Results 21 to 30 of about 765,605 (153)

Extreme accretion events: TDEs and changing‐look AGN

Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023
Abstract We present a review of the topics of X‐ray stellar tidal disruption events (TDEs) and changing‐look active galactic nuclei (AGN). Stars approaching a supermassive black hole (SMBH) can be tidally disrupted and accreted. TDEs were first discovered in the X‐ray regime and appear as luminous, giant‐amplitude flares from inactive galaxies.
S. Komossa, D. Grupe
wiley   +1 more source

Modelling gas around galaxy pairs and groups using the Q0107 quasar triplet [PDF]

, 2023
We examine to what extent disc and outflow models can reproduce observations of H I gas within a few virial radii of galaxies in pairs and groups. Using highly sensitive HST/COS and FOS spectra of the Q0107 quasar triplet covering Ly α for z≲1, as well ...
Fumagalli, Michele, Morris, S.L., Jannuzi, B., Tejos, N., Cantalupo, Sebastiano, Morris, Simon L, Beckett, Alexander, Tejos, Nicolas, Beckett, A., Fumagalli, M., Jannuzi, Buell, Cantalupo, S., Morris, Simon L., Simon L Morris, Nicolas Tejos, Alexander Beckett, Buell Jannuzi, Sebastiano Cantalupo, Michele Fumagalli   +18 more
core   +1 more source

The jet emitting disk‐standard accretion disk model applied to the active galactic nuclei ultra violet–X‐ray correlation

Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023
Abstract The non‐linear correlation between the UV and X‐ray emission observed in active galactic nuclei remains a puzzling question that challenges accretion models. While the UV emission originates from the cold disk, the X‐ray emission is emitted by a hot corona whose physical characteristics and geometry are still highly debated.
S. Barnier, P.‐O. Petrucci, J. Ferreira, G. Marcel   +3 more
wiley   +1 more source

Effect of the metallicity of the intergalactic medium in the Lyman‐α forest correlation function

Astronomische Nachrichten, Volume 344, Issue 1-2, January-February 2023., 2023
Abstract The Lyman‐α (Lyα) forest allows to constraint cosmological parameters at redshifts above 1.8$$ 1.8 $$ using the technique of standard rulers determined by baryon acoustic oscillations. This makes it an important tracer for the study of the universe at high redshift.
Andrea Muñoz‐Gutiérrez, Axel de la Macorra   +1 more
wiley   +1 more source

The road toward imaging a black hole: A personal perspective

Natural Sciences, Volume 2, Issue 4, October 2022., 2022
The article describes the authors personal journey towards developig the Event Horizon Telescope and the first image of a black hole. Left: predcition made by the author and collaborators proposing the black hole imaging in 2000. Right: the two images observed and published by the Event Horizon Telescope in 2019 and 2022.
Heino Falcke
wiley   +1 more source

Neutral hydrogen absorption and emission in the quasar/galaxy pair 3C 275.1/NGC 4651

The Astrophysical Journal, 1993
3C275.1 and \NGC4651 make a particularly interesting quasar/galaxy pairing because of the alignment of such a strong radio emitter behind the outer H\I disk of a relatively undisturbed spiral galaxy. This provides an opportunity to study the spin-temperature characteristics of atomic hydrogen at low column densities, in an apparently star-free ...
SCHNEIDER, SE, CORBELLI, E
openaire   +3 more sources

Galaxy And Mass Assembly (GAMA) : galaxy close pairs, mergers and the future fate of stellar mass [PDF]

, 2014
ASGR acknowledges STFC and SUPA funding that were used to do this work. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO and the participating institutions.We use a highly complete subset of the Galaxy And Mass Assembly II (GAMA-II) redshift
De Propris, R., De Propis, R., T McNaught-Roberts (16161611), Pimbblet, K. A., A Moffett (7731959), Driver, S. P., M S Owers (16161563), Lara-Lopez, M. A., A M Hopkins (16143587), Lopez-Sanchez, Angel R., B W Holwerda (16219943), Jonathan Loveday (4460899), Owers, M. S., R De Propris (16161587), Obreschkow, D., Holwerda, Benne W., M Cluver (16191152), Baldry, I. K., J Bland-Hawthorn (16111139), Davies, L. J. M., Bauer, A. E., E N Taylor (16143620), Brown, M. J. I., A S G Robotham (16143614), M A Lara-Lopez (16161575), A E Bauer (16161566), Hopkins, A. M., E van Kampen (16112642), Brough, S., Loveday, J., McNaught-Roberts, T., I K Baldry (16072595), Moffett, A., Liske, J., Wilkins, S. M., P Norberg (16143575), Holwerda, B. W., Mahajan, S., L S Kelvin (16143602), K Pimbblet (16191149), Penny, S. J., Robotham, A. S. G., van Kampen, E., M Prescott (10000280), M J Drinkwater (16091732), Bland-Hawthorn, J., N K Agius (16219940), Agius, N. K., Prescott, M., M J I Brown (16143632), Cluver, M., Drinkwater, M. J., S J Penny (16219955), Taylor, E. N., Stephen Wilkins (4461910), Lopez-Sanchez, A. R., D Obreschkow (16219952), S Brough (16143590), S Mahajan (16219949), L J M Davies (16219937), Norberg, P., J Liske (7814738), Kelvin, L. S., Pimbblet, K., S P Driver (16143581), A R López-Sánchez (16219946), Loveday, J, Hopkins AM, Moffett A, Kelvin LS, Agius, NK, Mahajan S, Brough, S, Robotham, ASG, Drinkwater, MJ, Moffett, A, Baldry, IK, McNaught-Roberts T, Hopkins, AM, De Propris, R, Pimbblet, K, van Kampen E, Driver, SP, Driver SP, Pimbblet K, van Kampen, E, Brown, MJI, De Propris R, Bland-Hawthorn, J, Davies LJM, Lopez-Sanchez AR, Wilkins SM, Lara-Lopez, MA, Penny SJ, Lopez-Sanchez, AR, Loveday J, Liske J, Lara-Lopez MA, Liske, J, Taylor EN, Davies, LJM, Norberg, P, Obreschkow D, Prescott M, Cluver, M, Brown MJI, Brough S, Robotham, A. S.G., Taylor, EN, Bland-Hawthorn J, Robotham ASG, Prescott, M, Davies, L. J.M., Drinkwater MJ, Obreschkow, D, Wilkins, SM, Kelvin, LS, Penny, SJ, Holwerda BW, Norberg P, Agius NK, Baldry IK, Bauer, AE, Cluver M, Brown, M. J.I., McNaught-Roberts, T, Owers, MS, Mahajan, S, Bauer AE, Holwerda, BW, Owers MS   +130 more
core   +1 more source

Neutral hydrogen absorption in the spectrum of the quasar-galaxy pair 4C 32.33/NGC 3067

The Astrophysical Journal, 1975
Radio spectra near 21 cm wavelength were taken of five close quasar- galaxy pairs. Neutral hydrogen absorption of radiation from the quasar 4C 32.33 (3C 232) has been detected at a velocity (C$delta$lambda/lambda$sub 0$) of 1418 km s$sup -1$. This feature lies 76 km s$sup -1$ away from the velocity of the galaxy NGC 3067 which is separated from the ...
A. D. Haschick, B. F. Burke
openaire   +1 more source

New observations of the gas cloud associated with the quasar-galaxy pair 3C 232/NGC 3067

The Astrophysical Journal, 1991
New optical Na I and Ca II spectra, new Hα images, and archival IUE ultraviolet spectra of the quasar-galaxy pair 3C 232/NGC 3067 are presented to study the H I gas cloud seen in 21 cm emission between the eastern edge of NGC 3067 and 3C 232. High-resolution optical spectra show two, and possibly three, absorption systems in Ca II and Na I, with a ...
John T. Stocke, James Case, Megan Donahue, J. Michael Shull, Theodore P. Snow   +4 more
openaire   +1 more source

Overdensity of galaxies in the environment of quasar pairs [PDF]

, 2017
We report on a study of the galaxy environments of low redshift physical quasars pairs. We selected 20 pairs having projected separation -1. Using Sloan Digital Sky Survey images, we evaluated the galaxy overdensity around these quasars in pairs and then
Sandrinelli, A., Treves, A., Falomo, R., M Uslenghi, A Sandrinelli, USLENGHI, MICHELA, R Falomo, R Scarpa, Scarpa, R., A Treves   +9 more
core   +1 more source