4C 19.44

{{Short description|Quasar in the constellation Boötes}} {{Infobox galaxy|name=[[Fourth Cambridge Survey|4C]] 19.44|epoch=[[J2000.0]]|constellation name=[[Boötes]]|ra={{RA|13|57|04.43}}<ref name="ned" />|dec={{DEC|+19|19|07.37}}<ref name="ned" />|z=0.719668<ref name="ned" />|h_radial_v=215751 [[kilometer per second|km/s]]<ref name="ned" />|dist_ly=6.605 [[light year|Gly]]|appmag_v=16.03|type=Opt.var. Sy1.5<ref name="ned" />|size=~{{convert|73.98|kpc|ly|abbr=on|lk=on|order=flip}} (estimated){{r|ned}}|names=CoNFIG 181, DA 354, [[Lyon-Meudon Extragalactic Database|LEDA]] 2819584, G4Jy 1108, OP +191, [[Parkes Catalogue of Radio Sources|PKS]] 1354+19, [[Sloan Digital Sky Survey|SDSS]] J135704.43+191907.3, VIPS 0717, WMAP 004, VRO 19.13.06<ref name="ned" />|image=File:Image of 4C 19.44.png|caption=The quasar 4C 19.44}}

'''4C 19.44''' is a [[quasar]] located in the constellation of [[Boötes]]. The [[redshift]] of the quasar is (z) 0.719<ref name="ned">{{Cite web |title=NED Search results for 4C 19.44 |url=https://ned.ipac.caltech.edu/byname?objname=4C+19.44&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1 |access-date=2025-12-13 |website=NASA/IPAC Extragalactic Database}}</ref> and it was first discovered in September 1966 by [[Astronomer|astronomers]] J.G. Bolton and T.D. Kinman as a quasi-stellar object.<ref>{{Cite journal |last1=Bolton |first1=J. G. |last2=Kinman |first2=T. D. |date=September 1966 |title=Radio and Optical Data on Twelve Quasi-Stellar Objects |url=https://articles.adsabs.harvard.edu/pdf/1966ApJ...145..951B |journal=The Astrophysical Journal |language=en |volume=145 |pages=951 |doi=10.1086/148842 |bibcode=1966ApJ...145..951B |issn=0004-637X}}</ref> This quasar is best known for its extremely long [[Astrophysical jet|radio jet]].<ref>{{Cite news |title=The remarkable jet of the quasar 4C+19.44 |url=https://phys.org/news/2017-10-remarkable-jet-quasar-4c1944.html |archive-url=http://web.archive.org/web/20221126233159/https://phys.org/news/2017-10-remarkable-jet-quasar-4c1944.html |archive-date=2022-11-26 |access-date=2025-12-13 |language=en}}</ref>

== Description == 4C 19.44 is found to be mildly variable based on [[Optics|optical]] monitoring, which it underwent least one steady brightening event between February 1969 and December 1970.<ref>{{Cite journal |last1=Tritton |first1=K. P. |last2=Selmes |first2=R. A. |date=1971-09-01 |title=Optical Monitoring of Radio Sources--III: Further Observations of Quasars |url=https://watermark02.silverchair.com/mnras153-0453.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAA10wggNZBgkqhkiG9w0BBwagggNKMIIDRgIBADCCAz8GCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMfnOFhU5I_Ex9XXK0AgEQgIIDEIVFrs5idqqvV2QyWpmvm6doYfvIEsTtLu6qx7LDNGqDIzKTabTa-qiTfv5_3irfAaf3vaRF6L7RPO-4_UXHL4S5DA3WTXmHSzK8ZY9Ze3tU5F38K2tRncvg4GjUG5ddnhvTybnvMpuRw0FVnt_gCHfNWCzzlgdf2PPge-xyahXuRlEUJGPussogoMWM9mH9n2Z6sQ9sOMFyFxaBlXAXyuIR-giluMzJeuBq6OfvzOrej2f8y3TfyJ5qUkbC3Kz2bZibgulS1MKLDzRTagvede0DD1SB-Ja_1yjfypSyjUQsXqBLml3FMEYitIvk3NHQ93i4Lcg3gmsWxfKSwfEQT-jtrmxerjGlXXG5jW0tYwEc7bHMoUAXD4J9AMztHMw9KBMSF4ZLElQo0IADrjE2c7GW43tfgAnwIfW1Ay-OD5RlsSWDA1XbjTC9Q0dpIMN51olyRtMBSRJqC3xLQgyzXWi2amsptz13RHf4TPSaUREMHok9Z3DGZ1yY-FU8ipwYbG37S5zQf1ty5R1M5tinok4Legxe8KtPdnz4gm0m7Uev-qWD4U1liCz4xuxPH-83l7e6pCY_5A5ryN5wRzv2s7VZjD-_JzYREXMKFtpvneqeUffZAUHhwGhrYBiJy_doHnoiCVrLjg77WYSzVxdr9tz5oz7xTGPZkGunJpbe0yD_1CFXIsWrSt4CMc-n0wnORML1_SoSe8cdoL8Gtf11KwgNzzT5gAKECmyuPmcEhg5N5Bhw8gTP559V7ZoeevbVLFeu0JoMk_ZDpSaO4gjXn041kVZtFRqS83sXye1ljDy8SHU04ZuDZrJJdddUnRxWs9N67h6L_8kICn1U5lUFloV8h7zSZrjZtuK6JsqJOwoJHCmr6vbUn0lGd0ztkY1CT5OWyUSTgyIYdiQI8ji4iTsgj_2JkC6VB2HtBE--g7NX13-HG6zf23rZ-aUxmVp0VPA_FIxJjMgwevLpmjqpUw4x7N30Pn0QBW2wTcPwIHmqe4ijKr6HAqQEkSCDvfEP4Woy66sGSnHysHFaqTfJyqI |journal=Monthly Notices of the Royal Astronomical Society |volume=153 |issue=4 |pages=453–469 |doi=10.1093/mnras/153.4.453 |doi-access=free |issn=0035-8711}}</ref><ref>{{Cite journal |last=Lu |first=Phillip K. |date=December 1972 |title=Optical Monitoring of Quasistellar Objects. I |url=https://articles.adsabs.harvard.edu//full/1972AJ.....77..829L/0000842.000.html |journal=The Astronomical Journal |language=en |volume=77 |pages=829 |doi=10.1086/111356 |bibcode=1972AJ.....77..829L |issn=0004-6256}}</ref> However, no variability was noted at 2.2 ɥm.<ref>{{Cite journal |last1=Cutri |first1=R. M. |last2=Wisniewski |first2=W. Z. |date=September 1983 |title=Simultaneous Optical and Infrared Photometry of Mildly Variable, Low Polarization QSO's |url=https://articles.adsabs.harvard.edu/full/1983BAAS...15..958C |journal=Bulletin of the American Astronomical Society |language=en |volume=15 |pages=958 |bibcode=1983BAAS...15..958C }}</ref>

The radio structure of 4C 19.44 is found to be compact. When observed by [[Very-long-baseline interferometry|Very Long Baseline Interferometry]] (VLBI), it is found to have a double structure, with its components separated by 0.75 [[Minute and second of arc|milliarcseconds]] from each other and orientated along the [[position angle]] of -29°. The [[radio spectrum]] of the quasar is categorized as of low frequencies and being dominated by a component of steep spectrum. When observed higher than 2 [[Hertz|GHz]], the radio spectrum becomes flat with a [[flux]] [[density]] mainly at 1.0 and 2.0 [[Jansky]].<ref>{{Cite journal |last1=Marscher |first1=A. P. |last2=Broderick |first2=J. J. |date=June 1983 |title=VLBI observations of the quasars CTD 20 (0234+285), OJ 248 (0827+243), and 4C 19.44 (1354+195) and the millimeter X-ray connection. |url=https://articles.adsabs.harvard.edu/pdf/1983AJ.....88..759M |journal=The Astronomical Journal |language=en |volume=88 |pages=759–763 |doi=10.1086/113364 |bibcode=1983AJ.....88..759M |issn=0004-6256}}</ref> Radio imaging made by [[Very Large Array]] (VLA), would find it as a triple source instead with its total extend of 44 arcseconds. There is also a north-west component present with a [[spectral index]] of 1.04 ± 0.05.<ref>{{Cite journal |last1=Saikia |first1=D. J. |last2=Shastri |first2=P. |last3=Sinha |first3=R. P. |last4=Kapahi |first4=V. K. |last5=Swarup |first5=G. |date=December 1984 |title=Extragalactic Sources with Asymmetric Radio Structure - Part One - Observations of 17 Sources |url=https://articles.adsabs.harvard.edu//full/1984JApA....5..429S/0000469.000.html |journal=Journal of Astrophysics and Astronomy |language=en |volume=5 |issue=4 |pages=429–473 |doi=10.1007/BF02714470 |bibcode=1984JApA....5..429S |issn=0250-6335}}</ref> A core-jet structure is found located mainly within its nucleus.<ref>{{Cite journal |last1=Saikia |first1=D. J. |last2=Holmes |first2=G. F. |last3=Kulkarni |first3=A. R. |last4=Salter |first4=C. J. |last5=Garrington |first5=S. T. |date=August 1998 |title=Polarization observations of the radio cores of AGN - I. A sample of quasars |journal=Monthly Notices of the Royal Astronomical Society |language=en |volume=298 |issue=3 |pages=877–887 |doi=10.1046/j.1365-8711.1998.01699.x |bibcode=1998MNRAS.298..877S |doi-access=free |issn=0035-8711}}</ref>

The [[Astrophysical jet|jet]] of 4C 19.44 is described as one-sided, long and straight with a distance of 18 [[Minute and second of arc|arcseconds]].<ref>{{Cite journal |last=Punsly |first=Brian |date=2015-06-05 |title=Evidence of the Dynamics of Relativistic Jet Launching in Quasars |url=https://doi.org/10.1088/0004-637x/806/1/47 |journal=The Astrophysical Journal |volume=806 |issue=1 |pages=47 |doi=10.1088/0004-637x/806/1/47 |arxiv=1504.00228 |bibcode=2015ApJ...806...47P |issn=1538-4357}}</ref><ref>{{Cite journal |last1=Schwartz |first1=D. A. |last2=Harris |first2=D. E. |last3=Landt |first3=H. |last4=Siemiginowska |first4=A. |last5=Marshall |first5=H. L. |last6=Gelbord |first6=J. M. |last7=Perlman |first7=E. S. |last8=Georganopoulos |first8=M. |last9=Birkinshaw |first9=M. |last10=Worrall |first10=D. M. |last11=Cheung |first11=C. C. |last12=Stawarz |first12=L. |last13=Jorstad |first13=S. G. |last14=Marscher |first14=A. P. |last15=Uchiyama |first15=Y. |date=October 2007 |title=The X-ray jet and lobes of PKS 1354+195 (=4C 19.44) |url=https://ui.adsabs.harvard.edu/abs/2007Ap&SS.311..341S/abstract |journal=Astrophysics and Space Science |language=en |volume=311 |issue=1–3 |pages=341–345 |doi=10.1007/s10509-007-9548-y |bibcode=2007Ap&SS.311..341S |issn=0004-640X}}</ref> When observed, the jet is found to extend towards the south-east direction before ending in a hotspot position with a knotty appearance containing 11 jet knots in total.<ref>{{Cite journal |last1=Harris |first1=D. E. |last2=Moldón |first2=J. |last3=Oonk |first3=J. R. R. |last4=Massaro |first4=F. |last5=Paggi |first5=A. |last6=Deller |first6=A. |last7=Godfrey |first7=L. |last8=Morganti |first8=R. |last9=Jorstad |first9=S. G. |date=March 2019 |title=LOFAR Observations of 4C+19.44: On the Discovery of Low-frequency Spectral Curvature in Relativistic Jet Knots |journal=The Astrophysical Journal |language=en |volume=873 |issue=1 |pages=21 |doi=10.3847/1538-4357/ab01ff |arxiv=1903.06824 |bibcode=2019ApJ...873...21H |doi-access=free |issn=0004-637X}}</ref> Further evidence also pointed out that the jet shows wiggles close to the position of the radio core but remains straight for about nine arcseconds within the core then turns towards east direction. There are also traces of high [[Polarization (waves)|polarization]] levels of around 24.7 ± 6.0% with a main [[position angle]] of 84 ± 6°.<ref name=":0">{{Cite journal |last1=Harris |first1=D. E. |last2=Lee |first2=N. P. |last3=Schwartz |first3=D. A. |last4=Siemiginowska |first4=A. |last5=Massaro |first5=F. |last6=Birkinshaw |first6=M. |last7=Worrall |first7=D. M. |last8=Cheung |first8=C. C. |last9=Gelbord |first9=J. M. |last10=Jorstad |first10=Svetlana G. |last11=Marscher |first11=Alan P. |last12=Landt |first12=H. |last13=Marshall |first13=H. |last14=Perlman |first14=E. S. |last15=Stawarz |first15=L. |date=2017-09-08 |title=A Multi-band Study of the Remarkable Jet in Quasar 4C+19.44 |journal=The Astrophysical Journal |volume=846 |issue=2 |pages=119 |doi=10.3847/1538-4357/aa845c |arxiv=1708.01500 |bibcode=2017ApJ...846..119H |doi-access=free |issn=0004-637X}}</ref> This jet is also observed by [[Chandra X-ray Observatory]] where detections of [[Astrophysical X-ray source|X-ray emission]] are found.<ref>{{Cite journal |last1=Sambruna |first1=Rita M. |last2=Maraschi |first2=L. |last3=Tavecchio |first3=F. |last4=Urry |first4=C. Megan |last5=Cheung |first5=C. C. |last6=Chartas |first6=G. |last7=Scarpa |first7=R. |last8=Gambill |first8=Jessica K. |date=2002-05-20 |title=A Survey of Extended Radio Jets in Active Galactic Nuclei with''Chandra''and the''Hubble Space Telescope'': First Results |url=https://iopscience.iop.org/article/10.1086/339859/fulltext/ |journal=The Astrophysical Journal |volume=571 |issue=1 |pages=206–217 |doi=10.1086/339859 |arxiv=astro-ph/0201412 |bibcode=2002ApJ...571..206S |issn=0004-637X}}</ref>

A study finds there are [[Radio galaxy|radio lobes]] present in the quasar. Based on studies, the lobe on the northern side is located in the direction of its counter-jet, about 16 arcseconds away and has a position angle of -14°. Evidence also found there are features inside the lobe, which is a bright hotspot and a bright knot feature that is separated from the hotspot and located four arcseconds west. Polarization is mainly low in the hotspot, only at 2% suggesting the possibility of its [[magnetic field]] [[rotation]] direction.<ref name=":0" />

== References == <references />

== External links == *[https://simbad.cds.unistra.fr/simbad/sim-id?Ident=ICRF%20J135704.4%2B191907 4C 19.44 on SIMBAD]

{{Boötes}} [[Category:Quasars]] [[Category:Boötes]] [[Category:Active galaxies]] [[Category:SDSS objects]] [[Category:4C objects|19.44]] [[Category:LEDA objects|2819584]] [[Category:Astronomical objects discovered in 1966]]