Context. In about half of the Seyfert galaxies, the X-ray emission is absorbed by an optically thin, ionized medium, the so-called "warm absorber", whose origin and location is still a matter of debate. Aims: The aim of this paper is to constrain the warm absorber further by studying its variability. Methods: We ...
NASA Astrophysics Data System (ADS)
The multifrequency radio continuum and 21 cm H I observations of five blue compact dwarf (BCD) galaxies, Mrk 104, Mrk 108, Mrk 1039, Mrk 1069, and I Zw 97, using the Giant Meterwave Radio Telescope (GMRT) are presented here. Radio continuum emission at 610 MHz and 325 MHz is detected from all ...
In an effort to study Damped Ly{alpha} (DLA) galaxies at low redshift, we have been using the Sloan Digital Sky Survey (SDSS) to identify galaxies projected onto quasi-stellar object (QSO) sight lines and to characterize their optical properties. For low-redshift galaxies, the H I 21 cm emission line can be used as an alternate tool ...
Energy Citations Database
We present new X-ray observations of Mrk 335 in the 0.4-10 keV band using the broadband X-ray telescope (BBXRT) and in the 2-18 keV band with Ginga. The BBXRT data show a gradual steepening of the spectrum to softer energies. We suggest that the nuclear emission can be explained by a self-consistent pair cascade model. The Ginga data show evidence for variability in ...
Context. The Seyfert 1 galaxy Mrk 279 was observed by XMM-Newton in November 2005 on three consecutive orbits, showing significant short-scale variability (average soft band variation in flux ~20%). The source is known to host a two-component warm absorber with distinct ionisation states from a previous Chandra observation. Aims: We ...
Low-resolution spectrophotometry from 2 to 4 microns is reported for the four Seyfert 1 galaxies Mrk
NASA Technical Reports Server (NTRS)
We present a detailed analysis of the Chandra High Energy Transmission Grating Spectrometer (HETGS) and XMM-Newton high-resolution spectra of the bright Seyfert 1 galaxy, Mrk 290. The Chandra HETGS spectra reveal complex absorption features that can be best described by a combination of three ionized absorbers. The outflow velocities ...
We present ultraviolet spectra of the z=0.0296 Seyfert 1 galaxy Mrk 290. For wavelengths extending from 920-1185 � we have obtained high spectral resolution, ~ 20 km s-1, observations with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our FUSE spectra exhibit broad line emission, narrow line emission, intrinsic absorption lines of O VI ? ? 1032, ...
The energy spectrum of the blazar-type galaxy Markarian 501 (Mrk 501), as measured by the High-Energy Gamma-Ray Astronomy (HEGRA) air Cerenkov telescopes, extends beyond 16 TeV and constitutes the most energetic photons observed from an extragalactic object. A fraction of the emitted spectrum is possibly absorbed in interactions with ...
AGN outflows impact the evolution of supermassive black holes, host galaxies, surrounding IGM, and cooling flows. However, the physical properties of these winds are poorly known. We propose to obtain the deepest RGS spectrum of any AGN, allowing us to determine the physical conditions of the gas. Through monitoring of the warm absorber using the combined ...
We present a detailed study of the ionized environment of the Seyfert 1 galaxy Mrk 704 using medium- and high-resolution X-ray spectra obtained with a long XMM-Newton observation. The 0.3-10 keV continuum, well described by a power law (? ? 1.86) and two blackbodies (kT ? 0.085 and 0.22 keV), is found to be affected by a neutral partial covering absorption ...
A new technique is demonstrated for using the signal from a source at a wavelength where it is strong to assist in determining its size at another wavelength. Observations of the size of the nucleus of Mrk 231 at 10 microns are consistent with a picture of a single luminosity source, perhaps obscured by dust. The variation with wavelength of the emissivity of the grains is ...
We present U BV R_CI_C magnitudes of 49 comparison stars in the fields of the Seyfert galaxies Mrk 335, Mrk 79, Mrk 279, Mrk 506, 3C 382, 3C 390.3, NGC 6814, Mrk 304, Ark 564, and NGC 7469 in order to facilitate the photometric monitoring of these objects; 36 of the stars ...
The analysis of the UV plus optical spectra of three star-forming galaxies, Mrk 496, Mrk 357, TOL1924-416, obtained by matching the size of the optical aperture with that of IUE, has given unexpected results. These can be summarized as follows: (1) the de...
National Technical Information Service (NTIS)
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 at three additional epochs. ...
Context. The Seyfert 1 galaxy Mrk 841 was observed five times between 2001 and 2005 by the XMM-Newton X-ray observatory. The source is well known for showing spectral complexity in the variable iron line and in the soft X-ray excess. Aims: The availability of multiple exposures obtained by the reflection grating spectrometer (RGS) cameras allows thorough ...
The Seyfert 1 galaxy Mrk841 was observed five times between 2001 and 2005 by the XMM-Newton X-ray observatory. The source is well known for showing spectral complexity in the variable iron line and in the soft X-ray excess. This paper reports on the first study of Mrk841 soft X-ray spectrum at high spectral resolution. The availability ...
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We present a new analysis of a 9-d long XMM-Newton monitoring of the narrow-line Seyfert 1 galaxy Mrk 766. We show that the strong changes in the spectral shape, which occurred during this observation, can be interpreted as due to broad-line region clouds crossing the line of sight to the X-ray source. Within the occultation scenario, the spectral and ...
Spectropolarimetry was used to study eight high-polarization Seyfert 2 galaxies. In four of them (Mrk 3, Mrk 348, Mrk 463E, and NGC 7674), evidence was found for a hidden broad-line region (BLR), visible only in the polarized flux spectrum. The other four objects, Mrk 78, ...
Aims: We seek a comprehensive analysis of all the information provided by the XMM-Newton satellite of the four Seyfert 1 galaxies ESO 359-G19, HE 1143-1810, CTS A08.12, and Mrk 110, including the UV range, to characterize the different components that are emitting and absorbing radiation in the vicinity of the active nucleus. Methods: ...
Results from BeppoSAX observations of Compton-thick Seyfert 2 galaxies are summarized and reviewed, and their general properties derived and discussed. In five out of the seven observed sources, the nucleus is directly visible at high X-ray energies, where the photons penetrate absorbers with column densities in the range 1.1-4.3�1024cm-2 (in the other ...
We report on the BeppoSAX detection of a hard X-ray excess in the X-ray spectrum of the classical high-ionization Seyfert 2 galaxy Tol 0109-383. The X-ray emission of this source observed below 7keV is dominated by reflection from both cold and ionized gas, as seen in the ASCA data. The excess hard X-ray emission is presumably caused by the central source ...
The paper presents new direct-imaging data for the disturbed spiral galaxy NGC 4319 (z = 0.005) and the apparently connected quasarlike object Markarian 205 (z = 0.072). Evidence supporting the hypothesis that the luminous connection extending from Mrk 205 into the nucleus of the spiral galaxy is a high red-shift interactive filament ...
Carbon dioxide (1 yields 0) emission has been detected from the UV-excess quasar Mrk 1014 (=PG 0157+001=IRAS 01572+0009) at z=0.163. Assuming the same empirical relationship between CO brightness and H2 surface mass density as has been found for giant molecular clouds in the Milky Way, the mass of H2 gas is approximately 4 x 10 to the 10th solar masses, i.e., more than ten ...
We present high angular resolution (~2 mas) radio continuum observations of five Seyfert galaxies with flat-spectrum radio nuclei, using the VLBA at 8.4 GHz. The goal of the project is to test whether these flat-spectrum cores represent thermal emission from the accretion disk, as inferred previously by Gallimore et al. for NGC 1068, or nonthermal, synchrotron ...
I present measurements of the metallicity of the circumnuclear gas in the narrow-line Seyfert 1 (NLS1) galaxy Markarian 1044 using O VI column density measurements from the Far Ultraviolet Spectroscopic Explorer together with C IV, N V, and H I measurements from the Hubble Space Telescope. From the absorption lines we find that the circumnuclear gas in Mrk ...
We present a clear detection of a broad Ly? absorber (BLA) with a matching O VI line in the nearby universe. The BLA is detected at z(Ly?}) = 0.01028 in the high signal-to-noise ratio spectrum of Mrk 290 obtained using the Cosmic Origins Spectrograph. The Ly? absorption has two components, with b(H I) = 55 � 1 km s-1 and b(H I) = 33 &plumsn; 1 km ...
We present a clear detection of a broad Ly{alpha} absorber (BLA) with a matching O VI line in the nearby universe. The BLA is detected at z(Ly{alpha})=0.01028 in the high signal-to-noise ratio spectrum of Mrk 290 obtained using the Cosmic Origins Spectrograph. The Ly{alpha} absorption has two components, with b(H i) = 55{+-}1 km s{sup -1} and b(H i) = ...
We present an investigation of the ultraviolet and X-ray spectra of the Seyfert 1.5 galaxy Markarian 817. The ultraviolet analysis includes two recent observations taken with the Cosmic Origins Spectrograph (COS) in 2009 August and December, as well as archival spectra from the International Ultraviolet Explorer and the Hubble Space Telescope. Twelve Ly? absorption features ...
We have examined the physical conditions within a bright emission-line knot in the inner narrow-line region (NLR) of the Seyfert 2 galaxy Mrk 573 using optical spectra and photoionization models. The spectra were obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph, through the 0farcs2 � 52farcs0 slit, at a position angle of ...
High resolution spectroscopy is acquiring increasing importance in the study of AGNs. We discuss the results on three Seyfert galaxies (Mrk 335, NGC 4051, and NGC 1365).
We present light curves and spectra of three Seyfert galaxies in the EUV and soft X-ray ranges. The data were obtained from EUVE and ROSAT observations of the galaxies MRK 279, MRK 478 and TON S180. The variability in the light curves provides an upper limit to the size of the EUV-soft X-ray emitting region which ...
CO(1-0) emission has been detected from the UV-excess quasar Mrk 1014 ( = PG 0157+001 = IRAS 01572+0009) at z = 0.163. Assuming the same empirical relationship between CO brightness and H2 surface mass density as has been found for giant molecular clouds in the Milky Way, the mass of H2 gas is about 4 x 10 to the 10th solar masses more than 10 times the H2 content of the ...
Markarian 6 is a nearby (D ~ 78 Mpc) Seyfert 1.5, early-type galaxy, with a double set of radio bubbles. The outer set spans ~7.5 kpc and is expanding into the halo regions of the host galaxy. We present an analysis of our new Chandra observation, together with archival XMM-Newton data, to look for evidence of emission from shocked gas around the external ...
Polar ring galaxies are systems with nearly orthogonally rotated components. We have found the gas on polar (or strongly inclined) orbits in two BCD galaxies using ionized gas velocity fields taken with a Fabry-Perot interferometer of the SAO RAS 6-m telescope. Our analysis shows that all ionized gas in Mrk 33 is concentrated in a ...
We present multiwavelength continuum light curves for the active galaxies 3C-120, Mrk 79, and Mrk 704 spanning the period March 2001 to May 2007. All CCD observations were made with the SARA 0.9-m telescope at Kitt Peak. Variations of several tenths of a magnitude are observed for all three objects; Mrk 79 exhibits ...
We detect high-velocity absorbing gas using Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer medium-resolution spectroscopy along two high-latitude active galactic nucleus (AGN) sight lines (Mrk 1383 and PKS 2005-489) above and below the Galactic center (GC). These absorptions are most straightforwardly interpreted as a wind emanating ...
Over the past three years, the Far Ultraviolet Spectroscopic Explorer (FUSE) has obtained 87 spectra of 56 low-redshift (z<0.15) active galactic nuclei (AGN). This sample comprises 53 Type 1 AGN and 3 Type 2. All the Type 1 objects show broad O VI 1034 emission; two of the Type 2s show narrow O VI emission. In addition to O VI, we also identify emission lines due to C III 977, N III 991, S IV ...
In HST/STIS optical spectra of Seyfert galaxies, there is often a bright knot of [O iii] emission in the inner NLR. In the case of the Seyfert 1 galaxy NGC 4151, we have shown that the emission-line gas may be associated with the mass outflow detected in absorption in UV spectra, which suggests that we are probing regions close to the AGN. Here we present ...
The possibility is explored that accretion on an intermediate-mass black hole contributes to the ionization of the interstellar medium of the compact blue dwarf galaxy MRK 996. Chandra observations set tight upper limits (99.7 per cent confidence level) in both the X-ray luminosity of the posited active galactic nucleus (AGN), LX(2-10 keV) < 3 � 1040 ...
We have used the Gemini Near-Infrared Integral-Field Spectrograph to map the age distribution of the stellar population in the inner 400 pc of the Seyfert 2 galaxy Mrk 1157 (NGC 591), at a spatial resolution of 35 pc. We have performed wavelet and principal component analysis on the data in order to remove instrumental signatures. An old stellar population ...
We present an analysis of the intrinsic UV absorption in the Seyfert 1 galaxy Mrk 279 based on simultaneous long observations with the ''Hubble Space Telescope'' (41 ks) and the ''Far Ultraviolet Spectroscopic Explorer'' (91 ks). To extract the line-of-sight covering factors and ionic ...
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Evidence for both red- and blue-shifted absorption lines due to ionized Fe in the X-ray spectrum of the Seyfert 1 galaxy Mrk 509 is reported. These features appear to be transient on time-scales as short as ~20 ks, and have been observed with two different satellites, BeppoSAX and XMM-Newton. The red- and blue-shifted lines are found at E�5.5 keV and ...
We analyzed EUV light curves and spectra of three Seyfert galaxies. The data were obtained from EUVE observations of the galaxies MRK 279, MRK 478 and TON S180. The variability in the light curves provides an upper limit to the size of the EUV emitting region which excludes the BLR and diffuse intercloud regions as ...
As described by Colin Lonsdale in this Workshop, VLBI observations reveal the presence of both AGN and Starburst activity in Luminous Infrared Galaxies. We highlight new results on two classical LIGs which span the range of LIG radio activity: Arp 220, which reveals luminous radio supernovae (RSN) produced in an intense starburst, and Mrk231, which has a ...
We present the results of timing analysis of XMM-Newton observations of Seyfert 2 galaxies in order to search for differences in the mean properties of Seyfert 1 galaxies and Seyfert 2 galaxies. We selected 13 Seyfert 2 galaxies from the XMM-Newton archive that have hard X-ray components in their spectra and ...
We present near-infrared (NIR) spectroscopic observations of five blue compact dwarf (BCD) galaxies, II Zw 40, Mrk 71, Mrk 930, Mrk 996, and SBS 0335-052E. The NIR spectra which cover the 0.90-2.40 ?m wavelength range show hydrogen, molecular hydrogen, helium, sulfur, and iron emission lines. The NIR data for all ...
This dissertation presents spectroscopic studies of gas in galaxy halos and large-scale structures through high-resolution quasar absorption lines. The broad goal of this effort is to learn how galaxies acquire their gas and how they return it to the intergalactic medium, or more generally, how galaxies interact with their environment. ...
The detection of X-ray emission from Mrk 180, an elliptical galaxy which has a BL Lac object embedded in its core is reported. The X-ray observations were made by the Einstein and HEAO 1 satellites. In addition, new multiaperture UBVR photometric observations are presented which were used to separate the nonthermal optical emission from the galactic ...
We present a study of the outflowing ionized gas in the resolved narrow-line region (NLR) of Mrk 78 using observations from Space Telescope Imaging Spectrograph (STIS) and Faint Object Camera (FOC) aboard the Hubble Space Telescope (HST). We determine that the double set of emission lines seen in ground based observations are due to an asymmetric distribution of outflowing gas ...
The Einstein X-ray data for the two luminous infrared galaxies, Arp 220 and Markarian 231 have been analyzed. There is an X-ray source about 1 arcmin from the position of Arp 220 that is probably associated with it. Mrk 231 was not detected. The size of the source and its soft X-ray spectrum implies that the bulk of the X-ray emission from Arp 220 cannot ...
Context. Part of the very high energy ?-ray radiation coming from extragalactic sources is absorbed through the pair production process on the extragalactic background light photons. Extragalactic magnetic fields alter the trajectories of these cascade pairs and, in turn, convert cosmic background photons to ?-ray energies by inverse Compton scattering. These secondary photons ...
We searched for evidence of soft X-ray absorption by hot gas in the vicinity of the Galaxy in a small sample of 15 type I active galactic nuclei (AGNs) observed with the high resolution X-ray gratings on board Chandra. We find that around half of the sight lines in our sample exhibit absorption due to local H- or He-like oxygen (or both) at confidence levels ranging from ...
We present a preliminary analysis of the first high-resolution X-ray spectrum of a Seyfert 2 galaxy, Markarian 3, obtained with the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory. The high-energy spectrum (?<~4 �) is dominated by reflection of the active galactic nucleus continuum radiation in a cold, optically thick medium and ...
The interpretation of the soft X-ray spectra of the Seyfert 1 galaxies, MCG-6-30-15 and Mrk 766, has remained controversial since high resolution data were first obtained with the grating instruments on Chandra and XMM-Newton, roughly one year ago. In an initial paper, Branduardi-Raymont et al. (2001), we argued that the RGS spectra of these two sources ...
Context. Blue compact dwarf (BCD) galaxies are low-luminosity, low-metal content dwarf systems undergoing violent bursts of star formation. They present a unique opportunity to probe galaxy formation and evolution and to investigate the process of star formation in a relatively simple scenario. Spectrophotometric studies of BCDs are essential to ...
We are presenting new results on kinematics and structure of the Mrk 334 Seyfert galaxy. Panoramic (3D) spectroscopy is performed at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using the integral-field Multi-Pupil Fiber Spectrograph (MPFS) and scanning Fabry-P�rot interferometer. The deep images have ...
We present 0.46--2.5 micron spectropolarimetry of four type 2 Seyfert nuclei, Mrk 463E, Mrk 1210, NGC 1068, and NGC 4388, obtained with TRISPEC (Triple Range Imager and SPECtrograph) at UKIRT. The polarizations from dust or electron scattering in ionization cones, dust scattering in a torus surrounding a type 1 nucleus, and dichroic absorption by aligned ...
We have studied the V-band variability on long and short timescales in 6 Narrow-Line Seyfert 1s (NLS1s): Ark 564, Mrk 335, Mrk 359, Mrk 478, Mrk 493, and NGC 4051. We searched for intra-night flux changes on 33 of 186 nights. Little evidence for any variability was found on an intra-night timescale, while ...
Radio and far-infrared continuum luminosities, hydrogen recombination-line luminosities, and other data were used to constrain the ionization rate, Type II supernova rate nu(SN), and bolometric luminosity of Mrk 325 and of other starburst galaxies. A new method was used to derive much lower values of nu(SN) from the nonthermal radio luminosity, thereby ...
Context. Parallel analysis of the large-scale morphology and local environment of matched active and control galaxy samples plays an important role in studies of the fueling of active galactic nuclei. Aims: We carry out a detailed morphological characterization of a sample of 35 Seyfert galaxies and a matched sample of inactive ...
The extranuclear regions of NGC 1068, 3C 120, NGC 1275, Mrk 1, and Mrk 3 have been examined spectrophotometrically. In every case gas approx.1 kpc or more from the nucleus exhibits certain spectroscopic similarities to the nucleus in terms of velocities and relative line intensities. These results strongly suggest that some sort of communication exists ...
We present EUV light curves and spectra of three Seyfert galaxies. The data were obtained from EUVE observations of the galaxies Mrk 279, Mrk 478, and Ton S180. The variability in the light curves provides an upper limit to the size of the EUV-emitting region which excludes the broad-line region and diffuse ...
We present moderate-resolution (10 A) spectropolarimetry of nine Seyfert 1 galaxies. Four of the objects are either essentially unpolarized (NGC 6212 and NGC 7469) or polarized by interstellar dust in our own Galaxy (III Zw 2 and NGC 6814). The most striking result for the remainder is that all of them show emission-line polarization and show evidence for ...
We provide new post-COSTAR data on one sightline (Mrk 421) and updated data from another (I Zw 1) from our Hubble Space Telescope (HST) survey of intergalactic Ly(alpha) clouds located along sightlines to four bright quasars passing through well-mapped ga...
We present HST/WFPC2 images, in narrowband filters containing the [O III] lambda 5007 and H alpha + [N II] emission lines and their adjacent continua, of a sample of seven Seyfert 2 galaxies selected because they possess either extended emission-line regions in ground-based observations or a hidden broad-line region in polarized light. Six of the galaxies ...
We have discovered a binary active galactic nucleus (AGN) in the galaxy Mrk 739 using Chandra and Swift BAT. We find two luminous (L 2-10 keV = 1.1 � 1043 and 1.0 � 1042 erg s�1), unresolved nuclei with a projected separation of 3.4 kpc (5farcs8 � 0farcs1) coincident with two bulge components in the optical image. The western X-ray source ...
In order to investigate the frequency of obscured broad-line regions in Seyfert 2 galaxies and the contribution such objects make to the X-ray background, we are conducting spectropolarimetric and hard X-ray surveys of a distance-limited sample of 31 nearby type 2 Seyfert galaxies. Using spectropolarimetry data obtained with the CTIO 4m and Keck 10m ...
We present new Spitzer, UKIRT, and MMT observations of the blue compact dwarf galaxy (BCD) Mrk 996, with an oxygen abundance of 12+log(O/H)=8.0. This galaxy possesses an extraordinarily dense nuclear star-forming region, with a central density of ~106 cm-3, a very red color J-K=1.8, broad- and narrow-line components, and ionizing ...
We present near-infrared (NIR) spectroscopic observations of the blue compact dwarf (BCD) galaxy Markarian 59 (Mrk 59), obtained with the TripleSpec spectrograph mounted on the 3.5 m Apache Point Observatory telescope. The NIR spectrum of Mrk 59, which covers the 0.90 ?m-2.40 ?m wavelength range, shows atomic hydrogen, molecular ...
We present an integral field spectroscopic study of the central 2 x 2 kpc{sup 2} of the blue compact dwarf galaxy Mrk 409, observed with the Potsdam MultiAperture Spectrophotometer (PMAS). This study focuses on the morphology, two-dimensional chemical abundance pattern, excitation properties, and kinematics of the ionized interstellar medium in the ...
We present near-infrared (NIR) spectroscopic observations of the blue compact dwarf (BCD) galaxy Markarian 59 (Mrk 59), obtained with the TripleSpec spectrograph mounted on the 3.5 m Apache Point Observatory telescope. The NIR spectrum of Mrk 59, which covers the 0.90 {mu}m-2.40 {mu}m wavelength range, shows atomic hydrogen, molecular ...
Previous ground-based observations of the Seyfert 2 galaxy Mrk 78 revealed a double set of emission lines, similar to those seen in several active galactic nuclei (AGNs) from recent surveys. Are the double lines due to two AGNs with different radial velocities in the same galaxy, or are they due to mass outflows from a single AGN? We ...
We report 0.8-4.5 ?m SpeX spectroscopy of the narrow-line Seyfert 1 galaxy Mrk 1239. The spectrum is outstanding because the nuclear continuum emission in the near-infrared (NIR) is dominated by a strong bump of emission peaking at 2.2 ?m, with a strength not reported before in an active galactic nucleus. A comparison of the Mrk 1239 ...
The relatively close BL Lac object, Markian 501 (z = 0.03364), has been a frequent object of research over the past decade after its outburst in 1997. The 16� Robotic Observatory for Variable Object Research (ROVOR) telescope of Brigham Young University has monitored this blazar for over 5 months, with more than 50 nights of observation in the B, V, and R bands. The purpose of the high ...
. What causes the dichotomy between very powerful and very weak radio emission from AGNs? Perhaps the engines are the same but the jets get disrupted by dense ISM in radio-quiet objects, or else the engines are intrinsically dierent with jet power scaling with, say, black hole spin. To distinguish, one can look for interaction between the jets and the NLR and measure the jet speed close to the ...
The Ly-alpha flux and the Ly-alpha/H-beta line ratio of three metal-poor blue galaxies, Mrk 496, Mrk 357, and Tol 1924-416 are analyzed here using archival IUE spectra together with new optical spectra obtained in an aperture which matches the size of the IUE aperture. Dereddened Ly-Alpha/H-beta ratios roughly constant over the range ...
. We report the detection of a new H 2 O megamaser in the Seyfert 2 galaxy Mrk 348 with the MPIfR 100 m telescope in Eelsberg. With an apparent isotropic luminosity of LH2O ' 420L the maser is the third most luminous maser discovered so far. The detected line is unusually broad (v ' 130 km s 1 ), is redshifted by 130 km s 1 from the systemic velocity, ...
Monte Carlo simulation is one of the best tools to study the complex spectra of Compton-thick active galactic nuclei (AGNs) and to figure out the relation between their nuclear structures and X-ray spectra. We have simulated X-ray spectra of Compton-thick AGNs obscured by an accretion torus whose structure is characterized by a half-opening angle, an inclination angle of the torus relative to the ...
We present a full high resolution SPIRE FTS spectrum of the nearby ultraluminous infrared galaxy Mrk 231. In total 25 lines are detected, including CO J = 5-4 through J = 13-12, 7 rotational lines of H2O, 3 of OH+ and one line each of H2O+, CH+, and HF. We find that the excitation of the CO rotational levels up to J = 8 can be accounted for by UV radiation ...
The largest catalog of strong MgII absorbers to date derived from the Sloan Digital Sky Survey (SDSS) quasar spectra was employed to describe statistical properties of absorbers and their clustering along sight lines as a function of redshift and rest-equivalent width (REW). The association of SDSS galaxies with MgII systems was ...
Active Galactic Nuclei (AGN) are among the most spectacular objects in the sky since they produce enormous amounts of energy in a tiny volume, having luminosities of L ? 10^{42} - 10^{48} erg s^{-1}. AGN emit in the continuum, as well as in the spectral lines, from ? and X-ray to the far infrared and radio domain. Their emission lines can be classified as narrow (NELs) or broad emission lines ...
Dashed lines show average rate (and +/- 1 sigma standard deviation) for this source (derived from this plot) Mrk79 Mrk 79.
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We present optical and near-infrared spectropolarimetry of the nuclei of four type 2 Seyfert galaxies, Mrk 463E, Mrk 1210, NGC 1068, and NGC 4388. The data were obtained simultaneously, covering the wavelength range of 0.46-2.5 ?m. We model the polarizations from two dust-scattering components: (1) scattering in dusty regions in ...
Multi-epoch X-ray spectroscopy (0.3-25 keV) of the Seyfert 1.2 galaxy Mrk 79 (UGC 3973) spanning nearly 8 yr and a factor of 3 in broad-band flux are analysed. The data are obtained at seven epochs with either XMM-Newton or Suzaku. Comparison with contemporaneous RXTE monitoring indicates that all flux states of Mrk 79 are represented ...
CCD images of seven active galactic nuclei were obtained during the period July 7-11 1995 with the 0.9-m telescope operated at Kitt Peak by the Southeastern Association for Research in Astronomy (SARA). Six of these objects (Mrk 335, Mrk 590, NGC 4151, NGC 5548, Mrk 817, and Mrk 509) are Seyfert ...
The velocity field in the central region of Mrk 538 is determined from image-tube spectrograms taken with the prime-focus grating spectrograph of the 6-m telescope. Noncircular gas motions are present near the position angle (150/sup 0/) of the line of nodes. The region of the galaxy interior to 1.3-kpc radius has a mass of up to 4.3 x 10/sup 9/ M/sub ...
Multiwavelength observations of IRAS 1652 + 395, an FIR and X-ray source serendipitously discovered in the field of the BL Lac object Mrk 501, are reported. They show that IRAS 1652 + 395 is a new Seyfert 1 galaxy at a redshift of z = 0.069. The Balmer emission lines are only slightly broader (1000 km/sec FWHM) than the forbidden lines, suggesting a ...
Recent sub-mm CO molecular line observations of nearby ultra-luminous IRAS galaxies, (U)LIRGs with LIR ? 1011 L&sun;, have shown that exceptionally large gas column densities (NH ? 1025 cm-2) can be present across some of the very dense gaseous disks that are typically found in these objects. In particular, Papadopoulos et al. proposed a diagnostic for finding such ...
A fundamental astrophysical question is the role of gas in galaxy evolution. Mg II absorption as observed in quasar spectra is found to arise in a broad range of gaseous galactic environments. But the overall relationship between the distribution of Mg II absorbers, their host galaxies, and the larger scale galactic structure is not ...
Context: There is growing evidence for the presence of blueshifted Fe K absorption lines in a number of radio-quiet AGNs and QSOs. These may be fundamental to probe flow dynamics near supermassive black holes. Aims: Here we aim to verify and better characterise the existence of such Fe K absorption at ~8-10 keV in the luminous Seyfert 1 galaxy Mrk 509, ...
Active Galactic Nuclei (AGNs) are among the most intriguing extragalactic sources. Notwithstanding they have been studied since several decades, their internal structure is still a matter of debate. Indeed, large efforts have been made in testing the AGNs Unified Model, since several indications seem to run against the Type 1 - Type 2 dichotomy of AGNs caused by a pure inclination effect. Other ...
The class of AGN known as Seyfert 1.8 and Seyfert 1.9 galaxies exhibit weak broad-Balmer emission lines and large Balmer decrements. One theory proposed to explain these characteristics is that the broad-line regions (BLRs) are reddened by dust along the line-of-sight. An alternative theory points out that BLR clouds with low optical depths and low ionization parameters can ...
High angular resolution observations of Arp 220 and Mrk 231 provide images of the nuclei and show that the source of the strong mid-IR emission is confined to regions less than about 0.5 arcsec or 400 pc in diameter in Mrk 231 and less than 1.5 arcsec x 0.9 arcsec or 320 x 530 pc in Arp 220. If much of the far-IR emission also derives from such a small ...
The current picture of galaxy evolution advocates co-evolution of galaxies and their nuclear massive black holes, through accretion and galactic merging. Pairs of quasars, each with a massive black hole at the centre of its galaxy, have separations of 6,000 to 300,000 light years (refs 2 and 3; 1?parsec = 3.26?light years) and ...
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The current picture of galaxy evolution advocates co-evolution of galaxies and their nuclear massive black holes, through accretion and galactic merging. Pairs of quasars, each with a massive black hole at the centre of its galaxy, have separations of 6,000 to 300,000 light years (refs 2 and 3; 1parsec = 3.26light years) and exemplify ...
The damped and sub-damped Ly? absorption (DLA and sub-DLA) line systems in quasar spectra are believed to be produced by intervening galaxies. However, the connection of quasar absorbers to galaxies is not well-understood, since attempts to image the absorbing galaxies have often failed. While ...
The damped and sub-damped Ly{alpha} absorption (DLA and sub-DLA) line systems in quasar spectra are believed to be produced by intervening galaxies. However, the connection of quasar absorbers to galaxies is not well-understood, since attempts to image the absorbing galaxies have often failed. ...
The nuclei of Seyfert 1 galaxies exhibit a range of optical polarization characteristics that can be understood in terms of two scattering regions producing orthogonal polarizations: an extended polar scattering region (PSR) and a compact equatorial scattering region (ESR), located within the circum-nuclear torus. Here we present NICMOS 2.0 ?m imaging polarimetry of six ...
We have carried out an extensive radio study with the Very Large Array on the Seyfert 1.5 galaxy Mrk 6 and imaged a spectacular radio structure in the source. The radio emission occurs on three different spatial scales, from ~7.5 kpc bubbles to ~1.5 kpc bubbles lying nearly orthogonal to them and a ~1 kpc radio jet lying orthogonal to the kpc-scale bubble. ...
We have carried out an extensive radio study with the Very Large Array on the Seyfert 1.5 galaxy Mrk 6 and imaged a spectacular radio structure in the source. The radio emission occurs on three different spatial scales: ~7.5 kpc bubbles, ~1.5 kpc bubbles lying nearly orthogonal to them, and a ~1 kpc radio jet lying orthogonal to the kiloparsec-scale ...
Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt ...
Analysis of data from the Chandra X-ray Observatory for the double nucleus ULIRG Mrk 273 reveals an absorbed hard X-ray source coincident with the southwest nucleus, implying that this unresolved, near-infrared source is where an active nucleus resides, while the northern nuclear region contains a powerful starburst that dominates the far infrared ...
Four Chandra High Energy Transmission Grating spectra of Mrk 290, a bright Seyfert 1, were carried out in 2003 with a total integration time of 251 ks. The nuclear X-ray spectrum is best described by a absorbed power law of photon index ? 1.83 plus a black body model with a temperature of 90 eV. Using the combined spectra, we detect significant ...
Using the Effelsberg 100-m telescope, detections of four extragalactic water vapor masers are reported. Isotropic luminosities are ~50, 1000, 1 and 230 L? for Mrk 1066 (UGC 2456), Mrk 34, NGC 3556 and Arp 299, respectively. Mrk 34 contains by far the most distant and one of the most luminous water vapor megamasers so far reported in a ...
NGC 4945 is one of the brightest Se.yfert galaxies on the sky at 100 keV, but is completely absorbed
Blueshifted absorption lines in the UV and X-ray spectra of active galaxies reveal the presence of massive outflows of ionized gas from their nuclei. The intrinsic UV and X-ray absorbers show large global covering factors of the central continuum source, ...
We present the results of observations of the extended emission-line region of the Seyfert 2 galaxy Mrk 573, obtained using the WFPC2 on board HST and the TIGER integral field spectrograph on the CFHT. We describe and use a new `guided' deconvolution technique in which the spatial resolution of the TIGER data cubes is improved, allowing us to obtain the ...
In this paper we present the first results of a study of BAL QSOs (at low and high redshift), based on very deep Gemini GMOS integral field spectroscopy. In particular, the results obtained for the nearest BAL IR-QSO Mrk 231 are presented. For the nuclear region of Mrk 231, the QSO and host galaxy components were modelled, using a new ...
The last years have seen a revolution in ground-based gamma-ray detectors. We can now detect the spectra of nearby TeV blazars like Mrk 421 and Mrk 501 out to ~20 TeV, and during the strongest flares, we can now follow fluctuations in these spectra on timescales close to the shortest ones likely in these objects. We point out that this represents a unique ...
We investigate the origin of the soft X-ray excess emission from Ark 564 and Mrk 1044. Based on a long XMM-Newton observation of Ark 564, we find clear evidence for time delays such that the variations in the 4-10 kev band lag behind that in the 0.2-0.5 kev band by 1768+/-122 s. The full-band power density spectrum (PDS) of Ark 564 has a break at ~1.2�1-3 Hz with power-law ...
Context: While there is growing consensus on the existence of numerous dust-enshrouded red quasars, their discovery and detailed exploration is still an observational challenge. In the course of the near-mid-infrared AGN search combining the 6.7 ?m ISOCAM Parallel Survey and 2MASS we have discovered 24 type-1 quasars about a third of which are too red to be discriminated by optical/UV search ...
We investigate the relative distribution of the gaseous contents of the Universe (as traced by a sample of Ly{alpha} absorbers), and the luminous baryonic matter (as traced by a redshift survey of galaxies in the same volume searched for Ly{alpha} absorbers), along 16 lines of sight (LOS) between redshifts 0 and 1. Our ...
The spectral energy distribution (SED) of the absorbed and unabsorbed objects are very different and so is their ratio of x-ray to total luminosity ...
... Subject Category: ACTIVE GALAXIES AND QUASARS Abstract: Photoionized, warm absorbing gas is an important component of the nuclear structure of AGN. ...
Jan 10, 2011 ... The detailed observations needed to see DIBs along a straight line ... which wavelengths are absorbed by all kinds of atoms and molecules. ...
Context. The oxygen and nitrogen-to-oxygen abundances relation is characterized by a plateau around log(N/O) = -1.6 at metallicities lower than 12+log(O/H) ~ 8.25. However, there is a subset of blue compact dwarf galaxies (BCDs) with unexpectedly high N/O values. Aims: We want to study the spatial distribution of the physical properties and of oxygen and nitrogen abundances ...
We describe recent discoveries of low column density (NHI = 1012.5-16.0 cm-2) H I Ly? absorbers made with the Hubble Space Telescope (HST) which have allowed us a first look at gas in local intergalactic space; i.e., between us and the "Great Wall". These absorbing clouds account for 29 � 4% of all baryons at z=0 and are, in general, only loosely related ...
We have mapped the stellar and gaseous kinematics, as well as the emission-line flux distributions and ratios, from the inner ?450 pc radius of the Seyfert 2 galaxy Mrk 1157, using two-dimensional near-infrared J- and Kl-band spectra obtained with the Gemini Near-Infrared Integral-Field Spectrograph instrument at a spatial resolution of ?35 pc and velocity ...
The CO(2-1) and CO(1-0) emission from four infrared-luminous galaxies, Arp 193, Arp 220, Mrk 231, and VII Zw 31, was mapped with the IRAM 30 m telescope. These maps show the molecular gas is concentrated in the central regions. The CO(2-1)/CO(1-0) brightness temperature ratio for these galaxies is low, 0.6-0.75, indicating the CO is ...
Simultaneous multifrequency observations of the BL Lac object Mrk 421 covering radio through X-ray wavelengths were performed on two occasions separated by 5 weeks in January and March 1984, and each observation was coordinated for about 1 week. Composite multifrequency spectra of the central nonthermal component were obtained at the two epochs after subtracting the optical ...
In recent years, an extremely successful method to study galaxy formation and evolution, has been provided by observation of quasar absorbers. Quasar absorbers are systems intercepting our line-of-sight to a given quasar and thus produce a feature in the quasar spectrum, the so-called absorption lines. The Damped Lyman-a (DLA) and ...
Optical emission-line profiles were evaluated in order to explore the structure of galactic nuclei containing H2O megamaser sources. Long-slit spectra of IC 2560, NGC 1386, NGC 1052 and Mrk 1210 were obtained at ~ 100 km s-1 spectral and ~ 2arcsec x 2 arcsec spatial resolution. The following individual properties of the objects were found: The active nucleus of IC 2560 ...
We present the analysis of the large population of star clusters in the blue compact galaxy (BCG) Mrk 930. The study has been conducted by means of a photometric analysis of multiband data obtained with the Hubble Space Telescope (HST). We have reconstructed the spectral energy distributions of the star clusters and estimated the age, mass and extinction ...
Signatures of warm absorbers are seen in soft X-ray spectra of about half of all Seyfert1 galaxies observed and in some quasars and blazars. We use the thermal equilibrium curve to study the influence of the shape of the ionizing continuum, density and the chemical composition of the absorbing gas on the existence and nature of the ...
We study the distribution and nature of neutral hydrogen in various environments. We start by exploring the disk and halos of galaxies in Chapter 1. Our sample consists of 23 sightlines through 15 low-redshift foreground galaxy - background quasar pairs with impact parameters ranging from 1.7 kpc up to 86.7 kpc. We detected one ...
Physical dust models are presented for 65 galaxies in SINGS that are strongly detected in the four IRAC bands and three MIPS bands. For each galaxy we estimate (1) the total dust mass, (2) the fraction of the dust mass contributed by PAHs, and (3) the intensity of the starlight heating the dust grains. We find that spiral galaxies have ...
We will present first results of ESO-VLT AO-assisted integral-field spectroscopy of a sample of X-ray bright AGN with redshifts of 0.04 < z < 1. We constructed this sample by cross-correlating the SDSS and ROSAT surveys and utilizing typical AO constraints. This sample allows for a detailed study of the NIR properties of the nuclear and host environments with high spectral resolution on the ...
We present new results on the research of isolated AGNs and quasars which are located in regions with the low density environment. Our sample of AGNs was compiled at the basis of the 2MIG Catalog (2MASS Isolated Galaxies, Karachentseva et al., Bull. SAO RAS, 2010) and Catalog of AGNs by Veron+ 2006. The 2MIG Catalog' galaxies (N=3227) were chosen by ...
We have obtained 8--18microns images of the Luminous Infrared Galaxies (LIGs) Mrk 231, Arp 220 & NGC 7469 with the UCSD Long Wavelength Imaging Spectrometer (LWS; and Puetter, 1993, Proc. S.P.I.E., 1946, pp. 610-621) on the W. M. Keck Telescope. Pixon-based image reconstruction techniques (Puetter, 1995, Int. J. Image Sys. & Tech., 6, pp. 314-331) ...
We present K-band imaging of fields around 30 strong CaII absorption-line systems, at 0.7 < z < 1.2, three of which are confirmed damped Lyman ? systems. A significant excess of galaxies is found within 6.0 arcsec (~=50kpc) from the absorber line of sight. The excess galaxies are preferentially luminous compared to the population ...
We present an H I 21 cm absorption survey with the Green Bank Telescope (GBT) of galaxy-quasar pairs selected by combining galaxy data from the Sloan Digital Sky Survey (SDSS) and radio sources from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey. Our sample consists of 23 sight lines through 15 low-redshift foreground ...
NGC 4945 is one of the brightest Se.yfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV, implying an optical depth of the absorber to electron scattering of a few; its absorption column is probably the largest which still allows ...
A complete picture of galaxy formation can only be obtained by detailed study of the processes by which galaxies convert their gas into stars. One approach is to relate the H I gas and the stars in galaxies. Damped and sub-damped Lyman-? systems (DLAs), which are galaxies probed by the absorption they produce in ...
Detecting HI using redshifted Ly? absorption lines is ~106 times more sensitive than using the 21 cm emission line. We review recent discoveries of HI Ly? absorbers made with the Hubble Space Telescope (HST) which have allowed us a first glimpse at gas in local intergalactic space between us and the ``Great Wall.'' Despite its mere 2.4 m aperture, HST can detect ...
Observations of H2O masers from circumnuclear disks in active galaxies for the Megamaser Cosmology Project (MCP) allow accurate measurement of the mass of supermassive black holes (BH) in these galaxies. We present the Very Long Baseline Interferometry images and kinematics of water maser emission in six active galaxies: NGC 1194, NGC ...
We present a study of the average properties of luminous infrared galaxies detected directly at 24 �m in the COSMOS field using a median stacking analysis at 70 �m and 160 �m. Over 35000 sources spanning 0
We present a study of the average properties of luminous infrared galaxies detected directly at 24 ?m in the COSMOS field using a median stacking analysis at 70 ?m and 160 ?m. Over 35,000 sources spanning 0 <= z <= 3 and 0.06 mJy <=S 24 <= 3.0 mJy are stacked, divided into bins of both photometric redshift and 24 ?m flux. We find no correlation of S 70/S 24 flux ...
It has been claimed in the past that in low-metallicity Blue Compact Dwarf (BCDs) galaxies, the N/O value is independent of metallicity (O/H ratio), implying the need to invoke a primary production of nitrogen in intermediate-mass stars, in addition to the secondary nitrogen produced from the CNO cycle in high-mass stars. In order to better understand this controversial issue ...
The soft X-ray background shows a general enhancement toward the inner region of the Galaxy. But whether this enhancement is a local feature (e.g., a superbubble within a distance of <~200 pc) and/or a phenomenon related to energetic outflows from the Galactic center/bulge remains unclear. Here we report a comparative X-ray emission and absorption study of diffuse hot gas ...
We report the results of three-dimensional spectroscopic observations of Mrk 493 (narrow-line Seyfert 1 galaxy) with the integral-field spectrograph MultiPupil Fiber Spectrograph of the Special Astrophysical Observatory of the Russian Academy of Sciences 6 m telescope. The difference in the slope of the optical continuum emission intensity across the ...
The soft X-ray background shows a general enhancement toward the inner region of the Galaxy. But whether this enhancement is a local feature (e.g., a superbubble within a distance of 200 pc or a phenomenon related to energetic outflows from the Galactic center/bulge remains unclear. Here we report a comparative X-ray emission and absorption study of diffuse hot gas along the ...
The properties of three BL Lacertae objects, namely Mrk 180, Mrk 421, and Mrk 501, were investigated using data gathered at UV, X-ray, optical, and radio wave lengths. From each time frozen spectrum an inhomogeneous, relativistic jet model was computed. It is noted that the UV is the one spectral region where synchrotron emission is ...
The Herschel survey, H-ATLAS, with its large areal coverage, has recently discovered a number of bright, strongly lensed high-z submillimeter galaxies. The strong magnification makes it possible to study molecular species other than CO, which are otherwise difficult to observe in high-z galaxies. Among the lensed galaxies already ...
We present deep ground based imaging of the environments of five quasi-stellar objects (QSOs) that contain sub-damped Lyman ? (sub-DLA) systems at z < 1 with the Southern Observatories Astrophysics Research (SOAR) telescope and SOAR Optical Imager (SOI) camera. We detect a clear surplus of galaxies in these small fields, supporting the assumption that we are detecting the ...
We study the cool gas around a galaxy at z = 0.4729 using Keck/LRIS spectroscopy of a bright (B = 21.7) background galaxy at z = 0.6942 at a transverse distance of 16.5h {sup -1}{sub 70} kpc. The background galaxy spectrum reveals strong Fe II, Mg II, Mg I, and Ca II absorption at the redshift of the foreground ...
We present a spectral analysis of the X-ray Chandraof the Seyfert 1 Galaxy NGC 5548. The warm absorber present in this object was modeled with the code PHASE. We detected two different outflow velocity systems in this source. One of the absorbing systems has outflow velocity of -1091+/-63 km s(-1) and the other of -568+/-49 km s(-1) . ...
In the standard scenario for galaxy evolution young star-forming galaxies transform into red bulge-dominated spheroids, where star formation has been quenched. To explain this transformation, a strong negative feedback generated by accretion onto a central super-massive black hole is often invoked. The depletion of gas resulting from quasar-driven outflows ...
We study the connections between ongoing star formation, galaxy mass, and extended halo gas, in order to distinguish between starburst-driven outflows and infalling clouds that produce the majority of observed Mg II absorbers at large galactic radii (gsim10 h -1 kpc) and to gain insights into halo gas contents around galaxies. We ...
We compare the kinematics and absorption properties of a sample of 30 strong MgII absorbers at z<1 to their host galaxy impact parameters and luminosities. The MgII absorption properties are derived from high resolution quasar spectra from the HIRES/Keck and UVES/VLT public archives. The host galaxy properties come from the larger ...
Monitor of all-sky X-ray Image (MAXI) was designed to be capable of monitoring variability of a medium-sized sample of active galactic nuclei. We examine current reliability of the MAXI light curves. As of October 2010, the light curves of more than forty sky regions of AGN are available at the MAXI web page, http://maxi.riken.jp/. Except for obvious flux changes of bright AGN (for example, those ...
Results are reported for OSO 8 and HEAO 1 X-ray observations of the BL Lac objects Mrk 421, Mrk 501,
This research focuses on understanding the formation and evolution of galaxies via their extended gaseous halos using the methods of quasar absorption line systems. Galaxy-absorber pairs provide direct observational constraints on competing scenarios aimed at establishing the role of gas in galaxy formation and evolution. Our sample ...
Galaxies must continuously accrete gas from the intergalactic medium in order to sustain their observed star formation rates. How this accretion proceeds is a fundamental problem in galaxy formation, as it determines how rapidly galaxies can grow as a function of mass and redshift, as well as the efficiency of feedback processes. While ...
Abstract. We present the results of a survey of galaxies selected by their gas cross-section which give rise to Mg ii absorption lines in the spectra of background quasars. The sample comprises 11 galaxies covering the redshift range 0.7
We present results from two projects in which we have used the HI 21cm emission line as a tracer of gas-rich galaxy populations in the vicinity of Lyman-? absorbers. In the first case, we examine the HI environment of sbs 1543+593, the nearest damped Lyman-? absorber. We use a vla map of the region around this lsb ...
We present stellar and gaseous kinematics of the inner ?350-pc radius of the Seyfert galaxy Mrk 1066 derived from J and Kl bands data obtained with the Gemini's Near-Infrared Integral Field Spectrograph (NIFS) at a spatial resolution of ?35 pc. The stellar velocity field is dominated by rotation in the galaxy plane but shows an S-shape ...
We report results from a survey of Mg II absorbers in the spectra of background quasi-stellar objects (QSOs) that are within close angular distances to a foreground galaxy at z < 0.5, using the Magellan Echellette Spectrograph. We have established a spectroscopic sample of 94 galaxies at a median redshift of langzrang = 0.24 in ...
Context. Narrow-line Seyfert 1 (NLS1) galaxies are a class of active galactic nuclei (AGN) that have all the properties of type 1 Seyfert galaxies but show peculiar characteristics, including the narrowest Balmer lines, strongest Fe II emission, and extreme properties in the X-rays. Line and continuum radio observations provide an optimal tool to access ...
We argue that most strong intervening metal absorption line systems, where the rest equivalent width of the Mg II ?2796 line is >0.5 �, are interstellar material in, and outflowing from, star-forming disks. We show that a version of the Kennicutt-Schmidt law is readily obtained if the Mg II equivalent widths are interpreted as kinematic broadening from absorbing gas in ...
r is like a "fog," and would therefore provide a simpler explanation for the microwave radiation, including its blackbody-shaped spectrum. Such a fog also explains the otherwise troublesome ratio of infrared to radio intensities of radio galaxies. [7] The amount of radiation emitted by distant galaxies falls with increasing wavelengths, as expected if ...
We examine the properties of two galaxy ``halos'' at z~0.7 in the Ton 153 (zem=1.01) quasar field. The first absorber-galaxy pair (G1) is a z=0.672, LB=4.3L*B, E/S0 galaxy probed at D=58 kpc. G1 is associated with a remarkable five-component Ly? complex having ?LL<=0.4, Wr(Ly?)=2.8 �, and a velocity spread of ?v=1420 km s-1. We ...
We present the results of a study on the optical and X-ray variability properties of eight Seyfert galaxies NGC 5548, NGC 7469, NGC 4051, NGC 4151, NGC 3227, Ark 564, Mrk 509, Mrk 79. Two objects, NGC 5548 and NGC 4051, show the highest probability for the positive lag (i.e., optical variations lag behind the X-ray) at about 97% ...
We methodically model the broad-band Suzaku spectra of a small sample of six 'bare' Seyfert galaxies: Ark 120, Fairall 9, MCG -02-14-009, Mrk 335, NGC 7469 and SWIFT J2127.4+5654. The analysis of bare Seyferts allows a consistent and physical modelling of active galactic nuclei due to a weak amount of any intrinsic warm absorption, removing the degeneracy ...
MgII QSO absorption lines detected in the spectra of background QSOs were used over a decade ago to infer that all redshift z > 0.2 galaxies have gaseous halos of radius ~ 60 kpc. The actual size of the halo was believed to be proportional to the luminosity of the galaxy. However, these conclusions are now much harder to understand in light of the ...
A substantial fraction of the distant absorbed AGNs detected in the Chandra Deep Fields (CDFs) lack optical evidence of nuclear activity in follow-up observations. However, it remains unclear whether the differences between nearby and distant AGNs are real or largely apparent in nature. Samples of of these objects are assembled in very different ways, which affects the ...
The jet of the radio galaxy M87 is misaligned, resulting in a Doppler factor ? ~ 1 for emission of plasma moving parallel to the jet. This makes the observed fast TeV flares on time-scales of tv ~ 5Rg/c harder to understand as emission from the jet. In previous work, we have proposed a jets-in-a-jet model for the ultrafast TeV flares with tv << Rg/c seen in ...
We search for a direct signature of discrete ``clouds`` in the broad line region (BLR) of the Seyfert galaxy NGC 4151. For this purpose we apply cross correlation (CC) analysis to a high resolution KECK spectrum of the galaxy. No such signature is found in the data. In order for cloud models to be compatible with this result, there must be at least ...
Aims. We study the dust properties of four low metallicity galaxies by modelling their spectral energy distributions. This modelling enables us to constrain the dust properties such as the mass, the temperature or the composition to characterise the global ISM properties in dwarf galaxies. Methods: We present 870 ?m images of four low metallicity ...
There exists a population of broad-line z~2 QSOs which have heavily absorbed X-ray spectra. These objects constitute ~10% of the population at luminosities and redshifts characteristic of the main producers of QSO luminosity in the Universe. Our follow up observations in the submm show that these QSOs are often embedded in ultraluminous starburst galaxies, ...
We present H I synthesis array mapping and CCD photometry in B and R for MCG+00-32-16. The H I disk
It has been known since the early 1940's that radiation can cause an instability in the interstellar medium. Absorbing dust particles in an isotropic radiation field shadow each other by a solid angle which is inversely proportional to the square of the d...
We present results from a search for galaxies that give rise to damped Lyman ? (DLA), sub-DLA and Lyman limit system (LLS) absorption at redshifts 0.1 ?z? 1 in the spectra of background quasars. The sample was formed from a larger sample of strong Mg II absorbers (W?27960? 0.3 �) whose H I column densities were determined by measuring the Ly? line in ...
Context. For the evolution of large-scale structures in the Universe, it is unclear whether active galaxies represent a phase that each galaxy undergoes, and whether and to which extent the evolution of black holes at their centers is important. Binary black hole (BBH) systems may play a key role in our understanding of the above questions. Aims: We ...
According to the unified scheme of AGN, the central engine, a supermassive black hole surrounded by an accretion disc, is embedded in a toroidal dusty structure. Orientation effects lead to the Seyfert 1 / Seyfert 2 dichotomy. Single dish telescopes fail to provide the necessary resolution to resolve the circumnuclear dusty torus, the key component in this picture. We have observed four ...
We present submillimetre (submm) and mid-infrared (MIR) imaging observations of five fields centred on quasi-stellar objects (QSOs) at 1.7< z<2.8. All five QSOs were detected previously at submm wavelengths. At 850 (450) m, we detect 17 (11) submillimetre galaxies (SMGs) in addition to the QSOs. The total area mapped at 850 m is arcmin2 down to rms noise levels of 1-2 ...
Strong foreground absorption features from singly ionized magnesium (Mg II) are commonly observed in the spectra of quasars and are presumed to probe a wide range of galactic environments. To date, measurements of the average dark matter (DM) halo masses of intervening Mg II absorbers by way of large-scale cross-correlations with luminous galaxies have ...
Absorption lines in quasar spectra allow us to locate and study intervening galaxies. In order to obtain a clearer picture of these absorber galaxies, we have used the Near-Infrared Camera Fabry-Perot System at Apache Point Observatory to obtain near-infrared broadband images in one or more filters (J and Ks ) of six quasar fields ...
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 greater than or equal to 10(exp 3...
�galactic background light (EBL) is necessary for studies of star and galaxy formation. However, measurement of the EBL in the Milky Way Galaxy. Very high energy (VHE) photons are absorbed by the EBL via pair production. For those observed[12]. This can be interpreted as scattering of VHE photons off the EBL at higher energies
The spectrum of the low-redshift QSO PG0953+415 shows two strong, intervening O VI absorption systems. To study the nature of these absorbers, we have used the Gemini Multiobject Spectrograph to conduct a deep spectroscopic galaxy redshift survey in the 5' x 5' field centered on the QSO. This survey is fully complete for r' < 19.7 and is 73% complete ...
Aims: We present results of an intensive spectroscopic variability campaign of the very broad-line Seyfert 1 galaxy Mrk 926. Our aim is to investigate the broad-line region (BLR) by studying the intensity and line profile variations of this galaxy on short timescales. Methods: High signal-to-noise ratio (S/N) spectra were taken with ...
We have mapped the stellar and gaseous kinematics, as well as the emission-line flux distributions and ratios, from the inner 450pc radius of Mrk1157, using 2D near-IR spectra obtained with the Gemini NIFS at a spatial resolution of 35pc. The stellar velocity field shows a rotation pattern, with a discrete S-shaped zero velocity curve. The presence of a bar is also supported ...
I discuss the discovery of a population of extremely luminous, but very dusty and very distant, galaxies in the submillimetre (submm) waveband. Almost all the light emitted by the stars in these galaxies is absorbed by interstellar dust (which is produced by the same stars) and re-radiated in the far-infrared. This leaves little to be ...
by absorbing the light they emit. Dust then reradiates the absorbed light in the infrared, the heat you feel." (after J.R.R. Tolkien) Galaxies are bright islands of light in the sea of darkness that is our Universe. They come in a wild variety of shapes, sizes and colors but can be grouped into a series of families
, less massive stars (but still radiating in the ultraviolet) are gone, and so on. As the population, or ultraviolet) into unhealthy wine (red, or infra- red). Dust absorbs the ultraviolet radiation from the massive, where the ultraviolet is being absorbed and re- radiated entirely in the infrared
We propose a 100 ks observation of the Seyfert 2 galaxy NGC4388 in the Virgo cluster. The presence of spectacular optical emission-line nebula extending up to 35 kpc has been known for this galaxy. While soft X-ray emission appears to be associated with the optical filaments, as suggested by the previous Chandra and Suzaku observations, the details of the ...
Aims.We present photoionization calculations for the spatially-extended absorbers observed in front of the extended emission-line spectrum of two high-redshift radio galaxies, 0943-242 (z_e=2.922) and 0200+015 (z_e=2.230), with the aim of reproducing the absorber column ratio, N_CIV/N_HI. Methods: .We explore the effects of using ...
Recent theoretical and observational studies show that most of the extremely bright submillimeter galaxies (SMGs) at wavelengths larger than 500 ?m are lensed by foreground objects. By targeting lensed objects, we can study the typical properties of the star forming galaxies in the early Universe that would otherwise be inaccessible in a blank survey due ...
I briefly describe a simple routine for emission-line profile fitting by Gaussian curves or Gauss-Hermite series. The profit (line- profile fitting) routine represent a new alternative for use in fits data cubes, as the ones from Integral Field Spectroscopy or Fabry-P�rot Interferometry, and may be useful to better study the emission-line flux distributions and gas kinematics in distinct ...
We present photometric and spectroscopic observations of two luminous blue variable (LBV) stars in two extremely metal-deficient blue compact dwarf (BCD) galaxies, DDO 68 with 12 + log (O/H) = 7.15 and PHL 293B with 12 + log (O/H) = 7.72. These two BCDs are the lowest-metallicity galaxies where LBV stars have been detected, allowing the study of the LBV ...
We present a physical model for the origin of z ~ 2 dust-obscured galaxies (DOGs), a class of high-redshift ultraluminous infrared galaxies (ULIRGs) selected at 24?m which are particularly optically faint (F24?m/FR > 1000). By combining N-body/smoothed particle hydrodynamic simulations of high-redshift galaxy evolution with 3D ...
The Cosmic Origins Spectrograph (COS) was installed aboard the Hubble Space Telescope (HST) in May 2009 and is functioning nominally (see Fig. 1). The unprecedented far-UV throughput of COS (20-30 times that of STIS at R ~ 20,000) will revolutionize many studies, including the investigation of the local intergalactic medium (IGM). In particular, COS will allow us to refine estimates of the baryon ...
The Cosmic Origins Spectrograph (COS) will be installed aboard the Hubble Space Telescope (HST) in 2009. The unprecedented far-UV throughput of COS (20-30 times that of STIS at R ~ 20,000) will revolutionize many studies, including the investigation of the local intergalactic medium (IGM). In particular, COS will allow us to refine estimates of the baryon content and metallicity of the IGM, as ...
The Cosmic Origins Spectrograph (COS) will be installed aboard HST in August, 2008. The unprecedented far-UV throughput of COS (20-30 times that of STIS at R ~ 20,000) will revolutionize many studies, including the investigation of the local intergalactic medium (IGM). In particular, COS will allow us to refine estimates of the baryon content and metallicity of the IGM, as well as the relationship ...
The Mg II (lambda)(lambda) 2796, 2803 doublets are among the absorption features commonly seen in the spectra of distant quasars. These absorbers arise primarily in photo-ionized halo gas around foreground galaxies. We propose to use MagE on the Magellan Clay telescope to observe 20 QSOs that are within ~ 100 h^-1 kpc projected distances of a foreground ...
