ~120 ks in a narrow-line Seyfert 1 galaxy NGC 4051 using simultaneous XMM-Newton and NuSTAR observations. The ~300 ks long NuSTAR observation and the…

We discuss the results of a campaign to monitor spectral variations in the low-luminosity Seyfert~1 galaxy NGC~4593, at X-rays, ultraviolet, optical and near IR frequencies. The observations and data analysis have been described in a…