Browsing by Author "Arav, Nahum"
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- 10 kpc Scale Seyfert Galaxy Outflow: HST/COS Observations of IRAS F22456-5125Borguet, Benoit C. J.; Edmonds, Douglas; Arav, Nahum; Dunn, Jay; Kriss, Gerard A. (IOP Publishing Ltd., 2012-06)We present analysis of the UV spectrum of the low-z AGN IRAS F22456-5125 obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The spectrum reveals six main kinematic components, spanning a range of velocities of up to 800 km s (1), which for the first time are observed in troughs associated with C II, C IV, N V, Si II, Si III, Si IV, and S IV. We also obtain data on the O VI troughs, which we compare to those available from an earlier Far Ultraviolet Spectroscopic Explorer epoch. Column densities measured from these ions allow us to derive a well-constrained photoionization solution for each outflow component. Two of these kinematic components show troughs associated with transitions from excited states of Si II and C II. The number density inferred from these troughs, in combination with the deduced ionization parameter, allows us to determine the distance to these outflow components from the central source. We find these components to be at a distance of similar to 10 kpc. The distances and the number densities derived are consistent with the outflow being part of a galactic wind.
- Absolute Flux Density Measurement and Associated Instrumentation for Radio Astronomy below 100 MHzTillman, Richard Henry (Virginia Tech, 2016-08-23)This dissertation reports new measurements of the absolute flux densities of the brightest astrophysical sources visible from the northern hemisphere with O[10%] accuracy between 30-78 MHz. These measurements provide additional confidence in the existing understanding of the flux density spectra of these sources in this frequency range. This dissertation also reports new measurements of the antenna temperature due to the diffuse Galactic background between 30-78 MHz, addressing a paucity of existing measurements in this band. These measurements are relevant especially in the context of contemporary interest in radio astronomy and 21 cm cosmology in this frequency range. A new active antenna system and measurement technique were developed to facilitate these measurements. The antennas are simple, thin dipoles, allowing for accurate characterization. Amplification is preceded by notch filters to mitigate interference induced non-linearity. Previous efforts have used well matched antennas. The narrowband antennas and notch filters on the front end create large, frequency varying impedance mismatch that must be accounted for, and we demonstrate how this can be done. We present a novel in situ technique that uses the antenna temperature measurements to improve the calibration of the antennas and internal noise sources.
- An Arcminute-Resolution Imaging Study of the H-alpha & [S II] Emission of the ISM from the Local Perseus Arm Using the Virginia Tech Spectral-Line SurveyNelson, Keith Phillip (Virginia Tech, 2011-08-08)The Virginia Tech Spectral-Line Survey (VTSS) is a series of 10-degree wide, arcminute-resolution images of the warm ionized interstellar medium (WIM) within the Milky Way for declinations greater than -15 degrees. The Wisconsin Hydrogen-Alpha Mapper (WHAM) studies the kinematics and distribution of this same material on an angular scale of one degree. Comparing the spatially-resolved images of the VTSS with WHAM's high spectral resolution images shows that the ISM's characteristics appear to be very similar at both degree and arcminute scales --- we see similar structures, and notice the same [S II]/H-alpha trend between those structures at both degree and arcminute scales. VTSS fields show three basic types of structures --- compact clouds with diameters greater than several degrees, those that are 1-degree or less in diameter, and extended filaments that differ from the clouds by spanning several degrees in length but having thicknesses of only a few tens of arcminutes. The latter two morphological types cannot be observed by WHAM. Additionally, VTSS data confirms that the [S II] intensity values are directly proportional to H-alpha intensities, a result that is also observed at degree resolutions. Finally, VTSS data show that [S II]/H-alpha ratios are, on average, nearly six times higher in the filaments. This would indicate that collisional excitation of singly-ionized sulfur ions is the dominant emission source within filaments. In clouds, the lower [S II]/H-alpha values observed are evidence that the H-alpha recombination line of photo-excited neutral hydrogen dominates. Because automating the VTSS was a key part of obtaining many of the images used in this project, I begin with a discussion of general observatory automation. I then address the specific processes and techniques used in automating the VTSS before discussing data collection and reduction techniques.
- BAL outflow contribution to AGN feedback: frequency of S IV outflows in the SDSSDunn, Jay P.; Arav, Nahum; Aoki, Kentaro; Wilkins, Ashlee; Laughlin, Courtney; Edmonds, Douglas; Bautista, Manuel (IOP Publishing Ltd., 2012-05)We present a study of broad absorption line (BAL) quasar outflows that show S IV lambda 1063 and S IV* lambda 1073 troughs. The fractional abundances of S IV and C IV peak at similar value of the ionization parameter, implying that they arise from the same physical component of the outflow. Detection of the S IV* troughs will allow us to determine the distance to this gas with higher resolution and higher signal-to-noise spectra, therefore providing the distance and energetics of the ubiquitous C IV BAL outflows. In our bright sample of 156 SDSS quasars, 14% show C IV and 1.9% S IV troughs, which are consistent with a fainter magnitude sample with twice as many objects. One object in the fainter sample shows evidence of a broad S IV trough without any significant trough present from the excited state line, which implies that this outflow could be at a distance of several kpc. Given the fractions of C IV and S IV, we establish firm limits on the global covering factor on S IV that ranges from 2.8% to 21% (allowing for the k-correction). Comparison of the expected optical depth for these ions with their detected percentage suggests that these species arise from common outflows with a covering factor closer to the latter.
- BAL phosphorus abundance and evidence for immense ionic column densities in quasar outflows: vlt/x-shooter observations of quasar SDSS J1512+1119Borguet, Benoit C. J.; Edmonds, Douglas; Arav, Nahum; Benn, C.; Chamberlain, Carter (IOP Publishing Ltd., 2012-10)We present spectroscopic analysis of the broad absorption line (BAL) outflow in quasar SDSS J1512+1119. In particular, we focus our attention on a kinematic component in which we identify P V and S IV/S IV* absorption troughs. The shape of the unblended phosphorus doublet troughs and the three S IV/S IV* troughs allow us to obtain reliable column density measurements for these two ions. Photoionization modeling using these column densities and those of He I* constrain the abundance of phosphorus to the range of 0.5-4 times the solar value. The total column density, ionization parameter, and metallicity inferred from the P V and S IV column densities lead to large optical depth values for the common transition observed in BAL outflows. We show that the true C IV optical depth is similar to 1000 times greater in the core of the absorption profile than the value deduced from its apparent optical depth.
- Core-collapse supernovae: neutrino-dark matter phenomenology and probes of internal physicsHeston, Sean MacDonald (Virginia Tech, 2024-05-08)The standard model of particle physics cannot currently explain the origin of neutrino masses and anomalies that have been observed at different experiments. One solution for this is to introduce a beyond the standard model origin for these issues, which introduces a coupling between neutrinos and dark matter. Such an interaction would have implications on cosmology and would be constrained by astrophysical neutrino sources. A promising astrophysical source to probe this interaction is core-collapse supernovae as they release ~3x10^53 erg in neutrinos for each transient. However, more observations that constrain the internal physics of core-collapse supernovae are needed in order to better understand their neutrino emission. This dissertation studies two probes of internal physics that allow for a better understanding of the neutrino emission from core-collapse supernovae. The first is a novel approach to try and detect more supernova neutrinos that do not come from galactic events nor from the diffuse supernova background. This is accomplished by doing an offline timing coincidence search at neutrino detectors with a search window determined by optical observations of core-collapse supernovae. With a two-tank Hyper-Kamiokande, this allows for ~1 neutrino detection every 10 years with a confidence level of ~2.6 sigma, resulting from low nearby core-collapse rates and large background rates in the energy range of interest. The second probe of internal physics is high energy gamma-rays from the decays of unstable nuclei in proto-magnetar jets. The abundance distribution of the unstable nuclei depends directly on the neutrino emission, which controls the electron fraction, as well as properties of the proto-magnetar. We find that different proto-magnetar properties produce gamma-ray signals that are distinguishable from each other, and multiple types of observations allow for estimations of the jet and proto-magnetar properties. These gamma-ray signals are detectable for on-axis jets out to extragalactic distances, ~35 Mpc in the best case, and for off-axis jets the signal is only detectable for galactic or local galaxies depending upon the viewing angle. This dissertation also studies a phenomenological constraint on the interactions between neutrinos and dark matter. Using the neutrino emission from supernovae and the inferred dark matter distributions in Milky Way dwarf spheroidals, we constrain the amount of energy the neutrinos can inject into the dark matter sub-halos. This then allows a constraint on the interaction cross-section between neutrinos and dark matter with assumptions about the interaction kinematics. Assuming Lambda-CDM to be correct, the neutrinos cannot interact with low mass dark matter too often as it will become gravitationally unbound, changing the mass of the core we see today. For high mass dark matter, neutrinos can only inject a fraction of ~6.8x10^-6 of their energy in order to not conflict with estimates of the current shapes of the dark matter sub-halos. The constraints we obtain are sigma_nu-DM(E_nu=15 MeV, m_DM>130 GeV) ~ 3.4x10^-23 cm^2 and sigma_nu-DM(E_nu=15 MeV, m_DM <130 GeV) ~ 3.2x10^-27} (m_DM/1 GeV)^2 cm^2, which is slightly stronger than previous bounds for these energies. Consideration of baryonic feedback or host galaxy effects on the dark matter profile can strengthen this constraint.
- Experiments on the Thermal, Electrical, and Plasmonic Properties of Nanostructured MaterialsMyers, Kirby (Virginia Tech, 2018-06-29)Nanofabrication techniques continue to advance and are rapidly becoming the primary route to enhancement for the electrical, thermal, and optical properties of materials. The work presented in this dissertation details fabrication and characterization techniques of thin films and nanoparticles for these purposes. The four primary areas of research presented here are thermoelectric enhancement through nanostructured thin films, an alternative frequency-domain thermoreflectance method for thin film thermal conductivity measurement, thermal rectification in nanodendritic porous silicon, and plasmonic enhancement in silver nanospheroids as a reverse photolithography technique. Nanostructured thermoelectrics have been proposed to greatly increase thermopower efficiency and to bring thermoelectrics to mainstream power generation and cooling applications. In our work, thermoelectric thin films of SbTe, BiTe, and PbTe grown by atomic layer deposition and electrochemical atomic layer deposition were characterized for enhanced performance over corresponding bulk materials. Seebeck coefficient measurements were performed at temperatures ranging from 77 K to 380 K. Atomic composition was verified by energy-dispersive X-ray spectroscopy and structures were imaged by scanning electron microscopy. All thin films measured were ultimately found to have a comparable or smaller Seebeck coefficient to corresponding materials made by conventional techniques, likely due to issues with the growth process. Frequency-domain thermoreflectance offers a minimally invasive optical pump-probe technique for measuring thermal conductivity. Like time-domain thermoreflectance, the version of frequency-domain thermoreflectance demonstrated here relies on a non-zero thermo-optic coefficient in the sample, but uses moderate cost continuous wave lasers modulated at kHz or MHz frequencies rather than a more expensive ultrafast laser system. The longer timescales of these frequency ranges enables this technique to take measurements of films with thicknesses ranging from 100 nm to 10 um, complimentary to time-domain thermoreflectance. This method differentiates itself from other frequency-domain methods in that it is also capable of simultaneous independent measurements of both the in plane and out of plane values of the thermal conductivity in anisotropic samples through relative reflective magnitude, rather than phase, measurements. We validated this alternate technique by measuring the thermal conductivity of Al2O3 and soda-lime and found agreement both with literature values and with separate measurements obtained with a conventional time-domain thermoreflectance setup. Thermal rectification has the potential to enhance microcircuit performance, improve thermoelectric efficiency, and enable the creation of thermal logic circuits. Passive thermal rectification has been proposed to occur in geometrically asymmetric nanostructures when heat conduction is dominated by ballistic phonons. Here, nanodendritic structures with branch widths of ~ 10 nm and lengths of ~ 20 nm connected to ~ 50 um long trunks were electrochemically etched from <111> silicon wafers. Thermal rectification measurements were performed at temperatures ranging from 80 K to 250 K by symmetric thermal conductivity measurements. No thermal rectification was ultimately found in these samples within the margin of thermal conductivity measurement error 1%. This result is consistent with another study which found thermal rectification with greater conduction in the direction opposite to what ballistic phonon heat conduction theories predicted. Plasmonic resonance concentrates incident photon energy and enables channeling of that energy into sub-wavelength volumes where it can be used for nanoscale applications. We demonstrated that surface plasmon polaritons induced in silver nanosphereoid films by 532 nm light defunctionalize previously photocleaved ligands adsorbed onto the films, to yield a reverse photolithographic technique. In this method, gold nanosphere conjugation were conjugated to a photocleaved ligand, however conjugation could be inhibited by exposing the cleaved ligand to 532 nm light and consequently yield a reversal technique. This defunctionalizion effect did not occur on gold films or nanoparticles conjugated with the ligand in IR spectroscopy, and was observed to have a reduced effect in silver films relative to silver nanospheroid film. As silver nanospheroid films and gold nanospheres of the size used in this study are known to have plasmon resonance in the green wavelengths, while gold and silver continuous films do not, this defunctionalization likely results from plasmonic effects.
- The Farthest Quasar Mini-Broad Absorption Line Outflow from Its Central Source: Very Large Telescope/UVES Observation of SDSS J0242+0049Byun, Doyee; Arav, Nahum; Hall, Patrick B. (IOP Publishing, 2022-03)We analyze Very Large Telescope/UVES observations of the quasar SDSS J024221.87+004912.6. We identify four absorption outflow systems: a C iv broad absorption line (BAL) at v approximate to -18,000 km s(-1) and three narrower low-ionization systems with centroid velocities ranging from -1200 to -3500 km s(-1). These outflows show similar physical attributes to the [O iii] outflows studied by Liu et al. (2013). We find that two of the systems are energetic enough to contribute to active galactic nucleus feedback, with one system reaching above 5% of the quasar's Eddington luminosity. We also find that this system is at a distance of 67 kpc away from the quasar, the farthest detected mini-BAL absorption outflow from its central source to date. In addition, we examine the time-variability of the BAL and find that its velocity monotonically increases, while the trough itself becomes shallower over time.
- A fast and long-lived outflow from the supermassive black hole in NGC 5548Kaastra, J. S.; Kriss, G. A.; Cappi, M.; Mehdipour, M.; Petrucci, P. O.; Steenbrugge, K. C.; Arav, Nahum; Behar, E.; Bianchi, S.; Boissay, R.; Branduardi-Raymont, G.; Chamberlain, C.; Costantini, E.; Ely, J. C.; Ebrero, J.; Di Gesu, L.; Harrison, F. A.; Kaspi, S.; Malzac, J.; De Marco, B.; Matt, G.; Nandra, K.; Paltani, S.; Person, R.; Peterson, B. M.; Pinto, C.; Ponti, G.; Nunez, F. P.; De Rosa, A.; Seta, H.; Ursini, F.; de Vries, C. P.; Walton, D. J.; Whewell, M. (Amer Assoc Advancement Science, 2014-07-04)Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six space observatories shows the nucleus to be obscured by a long-lasting, clumpy stream of ionized gas never seen before. It blocks 90% of the soft X-ray emission and causes simultaneous deep, broad UV absorption troughs. The outflow velocities of this gas are up to five times faster than those in the persistent outflow, and at a distance of only a few light days from the nucleus, it may likely originate from the accretion disk.
- Galactic-scale absorption outflow in the low-luminosity quasar IRAS F04250-5718: Hubble Space Telescope/Cosmic Origins Spectrograph observationsEdmonds, Douglas; Borguet, Benoit; Arav, Nahum; Dunn, Jay P.; Penton, S.; Kriss, G. A.; Korista, K. T.; Costantini, E.; Steenbrugge, K. C.; Gonzalez-Serrano, J. I.; Aoki, K.; Bautista, M. A.; Behar, E.; Benn, C.; Crenshaw, D. M.; Everett, J.; Gabel, J.; Kaastra, J.; Moe, M.; Scott, J. (IOP Publishing Ltd., 2011-09)We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph on board the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e. g., C IV, N V, and O VI) as well as low ionization ions (e. g., C II and Si III). We identify three kinematic components with central velocities ranging from similar to-50 to similar to-230 km s(-1). Velocity-dependent, non-black saturation is evident from the line profiles of the high ionization ions. From the non-detection of absorption from a metastable level of C II, we are able to determine that the electron number density in the main component of the outflow is less than or similar to 30 cm(-3). Photoionization analysis yields an ionization parameter log U-H similar to -1.6 +/- 0.2, which accounts for changes in the metallicity of the outflow and the shape of the incident spectrum. We also consider solutions with two ionization parameters. If the ionization structure of the outflow is due to photoionization by the active galactic nucleus, we determine that the distance to this component from the central source is greater than or similar to 3 kpc. Due to the large distance determined for the main kinematic component, we discuss the possibility that this outflow is part of a galactic wind.
- How Do Quasars Impact Their Host Galaxies? From the Studies of Quasar Outflows in Absorption and EmissionXu, Xinfeng (Virginia Tech, 2020-05-27)"Quasar-mode feedback" occurs when momentum and energy from the environment of accreting supermassive black hole couple to the host galaxy. One mechanism for such a coupling is by high-velocity (up to ~0.2c) quasar-driven ionized outflows, appearing as blue-shifted absorption and emission lines in quasar spectra. Given enough energy and momentum, these outflows are capable of affecting the evolution of their host galaxies. This dissertation presents the studies of emission and absorption quasar outflows from different perspectives. (1). By conducting large broad absorption line (BAL) quasar surveys in both Sloan Digital Sky Survey and Very Large Telescopes (VLT), we determined various physics properties of quasar absorption outflows, e.g., the electron number density ((ne), the distance of outflows to the central quasar (𝑅), and the kinetic energy carried by the outflow (𝐸̇k). We demonstrated that half of the typical BAL outflows are situated at 𝑅 > 100 pc, i.e., having the potential to affect the host galaxies. (2). Our group carried out a Hubble Space Telescope program (PI: Arav) for studying the outflows in the Extreme-UV, collaborating with Dr. Gerard Kriss from Space Telescope Science Institute (STScI). We developed a novel method to fit the multitude of quasar absorption troughs efficiently and accurately. We have identified the most energetic quasar-driven outflows on record and discovered the largest acceleration and velocity-shift for a quasar absorption outflow. (3). By using the VLT data, Xu led the project to study the relationships between BAL outflows and emission line outflows. We found possible connections between these two types of quasar outflows, e.g., the luminosity of the [𝑂III λ5007 emission profile decreases with increasing ne derived from the BAL outflow in the same quasar. These findings are consistent with BAL and emission outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution.
- HST/COS observations of galactic high-velocity clouds: four active galactic nucleus sight lines through complex CShull, J. M.; Stevans, M.; Danforth, C.; Penton, S. V.; Lockman, F. J.; Arav, Nahum (IOP Publishing Ltd., 2011-10)We report ultraviolet spectra of Galactic high-velocity clouds (HVCs) in Complex C, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), together with new 21 cm spectra from the Green Bank Telescope. The wide spectral coverage and higher signal-to-noise ratio, compared to previous HST spectra, provide better velocity definition of the HVC absorption, additional ionization species (including high ions), and improved abundances in this halo gas. Complex C has a metallicity of 10%-30% solar and a wide range of ions, suggesting dynamical and thermal interactions with hot gas in the Galactic halo. Spectra in the COS medium-resolution G130M (1133-1468 angstrom) and G160M (1383-1796 angstrom) gratings detect ultraviolet absorption lines from eight elements in low-ionization states (O I, N I, C II, S II, Si II, Al II, Fe II, P II) and three elements in intermediate-and high-ionization states (Si III, Si IV, C IV, N V). Our four active galactic nucleus sight lines toward Mrk 817, Mrk 290, Mrk 876, and PG 1259+593 have high-velocity Hi and Ovi column densities, log N-H (I) = 19.39-20.05 and logN(OVI) = 13.58-14.10, with substantial amounts of kinematically associated photoionized gas. The high-ion abundance ratios are consistent with cooling interfaces between photoionized and collisionally ionized gas: N(C IV)/N(O vi) approximate to 0.3-0.5, N(Si IV)/N(O VI) approximate to 0.05-0.11, N(N V)/N(O VI) approximate to 0.07-0.13, and N(Si IV)/N(Si III) approximate to 0.2.
- Major contributor to AGN feedback: VLT X-shooter observations of S iv BALQSO outflowsBorguet, Benoit C. J.; Arav, Nahum; Edmonds, Douglas; Chamberlain, Carter; Benn, C. (IOP Publishing Ltd., 2013-01)We present the most energetic BALQSO outflow measured to date, with a kinetic luminosity of at least 1046 erg s(-1), which is 5% of the bolometric luminosity of this high Eddington ratio quasar. The associated mass-flow rate is 400 solar masses per year. Such kinetic luminosity and mass-flow rate should provide strong active galactic nucleus feedback effects. The outflow is located at about 300 pc from the quasar and has a velocity of roughly 8000 km s-1. Our distance and energetic measurements are based in large part on the identification and measurement of S iv and S IV* broad absorption lines (BALs). The use of this high-ionization species allows us to generalize the result to the majority of high-ionization BALQSOs that are identified by their C iv absorption. We also report the energetics of two other outflows seen in another object using the same technique. The distances of all three outflows from the central source (100-2000 pc) suggest that we observe BAL troughs much farther away from the central source than the assumed acceleration region of these outflows (0.01-0.1 pc).
- Mass Outflow in the Seyfert 1 Galaxy NGC 5548Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Kaastra, J. S.; Arav, Nahum; Gabel, J. R.; Korista, K. T. (IOP PUBLISHING LTD, 2009-06)We present a study of the intrinsic UV absorption and emission lines in an historically low-state spectrum of the Seyfert 1 galaxy NGC 5548, which we obtained in 2004 February at high spatial and spectral resolution with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. We isolate a component of emission with a width of 680 km s(-1) that arises from an "intermediate-line region" (ILR), similar to that we discovered in NGC 4151, at a distance of similar to 1 pc from the central continuum source. From a detailed analysis of the five intrinsic absorption components in NGC 5548 and their behavior over a span of eight years, we present evidence that most of the UV absorbers only partially cover the ILR and do not cover an extended region of UV continuum emission, most likely from hot stars in the circumnuclear region. We also find that four of the UV absorbers are at much greater distances (greater than 70 pc) than the ILR, and none have sufficient N V or C IV column densities to be the ILR in absorption. At least a portion of the UV absorption component 3, at a radial velocity of -530 km s(-1), is likely responsible for most of the X-ray absorption, at a distance less than 7 pc from the central source. The fact that we see the ILR in absorption in NGC 4151 and not in NGC 5548 suggests that the ILR is located at a relatively large polar angle (similar to 45 degrees) with respect to the narrow-line region outflow axis.
- Measuring column densities in quasar outflows: VLT observations of QSO 2359-1241Arav, Nahum; Moe, Maxwell; Costantini, E.; Korista, K. T.; Benn, C.; Ellison, S. (IOP Publishing Ltd., 2008-07)We present high-resolution spectroscopic VLT observations of the outflow seen in QSO 2359-1241. These data contain absorption troughs from five resonance Fe II lines with a resolution of similar to 7 km s(-1) and a signal-to-noise ratio per resolution element of order 100. We use this unprecedented high-quality data set to investigate the physical distribution of the material in front of the source and by that to determine the column densities of the absorbed troughs. We find that the apparent optical depth model gives a very poor fit to the data and greatly underestimates the column density measurements. Power-law distributions and partial covering models give much better fits, with some advantage to power-law models, while both models yield similar column density estimates. The better fit of the power-law model solves a long-standing problem plaguing the partial covering model when applied to large distance scale outflow: how to obtain a velocity-dependent covering factor for an outflow situated at distances thousands of time greater than the size of the AGN emission source. This problem does not affect power-law models. Therefore, based on the better fit and plausibility of the physical model, we conclude that in QSO 2359-1241, the outflow covers the full extent of the emission source but in a nonhomogeneous way.
- Multiwavelength campaign on Mrk 509 I. Variability and spectral energy distributionKaastra, J. S.; Petrucci, P. O.; Cappi, M.; Arav, Nahum; Behar, E.; Bianchi, S.; Bloom, J.; Blustin, A. J.; Branduardi-Raymont, G.; Costantini, E.; Dadina, M.; Detmers, R. G.; Ebrero, J.; Jonker, P. G.; Klein, C.; Kriss, G. A.; Lubinski, P.; Malzac, J.; Mehdipour, M.; Paltani, S.; Pinto, C.; Ponti, G.; Ratti, E. M.; Smith, R. A. N.; Steenbrugge, K. C.; de Vries, C. P. (EDP Sciences, 2011-10)Context. Active galactic nuclei (AGN) show a wealth of interesting physical processes, some of which are poorly understood. In a broader context, they play an important role in processes that are far beyond their immediate surroundings, owing to the high emitted power. Aims. We want to address a number of open questions, including the location and physics of the outflow from AGN, the nature of the continuum emission, the geometry and physical state of the X-ray broad emission line region, the Fe-K line complex, the metal abundances of the nucleus, and finally the interstellar medium of our own Galaxy as seen through the signatures it imprints on the X-ray and UV spectra of AGN. Methods. We study one of the best targets for these aims, the Seyfert 1 galaxy Mrk 509 with a multiwavelength campaign using five satellites (XMM-Newton, INTEGRAL, Chandra, HST, and Swift) and two ground-based facilities (WHT and PAIRITEL). Our observations cover more than five decades in frequency, from 2 μm to 200 keV. The combination of high-resolution spectroscopy and time variability allows us to disentangle and study the different components. Our campaign covers 100 days from September to December 2009, and is centred on a simultaneous set of deep XMM-Newton and INTEGRAL observations with regular time intervals, spanning seven weeks. Results. We obtain a continuous light curve in the X-ray and UV band, showing a strong, up to 60% flux increase in the soft X-ray band during the three weeks in the middle of our deepest monitoring campaign, and which is correlated with an enhancement of the UV flux. This allows us to study the time evolution of the continuum and the outflow. By stacking the observations, we have also obtained one of the best X-ray and UV spectra of a Seyfert galaxy ever obtained. In this paper we also study the effects of the spectral energy distribution (SED) that we obtained on the photo-ionisation equilibrium. Thanks to our broad-band coverage, uncertainties on the SED do not strongly affect the determination of this equilibrium. Conclusions. Here we present our very successful campaign and in a series of subsequent papers we will elaborate on different aspects of our study.
- Multiwavelength campaign on Mrk 509 III. The 600 ks RGS spectrum: unravelling the inner region of an AGNDetmers, R. G.; Kaastra, J. S.; Steenbrugge, K. C.; Ebrero, J.; Kriss, G. A.; Arav, Nahum; Behar, E.; Costantini, E.; Branduardi-Raymont, G.; Mehdipour, M.; Bianchi, S.; Cappi, M.; Petrucci, P. O.; Ponti, G.; Pinto, C.; Ratti, E. M.; Holczer, T. (EDP Sciences, 2011-10)We present the results of our 600 ks RGS observation as part of the multiwavelength campaign on Mrk 509. The very high quality of the spectrum allows us to investigate the ionized outflow with an unprecedented accuracy due to the long exposure and the use of the RGS multipointing mode. We detect multiple absorption lines from the interstellar medium and from the ionized absorber in Mrk 509. A number of emission components are also detected, including broad emission lines consistent with an origin in the broad line region, the narrow O VII forbidden emission line and also (narrow) radiative recombination continua. The ionized absorber consists of two velocity components (upsilon = -13 +/- 11 km s(-1) and upsilon = -319 +/- 14 km s(-1)), which both are consistent with earlier results, including UV data. There is another tentative component outflowing at high velocity, -770 +/- 109 km s(-1), which is only seen in a few highly ionized absorption lines. The outflow shows discrete ionization components, spanning four orders of magnitude in ionization parameter. Due to the excellent statistics of our spectrum, we demonstrate for the first time that the outflow in Mrk 509 in the important range of log. between 1-3 cannot be described by a smooth, continuous absorption measure distribution, but instead shows two strong, discrete peaks. At the highest and lowest ionization parameters we cannot differentiate smooth and discrete components.
- Multiwavelength campaign on Mrk 509 V. Chandra-LETGS observation of the ionized absorberEbrero, J.; Kriss, G. A.; Kaastra, J. S.; Detmers, R. G.; Steenbrugge, K. C.; Costantini, E.; Arav, Nahum; Bianchi, S.; Cappi, M.; Branduardi-Raymont, G.; Mehdipour, M.; Petrucci, P. O.; Pinto, C.; Ponti, G. (EDP Sciences, 2011-10)Context. We present here the results of a 180 ks Chandra-LETGS observation as part of a large multi-wavelength campaign on Mrk 509. Aims. We study the warm absorber in Mrk 509 and use the data from a simultaneous HST-COS observation in order to assess whether the gas responsible for the UV and X-ray absorption are the same. Methods. We analyzed the LETGS X-ray spectrum of Mrk 509 using the SPEX fitting package. Results. We detect several absorption features originating in the ionized absorber of the source, along with resolved emission lines and radiative recombination continua. The absorption features belong to ions with, at least, three distinct ionization degrees. The lowest ionized component is slightly redshifted (Δv = 73 km s-1) and is not in pressure equilibrium with the others, and therefore it is not likely part of the outflow, possibly belonging to the interstellar medium of the host galaxy. The other components are outflowing at velocities of −196 and −455 km s-1, respectively. The source was observed simultaneously with HST-COS, finding 13 UV kinematic components. At least three of them can be kinematically associated with the observed X-ray components. Based on the HST-COS results and a previous FUSE observation, we find evidence that the UV absorbing gas might be co-located with the X-ray absorbing gas and belong to the same structure.
- Multiwavelength campaign on Mrk 509 VI. HST/COS observations of the far-ultraviolet spectrumKriss, G. A.; Arav, Nahum; Kaastra, J. S.; Ebrero, J.; Pinto, C.; Borguet, B.; Edmonds, Douglas; Costantini, E.; Steenbrugge, K. C.; Detmers, R. G.; Behar, E.; Bianchi, S.; Blustin, A. J.; Branduardi-Raymont, G.; Cappi, M.; Mehdipour, M.; Petrucci, P. O.; Ponti, G. (EDP Sciences, 2011-10)We present medium-resolution (lambda/Delta lambda similar to 20 000) ultraviolet spectra covering the 1155-1760 angstrom spectral range of the Seyfert 1 galaxy Mrk 509 obtained using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). Our observations were obtained simultaneously with a Low Energy Transmission Grating Spectrometer observation using the Chandra X-ray Observatory, and they are part of a multiwavelength campaign in September through December 2009 which also included observations with XMM-Newton, Swift, and INTEGRAL. Our spectra are the highest signal-to-noise observations to date of the intrinsic absorption components seen in numerous prior ultraviolet observations. To take advantage of the high S/N, we describe special calibrations for wavelength, flat-field and line-spread function corrections that we applied to the COS data. We detect additional complexity in the absorption troughs compared to prior observations made with the Space Telescope Imaging Spectrograph (STIS) on HST. We attribute the UV absorption to a variety of sources in Mrk 509, including an outflow from the active nucleus, the interstellar medium and halo of the host galaxy, and possible infalling clouds or stripped gaseous material from a merger that are illuminated by the ionizing radiation of the active nucleus. Variability between the STIS and COS observation of the most blue-shifted component (#1) allows us to set an upper limit on its distance of <250 pc. Similarly, variability of component 6 between FUSE observations limits its distance to <1.5 kpc. The absorption lines in all components only partially cover the emission from the active nucleus with covering fractions that are lower than those seen in the prior STIS observations and are comparable to those seen in spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE). Given the larger apertures of COS and FUSE compared to STIS, we favor scattered light from an extended region near the active nucleus as the explanation for the partial covering. As observed in prior X-ray and UV spectra, the UV absorption has velocities comparable to the X-ray absorption, but the bulk of the ultraviolet absorption is in a lower ionization state with lower total column density than the gas responsible for the X-ray absorption. We conclude that the outflow from the active nucleus is a multiphase wind.
- Multiwavelength campaign on Mrk 509 VII. Relative abundances of the warm absorberSteenbrugge, K. C.; Kaastra, J. S.; Detmers, R. G.; Ebrero, J.; Ponti, G.; Costantini, E.; Kriss, G. A.; Mehdipour, M.; Pinto, C.; Branduardi-Raymont, G.; Behar, E.; Arav, Nahum; Cappi, M.; Bianchi, S.; Petrucci, P. O.; Ratti, E. M.; Holczer, T. (EDP Sciences, 2011-10)Context. The study of abundances in the nucleus of active galaxies allows us to investigate the evolution of the abundance by comparing local and higher redshift galaxies. However, the methods used so far have substantial drawbacks or rather large uncertainties. Some of the measurements are at odds with the initial mass function derived from the older stellar population of local elliptical galaxies. Aims. We determine accurate and reliable abundances of C, N, Ne, and Fe relative to O from the narrow absorption lines observed in the X-ray spectra of Mrk 509. Methods. We use the stacked 600 ks XMM-Newton RGS and 180 ks Chandra LETGS spectra. Thanks to simultaneous observations with INTEGRAL and the optical monitor on-board XMM-Newton for the RGS observations and HST-COS and Swift for the LETGS observations, we have an individual spectral energy distribution for each dataset. Owing to the excellent quality of the RGS spectrum, the ionisation structure of the absorbing gas is well constrained, allowing for a reliable abundance determination using ions over the whole observed range of ionisation parameters. Results. We find that the relative abundances are consistent with the proto-solar abundance ratios: C/O = 1.19 ± 0.08, N/O = 0.98 ± 0.08, Ne/O = 1.11 ± 0.10, Mg/O = 0.68 ± 0.16, Si/O = 1.3 ± 0.6, Ca/O = 0.89 ± 0.25, and Fe/O = 0.85 ± 0.06, with the exception of S, which is slightly under-abundant, S/O = 0.57 ± 0.14. Our results, and their implications, are discussed and compared to the results obtained using other techniques to derive abundances in galaxies.