Browsing by Author "Velzen, Sjoert van"

Now showing items 1-4 of 4

    • Megahertz peaked-spectrum sources in the Boötes field I - a route towards finding high-redshift AGN? 

      Coppejans, Rocco; Cseh, David; Williams, Wendy L.; Velzen, Sjoert van; Falcke, Heino (2015-06-21)
      We present a 324.5MHz image of the NOAO Bo\"otes field that was made using Very Large Array (VLA) P-band observations. The image has a resolution of 5.6x5.1arcsec, a radius of $2.05^\circ$ and a central noise of ~0.2mJy\beam. ...

    • Radio spectra of bright compact sources at z>4.5 

      Coppejans, Rocco; Velzen, Sjoert van; Intema, Huib T.; Müller, Cornelia; Frey, Sándor; Coppejans, Deanne L.; Cseh, Dávid; Williams, Wendy; Falcke, Heino; Körding, Elmar G.; Orrú, Emanuela; Paragi, Zsolt; Gabányi, Krisztina É. (2017-05-01)
      High-redshift quasars are important to study galaxy and active galactic nuclei (AGN) evolution, test cosmological models, and study supermassive black hole growth. Optical searches for high-redshift sources have been very ...

    • The Tidal Disruption Event AT2021ehb : Evidence of Relativistic Disk Reflection, and Rapid Evolution of the Disk-Corona System 

      Yao, Yuhan; Lu, Wenbin; Guolo, Muryel; Pasham, Dheeraj R.; Gezari, Suvi; Gilfanov, Marat; Gendreau, Keith C.; Harrison, Fiona; Cenko, S. Bradley; Kulkarni, S. R.; Miller, Jon M.; Walton, Dominic J.; García, Javier A.; Velzen, Sjoert van; Alexander, Kate D.; Miller-Jones, James C. A.; Nicholl, Matt; Hammerstein, Erica; Medvedev, Pavel; Stern, Daniel; Ravi, Vikram; Sunyaev, R.; Bloom, Joshua S.; Graham, Matthew J.; Kool, Erik C.; Mahabal, Ashish A.; Masci, Frank J.; Purdum, Josiah; Rusholme, Ben; Sharma, Yashvi; Smith, Roger; Sollerman, Jesper (2022-09-15)
      We present X-ray, UV, optical, and radio observations of the nearby ($\approx78$ Mpc) tidal disruption event (TDE) AT2021ehb/ZTF21aanxhjv during its first 430 days of evolution. AT2021ehb occurs in the nucleus of a galaxy ...

    • What are the megahertz peaked-spectrum sources? 

      Coppejans, Rocco; Cseh, David; Velzen, Sjoert van; Falcke, Heino; Intema, Huib T.; Paragi, Zsolt; Muller, Cornelia; Williams, Wendy L.; Frey, Sandor; Gurvits, Leonid I.; Kording, Elmar G. (2016-07-01)
      Megahertz peaked-spectrum (MPS) sources have spectra that peak at frequencies below 1 GHz in the observer's frame and are believed to be radio-loud active galactic nuclei (AGN). We recently presented a new method to search ...