Kimberly Ann Weaver

NASA · X-ray Astrophysics Laboratory

The BBXRT observed nine supernova remnants during its nine-day flight. We present preliminary results from some of these observations, emphasizing the ability of BBXRT to perform spatially resolved spectroscopy. The improved spectral resolution and efficiency over previous instruments makes possible measurements of previously undetectable lines, an...

The narrow-line region (NLR) in AGN plays a crucial role in understanding AGN structure and evolution, as well as the interaction between the nuclear engine and the ISM of host galaxies in the form of outflows. Here, we present results from the Chandra SOARS (Survey Outflows in AGN with Resolved Spectroscopy) program, a 1.4 Ms Chandra GO, GTO, and...

The narrow-line region (NLR) in AGN plays a crucial role in understanding AGN structure and evolution, as well as the interaction between the nuclear engine and the ISM of host galaxies in the form of outflows. Here, we present results from the Chandra SOARS (Survey Outflows in AGN with Resolved Spectroscopy) program, a 1.4 Ms Chandra GO, GTO, and...

The LINER galaxy NGC 1052 is the nearest radio-loud active galactic nucleus (RLAGN), and one of only four megamaser sources in an RLAGN. Though broad iron emission lines from the inner accretion disk are typically challenging to observe in RLAGN, NGC 1052 has displayed such a feature dating back to 1996. Herein, we present the results of our multi-...

The shape of the spectral energy distribution (SED) of active galaxies in the extreme-ultraviolet (EUV)-soft X-ray band (13.6?eV-1?keV) is uncertain because obscuration by dust and gas can hamper our view of the continuum. To investigate the shape of the SED in this energy band, we have generated a set of photoionization models which reproduce the...

AGN outflows are widely invoked as the key mediators between the co-evolution of black holes and their host galaxies. Yet, the key question remains: do the outflows actually deliver enough power to their environments to alter evolution in a meaningful way? To address this, we present results from a new 440-ks Chandra HETG GTO observation of the kpc...

We compare mid-infrared emission-line properties, from high-resolution Spitzer spectra of a hard X-ray (14 -- 195 keV) selected sample of nearby (z < 0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 micron, [Ne II] 12.81 micron, [Ne III] 15.56 micron an...

The radio loud galaxy NGC 1052 has been monitored for the past fifteen years with Very Long Baseline Interferometry (VLBI) observations and has been the target of an intense multiwave-length monitoring campaign since 2005. This provides an excellent dataset for analyzing the relationship between properties of the relativistic jet and the accretion...

We compare mid-IR emission-lines properties, from high-resolution Spitzer IRS spectra,of a statistically-complete hard X-ray (14-195 keV) selected sample of nearby (z < 0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 mum, [Ne II] 12.81mum , [Ne III] 15...

We present the full low-resolution (60 < R < 127) and high-resolution (R 600) spectra of five active galactic nuclei (AGN) taken with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. The sample was selected from the Swift BAT AGN catalog, derived from a hard X-ray (14-195 keV), all-sky mosaic. This nearly unbiased catalog can de...

This is the second of two papers examining Spitzer Infrared Spectrograph (IRS) observations of the ultraluminous X-ray source (ULX) in Holmberg II. Here we perform detailed photoionization modeling of the infrared lines. Our analysis suggests that the luminosity and morphology of the [O IV] 25.89 $\mu$m emission line is consistent with photoionizat...

The LINER galaxy NGC 1052 represents the rare case of a radio-loud AGN with a prominent compact jet structure and a broad Fe K line. As part of a multi-mission monitoring program begun in 2005, including VLBI radio observations and several pointings with different X-ray missions, a 101 ks Suzaku spectrum has yielded the highest signal-to-noise X-ra...

We present the first Spitzer Infrared Spectrograph observations of the [O IV] 25.89??m emission line detected from the ultraluminous X-ray source (ULX) in Holmberg?II. This line is a well-established signature of high excitation, usually associated with active galactic nucleus (AGN). Its detection suggests that the ULX has a strong impact on the su...

We present an analysis of the 101 ks, 2007 Suzaku spectrum of the LINER galaxy NGC 1052. The 0.5-10 keV continuum is well-modeled by a power-law modified by Galactic and intrinsic absorption, and it exhibits a soft, thermal emission component below 1 keV. Both a narrow core and a broader component of Fe K emission centered at 6.4 keV are robustly d...

Based on our discovery that ultraluminous X-ray sources (ULX sources) in galaxies can impact their surroundings and thus produce key diagnostic IR spectral signatures, we propose IRS mapping observations of six ULX sources with Spitzer. These are chosen from established X-ray catalogs and have optical evidence for extended nebula or 'bubbles' or ar...

We present the first measurements of the Fe Kα line profile in NGC 4151 from ASCA observations performed in 1993 May, November, and December. The apparent line profile is asymmetric, consisting of a peak at ~6.3-6.4 keV, a sharp drop on the blue side below ~7 keV, and a broad red wing extending to ~4-5 keV. This first clear indication of complex st...

We discuss X-ray and optical spectra and images of the infrared-bright double-nucleus system Mrk 266 = NGC 5256, with an emphasis on its spectacular gaseous nebula. In soft X-rays, the nebula has a diameter of ? 100 kpc, a temperature of a few × 10⁶ K, and a luminosity of about 10⁴² ergs s⁻¹. The optical emission-line nebula is smaller (35 kpc) but...

We report the presence of an absorption feature in the X-ray spectrum of the BL Lacertae object H1426+428 (z = 0.129). H1426+428 was observed at three separate epochs with BBXRT, ROSAT, and ASCA. In the BBXRT spectrum an absorption feature is clearly present at ~0.66 keV, consistent with absorption by highly ionized oxygen. The phenomenological mod...

We have analyzed all available ROSAT PSPC and HRI and ASCA data for a small far-infrared flux-limited sample of seven nearby edge-on starburst galaxies in order to search for hot gas in their halos. We find that all five normal-sized spiral galaxies (NGC 253, NGC 3079, NGC 3628, NGC 4631, and NGC 4666) have hot gas in their halos, as does the small...

X-ray grating spectroscopy, combined with high-resolution multiwavelength imaging, are powerful tools for probing the nuclei and circumnuclear environments of AGN and elucidating the connections between accretion and outflows in active galaxies. We present the results from a new series of Chandra, XMM-Newton, and Suzaku observations of radio-loud a...

Studies of black holes are at a threshold. There is compelling evidence for the existence of both stellar-mass and supermassive black holes, and research is now focused on determining their properties and environmental effects. Most importantly, we are starting to realize the long-held promise of black holes as the ultimate laboratories for studyin...

We present our preliminary results of the analysis of Spitzer observations of the first unbiased AGN sample of the local universe. High column densities of absorbing material along our line of sight can significantly change the observed properties of AGNs. Thus, optical, infrared, and soft X-ray selected samples are hampered by extinction, star for...

Observations of the Seyfert 2 and starburst galaxy NGC 5135 with the Chandra X-Ray Observatory demonstrate that both of these phenomena contribute significantly to its X-ray emission. We spatially isolate the active galactic nucleus (AGN) and demonstrate that it is entirely obscured by column density NH > 1024 cm-2, detectable in the Chandra bandpa...

Using Rossi X-Ray Timing Explorer Seyfert 1 and 1.2 data spanning 9 years, we study correlations between X-ray spectral features. The sample consists of 350 time-resolved spectra from 12 Seyfert 1 and 1.2 galaxies. Each spectrum is fitted to a model with an intrinsic power-law X-ray spectrum produced close to the central black hole that is reproces...

We present the results of the simultaneous deep XMM-Newton and Chandra observations of the bright Seyfert 1.9 galaxy MCG -5-23-16, which is thought to have one of the best known examples of a relativistically broadened iron Kα line. The time-averaged spectral analysis shows that the iron K-shell complex is best modeled with an unresolved narrow emi...

(abbreviated) We have undertaken an X-ray survey of a far-infrared flux limited sample of seven nearby edge-on starburst galaxies. Here, we examine the two X-ray-brightest sample members NGC 253 and M 82 in a self-consistent manner, taking account of the spatial distribution of the X-ray emission in choosing our spectral models. There is significan...

We present results from new Chandra, archival Hubble Space Telescope (HST), and VLA imaging observations of the circumnuclear extended emission in the nearby Type 2 Seyfert galaxy NGC 2110. We find resolved soft-band X-ray emission ~4'' (~160 pc) north of the nucleus, which is spatially coincident with [O III] emission, but lies just beyond the nor...

We present a study of the intrinsic X-ray and far-ultraviolet absorption in the Seyfert 1.5 galaxy Markarian 279 using simultaneous observations from the Chandra X-ray Observatory, the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope, and the Far Ultraviolet Spectroscopic Explorer (FUSE). We also present FUSE observations made...

We present initial results from a Chandra survey of a complete sample of the eight nearest (z ≤ 0.04) ultraluminous IR galaxies (ULIRGs) and also include the IR-luminous galaxy NGC 6240 for comparison. In this paper we use the hard X-rays (2-8 keV) to search for the possible presence of an obscured active galactic nucleus (AGN). In every case, a ha...

To test the idea that ultraluminous X-ray sources (ULXs) in external galaxies represent a class of accreting intermediate-mass black holes (IMBHs), we have undertaken a program to identify ULXs and a lower luminosity X-ray comparison sample with the highest quality data in the {\it Chandra} archive. We establish as a general property of ULXs that t...

What does the core of an active galactic nucleus truly look like? Do all Seyfert 2s have a Seyfert 1 at their core? How does the environment of their central regions affect our view of the central engine? We explore these questions with a systematic X-ray spectral study of bright Seyfert galaxies observed by the Rossi X-Ray Timing Explorer (RXTE)....

X-ray grating spectroscopy, combined with high-resolution imaging, are powerful tools for probing the nuclear and circumnuclear environments of Seyfert galaxies. Here, we present Chandra HETGS (250 ks), ACIS-S (50 ks) and XMM-Newton RGS (60 ks) imaging and spectroscopic observations of NGC 2110, a source classified as a Narrow Emission Line Galaxy,...

Active galactic nuclei (AGNs) have been a major focus of extragalactic astronomy for decades, but because of obscuration effects, virtually all surveys for AGN based purely on optical, IR, UV or soft X-ray data have been highly biased in their selection (cf. Mushotzky 2004). Thus, to truly understand the intrinsic nature of AGN as a class, it is cr...

Relativistically broad iron lines in active galactic nuclei (AGN) provide a powerful diagnostic probe of the inner accretion flow onto supermassive black holes. It is thought that the formation of relativistic jets is closely related to black hole/accretion disk dynamics; observations in support of this hypothesis have been lacking, however. The LI...

We present results from Chandra HETGS (250 ks over two epochs) and XMM-Newton EPIC and RGS (60 ks) observations of NGC 2110, which has been historically classified as a narrow emission line galaxy. Our results support the interpretation that the source is a Seyfert 2 viewed through a patchy absorber. The nuclear X-ray spectrum of the source is best...

The formation of powerful extragalactic jets is not well understood at present as well as the associated key question:“What makes an AGN radio loud?”. Here we discuss how the combination of VLBI and X-ray spectroscopic observations allows the inter-relation between the accretion flow and the formation of relativistic jets in AGN to be explored.

Active Galactic Nuclei (AGN) can be probed by at different regions of the electromagnetic spectrum: e.g., radio observations reveal the nature of their relativistic jets and their magnetic fields, and complementarily, X-ray observations give insight into the changes in the accretion disk flows. Here we present an overview over the AGN research and...

We present the results of the simultaneous XMM-Newton and Chandra observations of the bright Seyfert 1.9 galaxy MCG–5-23-16, which is one of the best known examples of a relativistically broadened iron K line. We find that: a) the soft X-ray emission is likely to be dominated by photoionized gas, b) the complex iron emission line is best modelled w...

The archival BeppoSAX (MECS and PDS) data, for a sample of the fifteen brightest Seyfert 1 galaxies, are analyzed to examine the broad-band X-ray spectral features of Compton reflection and iron line flourescence, which arise from the inner regions around the supermassive black hole, such as the putative torus and/or the accretion disk. The results...

We report preliminary results of an on-going systematic X-ray spectral variability study of bright Seyfert galaxies observed by the Rossi X-Ray Timing Explorer (RXTE). The RXTE public archive contains data for 40 Seyfert galaxies with suitable temporal coverage to perform variability studies covering short (days/weeks) to long (years) timescales. W...

Without Abstract

You have an amazing result based on NASA data or a NASA mission, you have written your seminal paper and submitted it to your favorite journal. You believe it has press potential and maybe you've even gotten help from your PR folks in writing a press release. Now you would really like NASA to issue this as a press release. But how do you do that? T...

High resolution X-ray spectroscopy, when combined with multiwavelength imaging, is a powerful tool for probing the circumnuclear environments of Seyfert galaxies. Here, we present results from Chandra, HST, and VLA observations of the nearby Seyfert 2 galaxy NGC 2110. We find resolved soft X-ray emission 4'' (650 pc) north of the nucleus, which is...

We report preliminary results of an on-going systematic X-ray spectral variability study of bright Seyfert galaxies observed by the Rossi X-Ray Timing Explorer (RXTE). The RXTE public archive contains data for 40 Seyfert galaxies with suitable temporal coverage to perform variability studies covering short (days/weeks) to long (years) timescales. W...

We analyze observations obtained with the Chandra X-ray Observatory of bright Compton thick active galactic nuclei (AGNs), those with column densities in excess of 1.5 x 10^{24} cm^{-2} along the lines of sight. We therefore view the powerful central engines only indirectly, even at X-ray energies. Using high spatial resolution and considering only...

Evidence is mounting for the existence of intermediate mass black holes, which occupy the mass spectrum somewhere between the stellar-mass variety (a few to tens of solar masses) and the supermassive variety (millions to billions of solar masses). Theoretical stellar and black hole evolutionary models predict intermediate mass black holes, but unti...

We have discovered a correlation between the X-ray absorbing column densities within Seyfert galaxies and the relative alignment between the central engines and their host galactic disks. This correlation carries several implications for Seyfert unification models. (1) In addition to small-scale circumnuclear absorbers, there are absorbing systems...

Earlier observations of NGC1808 in various wavebands (X-ray, optical, near-infrared, radio) provided evidence for the existence of either a starburst or a Seyfert 2 nucleus. We here present the results of multiwavelength XMM-Newton and Chandra observations, which directly prove the co-existence of thermal diffuse plasma and non-nuclear unresolved p...

Results obtained from an X-ray spectral survey of nearby Seyfert galaxies using XMM--Newton are reported. The sample was optically selected, well defined, complete in B mag, and distance limited: it consists of the nearest (D<22 Mpc) 27 Seyfert galaxies (9 of type 1, 18 of type 2) taken from the Ho et al. (1997) sample. This is one of the largest a...

We found several extranuclear (r >~ 3") X-ray nebulae within 40" (6.3 kpc at 32.5 Mpc) of the nucleus of the Seyfert galaxy NGC 2992. The net X-ray luminosity from the extranuclear sources is ~2-3 E39 erg/s (0.3-8.0 keV). The X-ray core itself (r <~ 1") is positioned at 9:45:41.95 -14:19:34.8 (J2000) and has a remarkably simple power-law spectrum w...

We have used X-ray spectra to measure attenuating columns in a large sample of Seyfert galaxies. Over 30 of these sources have resolved radio jets, allowing the relative orientation of the nucleus and host galaxy to be constrained. We have discovered that the distribution of absorbing columns is strongly correlated with the relative orientation of...

Surveys at all wavelengths are biased against finding strongly obscured active galactic nuclei (AGN), especially at high redshift. Locally, up to half of all Seyfert 2 galaxies are Compton thick, with obscuring column densities that exceed 1024 cm-2, yet even X-ray surveys would fail to classify them correctly using crude techniques such as hardnes...

We present an analysis of a Chandra ACIS observation of the edge-on Seyfert galaxy NGC 2992. We find extended X-ray emission with Lx(total) in excess of 10**40 erg/s. The brightest nebula is positioned a few 100 pc from the X-ray core, and is spatially coincident with optical line and radio emission. This emission nebula may be energized by the AGN...

Observations of the Seyfert 2 and starburst galaxy NGC 7130 with the Chandra X-ray Observatory illustrate that both of these phenomena contribute significantly to the galaxy's detectable X-ray emission. The active galactic nucleus (AGN) is strongly obscured, buried beneath column density N_H > 10^{24} cm^{-2}, and it is most evident in a prominent...

The Constellation-X mission will address the questions: "What happens to matter close to a black hole?" and "What is Dark Energy?" These questions are central to the NASA Beyond Einstein Program, where Constellation-X plays a central role. The mission will address these questions by using high throughput X-ray spectroscopy to observe the effects of...

Detailed analyses of individual AGN are essential to interpret surveys and to understand their biases. With higher spatial resolution and sensitivity, observations of nearby examples reveal differences between intrinsic and observed luminosity and demonstrate the effects of the multiple emission contributions that are present. In particular, star f...

The Constellation X-ray Mission is a high-throughput X-ray facility emphasizing observations at high spectral resolution (R similar to 300-3000) while covering a broad energy band (0.25-60 keV). The mission is intended to achieve a factor of 25-100 increase in sensitivity over current high resolution X-ray spectroscopy missions. Constellation-X is...

X-ray selection is biased against finding strongly-obscured active galactic nuclei (AGN), yet up to half of all Seyfert 2 galaxies are Compton thick, with obscuring column densities that exceed 1024 cm-2. We analyze new Chandra observations of three Compton thick Seyfert 2s. We determine the physical conditions of their immediate circumnuclear regi...

We have examined every Seyfert galaxy in the ASCA archive, using X-ray spectral modeling to separate the absorption into high and low column density types (divided at NH ˜ 1023 {cm}-2). This classification is convenient because it can be robustly made even for low S/N data sets. Over 30 of these sources have resolved radio jets, allowing the relati...

The Constellation-X mission is a high through-put X-ray facility, emphasizing observations at high spectral resolution (Delta E/E 300 to 3000) while covering a broad energy band up to 60 keV. Constellation-X is the x-ray astronomy equivalent of large ground-based optical telescopes such as the Keck and the VLT, complementing the high spatial resolu...

The dwarf starburst galaxy NGC 1569 was observed for 96.8 ks with Chandra. We detected several variable X-ray point sources in the central region of NGC 1569. Inparticular, two bright point sources, CXOU 043048.1+645050 and CXOU 043048.6+645058, exhibit a prominent variability in time. Fitting with the disk blackbody model, we find that CXOU 043048...

Relativistically broadened iron lines from active galactic nuclei (AGN) provide a powerful tool to study dynamical processes in the accretion of gas onto supermassive black holes. The formation of relativistic jets, on the other hand, is thought to be closely related to the accretion disk dynamics. The characteristic skewed iron line profile, which...

Optimism is mounting for the existence of intermediate mass black holes (IMBH), which occupy the mass spectrum somewhere between the stellar-mass and supermassive varieties. IMBH are naturally predicted by theoretical stellar and black hole evolution models, but the strong attention to them began only recently with the discovery of ultraluminous x-...

The Constellation-X mission will address the questions: "What happens to matter close to a black hole?" and "What is Dark Energy?" These questions are central to the NASA Beyond Einstein Program, where Constellation-X plays a central role. The mission will address these questions by using high throughput X-ray spectroscopy to observe the effects of...

We examine the spectral variability of the Seyfert 1.9 galaxy MCG -5-23-16 using RXTE and BeppoSAX observations spanning 2 years from April 1996 to April 1998. During the first year the X-ray source brightens by a factor of ~25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond mea...

Why do GIANT BLACK HOLES and STELLAR BABY BOOMS, two phenomena with little in common, so often go together?

We present arcsecond resolution Chandra X-ray and ground-based optical H-alpha imaging of a sample of ten edge-on star-forming disk galaxies (seven starburst and three ``normal'' spiral galaxies), a sample which covers the full range of star-formation intensity found in disk galaxies. We use the unprecedented spatial resolution of the Chandra X-ray...

We investigate how the empirical properties of hot X-ray-emitting gas in a sample of seven starburst and three normal edge-on spiral galaxies (a sample which covers the full range of star-formation intensity found in disk galaxies) correlate with the size, mass, star formation rate and star formation intensity in the host galaxies. Intriguingly, th...

We report the detection of Fe XXV and Fe XXVI $K\alpha$ emission lines from a Chandra HETGS observation of the Seyfert~1 galaxy NGC 7314, made simultaneously with RXTE. The lines are redshifted (cz ~ 1500 km/s) relative to the systemic velocity and unresolved. We argue that the lines originate in a near face-on (<7 degrees) disk having a radial lin...

From the analysis of a ~100 ks Chandra observation of the dwarf starburst galaxy NGC 1569, we have found that the X-ray point sources, CXOU 043048.1+645050 and CXOU 043048.6+645058, showed significant time variability. During this observation, the X-ray flux of CXOU 043048.1+645050 increased by 10 times in only 2 x 10^4 s. Since the spectrum in its...

We analyzed 1441 Chandra X-ray point sources in 32 nearby galaxies. The total point-source X-ray luminosity L_XP is well correlated with B, K, and FIR+UV luminosities of spiral host galaxies, and with the B and K luminosities for ellipticals. This suggests an intimate connection between L_XP and both the old and young stellar populations, for which...

XMM-Newton observations of the starburst galaxy NGC 1511 reveal the presence of a previously unknown extended hot gaseous phase of its ISM, which partly extends out of the disk plane. The emission distribution is asymmetric, being brightest in the eastern half of the galaxy, where also radio continuum observations suggest the highest level of star...

An unbiased estimate of the average intrinsic X-ray properties and column density distribution of Seyfert galaxies in the local Universe is crucial to validate unified models of active galactic nuclei (AGNs) and to synthesis models for the X-ray background. We present here preliminary results obtained from an on-going XMM-Newton study (~250 ks awar...

We have analyzed Chandra ACIS observations of 32 nearby spiral and elliptical galaxies and present the results of 1441 X-ray point sources, which are presumed to be mostly X-ray binaries (XRBs) and Intermediate-luminosity X-ray Objects (IXOs, a.k.a. ULXs). The X-ray luminosity functions (XLFs) of the point sources show that the slope of the ellipti...

We report the detection of Fe xxv and Fe xxvi Kalpha emission lines from a Chandra HETGS observation of the narrow-line Seyfert 1 galaxy NGC 7314. The lines are redshifted (cz ˜ 1500 \ km \ s-1) and unresolved. The most viable geometry for the origin of the lines is a disk. The redshift and width constraints on Fe xxvi Lyalpha alone imply that the...

The Constellation X-ray Mission is a high throughput X-ray facility emphasizing high spectral resolution (E/Delta E ˜300-3000) over a broad energy band ( 0.25 - 40 keV). We provide a brief description of the mission approach and the instrumentation which will provide a factor of 100 increase in sensitivity over current high resolution spectroscopy...

The Constellation X-ray mission will revolutionize X-ray spectroscopy and will provide a key component of NASA's '!Beyond Einstein" program. Over the past 35 years, X-ray astronomy has grown from infancy to near-maturity and is now an indispensable astrophysical tool. Constellation-X will transform this field from the exploratory spectroscopic era...

We report the detection of Fe xxv and Fe xxvi Kalpha emission lines from a Chandra HETGS observation of the Seyfert 1 galaxy NGC 7314. The lines are redshifted (cz ~ 1500 km/s) and unresolved. The ionization balance of Fe responds to rapid continuum variations on timescales less than 12.5~ks. The most viable geometry for the origin of the lines is...

Circumnuclear starbursts are common in Seyfert 2 galaxies, producing distinct X-ray signatures. As we demonstrate with new Chandra observations of starburst/AGN composite galaxies, stellar processes generate significant soft X-ray emission. The AGN are more important at higher energies, and they tend to be heavily obscured, by NH > 1024 cm-2. Their...

We present arcsecond resolution Chandra X-ray and ground-based optical Halpha imaging of a sample of ten edge-on star-forming disk galaxies (seven starburst and three ``normal'' spiral galaxies), a sample which covers the full range of star-formation intensity found in disk galaxies. The X-ray observations make use of the unprecented spatial resolu...

Using archival X-ray observations of Seyfert galaxies, we test the limits of the unified model for Seyfert galaxies. By considering the line-of-sight attenuating columns within the context of the relative arrangement of the Seyfert structural components, we find evidence suggesting that there are two distinct structures which are capable of absorbi...

A Chandra observation of the nearby (~2.5 Mpc) starburst galaxy NGC 253 has shown tantalizing evidence for an AGN-like photoionizing source at the center of a strong, but aging circumnuclear starburst. If true, this is the first clear snapshot of the complex interplay between starburst and AGN activity and could be key to our understanding of the e...

In this contribution we present a few selected examples of how the latest generation of space-based instrumentation -- NASA's Chandra X-ray Observatory and the Far-Ultraviolet Spectroscopic Explorer (FUSE) -- are finally answering old questions about the influence of massive star feedback on the warm and hot phases of the ISM and IGM. In particular...

(abridged) Based on observations of the Seyfert nucleus in NGC1068 with ASCA, RXTE and BeppoSAX, we report the discovery of a flare (increase in flux by a factor of ~1.6) in the 6.7 keV Fe K line component between observations obtained 4 months apart, with no significant change in the other (6.21, 6.4, and 6.97 keV) Fe K_alpha line components. Duri...

Chandra observations of the core of the nearby starburst galaxy NGC 253 reveal a heavily absorbed source of hard X-rays embedded within the nuclear starburst region. The source has an unabsorbed, 2 to 10 keV luminosity of >=10^39 erg/s and photoionizes the surrounding gas. We observe this source through a dusty torus with a neutral absorbing column...

We analyze X-ray spectra of heavily obscured (N_H > 10^{24} cm^{-2}) active galaxies obtained with Chandra, concentrating on the iron K alpha fluorescence line. We measure very large equivalent widths in most cases, up to 5 keV in the most extreme example. The geometry of an obscuring torus of material near the active galactic nucleus (AGN) determi...

We analyze X-ray spectra and images of a sample of Seyfert 2 galaxies that unambiguously contain starbursts, based on their optical and UV characteristics. Although all sample members contain active galactic nuclei (AGNs), supermassive black holes or other related processes at the galactic centers alone cannot account for the total X-ray emission i...

The hard-X-ray luminosity of non-active galaxies has been known to be fairly well correlated with the total blue luminosity since the days of the Einstein satellite. However, the origin of this hard component was not well understood. Some possibilities that were considered included X-ray binaries, extended upscattered far-infrared light via the inv...

We discuss Fe Kalpha line profile variability in an ASCA sample of Seyfert 1 galaxies. In particular, we examine the line core energies defined by fitting narrow Gaussians. Such an empirical analysis is simplistic but avoids modeling uncertainties. We find significant Fe flux and/or energy variability in ~60% of the sample on time scales ranging fr...

We present results from new, simultaneous Chandra/HETG and RXTE observations of Mkn 509, NGC 4593, and F9. The data are used to diagnose the physics of the photoionized absorbers and the complex Fe-K lines. These new results are compared with results from high-resolution X-ray spectroscopy of other type 1 AGN.

We present a detailed case study of the diffuse X-ray and H-alpha emission in the halo of NGC 253, a nearby edge-on starburst galaxy driving a galactic superwind. The arcsecond spatial resolution of the Chandra ACIS instrument allows us to study the spatial and spectral properties of the diffuse X-ray emitting plasma with greatly superior spatial a...

We report here preliminary results from a survey of nearby Seyfert galaxies using the EPIC CCDs on board XMM-Newton. The total sample consists of 28 Seyfert galaxies, and constitute a well-defined, complete (B<12.5 mag), and volume-limited (D<22 Mpc) sample of Seyfert galaxies in the northern (Delta > 0 deg.) hemisphere. The survey has been initiat...

Constellation-X is a premiere X-ray spectroscopy mission due to launch within the next decade. With a factor of 100 increase in sensitivity over current X-ray spectroscopy missions and an excellent energy resolution of 2 eV at 6 keV, one of the prime science goals of the mission will be to observe activity near the black hole event horizon by measu...

The X-ray properties of 15 nearby (v<3,000 km/s) galaxies that possess AGN and/or starbursts are discussed. Two-thirds have nuclear extended emission on scales from ~0.5 to ~1.5 kpc that is either clearly associated with a nuclear outflow or morphologically resembles an outflow. Galaxies that are AGN-dominated tend to have linear structures while s...

In a 52 ks-long Chandra ACIS-S observation of the nearby starburst galaxy NGC 3628, obtained to study the starburst-driven outflow from this galaxy, we have detected a very luminous (L_X = 1.1e40 erg/s in the 0.3-8.0 keV energy band) point source located at least 20 arcsec (~970 pc) from the nucleus of the galaxy. No radio, optical or near-IR count...

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 characterized as a starburst galaxy, but in X-rays, NGC 6221 is similar to Seyfert 1 galaxies, exhibiting a po...

We find that variability of the iron Kalpha line is common in Seyfert 1 galaxies. Using data from the ASCA archive for objects that have been observed more than once during the mission, we study the time-averaged spectra from individual observations, thereby probing variability on timescales that range from days to years. Since the statistics of th...