scholarly journals Spectrophotometry of Supernovae

1974 ◽  
Vol 3 ◽  
pp. 533-544
Author(s):  
R. P. Kirshner
Keyword(s):  
Emission Lines ◽  
Absorption Lines ◽  
Spectral Energy ◽  
Line Profiles ◽  
Energy Distributions ◽  
Maximum Light ◽  
Balmer Lines ◽  
B Lines ◽  
Infrared Triplet ◽  
The Continuum

AbstractAbsolute spectral energy distributions for supernovae of both types I and II have been obtained. These observations demonstrate three facets of supernova spectra. First, both SN I’s and SN II’s have a continuum that varies slowly and uniformly with time, and which carries the bulk of the radiated flux at early epochs. Second, some lines in both SN I’s and SN II’s have P Cygni profiles: broad emissions flanked on their violet edges by broad absorptions. Third, some lines are common to SN I’s and SN II’s and persist throughout the evolution of the spectrum. The continuum temperatures for both SN I’s and SN II’s are about 10000 K at the earliest times of observation and drop in one month’s time to about 6000 K for SN II’s and about 7000 K for SN I’s. After several months, the continuum may cease to carry the bulk of the flux, which might be in emission lines, but continues to exist, as shown by the presence of absorption lines. The P Cygni line profiles indicate expansion velocities of 15000 km s-1 in SN II’s and 20000 km s-11 in the SN I 1972e in NGC 5253. Line identifications for SN II’s include Hα, Hβ, H and K of Ca II, the Ca II infrared triplet at λ8600, the Na I D-lines, the Mg I b-lines at λ5174, and perhaps Fe II. The [O I] lines λλ6300, 6363 and [Ca II] lines λλ7291, 7323 appear after eight months. For SN I’s, the lines identified are H and K of Ca II, the infrared Ca II lines, the Na I D-lines, and the Mg I b-lines. There is some evidence that Balmer lines are present two weeks after maximum. The strong and puzzling λ4600 features drifts with time from λ4600 near maximum light to λ4750 after 400 days.

scholarly journals NOEMA redshift measurements of bright Herschel galaxies

2020 ◽  
Vol 635 ◽  
pp. A7 ◽  
Author(s):  
R. Neri ◽  
P. Cox ◽  
A. Omont ◽  
A. Beelen ◽  
S. Berta ◽  
...  
Keyword(s):  
Mean Value ◽  
Emission Lines ◽  
Spectral Energy ◽  
Future Prospects ◽  
Large Area ◽  
Ancillary Data ◽  
Energy Distributions ◽  
Area Survey ◽  
Comprehensive Survey ◽  
The Continuum

Using the IRAM NOrthern Extended Millimeter Array (NOEMA), we conducted a program to measure redshifts for 13 bright galaxies detected in the Herschel Astrophysical Large Area Survey with S500 μm ≥ 80 mJy. We report reliable spectroscopic redshifts for 12 individual sources, which are derived from scans of the 3 and 2 mm bands, covering up to 31 GHz in each band, and are based on the detection of at least two emission lines. The spectroscopic redshifts are in the range 2.08 <  z <  4.05 with a median value of z = 2.9 ± 0.6. The sources are unresolved or barely resolved on scales of 10 kpc. In one field, two galaxies with different redshifts were detected. In two cases the sources are found to be binary galaxies with projected distances of ∼140 kpc. The linewidths of the sources are large, with a mean value for the full width at half maximum of 700 ± 300 km s−1 and a median of 800 km s−1. We analyze the nature of the sources with currently available ancillary data to determine if they are lensed or hyper-luminous (LFIR >  1013 L⊙) galaxies. We also present a reanalysis of the spectral energy distributions including the continuum flux densities measured at 3 and 2 mm to derive the overall properties of the sources. Future prospects based on these efficient measurements of redshifts of high-z galaxies using NOEMA are outlined, including a comprehensive survey of all the brightest Herschel galaxies.

scholarly journals Predicting the broad-lines polarization emitted by supermassive binary black holes

2019 ◽  
Vol 623 ◽  
pp. A56 ◽  
Author(s):  
D. Savić ◽  
F. Marin ◽  
L. Č. Popović
Keyword(s):  
Black Holes ◽  
Emission Lines ◽  
Polarization Angle ◽  
Broad Line ◽  
Line Profiles ◽  
Binary Black Holes ◽  
True Nature ◽  
Line Shapes ◽  
Highly Sensitive ◽  
Balmer Lines

Context. Some Type-1 active galactic nuclei (AGN) show extremely asymmetric Balmer lines with the broad peak redshifted or blueshifted by thousands of km s−1. These AGN may be good candidates for supermassive binary black holes (SMBBHs). The complex line shapes can be due to the complex kinematics of the two broad line regions (BLRs). Therefore other methods should be applied to confirm the SMBBHs. One of them is spectropolarimetry. Aims. We rely on numerical modeling of the polarimetry of binary black holes systems, since polarimetry is highly sensitive to geometry, in order to find the specific influence of supermassive binary black hole (SMBBH) geometry and dynamics on polarized parameters across the broad line profiles. We apply our method to SMBBHs in which both components are assumed to be AGN with distances at the subparsec scale. Methods. We used a Monte Carlo radiative transfer code that simulates the geometry, dynamics, and emission pattern of a binary system where two black holes are getting increasingly close. Each gravitational well is accompanied by its own BLR and the whole system is surrounded by an accretion flow from the distant torus. We examined the emission line deformation and predicted the associated polarization that could be observed. Results. We modeled scattering-induced broad line polarization for various BLR geometries with complex kinematics. We find that the presence of SMBBHs can produce complex polarization angle profiles φ and strongly affect the polarized and unpolarized line profiles. Depending on the phase of the SMBBH, the resulting double-peaked emission lines either show red or blue peak dominance, or both the peaks can have the same intensity. In some cases, the whole line profile appears as a single Gaussian line, hiding the true nature of the source. Conclusions. Our results suggest that future observation with the high resolution spectropolarimetry of optical broad emission lines could play an important role in detecting subparsec SMBBHs.

scholarly journals The Early Outburst Spectra of Nova V1500 Cygni

1990 ◽  
Vol 122 ◽  
pp. 161-162
Author(s):  
M. Mikołajewski ◽  
J. Mikołajewska
Keyword(s):  
Spectral Range ◽  
Research Group ◽  
Energy Scale ◽  
Absorption Lines ◽  
Spectral Energy ◽  
Spectral Evolution ◽  
Energy Distributions ◽  
Balmer Series ◽  
Absolute Energy ◽  
Evolution With Time

Nova Cygni 1975 (V1500 Cyg) was outstanding in several respects. It was the most luminous galactic nova ever observed, had the largest outburst amplitude, and had the fastest evolution with time.The spectra, with dispersion 28 A/mm and in spectral range λλ3560-5055 A, were obtained with the CCS spectrograph on 90 cm reflector at Toruń Observatory by the research group supervised by prof. A. WoszczyK. The CCS spectrograph was equipped with the 3.5 arcsec aperture Richardson’s image slicer and stars with known spectral energy distributions were observed on each night, so we were able to derive absolute energy distributions for the V1500 Cyg spectra. The calibration of the energy scale was performed by comparing synthetic B magnitudes calculated from our spectra with numerous published B photometry of the nova. The first spectra were obtained about 3h later than spectra reported by Boyarchuk (1977) and about 6h earlier than spectra discussed by Duerbeck and Wolf (1977); thus they are among the earliest spectra of the nova available. Simultaneously, the spectra correspond to the earliest state of spectral evolution of a nova ouburst yet observed. The pre-maximum spectral evolution of Nova V1500 Cyg is extremely fast. The spectra (Figures 1 and 2) secured on JD 2442654 are characterized by a very strong continuum and broad blueshifted absorption lines of OII, NII and CII of unusual strengths, as well as the Balmer series and Hel.

scholarly journals O and Of Stars

1973 ◽  
Vol 49 ◽  
pp. 93-107
Author(s):  
Peter S. Conti
Keyword(s):  
Visible Spectrum ◽  
Emission Lines ◽  
Absorption Lines ◽  
Evolutionary Status ◽  
Be Stars ◽  
Type B ◽  
No Emission ◽  
Hot Stars ◽  
Hydrogen Lines ◽  
The Continuum

My intention here is to discuss the ‘high temperature’ portion of this symposium and call attention to those stars that are called Of. There are some similarities in spectral appearance to WR stars, e.g. emission lines. I should first like to define what I think are the essential differences among four groups of hot stars;O stars: Stars that have only absorption lines in the visible spectrum. Type O is distinguished from type B by the presence of He ii 4541 at MK dispersion. It may be that some (supergiants) O stars will have emission lines in the rocket UV region but this description will be primarily concerned with ground based observations.Of stars: These are O type stars that also have λλ 4634,40 N iii in emission above the continuum. In addition to normal O star absorption lines and N iii emission, they may also have other lines in emission. I will discuss this further below.Oe stars: These are O type stars that have emission in the hydrogen lines (or at least at Hα), but with no emission in N iii or in other lines. I personally think that this small class of objects is related to the Be stars in their evolutionary status and in their emission mechanism.WR stars: These stars are primarily characterized by emission lines. The only absorption lines seen are violet shifted (P Cyg type). Although in some cases emission lines appear which are similar to those found in some Of stars, the latter types always have some unshifted absorption lines present. Several Of stars have P Cyg profiles in some lines.

scholarly journals ISO Observations of AGN and Ultraluminous IR Galaxies

1998 ◽  
Vol 11 (2) ◽  
pp. 1131-1133 ◽  
Author(s):  
Alan F. M. Moorwood
Keyword(s):  
Ionization Potential ◽  
Elliptical Galaxy ◽  
Emission Lines ◽  
Spectral Energy ◽  
High Excitation ◽  
Low Resolution ◽  
Energy Distributions ◽  
Diagnostic Features ◽  
Wide Range ◽  
First Time

All the ISO instruments are contributing to the study of activity in galaxies of essentially all types. Although AGN's as such are pointlike, the beautiful CAM image of CenA shown by Catherine Cesarsky has given us the clearest view so far of its visually obscured nucleus and surrounding spiral disc embedded in an elliptical galaxy. The CAM CVF is also providing spectral images of the PAH features and important diagnostic ionic lines (e.g [NeII] and [NeIII]) in the circumnuclar regions of AGN and merging starburst systems (Vigroux et al., 1996). PHT is providing detailed spectral energy distributions over the complete 2.5-240µm range and PHTS is proving invaluable for assembling a catalogue of low resolution (R ⋍ 90) galaxy spectra covering the 6-12µm PAH features. SWS and LWS are generating higher resolution (R ⋍ 2000-200) spectra over the range 2.5-200µm such as that shown in Fig. 1. of the Circinus galaxy which exhibits both AGN and starburst activity and well illustrates the wide range of diagnostic features, many seen for the first time, accessible to ISO studies of galaxies. It shows the overall continuum with a peak around 100µm; PAH features and Si absorption which dominate the spectrum around 10µm; H recombination lines; H2 pure rotational emission lines; low ionization potential ionic lines excited by starburst activity and high excitation lines (up to ⋍ 300eV) excited by the visually obscured AGN.

Galactic outflows in star-forming galaxies at z ∼ 6 studied with deep UV spectra and ALMA emission line

2019 ◽  
Vol 15 (S341) ◽  
pp. 307-308
Author(s):  
Yuma Sugahara ◽  
Masami Ouchi ◽  
Yuichi Harikane ◽  
Nicolas Bouché ◽  
Peter D. Mitchell ◽  
...  
Keyword(s):  
Maximum Velocity ◽  
Uv Spectra ◽  
Emission Lines ◽  
Absorption Lines ◽  
Line Profiles ◽  
Strong Emission ◽  
Star Forming ◽  
Lyman Break Galaxies ◽  
Metal Absorption ◽  
Galactic Outflows

AbstractWe present a velocity of galactic outflows in star-forming galaxies at the highest redshift, z ∼ 6, so far studied with metal absorption lines. Absorption-line studies of galactic outflows need well-determined redshifts, but there are few strong emission lines in the observed-frame optical spectra of galaxies at high redshifts. In this work, we use the systemic redshifts determined by the ALMA [CII]158 μm emission lines. The sample consists of seven Lyman break galaxies at 5.1 < z < 5.7 whose Keck/DEIMOS and ALMA data are available in the archive. The outflow maximum velocity (νmax) is estimated by a fitting of line profiles to metal absorption lines in a composite spectrum. We find that νmax monotonically increases from z ∼ 0 to 6 and that νmax tightly correlates with the halo circular velocity estimated from the stellar mass.

scholarly journals Modeling the Orientation of AGN

2009 ◽  
Vol 5 (S267) ◽  
pp. 107-107
Author(s):  
Emily Down
Keyword(s):  
Accretion Disk ◽  
Power Law ◽  
Emission Lines ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Near Ir ◽  
Bayesian Evidence ◽  
Hα Emission

The orientation of nineteen 0.8< z < 2.3 radio-loud quasars was measured using two independent methods. First, Hα was observed in the near IR using ISAAC at the VLT. The complex Hα emission lines were fitted with a range of models, some including emission from a flattened, extended accretion disk following Chen & Halpern (1989). The models were compared using the Bayesian evidence, and the disk axis angles recovered. Second, models were fitted to the ~10 MHz to 20 GHz radio spectral energy distributions (SEDs) to recover the jet angles, assuming that the emission is comprised of a broken power law arising from the radio lobes plus a Doppler-boosted core.

scholarly journals Investigation of the Relation between the Spectral Energy Distributions and the Emission Lines in Low‐Redshift Quasars

1999 ◽  
Vol 513 (1) ◽  
pp. 76-107 ◽  
Author(s):  
Belinda J. Wilkes ◽  
Joanna Kuraszkiewicz ◽  
Paul J. Green ◽  
Smita Mathur ◽  
Jonathan C. McDowell
Keyword(s):  
Emission Lines ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions

Two New T Tauri stars and a Candidate FU Orionis Star associated with Bok Globules

1997 ◽  
Vol 163 ◽  
pp. 839-839
Author(s):  
J. L. Yun ◽  
M. Moreira
Keyword(s):  
Infrared Emission ◽  
T Tauri Stars ◽  
Emission Lines ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Stellar Objects ◽  
T Tauri ◽  
Bok Globules ◽  
Reflection Nebulae

AbstractWe present photometric and spectroscopic evidence of two new T Tauri stars formed in the conditions of isolated small Bok globules. The spectral energy distributions of these objects display excess infrared emission, they are associated with optical reflection nebulae, and their optical spectra reveal Balmer emission lines and the Li I λ6707 Å absorption line. Additionnally, we report the discovery of what is likely to be a new FU Orionis star seen towards Bok globule CB34. The star is about 4 magnitudes brighter than it appears on the Palomar plates and is associated with the aggregate of young stellar objects forming in Bok globule CB34.

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