Gisella De Rosa
A5083732858- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Atmospheric and Environmental Gas Dynamics
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Astrophysics and Star Formation Studies
- Dark Matter and Cosmic Phenomena
- Astro and Planetary Science
- Laser Design and Applications
- Magnetic confinement fusion research
- Particle Accelerators and Free-Electron Lasers
- Pulsars and Gravitational Waves Research
- Atmospheric Ozone and Climate
- Plasma Diagnostics and Applications
- Advanced Optical Sensing Technologies
- Particle physics theoretical and experimental studies
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Scientific Research and Discoveries
Space Telescope Science Institute
2015-2024
Michigan Science Center
2019
Max Planck Institute for Astronomy
2010-2019
Max Planck Society
2012-2019
The Ohio State University
2013-2018
After the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered a significant brightening of inner region NGC 2617, we began ~70 day photometric and spectroscopic monitoring campaign from X-ray through near-infrared (NIR) wavelengths. We report that 2617 went dramatic outburst, during which its flux increased by over an order magnitude followed increase optical/ultraviolet (UV) continuum almost magnitude. classified as Seyfert 1.8 galaxy in 2003, is now 1 due to appearance broad...
We present an updated and revised analysis of the relationship between Hβ broad-line region (BLR) radius luminosity active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions host galaxies nine new AGNs imaged with Hubble Space Telescope Wide Field Camera 3. The allow us to create "AGN-free" images galaxies, from which measure starlight contribution optical measured through ground-based spectroscopic aperture. also incorporate 20...
Abstract Quasars are galaxies hosting accreting supermassive black holes; due to their brightness, they unique probes of the early universe. To date, only a few quasars have been reported at <?CDATA $z\gt 6.5$?> (<800 Myr after big bang). In this work, we present six additional $z\gtrsim discovered using Pan-STARRS1 survey. We use sample 15 perform homogeneous and comprehensive analysis highest-redshift quasar population. report four main results: (1) majority show large blueshifts broad...
Studying quasars at the highest redshifts can constrain models of galaxy and black hole formation, it also probes intergalactic medium in early universe. Optical surveys have to date discovered more than 60 up z~6.4, a limit set by use z-band CCD detectors. Only one z>6.4 quasar has been discovered, namely z=7.08 ULAS J1120+0641, using near-infrared imaging. Here we report discovery three new 332 square degrees Visible Infrared Survey Telescope for Astronomy Kilo-degree Galaxy (VIKING)...
We present the analysis of optical and near-infrared spectra only four $z>6.5$ quasars known to date, discovered in UKIDSS-LAS VISTA-VIKING surveys. Our data-set consists new VLT/X-Shooter Magellan/FIRE observations. These are best optical/NIR spectroscopic data that likely be obtained for sample using current $6$ - $10$ m facilities. estimate black hole mass, Eddington ratio, SiIV/CIV, CIII]/CIV, FeII/MgII emission-line flux ratios. perform spectral modeling a procedure allows us derive...
ABSTRACT We present ALMA detections of the [C ii ] 158 μ m emission line and underlying far-infrared (FIR) continuum three quasars at 6.6 < z 6.9 selected from VIKING survey. The fluxes range between 1.6 3.4 Jy km s −1 ([C luminosities ∼(1.9–3.9) × 10 9 L ⊙ ). measure flux densities 0.56–3.29 mJy around (rest frame), with implied FIR (0.6–7.5) 12 dust masses M d = (0.7–24) 8 . In one quasar we derive a temperature <?CDATA ${30}_{-9}^{+12}$?> <?MML <mml:math> <mml:msubsup> <mml:mrow>...
We present measurements of black hole masses and Eddington ratios for a sample 38 bright (M$_{1450}$ < -24.4 mag) quasars at 5.8 z 7.5, derived from VLT/X-shooter near-IR spectroscopy their broad CIV MgII emission lines. The (on average M$_{BH}$ ~ 4.6 x 10$^9$ M$_{\odot}$) accretion rates (with ranging between 0.1 1.0) are broadly consistent with that similarly luminous 0.3 2.3 quasars, but there is evidence mild increase in the median ratio going towards > 6. Combined deep ALMA observations...
We present the first results from JWST ASPIRE program (A SPectroscopic survey of biased halos In Reionization Era). This represents an imaging and spectroscopic 25 reionization-era quasars their environments by utilizing unprecedented capabilities NIRCam Wide Field Slitless Spectroscopy (WFSS) mode. will deliver largest ($\sim280~{\rm arcmin}^2$) galaxy redshift at 3-4 $\mu$m among Cycle-1 programs provide extensive legacy values for studying formation earliest supermassive black holes...
Quasars (QSOs) at the highest known redshift (z ∼ 6) are unique probes of early growth supermassive black holes (BHs). Until now, only most luminous QSOs have been studied, often one object a time. Here we present extensive consistent analysis to date 4 < z 6.5 with observed near-infrared spectra, combining three new 6 objects from our ongoing Very Large Telescope–Infrared Spectrometer And Array Camera program nineteen sources literature. The extend existing Sloan Digital Sky Survey (SDSS)...
We present multi-wavelength observations that trace more than 40 years in the life of active galactic nucleus (AGN) Mrk 590, traditionally known as a classic Seyfert 1 galaxy. From spectra recently obtained from HST, Chandra, and Large Binocular Telescope, we find activity 590 has diminished so significantly continuum luminosity is factor 100 lower peak probed by our long baseline observations. Furthermore, broad emission lines, once prominent UV/optical spectrum, have all but disappeared....
We present velocity-resolved reverberation results for five active galactic nuclei. recovered velocity-delay maps using the maximum-entropy method four objects: Mrk 335, 1501, 3C120, and PG2130+099. For fifth, 6, we were only able to measure mean time delays in different velocity bins of Hbeta emission line. The show unique dynamical signatures each object. Balmer lines kinematic consistent with both an inclined disk infalling gas, but HeII 4686 line is suggestive inflow. PG 2130+099 signs...
ABSTRACT Luminous quasars at <?CDATA $z\gt 5.6$?> can be studied in detail with the current generation of telescopes and provide us unique information on first gigayear universe. Thus far, these studies have been statistically limited by number known redshifts. Such are rare, therefore, wide-field surveys required to identify them, multiwavelength data separate them efficiently from their main contaminants, far more numerous cool dwarfs. In this paper, we update extend selection for $z\sim...
Recent intensive Swift monitoring of the Seyfert 1 galaxy NGC 5548 yielded 282 usable epochs over 125 days across six UV/optical bands and X-rays. This is densest extended AGN continuum sampling ever obtained, with a mean rate <0.5 day. Approximately daily HST UV was also obtained. The light curves show strong correlations (r_max = 0.57 - 0.90) clearest measurement to date interband lags. These lags are well-fit by \tau propto \lambda^4/3 wavelength dependence, normalization that indicates...
We describe the first results from a six-month long reverberation-mapping experiment in ultraviolet based on 170 observations of Seyfert 1 galaxy NGC 5548 with Cosmic Origins Spectrograph Hubble Space Telescope. Significant correlated variability is found continuum and broad emission lines, amplitudes ranging ~30% to factor two lines three continuum. The variations all strong lag behind those continuum, He II 1640 lagging by ~2.5 days Lyman alpha 1215, C IV 1550, Si 1400 ~5-6 days....
ABSTRACT We present ground-based optical photometric monitoring data for NGC 5548, part of an extended multiwavelength reverberation mapping campaign. The light curves have nearly daily cadence from 2014 January to July in nine filters ( BVRI and ugriz ). Combined with ultraviolet the Hubble Space Telescope Swift , we confirm significant time delays between continuum bands as a function wavelength, extending wavelength coverage 1158 Å z band (~9160 Å). find that lags at wavelengths longer...
High-redshift quasars are currently the only probes of growth supermassive black holes and potential tracers structure evolution at early cosmic time. Here we present our candidate selection criteria from Panoramic Survey Telescope & Rapid Response System 1 follow-up strategy to discover in redshift range 5.7 ≲ z 6.2. With this discovered eight new ⩽ 6.0 quasars, increasing number known > by more than 10%. We additionally recovered 18 previously quasars. The presented here span a large...
We present spectral energy distributions (SEDs) of 69 QSOs at z > 5, covering a rest frame wavelength range 0.1 μm to ∼80 μm, and centered on new Spitzer Herschel observations. The detection rate the with is very high (97% λrest ≲ 4 μm), but drops toward bands 30% detected in PACS (rest mid-infrared) 15% additionally SPIRE far-infrared; FIR). perform multi-component SED fits for Herschel-detected objects confirm that match observed SEDs, clumpy torus model needs be complemented by hot (∼1300...
We present the first results from an optical reverberation mapping campaign executed in 2014, targeting active galactic nuclei (AGN) MCG+08-11-011, NGC 2617, 4051, 3C 382, and Mrk 374. Our targets have diverse interesting observational properties, including a "changing look" AGN broad-line radio galaxy. Based on continuum-H$\beta$ lags, we measure black hole masses for all five targets. also obtain H$\gamma$ He{\sc ii}\,$\lambda 4686$ lags objects except 382. The indicate radial...
Abstract It is well known that reverberation mapping of active galactic nuclei (AGNs) reveals a relationship between AGN luminosity and the size broad-line region, use this relationship, combined with Doppler width broad emission line, enables an estimate mass black hole at center nucleus based on single spectrum. An unresolved key issue choice parameter used to characterize line width, either FWHM or dispersion <?CDATA ${\sigma }_{\mathrm{line}}$?> (the square root second moment profile)....
We present the first results from ongoing, intensive, multi-wavelength monitoring program of luminous Seyfert 1 galaxy Mrk 817. While this AGN was, in part, selected for its historically unobscured nature, we discovered that X-ray spectrum is highly absorbed, and there are new blueshifted, broad narrow UV absorption lines, which suggest a dust-free, ionized obscurer located at inner line region partially covers central source. Despite obscuration, measure optical continuum reverberation lags...
Studies of rest-frame optical emission in quasars at $z>6$ have historically been limited by the wavelengths accessible ground-based telescopes. The James Webb Space Telescope (JWST) now offers opportunity to probe this deep into reionization epoch. We report observations eight $z>6.5$ using JWST/NIRCam Wide Field Slitless Spectroscopy, as a part ''A SPectroscopic survey biased halos In Reionization Era (ASPIRE)" program. Our JWST spectra cover quasars' between rest frame $\sim$ 4100 and...
The narrow [O iii] λλ4959, 5007 emission-line fluxes in the spectrum of well-studied Seyfert 1 galaxy NGC 5548 are shown to vary with time. From this we show that narrow-line-emitting region has a radius only 1–3 pc and is denser (ne ∼ 105 cm−3) than previously supposed. line width consistent virial motions at given previous determinations black hole mass. Since flux usually assumed be constant therefore used calibrate spectroscopic monitoring data, variability ramifications for long-term...
We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved almost daily cadence with observations from five ground-based telescopes. H$\beta$ He II $\lambda$4686 broad emission-line light curves lag that 5100 $\AA$ continuum by $4.17^{+0.36}_{-0.36}$ days $0.79^{+0.35}_{-0.34}$ days, respectively. relative to 1158 ultraviolet curve measured Hubble Space...
Abstract We present optical continuum lags for two Seyfert 1 galaxies, MCG+08-11-011 and NGC 2617, using monitoring data from a reverberation mapping campaign carried out in 2014. Our light curves span the ugriz filters over four months, with median cadences of 1.0 0.6 days respectively, combined roughly daily X-ray near-UV Swift 2617. find consistent geometrically thin accretion-disk models that predict lag-wavelength relation τ ∝ λ 4/3 . However, observed are larger than predictions based...
Abstract The AGN STORM 2 campaign is a large, multiwavelength reverberation mapping project designed to trace out the structure of Mrk 817 from inner accretion disk broad emission line region and dusty torus. As part this campaign, Swift performed daily monitoring for approximately 15 months, obtaining observations in X-rays six UV/optical filters. X-ray shows that was significantly fainter state than previous observations, with only brief flare where it reached prior flux levels. spectrum...