Related papers: Deep-Survey Constraints on X-ray Outbursts from Ga…

In recent years, luminous X-ray outbursts with variability amplitudes as high as ~ 400 have been serendipitously detected from a small number of active and inactive galaxies. These outbursts may result from the tidal disruptions of stars by…

We systematically analyze X-ray variability of active galactic nuclei (AGNs) in the 7~Ms \textit{Chandra} Deep Field-South survey. On the longest timescale ($\approx~17$ years), we find only weak (if any) dependence of X-ray variability…

We report on exploratory Chandra observations of five galactic nuclei that were found to be X-ray bright during the ROSAT all-sky survey (with L_X > 10^43 erg s^-1) but subsequently exhibited a dramatic decline in X-ray luminosity. Very…

About half of nearby galaxies have a central surface brightness >1 magnitude below that of the sky. The overall properties of these low-surface-brightness galaxies (LSBGs) remain understudied, and in particular we know very little about…

We study the nature of the changing-look Active Galactic Nucleus NGC 1566 during its June 2018 outburst. During the outburst, the X-ray intensity of the source rises up to ~25-30 times compared to its quiescent state intensity. We perform…

We report nine long X-ray bursts from neutron stars, detected with Monitor of All-sky X-ray Image (MAXI). Some of these bursts lasted for hours, and hence are qualified as superbursts, which are prolonged thermonuclear flashes on neutron…

We investigate the extreme X-ray variability of a z = 1.608 active galactic nucleus in the 7 Ms Chandra Deep Field-South (XID 403), which showed two significant X-ray brightening events. In the first event, XID 403 brightened by a factor of…

We present results from stacking analyses, using the 1 Ms Chandra Deep Field North data, that constrain the X-ray emission of Lyman break galaxies at z = 2-4. Stacking the counts from 24 individually undetected Lyman break galaxies located…

We present the results of a 17 ks Chandra ACIS-S observation of the nearby dwarf spiral galaxy NGC 4395. Chandra affords the first high-quality, broadband X-ray detection of the active nucleus of this object that is uncontaminated by nearby…

We have analyzed observations with the Chandra X-ray Observatory of the diffuse emission by hot gas in 7 dwarf starburst galaxies, 6 edge-on starburst galaxies, and 9 Ultra Luminous Infrared Galaxies. These systems cover ranges of \~ 10^4…

The low-luminosity active galactic nucleus of M81 has been monitored at centimeter wavelengths since early 1993 as a by-product of radio programs to study the radio emission from Supernova 1993J. The extensive data sets reveal that the…

Chandra is detecting a significant population of normal and starburst galaxies in extremely deep X-ray exposures. For example, approximately 15% of the sources arising in the 2 Ms Chandra Deep Field-North survey are fairly normal galaxies,…

Nuclear hard X-ray luminosities (Lx,nuc) for a sample of 112 early type galaxies within a distance of 67 Mpc are used to investigate their relationship with the central galactic black hole mass Mbh, the inner galactic structure (using the…

We present a measure of the hard (2-8 keV) X-ray luminosity function (XLF) of Active Galactic Nuclei up to z~5. At high redshifts, the wide area coverage of the Chandra Multiwavength Project is crucial to detect rare and luminous (Lx >…

We measure the duty cycles for an existing sample of well observed, nearby dwarf novae using data from AAVSO, and present a quantitative empirical relation between the duty cycle of dwarf novae outbursts and the X-ray luminosity of the…

In the last few years, giant-amplitude, non-recurrent X-ray flares have been observed from several non-active galaxies (NGC 5905, RXJ1242-11, RXJ1624+75, RXJ1420+53, RXJ1331-32). All of them share similar properties, namely: extreme X-ray…

We perform long-term ($\approx 15$ yr, observed-frame) X-ray variability analyses of the 68 brightest radio-quiet active galactic nuclei (AGNs) in the 6 Ms $Chandra$ Deep Field-South (CDF-S) survey; the majority are in the redshift range of…

We present the results of a 17 ks Chandra observation of the nearby dwarf spiral galaxy NGC 4395, focusing on the X-ray properties of the moderate-mass black hole that resides in its nucleus. Chandra affords the first high-quality,…

Multiwavelength flares from tidal disruption and accretion of stars can be used to find and study otherwise dormant massive black holes in galactic nuclei. Previous well-monitored candidate flares are short-lived, with most emission…

The highly energetic outflows from Active Galactic Nuclei detected in X-rays are one of the most powerful mechanisms by which the central supermassive black hole (SMBH) interacts with the host galaxy. The last two decades of high resolution…