scholarly journals Is IRAS F10214+4724 Gravitationally Lensed?

1996 ◽  
Vol 173 ◽  
pp. 247-252
Author(s):  
J. Lehár ◽  
T. Broadhurst
Keyword(s):  
Host Galaxy ◽  
Optical Source ◽  
Iras Source ◽  
Near Ir ◽  
Spectral Evidence ◽  
Optical Images ◽  
Central Regions

We show that the z = 2.3 IRAS source F10214+4724 is gravitationally lensed by an intervening galaxy, as suggested by the observed near-IR structures. Its many anomalous properties can be explained if the source is an ordinary Seyfert 2 nucleus whose central regions are much more highly magnified than the surrounding host galaxy. Confirming expectations, we find a counterimage to the near-IR arc, and find spectral evidence for the lensing galaxy at z ∼ 1. We present new optical images which show that the optical source is compact and highly magnified. F10214+4724 may represent a population of lensed AGNs whose central engines are obscured.

Tracing young SMBHs in the dusty distant universe – a Chandra view of DOGs

2020 ◽  
Vol 15 (S359) ◽  
pp. 17-21
Author(s):  
Karín Menéndez-Delmestre ◽  
Laurie Riguccini ◽  
Ezequiel Treister
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Far Infrared ◽  
Host Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Near Ir ◽  
X Ray Imaging ◽  
Combined Use ◽  
Dusty Galaxies

AbstractThe coexistence of star formation and AGN activity has geared much attention to dusty galaxies at high redshifts, in the interest of understanding the origin of the Magorrian relation observed locally, where the mass of the stellar bulk in a galaxy appears to be tied to the mass of the underlying supermassive black hole. We exploit the combined use of far-infrared (IR) Herschel data and deep Chandra ˜160 ksec depth X-ray imaging of the COSMOS field to probe for AGN signatures in a large sample of >100 Dust-Obscured Galaxies (DOGs). Only a handful (˜20%) present individual X-ray detections pointing to the presence of significant AGN activity, while X-ray stacking analysis on the X-ray undetected DOGs points to a mix between AGN activity and star formation. Together, they are typically found on the main sequence of star-forming galaxies or below it, suggesting that they are either still undergoing significant build up of the stellar bulk or have started quenching. We find only ˜30% (6) Compton-thick AGN candidates (NH > 1024 cm–2), which is the same frequency found within other soft- and hard-X-ray selected AGN populations. This suggests that the large column densities responsible for the obscuration in Compton-thick AGNs must be nuclear and have little to do with the dust obscuration of the host galaxy. We find that DOGs identified to have an AGN share similar near-IR and mid-to-far-IR colors, independently of whether they are individually detected or not in the X-ray. The main difference between the X-ray detected and the X-ray undetected populations appears to be in their redshift distributions, with the X-ray undetected ones being typically found at larger distances. This strongly underlines the critical need for multiwavelength studies in order to obtain a more complete census of the obscured AGN population out to higher redshifts. For more details, we refer the reader to Riguccini et al. (2019).

The range of UV upturn strengths in early-type galaxies can be caused by dissolved metal-rich Globular Clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 112-116
Author(s):  
Paul Goudfrooij
Keyword(s):  
Globular Clusters ◽  
Dynamical Evolution ◽  
Virgo Cluster ◽  
Host Galaxy ◽  
Early Type ◽  
Luminosity Functions ◽  
Central Regions ◽  
Specific Frequency ◽  
Uv Upturn

AbstractI summarize the scenario by Goudfrooij (2018) in which the bulk of the ultraviolet (UV) upturn of giant early-type galaxies (ETGs) is due to helium-rich stellar populations that formed in massive metal-rich globular clusters (GCs) and subsequently dissolved in the strong tidal field in the central regions of the massive host galaxy. These massive GCs are assumed to show UV upturns similar to those observed recently in M87, the central galaxy in the Virgo cluster of galaxies. Data taken from the literature reveals a strong correlation between the strength of the UV upturn and the specific frequency of metal-rich GCs in ETGs. Adopting a Schechter function parametrization of GC mass functions, simulations of long-term dynamical evolution of GC systems show that this correlation can be explained by variations in the characteristic truncation mass Mc such that Mc increases with ETG luminosity in a way that is consistent with observed GC luminosity functions in ETGs. These findings suggest that the nature of the UV upturn in ETGs and the variation of its strength among ETGs are causally related to that of helium-rich populations in massive GCs, rather than intrinsic properties of field stars in ETGs.

Preliminary analysis of the X-ray emission from the central regions of the Pictor A

2018 ◽  
Vol 14 (S342) ◽  
pp. 224-226
Author(s):  
R. Thimmappa ◽  
Ł. Stawarz ◽  
K. Balasubramaniam ◽  
V. Marchenko
Keyword(s):  
Surface Brightness ◽  
Radio Galaxy ◽  
Radial Profile ◽  
Host Galaxy ◽  
Active Nucleus ◽  
X Ray ◽  
Central Regions ◽  
Total Exposure Time ◽  
Radiative Output ◽  
The Individual

AbstractHere we present some preliminary results of our analysis of the combined Chandra observations of the Pictor A radio galaxy. All the available Chandra data for the target, consisting of multiple pointings spanning over 15 years and amounting to the total exposure time of 464 ks, have been included in the analysis. We studied in detail the PSFs of the core region in the individual pointings, as well as the radial profile of the X-ray surface brightness of the source in the combined dataset, in order to discriminate between the radiative output of the unresolved core and the host galaxy. Based on these, we have performed spectral modeling of the active nucleus, constraining its variability.

scholarly journals A nearby super-luminous supernova with a long pre-maximum & “plateau” and strong C II features

2018 ◽  
Vol 620 ◽  
pp. A67 ◽  
Author(s):  
J. P. Anderson ◽  
P. J. Pessi ◽  
L. Dessart ◽  
C. Inserra ◽  
D. Hiramatsu ◽  
...  
Keyword(s):  
Formation Rate ◽  
Early Time ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Type I ◽  
Optical Wavelength ◽  
Near Ir ◽  
Spectral Models ◽  
Multi Wavelength ◽  
Ir Photometry

Context. Super-luminous supernovae (SLSNe) are rare events defined as being significantly more luminous than normal terminal stellar explosions. The source of the additional power needed to achieve such luminosities is still unclear. Discoveries in the local Universe (i.e. z < 0.1) are scarce, but afford dense multi-wavelength observations. Additional low-redshift objects are therefore extremely valuable. Aims. We present early-time observations of the type I SLSN ASASSN-18km/SN 2018bsz. These data are used to characterise the event and compare to literature SLSNe and spectral models. Host galaxy properties are also analysed. Methods. Optical and near-IR photometry and spectroscopy were analysed. Early-time ATLAS photometry was used to constrain the rising light curve. We identified a number of spectral features in optical-wavelength spectra and track their time evolution. Finally, we used archival host galaxy photometry together with H II region spectra to constrain the host environment. Results. ASASSN-18km/SN 2018bsz is found to be a type I SLSN in a galaxy at a redshift of 0.0267 (111 Mpc), making it the lowest-redshift event discovered to date. Strong C II lines are identified in the spectra. Spectral models produced by exploding a Wolf-Rayet progenitor and injecting a magnetar power source are shown to be qualitatively similar to ASASSN-18km/SN 2018bsz, contrary to most SLSNe-I that display weak or non-existent C II lines. ASASSN-18km/SN 2018bsz displays a long, slowly rising, red “plateau” of >26 days, before a steeper, faster rise to maximum. The host has an absolute magnitude of –19.8 mag (r), a mass of M⋆ = 1.5−0.33+0.08 × 109 M⊙, and a star formation rate of = 0.50−0.19+2.22 M⊙ yr −1. A nearby H II region has an oxygen abundance (O3N2) of 8.31 ± 0.01 dex.

scholarly journals Quasar Metal Abundances & Host Galaxy Evolution

2009 ◽  
Vol 5 (S265) ◽  
pp. 171-178
Author(s):  
Fred Hamann ◽  
Leah E. Simon
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
High Redshift ◽  
Big Bang ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Massive Galaxies ◽  
Central Regions ◽  
Metal Abundances ◽  
The Big Bang

AbstractHigh-redshift quasars provide a unique glimpse into the early evolution of massive galaxies. The physical processes that trigger major bursts of star formation in quasar host galaxies (mergers and interactions) probably also funnel gas into the central regions to grow the super-massive black holes (SMBHs) and ignite the luminous quasar phenomenon. The globally dense environments where this occurs were probably also among the first to collapse and manufacture stars in significant numbers after the big bang. Measurements of the elemental abundances near quasars place important constraints on the nature, timing and extent of this star formation. A variety of studies using independent emission and absorption line diagnostics have shown that quasar environments have gas-phase metallicities that are typically a few times solar at all observed redshifts. These results are consistent with galaxy evolution scenarios in which large amounts of star formation (e.g., in the central regions) precede the visibly bright quasar phase. An observed trend for higher metallicities in more luminmous quasars (powered by more massive SMBHs) is probably tied to the well-known mass–metallicity relation among ordinary galaxies. This correlation and the absence of a trend with redshift indicate that mass is a more important parameter in the evolution than the time elapsed since the big bang.

scholarly journals Optical, Near-IR, and X-Ray Observations of SN 2015J and Its Host Galaxy

2017 ◽  
Vol 850 (2) ◽  
pp. 111
Author(s):  
A. A. Nucita ◽  
F. De Paolis ◽  
R. Saxton ◽  
V. Testa ◽  
F. Strafella ◽  
...  
Keyword(s):  
Host Galaxy ◽  
X Ray ◽  
Near Ir

scholarly journals A VST and VISTA study of globular clusters in NGC 253

2018 ◽  
Vol 611 ◽  
pp. A21 ◽  
Author(s):  
Michele Cantiello ◽  
Aniello Grado ◽  
Marina Rejkuba ◽  
Magda Arnaboldi ◽  
Massimo Capaccioli ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Radial Profile ◽  
Host Galaxy ◽  
Near Ir ◽  
Free Sample ◽  
Radial Density Profile ◽  
The Galaxy ◽  
Definition Of ◽  
Distance Indicators ◽  
Ir Photometry

Context. Globular clusters (GCs) are key to our understanding of the Universe, as laboratories of stellar evolution, fossil tracers of the past formation epoch of the host galaxy, and effective distance indicators from local to cosmological scales.Aim. We analyze the properties of the sources in the NGC 253 with the aim of defining an up to date catalog of GC candidates in the galaxy. Given the distance of the galaxy, GCs in NGC 253 are ideal targets for resolved color-magnitude diagram studies of extragalactic GCs with next-generation diffraction limited ground-based telescopes.Methods. Our analysis is based on the science verification data of two ESO survey telescopes, VST and VISTA. Using ugri photometry from VST and JKs from VISTA, GC candidates were selected using as reference the morpho-photometric and color properties of spectroscopically confirmed GCs available in the literature. The strength of the results was verified against available archival HST/ACS data from the GHOSTS survey: all but two of the selected GC candidates appear as star clusters in HST footprints.Results. The adopted GC selection leads to the definition of a sample of ∼350 GC candidates. At visual inspection, we find that 82 objects match all the requirements for selecting GC candidates and 155 are flagged as uncertain GC candidate; however, 110 are unlikely GCs, which are most likely background galaxies. Furthermore, our analysis shows that four of the previously spectroscopically confirmed GCs, i.e., ∼20% of the total spectroscopic sample, are more likely either background galaxies or high-velocity Milky Way stars. The radial density profile of the selected best candidates shows the typically observed r1∕4-law radial profile. The analysis of the color distributions reveals only marginal evidence of the presence of color bimodality, which is normally observed in galaxies of similar luminosity. The GC luminosity function does not show the typical symmetry, mainly because of the lack of bright GCs. Part of the bright GCs missing might be at very large galactocentric distances or along the line of sight of the galaxy dusty disk. As an alternative possibility, we speculate that a fraction of low luminosity GC candidates might instead be metal-rich, intermediate age clusters, but fall in a similar color interval of old, metal-poor GCs.Conclusions. Defining a contaminant-free sample of GCs in extragalactic systems is not a straight forward exercise. Using optical and near-IR photometry we purged the list of GCs with spectroscopic membership and photometric GC candidates in NGC 253. Our results show that the use of either spectroscopic or photometric data only does not generally ensure a contaminant-free sample and a combination of both spectroscopy and photometry is preferred.

scholarly journals Simulations of Recoiling Massive Black Holes

2009 ◽  
Vol 5 (S267) ◽  
pp. 262-262
Author(s):  
Javiera Guedes ◽  
Piero Madau ◽  
Lucio Mayer ◽  
Michael Kuhlen ◽  
Jürg Diemand ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Return Time ◽  
Wave Radiation ◽  
Host Galaxy ◽  
Massive Black Holes ◽  
Black Hole Binaries ◽  
The Galaxy ◽  
Central Regions ◽  
Black Hole Remnant

AbstractThe coalescence of black hole binaries is a significant source of gravitational wave radiation. The typically asymmetric nature of this emission, which carries linear momentum, can result in the recoil of the black hole remnant with velocities in the range 100 < Vrecoil < 3750 km s−1. The detectability of recoiling massive black holes (MBH) as off-nuclear QSOs is tightly connected with the properties of the host galaxy, which determine the MBH's orbit and fuel reservoir. We present the results of N-body simulations of recoiling MBHs in high-resolution, non-axisymmetric potentials. We find that if the recoil velocities are high enough to reach regions of the galaxy dominated by the generally triaxial dark matter distribution, the return time is significantly extended when compared to a spherical distribution. We also perform simulations of recoiling MBHs traveling in gas merger remnants, where large amounts of gas have been funneled to the central regions, In this case, the MBHs remain within R<1 kpc from the center of the host even for high recoil velocities (Vrecoil = 1200 km s−1) due to the compactness of the remnant galaxy's nuclear disk. We discuss the implications of both scenarios for detectability.

scholarly journals Disturbed radio and optical morphology in the interacting galaxy pairs

2012 ◽  
Vol 8 (S290) ◽  
pp. 241-242
Author(s):  
M. Kunert-Bajraszewska ◽  
A. Janiuk ◽  
M. Hajduk
Keyword(s):  
High Resolution ◽  
Radio Source ◽  
Host Galaxy ◽  
Radio Observations ◽  
The North ◽  
Complex Morphology ◽  
Optical Images ◽  
North Eastern ◽  
5 Ghz ◽  
Small Separation

AbstractWe present high resolution radio observations and their analysis of a radio-loud compact steep spectrum (CSS) sources FIRST J164311.3+315618 and FIRST J150805.6+342323. The radio observations presented here were made with the multi-element radio linked interferometer network (MERLIN) at 1.66 GHz and 5 GHz. The radio source FIRST J164311.3+315618 is associated with a small separation, 2.3 arcsec, radio-loud/radio-quiet binary quasar. The radio object FIRST J150805.6+342323 is associated with the north-eastern member of an interacting galaxy pair separated by 24 arcseconds. Our observations revealed disrupted radio morphology of both CSS sources. The distortions of the host galaxy of the two systems are also clearly visible in the optical images and, in the case of binary quasar FIRST J164311.3+315618, are well correlated with the radio ones. We suggest that the ignition of the AGN activity and its complex morphology is caused by the interaction with the companion in the process of merging.

scholarly journals The Carnegie Supernova Project I

2018 ◽  
Vol 609 ◽  
pp. A136 ◽  
Author(s):  
F. Taddia ◽  
M. D. Stritzinger ◽  
M. Bersten ◽  
E. Baron ◽  
C. Burns ◽  
...  
Keyword(s):  
Binary Systems ◽  
Light Curves ◽  
Host Galaxy ◽  
Expansion Velocity ◽  
Late Time ◽  
Exact Nature ◽  
Intermediate Mass ◽  
Hydrodynamical Models ◽  
Near Ir ◽  
Linear Slope

Stripped-envelope (SE) supernovae (SNe) include H-poor (Type IIb), H-free (Type Ib), and He-free (Type Ic) events thought to be associated with the deaths of massive stars. The exact nature of their progenitors is a matter of debate with several lines of evidence pointing towards intermediate mass (Minit< 20 M⊙) stars in binary systems, while in other cases they may be linked to single massive Wolf-Rayet stars. Here we present the analysis of the light curves of 34 SE SNe published by the Carnegie Supernova Project (CSP-I) that are unparalleled in terms of photometric accuracy and wavelength range. Light-curve parameters are estimated through the fits of an analytical function and trends are searched for among the resulting fit parameters. Detailed inspection of the dataset suggests a tentative correlation between the peak absolute B-band magnitude and Δm15(B), while the post maximum light curves reveals a correlation between the late-time linear slope and Δm15. Making use of the full set of optical and near-IR photometry, combined with robust host-galaxy extinction corrections, comprehensive bolometric light curves are constructed and compared to both analytic and hydrodynamical models. This analysis finds consistent results among the two different modeling techniques and from the hydrodynamical models we obtained ejecta masses of 1.1–6.2M⊙, 56Ni masses of 0.03–0.35M⊙, and explosion energies (excluding two SNe Ic-BL) of 0.25–3.0 × 1051 erg. Our analysis indicates that adopting κ = 0.07 cm2 g-1 as the mean opacity serves to be a suitable assumption when comparing Arnett-model results to those obtained from hydrodynamical calculations. We also find that adopting He i and O i line velocities to infer the expansion velocity in He-rich and He-poor SNe, respectively, provides ejecta masses relatively similar to those obtained by using the Fe ii line velocities, although the use of Fe ii as a diagnostic does imply higher explosion energies. The inferred range of ejecta masses are compatible with intermediate mass (MZAMS ≤ 20M⊙) progenitor stars in binary systems for the majority of SE SNe. Furthermore, our hydrodynamical modeling of the bolometric light curves suggests a significant fraction of the sample may have experienced significant mixing of 56Ni, particularly in the case of SNe Ic.

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