Minfeng Gu & Yongjun ChenSHAO

2009 East-Asia VLBI workshopSeoul, March 18 – 20

The compact radio structure of radio-loud narrow line Seyfert

1 galaxies

Outline

Radio-loud narrow line Seyfert 1 galaxies (RL NLS1s)/blazars

VLBA images of 4 RL NLS1s

Discussion/summary

Active Galactic NucleiSuper-massive black holeAccretion disk + jetBroad line regionTorusNarrow line region……

Narrow Line Seyfert 1 galaxies (NLS1s)

Balmer lines broader than forbidden lines but narrower than normal type 1 AGNs (FWHM<2000km/s)

Some peculiar properties: softer X-ray spectra, fast X-ray variability, strong optical Fe II multiplets

Relatively small black hole mass (e.g. Collin & Kawaguchi 2004), however still controversial: viewing angle, radiation pressure …

Accretion close to the Eddington rate Lbol/Ledd ~ 1 Accretion possible via slim disk (e.g. Abramowicz et al.

1988; Mineshige et al. 2000)

Blazars: flat-spectrum radio quasars (FSRQ) + BL Lac objectsObserved properties: flat radio spectrum,

compact radio core, high brightness temperature, superluminal motion, rapid variability, high polarization, broad-band SED with two humps: synchrotron & inverse Compton process

Jet pointing towards us – small viewing angle - beaming effect

Blazar sequence: FSRQs – LBL – IBL – HBL.

Radio-loud NLS1sRadio properties of NLS1s is poorly exploredNLS1s were long thought to be radio-quietRadio emission detected in some NLS1s in early

studies (e.g. Ulvestad et al. 1995, Moran et al. 2000, Stepanian et al. 2003)

Two small samples of RL NLS1s studied recently (Komossa et al. 2006, Whalen et al. 2006): mostly steep-spectrum radio sources.

RL NLS1s sample from SDSS: >100 out of ~2000 NLS1s (Zhou et al. 2006) – RL (R>10) fraction = 7%; very radio-loud (R>100) NLS1s: very rare – 23 from SDSS DR5 (Yuan et al. 2008).

Existing VLBI imaging of RL NLS1sDoi et al. (2007): JVN 8 GHz phase-

referencing: all 5 targets detected – strong jets; 2/5 sources showing inverted spectra suggesting Doppler boosting in pole-on view.

Doi et al. (2006): VLBA for SDSS J094857.3+002225High brightness temperatures; apparent

flux variationDoppler factor > 2.7–5.5 – from the high

brightness T.Highly relativistic non-thermal jets in an

NLS1.

VLBA Data archived: unpublished; RL NLS1s; see Doi et al.(2007) for JVN images

dd

Data reductionPhase referencing mode: angular distance < 2.3 d

(B3 1702+457: 3.98 d at 5 GHz).The average on-source observational time ~ 70 mins.AIPS: atmosphere and parallactic angle effects are

calibrated before fringe fitting of phase referencing calibrator are made, and its solutions are applied to the corresponding target.

Bandpass corrections and self-calibrations are made before data are averaged in 30 seconds – high S/N ratio.

The imaging and model fitting process is performed in DIFMAP with all the base contour levels given below being 3 sigma in the final residual images.

ResultsCore – component: flux density, position angle,

angular size, flux variabilityBrightness temperature

Variability brightness temperature: (Yuan et al. 2008)

Equipartition brightness temperature Teq=5×10^10 K (Readhead 1994); Inverse Compton limit Tb,int ~ 10^12 K (Kellermann & Pauliny-Toth 1969)

dd

(1). RXS J08066+7248Unresolved in 1.6 GHz in beam size ~ 4×10

masSteep spectrum between 1.4, 1.6, 5 and 8.4

GHz – resemble to compact steep spectrum though to be young radio source.

Log Tb= 11.4, 11.0 K; X-ray photon index 2.3 (Xu et al. 2003)

(2). RXS J16290+4007Inverted spectrum from the simultaneous

observations at 2.3 and 8.4 GHz (see also Zhou & Wang 2002).

Slightly resolved: an eastern component at 5 GHz of Dec. 2005.

Log Tb ~11 K - 12.4 K; log Tb,var = 12.2 at 8.4 GHz

RXS J16290+4007Blazar-like NLS1s: jet moving towards us with

small v.a.HFSRQ: synchrotron peak 2e16 Hz; BeppoSAX X-

ray photon index 2.58 (Grandi et al. 2006) – synchrotron origin

High Frequency Peakers (HFPs) (Dallacasa et al. 2000): 2.3/5/8.4 GHz

(3). RXS J16333+4718Core-jet at 5GHz, flat 1.6 – 5 GHz (see also

Zhou & Wang 2002), steep 5 – 8.4 GHz, inverted spectra above 5 GHz from simultaneous observations (Neumann et al. 1994)

RXS J16333+4718Log Tb = 11.3, 10.5 KOne of two nuclei, separated by 4 arcsec, in

an interacting/merger systemFlat X-ray photon index 1.37 - inverse

Compton scenario; Broadband SED similar to that of HFSRQs (Yuan et al. 2008).

(4). B3 1702+457Core-jet: flat at 1.6 & 5 GHz for core,

however steep at 1.6 & 8.4 GHz/previous: steep 1.4 & 5 GHz, flat 5 & 8.4 GHz.

At 5 GHz, component moves toward the core with 3.7 mas in about two month ~ 80 c ?

CSO J11584+2450: hot spots retreating toward the core ~ 0.3c (Tremblay et al. 2008); companion galaxy in clusters –relative motion – jet/ISM interaction

B3 1702+457Retreatment – different componets ?

projection effects ?.Log Tb= 10.6, 11 KIt is classified as Compact Steep Spectrum

(CSS) sources with turnover frequency < 150 MHz in the sample of Compact Radio sources at Low Redshift (CORALZ) (Snellen et al. 2004).

The X-ray spectral was investigated by Vaughan et al. (1999), and the photon index from the power-law fit is 2.2.

DiscussionsNLS1s/CSS (HFPs) – young radio sources ?NLS1s/blazar (HFSRQs) – blazar sequence ?Compact radio structure of large sample of RL

NLS1s (e.g. Yuan et al. 2008), polarizationMulti-band SED for RL NLS1sVariability – X-ray & optical bandJet formation & accretion modeFermi gamma-ray space telescope detection ?

Complete SED

NLS1s/BALQs/CSS,GPS/high-z quasars – young AGNs ?

KVN – multi-band simultaneous high-frequency observations

Observe violent variable sources simultaneously, e.g. blazars, to determine the spectral shape, temporal variability.

Inverted-spectrum sources, e.g. GPS/HFP – high-frequency spectral shape

Fermi-detected AGNs: high-frequency observations

FIRST-based (faint) CSS/GPS/HFP surveyOptical – radio simultaneous monitoring of e.g. blazars……

Summary Three out of four sources are unresolved or slightly

resolved in mas resolutions, and the remaining one is resolved into core – jet structures at 1.6 and 5 GHz.

Two sources have flat spectrum between 1.6 and 5 GHz, and one source have steep spectrum (non-simultaneously)/One source has inverted spectrum between 2.3 and 8.4 GHz (simultaneously).

All sources have brightness temperature Tb>10^11 K and one source even exceed 10^12 K, which is confirmed by the estimated variability brightness temperature.

The high brightness temperature and/or flat radio spectrum implies a at least mildly relativistic jets may exist in all our sources.

Thanks for your attention !