scholarly journals Hot Dust on the Outskirts of the BLR in Fairall 9

1989 ◽  
Vol 134 ◽  
pp. 387-389
Author(s):  
J. Clavel ◽  
W. Wamsteker ◽  
I. Glass
Keyword(s):  
Broad Band ◽  
Light Curves ◽  
Emission Lines ◽  
Optical Range ◽  
Effective Wavelength ◽  
Optical Photometry ◽  
Near Ir ◽  
Photometric Measurements ◽  
Far Ultraviolet ◽  
The Continuum

Since 1978, the Seyfert I galaxy F9 (z = 0.0461) has been observed at 54 epochs in the far ultraviolet and optical range with the IUE (Boggess et al 1978), and 27 times in the near IR from SAAO. The IUE provided spectrophotometric low resolution (900 km.s−1) datá over the 1200–3200 Å range as well as simultaneous broad band optical photometry at an effective wavelength of 5200 Å. SAAO data consist of photometric measurements in the J, H, K and L bands. From the IUE data, we obtained the light-curves of the continuum at 1328 Å and 1826 Å (rest wavelengths), as well as those of the Lyα1216, CIV1550 and MgII2800 emission lines. More details can be found in Clavel, Wamsteker and Glass (1989).

scholarly journals Variability of the Ultraviolet Continuum and Emission Lines of NGC 3783

1994 ◽  
Vol 159 ◽  
pp. 403-403
Author(s):  
G.A. Reichert
Keyword(s):  
Seyfert Galaxy ◽  
Light Curves ◽  
Emission Lines ◽  
Power Density Spectrum ◽  
Ultraviolet Continuum ◽  
Density Spectrum ◽  
International Ultraviolet Explorer ◽  
Monitoring Effort ◽  
Ngc 5548 ◽  
The Continuum

On behalf of the International AGN Watch, I report on the results of intensive ultraviolet spectral monitoring of the Seyfert 1 galaxy NGC 3783. The nucleus of NGC 3783 was observed with the International Ultraviolet Explorer satellite on a regular basis for a total of seven months, once every 4 days for the first 172 days and once every other day for the final 50 days. Significant variability was observed in both continuum and emission-line fluxes. The light curves for the continuum fluxes exhibited two well-defined local minima or “dips,” the first lasting ≲ 20 days and the second ≲ 4 days, with additional episodes of relatively rapid flickering of approximately the same amplitude. As in the case of NGC 5548 (the only other Seyfert galaxy that has been the subject of such an intensive, sustained monitoring effort), the largest continuum variations were seen at the shortest wavelengths, so that the continuum became “harder” when brighter. The variations in the continuum occurred simultaneously at all wavelengths (Δt < 2 days). Generally, the amplitude of variability of the emission lines was lower than (or comparable to) that of the continuum. Apart from Mg II (which varied little) and N V (which is relatively weak and badly blended with Lyα) the light curves of the emission lines are very similar to the continuum light curves, in each case with a small systematic delay or “lag.” As for NGC 5548, the highest ionization lines seem to respond with shorter lags than the lower ionization lines. The lags found for NGC 3783 are considerably shorter than those obtained for NGC 5548, with values of (formally) ∼ 0 days for He II+O III], and ∼ 4 days for Lyα, and C IV. The data further suggest lags of ∼ 4 days for Si IV+O IV], and 8–30 days for Si III]+C III]. Uncertainties in these quantities are likely to be of order 2–3 days for the stronger features (Lyα, C IV), and 3–4 days for the weaker ones (He II+O III], Si IV+O IV], Si III]+C III]). Mg II lagged the 1460 Å continuum by ∼ 9 days, although this result depends on the method of measuring the line flux, and may in fact be due to variability of the underlying Fe II lines. Correlation analysis further shows that the power density spectrum contains substantial unresolved power over time scales of ≲ 2 days, and that the character of the continuum variability may change with time.

scholarly journals The Timescales of Variations in Continuum and Hydrogen Lines During Stellar Flares

1983 ◽  
Vol 71 ◽  
pp. 239-243
Author(s):  
B.R. Pettersen
Keyword(s):  
Emission Line ◽  
Narrow Band ◽  
Light Curves ◽  
Emission Lines ◽  
Continuum Radiation ◽  
Stellar Flares ◽  
Hydrogen Lines ◽  
The Continuum

AbstractLight curves of major stellar flares have been used to study the behavior of U-B, B-V, and V-R. The majority of the flux transmitted through these filters is continuum radiation, but U and B are affected by emission lines. The variability of Ha and H$ emission lines were monitored through narrow band filters. The timescales of emission line variability are considerably longer than those for the continuum, and the emission line flare peak occurs a few minutes after the continuum flare maximum. No variability in lines at a timescale of seconds is detected in our data.

scholarly journals Longslit spectroscopy of the peculiar Seyfert 2 galaxy HRG 10103

2010 ◽  
Vol 6 ◽  
pp. 11-16
Author(s):  
Paulo C.R. Poppe ◽  
Vera A.F. Martin ◽  
Max Faúndez-Abans ◽  
Mariângela De Oliveira-Abans ◽  
Iranderly F. De Fernandes
Keyword(s):  
Spectroscopic Data ◽  
Rotation Curve ◽  
Abundance Ratio ◽  
Emission Lines ◽  
Physical Parameters ◽  
Narrow Line ◽  
Optical Range ◽  
Peculiar Galaxy ◽  
The Galaxy ◽  
The Continuum

We present the rst optical longslit spectroscopy for the galaxy HRG 10103, an Sa(r) type peculiar galaxy seen face-on with an asymmetrical elliptical structure. The main goal of this work is to provide the spectral classication of the current object using the `traditional' diagnostic diagrams. However, we also present a diagnostic involving the known emission line ratio R23, usually used to estimate the O/H abundance ratio. The idea is to make a better distinction between the narrow-line AGNs and the H II galaxies. The spectra were obtained in two observatories (OPD-LNA/MCT and Gemini-South) and includes some of the most important emission lines for ionization diagnostic. Based on the observed spectra, HRG 10103 is a Seyfert 2 galaxy with typical line-ratios values in the optical range. We have estimated nuclear redshift of z = 0.039. The resulting reddening values as a function of distance from the nucleus are presented too. The errors in the  fluxes were mostly caused by uncertainties in the placement of the continuum level. The rotation curve is typical of spiral disks, rising shallowly and  attening at an observed amplitude of about 200 km s^(-1). Some other physical parameters have been derived whenever possible. The spectroscopic data reduction was carried out using the GEMINI.GMOS package as well as the standard IRAF procedures.

scholarly journals Multiwavelength consensus of large-scale linear bias

2020 ◽  
Vol 493 (1) ◽  
pp. 747-764 ◽  
Author(s):  
Hengxing Pan ◽  
Danail Obreschkow ◽  
Cullan Howlett ◽  
Claudia del P Lagos ◽  
Pascal J Elahi ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Broad Band ◽  
Far Infrared ◽  
Absolute Magnitude ◽  
Emission Lines ◽  
Continuum Emission ◽  
Star Forming ◽  
Galaxy Bias ◽  
The Continuum

ABSTRACT We model the large-scale linear galaxy bias bg(x, z) as a function of redshift z and observed absolute magnitude threshold x for broad-band continuum emission from the far-infrared to ultraviolet, as well as for prominent emission lines, such as the H α, H β, Ly a, and [O ii] lines. The modelling relies on the semi-analytic galaxy formation model galform, run on the state-of-the-art N-body simulation surfs with the Planck 2015 cosmology. We find that both the differential bias at observed absolute magnitude x and the cumulative bias for magnitudes brighter than x can be fitted with a five-parameter model: bg(x, z) = a + b(1 + z)e(1 + exp [(x − c)d]). We also find that the bias for the continuum bands follows a very similar form regardless of wavelength due to the mixing of star-forming and quiescent galaxies in a magnitude-limited survey. Differences in bias only become apparent when an additional colour separation is included, which suggest extensions to this work could look at different colours at fixed magnitude limits. We test our fitting formula against observations, finding reasonable agreement with some measurements within 1σ statistical uncertainties, and highlighting areas of improvement. We provide the fitting parameters for various continuum bands, emission lines, and intrinsic galaxy properties, enabling a quick estimation of the linear bias in any typical survey of large-scale structure.

scholarly journals Near-IR spectroscopic monitoring of WR 140 (WC7pd+O4-5) during the 2001 periastron passage

2003 ◽  
Vol 212 ◽  
pp. 253-254
Author(s):  
Watson P. Varricatt ◽  
Peredur M. Williams ◽  
Nagarhalli M. Ashok
Keyword(s):  
Emission Line ◽  
Ir Spectrum ◽  
Emission Lines ◽  
X Ray ◽  
Spectroscopic Monitoring ◽  
Near Ir ◽  
Wind Activity ◽  
Ir Spectroscopic ◽  
Emission Line Profile ◽  
The Continuum

The near-IR spectrum of the periodic dust making WCpd+O4-5 binary WR 140 was monitored to cover the 2001 periastron passage and maximum colliding-wind activity. The He i λ1.083μm emission-line profile showed the appearence of a subpeak on epochs close to periastron passage. The evolution of the subpeak was consistent with the motion of the stars and the colliding wind region. The appearance and evolution of the emission subpeak suggests that the theoretical 1/r dependence of X-ray flux does not hold, so that there is no need to change the values of eccentricity and epoch of periastron passage derived from the RV orbit. JHK spectra show variations of the continuum and and dilution of the emission lines, in agreement with the production and cooling of dust.

scholarly journals Photometry and Multipolar Magnetic Field Modeling of Polars: BY Camelopardalis and FL Ceti

2015 ◽  
Vol 2 (1) ◽  
pp. 71-75 ◽  
Author(s):  
P. A. Mason ◽  
A. G. Zhilkin ◽  
D. V. Bisikalo ◽  
S. Gomez ◽  
J. Morales ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Broad Band ◽  
Cataclysmic Variables ◽  
Variable Stars ◽  
Field Structure ◽  
Light Curves ◽  
Optical Photometry ◽  
Quadrupole Field ◽  
Short Period ◽  
Mhd Modeling

We present new broad band optical photometry of two magnetic cataclysmic variable stars, the asynchronous polar BY Camelopardalis and the short period polar FL Ceti. Observations were obtained at the 2.1-m Otto Struve Telescope of McDonald Observatory with 3s and 1s integration times respectively. In an attempt to understand the observed complex changes in accretion flow geometry observed in BY Cam, we performed full 3D MHD simulations assuming a variety of white dwarf magnetic field structures. We investigate fields with increasing complexity including both aligned and non-aligned dipole plus quadrupole field components. We compare model predictions with photometry at various phases of the beat cycle and find that synthetic light curves derived from a multipolar field structure are broadly consistent with optical photometry. FL Ceti is observed to have two very small accretion regions at the foot-points of the white dwarf’s magnetic field. Both accretion regions are visible at the same time in the high state and are about 100 degrees apart. MHD modeling using a dipole plus quadrupole field structure yields quite similar accretion regions as those observed in FL Ceti. We conclude that accretion flows calculated from MHD modeling of multi-polar magnetic fields produce synthetic light curves consistent with photometry of these magnetic cataclysmic variables.

scholarly journals How Large are Quasar Broad-Line-Regions? Results from a Program to Monitor the PG Quasars

1994 ◽  
Vol 159 ◽  
pp. 399-399
Author(s):  
Dan Maoz ◽  
Buell T. Jannuzi ◽  
Paul S. Smith ◽  
Shai Kaspi ◽  
Hagai Netzer
Keyword(s):  
Large Amplitude ◽  
Sampling Interval ◽  
Light Curves ◽  
The Other ◽  
Emission Lines ◽  
Broad Line ◽  
High Luminosity ◽  
Optical Continuum ◽  
Low Amplitude ◽  
The Continuum

We have monitored spectrophotometrically a subsample (28) of the Palomar-Green Bright Quasar Sample for two years in order to measure the sizes of the broad-line regions of high-luminosity AGNs. Half of the quasars showed optical continuum variations with amplitudes in the range 20–75%. In most objects with continuum variations, we detect correlated variations in the broad Hα and Hβ emission lines. The amplitude of the line variations is usually 2–4 times smaller than the optical continuum fluctuations. The lines respond to the continuum variations with a lag that is smaller than or comparable to our typical sampling interval (a few months). This suggests that the quasars have broad-line regions smaller than about 1 lt-year. The figures below show spectra and light curves for one of the quasars. Two of the quasars monitored show no detectable line variations despite relatively large-amplitude continuum changes. This could be a stronger manifestation of the low-amplitude line-response phenomenon we observe in the other quasars. Further details appear in Maoz et al. (1994, ApJ, Jan 20, in press).

scholarly journals A minimal timescale for the continuum in 4U 1608-52 and Aql X-1

2021 ◽  
Vol 502 (1) ◽  
pp. L72-L78
Author(s):  
K Mohamed ◽  
E Sonbas ◽  
K S Dhuga ◽  
E Göğüş ◽  
A Tuncer ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Power Spectra ◽  
Light Curves ◽  
State Transitions ◽  
Strong Positive Correlation ◽  
Present Evidence ◽  
X Ray ◽  
X Ray Binaries ◽  
The Continuum

ABSTRACT Similar to black hole X-ray binary transients, hysteresis-like state transitions are also seen in some neutron-star X-ray binaries. Using a method based on wavelets and light curves constructed from archival Rossi X-ray Timing Explorer observations, we extract a minimal timescale over the complete range of transitions for 4U 1608-52 during the 2002 and 2007 outbursts and the 1999 and 2000 outbursts for Aql X-1. We present evidence for a strong positive correlation between this minimal timescale and a similar timescale extracted from the corresponding power spectra of these sources.

Absolute Spectrophotometry of Wolf-Rayet Stars: Are the Colors the Same?

1982 ◽  
Vol 99 ◽  
pp. 121-125
Author(s):  
Philip Massey
Keyword(s):  
Broad Band ◽  
Emission Lines ◽  
Photoelectric Photometry ◽  
Interference Filters ◽  
One Step

Until now, all that we've known about the magnitudes and colors of Wolf-Rayet stars has been based on photoelectric photometry made with 50–150 A wide interference filters, selected to exclude as far as possible the stronger emission lines (Westerlund 1966; Smith 1968, Lundstrom and Stenholm 1979). This was clearly an improvement on the pioneering efforts of Pyper (1966), who obtained broad band photometry and attempted to correct for the presence of emission; nevertheless, with modern detectors it is possible to go one step further.

scholarly journals Restframe UV-to-optical spectroscopy of APM 08279+5255

2018 ◽  
Vol 617 ◽  
pp. A118 ◽  
Author(s):  
F. G. Saturni ◽  
M. Bischetti ◽  
E. Piconcelli ◽  
A. Bongiorno ◽  
C. Cicone ◽  
...  
Keyword(s):  
Emission Lines ◽  
Magnification Factor ◽  
Uv Spectrum ◽  
Reverberation Mapping ◽  
Broad Absorption Line ◽  
Near Ir ◽  
A Value ◽  
High Ionization ◽  
Single Epoch ◽  
Absorption Features

We present the analysis of the restframe optical-to-UV spectrum of APM 08279+5255, a well-known lensed broad absorption line (BAL) quasar at z = 3.911. The spectroscopic data were taken with the optical DOLoRes and near-IR NICS instruments at TNG, and include the previously unexplored range between C III] λ1910 and [O III] λλ4959,5007. We have investigated the possible presence of multiple BALs by computing “balnicity” and absorption indexes (i.e., BI, BI0, and AI) for the transitions Si IV λ1400, C IV λ1549, Al III λ1860, and Mg II λ2800. No clear evidence for the presence of absorption features is found in addition to the already known, prominent BAL associated to C IV, which supports a high-ionization BAL classification for APM 08279+5255. We also studied the properties of the [O III], Hβ, and Mg II emission lines. We find that [O III] is intrinsically weak (F[OIII]∕FHβ ≲ 0.04), as it is typically found in luminous quasars with a strongly blueshifted C IV emission line (~2500 km s−1 for APM 08279+5255). We computed the single-epoch black hole mass based on Mg II and Hβ broad emission lines, finding MBH = (2 ÷ 3) × 1010μ−1 M⊙, with the magnification factor μ that can vary between 4 and 100 according to CO and restframe UV-to-mid-IR imaging respectively. Using a Mg II equivalent width (EW)-to-Eddington ratio relation, the EWMgII ~ 27 Å measured for APM 08279+5255 translates into an Eddington ratio of ~0.4, which is more consistent with μ = 4. This magnification factor also provides a value of MBH that is consistent with recent reverberation-mapping measurements derived from C IV and Si IV.

Sign in / Sign up

Export Citation Format

Share Document