scholarly journals Optical spectral characterization of the TeV extreme blazar 2WHSP J073326.7+515354

2020 ◽  
Vol 494 (4) ◽  
pp. 6036-6042
Author(s):  
J Becerra González ◽  
J A Acosta-Pulido ◽  
R Clavero
Keyword(s):  
Stellar Population ◽  
Gamma Ray ◽  
Velocity Dispersion ◽  
Optical Emission ◽  
Absolute Magnitude ◽  
Brightness Distribution ◽  
Host Galaxy ◽  
Mass Relation ◽  
Relativistic Jets

ABSTRACT The emission from the relativistic jets in blazars usually outshines their host galaxies, challenging the determination of their distances and the characterization of the stellar population. The situation becomes more favourable in the case of the extreme blazars (EHBLs), for which the bulk of the emission of the relativistic jets is emitted at higher energies, unveiling the optical emission from the host galaxy. The distance determination is fundamental for the study of the intrinsic characteristics of the blazars, especially to estimate the intrinsic gamma-ray spectra distorted due to the interaction with the extragalactic background light. In this work, we report on the properties of 2WHSP J073326.7+515354 host galaxy in the optical band, which is one of the few EHBLs detected at TeV energies. We present the first measurement of the distance of the source, z = 0.065 04 ± 0.000 02 (velocity dispersion $\sigma =237 \pm 9\, \mathrm{km s^{-1}}$). We also perform a detailed study of the stellar population of its host galaxy. We find that the mass-weighted mean stellar age is $11.72\pm 0.06\, \mathrm{Gyr}$ and the mean metallicity [M/H] = 0.159 ± 0.016. In addition, a morphological study of the host galaxy is also carried out. The surface brightness distribution is modelled by a composition of a dominant classical bulge (Re = 3.77 ± 1 arcsec or equivalently 4.74 kpc) plus an unresolved source which corresponds to the active nucleus. The black hole mass is estimated using both the mass relation with the velocity dispersion and the absolute magnitude from the bulge yielding comparable results: $(4.8\pm 0.9)\times 10^8$ and $(3.7\pm 1.0)\times 10^8\, \mathrm{ M}_{\odot }$, respectively.

scholarly journals LINER-like emission in red galaxies: evolutionary phase or recurring phenomenon?

2007 ◽  
Vol 3 (S245) ◽  
pp. 181-184
Author(s):  
Genevieve J. Graves
Keyword(s):  
Stellar Population ◽  
Velocity Dispersion ◽  
Large Fraction ◽  
Optical Emission ◽  
Ionized Gas ◽  
Satellite Galaxy ◽  
The Galaxy ◽  
Evolutionary Phase ◽  
Interstellar Material ◽  
Red Galaxies

AbstractWe present recent results showing that a large fraction of red sequence galaxies contain ionized gas with LINER-like optical emission line ratios. This emission is more frequently found in galaxies with lower central velocity dispersion (σ) and these galaxies typically have younger mean ages than galaxies at the same σ which do not host emission. We suggest that the presence of LINER-like emission may be determined by the quantity of interstellar material in these galaxies and may be associated with the recent accretion of a gas-rich satellite galaxy or alternatively with stellar mass loss that declines as the galaxy stellar population ages.

scholarly journals Exceptionally bright optical emission from a rare and distant gamma-ray burst

2021 ◽  
Author(s):  
Gor Oganesyan ◽  
Sergey Karpov ◽  
Martin Jelinek ◽  
Gregory Beskin ◽  
Samuele Ronchini ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Massive Stars ◽  
Optical Emission ◽  
Gamma Ray Bursts ◽  
Additional Component ◽  
Relativistic Jets ◽  
X Ray ◽  
Forward Shock ◽  
Multi Wavelength ◽  
Wavelength Emission

Abstract Long gamma-ray bursts (GRBs) are produced by the dissipation of ultra-relativistic jets launched by newly-born black holes after the collapse of massive stars. Right after the luminous and highly variable gamma-ray emission, the multi-wavelength afterglow is released by the external dissipation of the jet in circumburst medium. We report the discovery of a very bright (10 mag) optical emission 28 s after the explosion of the extremely luminous and energetic GRB 210619B located at redshift 1.937. Early multi-filter observations allowed us to witness the end of the shock wave propagation into the GRB ejecta. We observed the spectral transition from a bright reverse to the forward shock emission, demonstrating that the early and late GRB multi-wavelength emission is originated from a very narrow jet propagating into an unusually rarefied interstellar medium. We also find evidence of an additional component of radiation, coming from the jet wings which is able explain the uncorrelated optical/X-ray emission.

Kinematics and stellar populations of the double-barred early-type galaxy NGC357

2007 ◽  
Vol 3 (S245) ◽  
pp. 137-138
Author(s):  
Adriana de Lorenzo-Cáceres ◽  
Alexandre Vazdekis ◽  
J. Alfonso L. Aguerri
Keyword(s):  
Radial Velocity ◽  
Stellar Population ◽  
Velocity Dispersion ◽  
Population Analysis ◽  
Stellar Populations ◽  
Abundance Ratio ◽  
Complete Characterization ◽  
Early Type ◽  
Early Type Galaxy

AbstractWe have carried out a kinematical and stellar population analysis of the double-barred galaxy NGC357 to provide a more complete characterization of these systems and their role in the formation of galaxy bulges. We clearly identify the presence of the inner bar in the radial velocity and velocity dispersion profiles. The age, metallicity and [Mg/Fe] abundance ratio estimates are very similar to those of ellipticals of equivalent central σ. The [Mg/Fe] value for the bulge of this galaxy suggests formation timescales shorter than 1Gyr.

scholarly journals The luminous host galaxy, faint supernova and rapid afterglow rebrightening of GRB 100418A

2018 ◽  
Vol 620 ◽  
pp. A190 ◽  
Author(s):  
A. de Ugarte Postigo ◽  
C. C. Thöne ◽  
K. Bensch ◽  
A. J. van der Horst ◽  
D. A. Kann ◽  
...  
Keyword(s):  
Light Curve ◽  
Gamma Ray ◽  
Formation Rate ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Absorption And Emission ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Central Engine

Context. Long gamma-ray bursts (GRBs) give us the chance to study both their extreme physics and the star-forming galaxies in which they form. Aims. GRB 100418A, at a redshift of z = 0.6239, had a bright optical and radio afterglow, and a luminous star-forming host galaxy. This allowed us to study the radiation of the explosion as well as the interstellar medium of the host both in absorption and emission. Methods. We collected photometric data from radio to X-ray wavelengths to study the evolution of the afterglow and the contribution of a possible supernova (SN) and three X-shooter spectra obtained during the first 60 h. Results. The light curve shows a very fast optical rebrightening, with an amplitude of ∼3 magnitudes, starting 2.4 h after the GRB onset. This cannot be explained by a standard external shock model and requires other contributions, such as late central-engine activity. Two weeks after the burst we detect an excess in the light curve consistent with a SN with peak absolute magnitude MV = −18.5 mag, among the faintest GRB-SNe detected to date. The host galaxy shows two components in emission, with velocities differing by 130 km s−1, but otherwise having similar properties. While some absorption and emission components coincide, the absorbing gas spans much higher velocities, indicating the presence of gas beyond the star-forming regions. The host has a star formation rate of SFR = 12.2 M⊙ yr−1, a metallicity of 12 + log(O/H) = 8.55, and a mass of 1.6 × 109 M⊙. Conclusions. GRB 100418A is a member of a class of afterglow light curves which show a steep rebrightening in the optical during the first day, which cannot be explained by traditional models. Its very faint associated SN shows that GRB-SNe can have a larger dispersion in luminosities than previously seen. Furthermore, we have obtained a complete view of the host of GRB 100418A owing to its spectrum, which contains a remarkable number of both emission and absorption lines.

scholarly journals The Gravity Collective: A Search for the Electromagnetic Counterpart to the Neutron Star–Black Hole Merger GW190814

2021 ◽  
Vol 923 (2) ◽  
pp. 258
Author(s):  
Charles D. Kilpatrick ◽  
David A. Coulter ◽  
Iair Arcavi ◽  
Thomas G. Brink ◽  
Georgios Dimitriadis ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gamma Ray ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Opening Angle ◽  
Gamma Ray Burst ◽  
Localization Region ◽  
Rule Out

Abstract We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Telescope, Swope Telescope, and Thacher Telescope of the LIGO/Virgo gravitational wave (GW) signal from the neutron star–black hole (NSBH) merger GW190814. We searched the GW190814 localization region (19 deg2 for the 90th percentile best localization), covering a total of 51 deg2 and 94.6% of the two-dimensional localization region. Analyzing the properties of 189 transients that we consider as candidate counterparts to the NSBH merger, including their localizations, discovery times from merger, optical spectra, likely host galaxy redshifts, and photometric evolution, we conclude that none of these objects are likely to be associated with GW190814. Based on this finding, we consider the likely optical properties of an electromagnetic counterpart to GW190814, including possible kilonovae and short gamma-ray burst afterglows. Using the joint limits from our follow-up imaging, we conclude that a counterpart with an r-band decline rate of 0.68 mag day−1, similar to the kilonova AT 2017gfo, could peak at an absolute magnitude of at most −17.8 mag (50% confidence). Our data are not constraining for “red” kilonovae and rule out “blue” kilonovae with M > 0.5 M ⊙ (30% confidence). We strongly rule out all known types of short gamma-ray burst afterglows with viewing angles <17° assuming an initial jet opening angle of ∼5.°2 and explosion energies and circumburst densities similar to afterglows explored in the literature. Finally, we explore the possibility that GW190814 merged in the disk of an active galactic nucleus, of which we find four in the localization region, but we do not find any candidate counterparts among these sources.

scholarly journals No velocity-kicks are required to explain large-distance offsets of Ca-rich supernovae and short-GRBs

2021 ◽  
Vol 503 (4) ◽  
pp. 5997-6004
Author(s):  
Hagai B Perets ◽  
Paz Beniamini
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Gamma Ray ◽  
Stellar Populations ◽  
Host Galaxy ◽  
Early Type ◽  
Late Type ◽  
Remote Locations ◽  
Large Velocity ◽  
Short Grbs

ABSTRACT Environments of supernovae (SNe) and gamma-ray bursts (GRBs) link their progenitors to the underlying stellar population, providing critical clues for their origins. However, various transients including Ca-rich SNe and short-GRBs, appear to be located at remote locations, far from the stellar population of their host galaxy, challenging our understanding of their origin and/or physical evolution. These findings instigated models suggesting that either large velocity-kicks were imparted to the transient progenitors, allowing them to propagate to large distances and attain their remote locations; or that they formed in dense globular-clusters residing in the haloes. Here we show that instead, large spatial-offsets of such transients are naturally explained by observations of highly extended stellar populations in (mostly early-type) galaxy haloes, typically missed since they can only be identified through ultra-deep/stacked images. Consequently, no large velocity kicks, nor halo globular–cluster environments are required in order to explain the origin of these transients. These findings support thermonuclear explosions on white-dwarfs, for the origins of Ca-rich SNe progenitors, and the existence of small (or zero) kick-velocities given to short-GRB progenitors. Furthermore, since stacked/ultra-deep imaging show that early-type galaxies are more extended than late-type galaxies, studies of transients’ offset-distribution (e.g. type Ia SNe or FRBs) should account for host galaxy-type. Since early-type galaxies contain older stellar populations, transient arising from older stellar populations would have larger fractions of early-type hosts, and consequently larger fractions of large-offset transients. In agreement with our results for short-GRBs and Ca-rich SNe showing different offset distributions in early versus late-type galaxies.

scholarly journals A panchromatic view of relativistic jets in narrow-line Seyfert 1 galaxies

2016 ◽  
Author(s):  
Filippo D'Ammando ◽  
Monica Orienti ◽  
Justin Finke ◽  
Josefin Larsson ◽  
Marcello Giroletti ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Systematic Investigation ◽  
Host Galaxy ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Large Area ◽  
Very High Energy ◽  
Very High ◽  
Level Analysis

The discovery by the Large Area Telescope on board Fermi of variable gamma-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1) galaxies revealed the presence of a possible third class of AGN with relativistic jets in addition to blazars and radio galaxies. Considering that NLSy1 are usually hosted in spiral galaxies, this finding poses intriguing questions about the nature of these objects and the formation of relativistic jets. We report on a systematic investigation of the gamma-ray properties of a sample of radio-loud NLSy1, including the detection of new objects, using 7 years of Fermi-LAT data with the new Pass 8 event-level analysis. In addition we discuss the radio-to-very-high-energy properties of the gamma-ray emitting NLSy1, their host galaxy, and black hole mass in the context of the blazar scenario and the unification of relativistic jets at different scales.

scholarly journals Relativistic Jets in Gamma-Ray-Emitting Narrow-Line Seyfert 1 Galaxies

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 87 ◽  
Author(s):  
Filippo D’Ammando
Keyword(s):  
Black Hole ◽  
Gamma Ray ◽  
Broad Band ◽  
Jet Physics ◽  
Host Galaxy ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Large Area ◽  
Small Black Hole ◽  
Γ Ray

Before the launch of the Fermi Gamma-ray Space Telescope satellite only two classes of active galactic nuclei (AGN) were known to generate relativistic jets and thus to emit up to the γ -ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The discovery by the Large Area Telescope (LAT) on-board the Fermi satellite of variable γ -ray emission from a few radio-loud narrow-line Seyfert 1 galaxies (NLSy1) revealed the presence of an emerging third class of AGN with powerful relativistic jets. Considering that NLSy1 are usually hosted in late-type galaxies with relatively small black hole masses, this finding opened new challenging questions about the nature of these objects, the disc/jet connection, the emission mechanisms at high energies, and the formation of relativistic jets. In this review, I will discuss the broad-band properties of the γ -ray-emitting NLSy1 included in the Fourth Fermi LAT source catalog, highlighting major findings and open questions regarding jet physics, black hole mass estimation, host galaxy and accretion process of these sources in the Fermi era.

scholarly journals A Population of Fast Radio Bursts at Cosmological Distances

Science ◽  
2013 ◽  
Vol 341 (6141) ◽  
pp. 53-56 ◽  
Author(s):  
D. Thornton ◽  
B. Stappers ◽  
M. Bailes ◽  
B. Barsdell ◽  
S. Bates ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Galactic Plane ◽  
Host Galaxy ◽  
Source Population ◽  
Radio Bursts ◽  
Host Galaxies ◽  
Fast Transients ◽  
Radio Transients ◽  
The Universe

Searches for transient astrophysical sources often reveal unexpected classes of objects that are useful physical laboratories. In a recent survey for pulsars and fast transients, we have uncovered four millisecond-duration radio transients all more than 40° from the Galactic plane. The bursts’ properties indicate that they are of celestial rather than terrestrial origin. Host galaxy and intergalactic medium models suggest that they have cosmological redshifts of 0.5 to 1 and distances of up to 3 gigaparsecs. No temporally coincident x- or gamma-ray signature was identified in association with the bursts. Characterization of the source population and identification of host galaxies offers an opportunity to determine the baryonic content of the universe.

scholarly journals Intra-night optical variability of γ −ray detected narrow-line Seyfert1 galaxies

2020 ◽  
Author(s):  
Vineet Ojha ◽  
Hum Chand ◽  
Gopal Krishna
Keyword(s):  
Significant Contribution ◽  
Accretion Rate ◽  
Optical Emission ◽  
Light Curves ◽  
Host Galaxy ◽  
Optical Variability ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Γ Ray ◽  
Optical Flux

Abstract We report the first attempt to systematically characterise intra-night optical variability (INOV) of the rare and enigmatic subset of Narrow-Line Seyfert1 galaxies (NLSy1s), which is marked by detection in the γ-ray band and is therefore endowed with Doppler boosted relativistic jets, like blazars. However, the central engines in these two types of AGN are thought to operate in different regimes of accretion rate. Our INOV search in a fairly large and unbiased sample of 15 γ-ray NLSy1s was conducted in 36 monitoring sessions, each lasting ≥ 3 hrs. In our analysis, special care has been taken to address the possible effect on the differential light curves, of any variation in the seeing disc during the session, since that might lead to spurious claims of INOV from such AGN due to the possibility of a significant contribution from the host galaxy to the total optical emission. From our observations, a duty cycle (DC) of INOV detection in the γ-ray NLSy1s is estimated to be around 25% - 30%, which is comparable to that known for blazars. This estimate of DC will probably need an upward revision, once it becomes possible to correct for the dilution of the AGN’s nonthermal optical emission by the (much steadier) optical emission contributed not only by the host galaxy but also the nuclear accretion disc in these high Eddington rate accretors. Finally, we also draw attention to the possibility that sharp optical flux changes on sub-hour time scale are less rare for γ-ray NLSy1s, in comparison to blazars.

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